Room-temperature Single-crystal X-ray Research Articles

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXIV Syntheses, Spectroscopy and Structures of Some 1 : 4 Adducts of Copper(I) and Silver(I) Perchlorates with Triphenylarsine and Triphenylstibine

Syntheses and room-temperature single crystal X-ray structure determinations are recorded for adducts [M(EPh3)4] (ClO4), M = Cu, E = As (1), Sb (2); M = Ag, E = As (3), Sb (4), enabling comparison with analogous, previously studied MP4 and MN4 environments. The four complexes so characterized all crystallize in the familiar rhombohedral R-3 array (a ≈ 14·4, c ≈ 52 Å, hexagonal setting) with the metal and chlorine atoms located on crystallographic threefold axes. In these arrays Cu–E (axial, off axis) are 2·493(2), 2·533(1) for (1), and 2·572(1), 2·577(1) Å for (2), the disparity in the two independent M-E distances being diminished relative to those of previously studied phosphorus analogues, perhaps in consequence of increasing E size. In (3) and (4), some cation disorder is evident in respect of the ligand pnictide atom (E); for the major components Ag-E are 2·652(3), 2·680(2) in (3); 2·732(2), 2·7295(8) Å in (4). Problems associated in defining the metal atom environment geometries in the latter are, nevertheless, more satisfactorily overcome in two further determinations of nitrate salts: [Ag(SbPh3)4] (NO3) (5) is of the rhombohedral family with no cation core disorder, Ag–E (axial, off axis) being 2·720(4), 2·725(2) Å, while the structural characterization of a 1 : 4 triphenylarsine adduct of silver nitrate is recorded as its tetraethanol solvate, namely [Ag(AsPh3)4] (NO3).~ 4C2H5OH(6), monoclinic, C2/c, a 18·373(4), b 20·786(5), c 21·070(8) Å, β 108·18(3)°, Z = 4 f.u. The silver atom of the [Ag(AsPh3)4]+cation unusually lies on a crystallographic 2 (rather than a 3 ) axis of the incipiently23 (T) array, with Ag-As 2·649(2), 2·650(2) Å and As-Ag-As ranging from 108·22(4) to 111·41(6)°. The structure determination of a chloroform solvate of (2), denoted (2a), of low precision, is noted, together with the structure of an interesting artefact, isomorphous with the rhombohedral oxoanion array, modelled as [Ag(PPh3)4]2 (SiF6).py (7). Bands in the far-infrared spectra of [M(AsPh3)4] (ClO4) are assigned to v(MAs) vibrations at 119 (M = Cu) and 103 cm¯1 (M = Ag); this produces a more consistent picture of the variation in the wavenumbers of the v(ME) modes in [M(EPh3)4]+ compounds than was available previously.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXI Synthesis, Spectroscopy and Structural Systematics of Some 1 : 2 Binuclear Adducts of Silver(I) Compounds with Triphenylarsine, [(Ph3As)2Ag(µ-X)2Ag(AsPh3)2], X = Cl, Br, I, SCN

The syntheses and room-temperature single-crystal X-ray structural characterization of binuclear 1 : 2 adducts formed between silver(I) (pseudo-)halides, AgX, and triphenylarsine, AsPh3, for X = Cl, Br, I, SCN (1)–(4), are described. The chloride (1), obtained from 2-methylpyridine, is triclinic, P-1, a 10·410(2), b 12·716(2), c 14·196(6) Å, α 113·38(2), β 109·41(2), γ 75·08(1)°, Z = 1 (dimer); conventional R on F was 0·037 for No 3979 independent ‘observed’ (I > 3σ(I)) reflections. The bromide (2a), obtained from 2,6-dimethylpyridine, and iodide (3), obtained from a mixture of AgI/saturated KI in MeOH solutions, are isomorphous, monoclinic, P 21/c a≈ 24·2, b ≈ 13·9, c ≈ 20·2 Å, β ≈ 109·5°, Z = 4 dimers; R was 0·046 and 0·044 for No 5670 and 6039 respectively. The thiocyanate (4) has a similar cell, a 24·12(1), b 12·558(8), c 23·244(4) Å, β 110·11(3)°, Z = 4 dimers, R being 0·044 for No 7956; one of the thiocyanate ligands (which bridge in Ag-SCN-Ag mode) is disordered. A second polymorph of the bromide (2b) (from a mixture of AgBr/saturated KBr in H2O) is also monoclinic, P 21/c, a 14·121(8), b 25·577(3), c 21·968(2) Å, β 125·54(3)°, Z = 4 dimers (R was 0·047 for No 5715). Ag–As range between 2·568(1) and 2·633(1) Å throughout the series; in the isomorphous bromide and iodide, values increase slightly: 2·578(1)–2·611(1), cf. 2·601(2)-2·633(1) Å respectively. Ag–X are 2·568(2)-2·670(2) (Cl); 2·688(2)–2·715(2) (Br); 2·828(2)–2·856(1) Å (I); Ag-S, N for the ordered SCN group are 2·646(3), 2·255(6) Å. A redetermination of improved precision (R 0·035, No 6030) is reported for the triphenylphosphine/thiocyanate analogue. The far-infrared spectra of [(Ph3As)2Ag(µ-X)2Ag (AsPh3)2] show v(AgX) bands at 185, 145 (X = Cl), 145, 130, 106 (X = Br) and 121 cm-1 (X = I). The splittings and band widths reflect a decrease in the degree of distortion of the Ag(µ-X)2Ag units from a symmetrically bridged structure from X = Cl to I.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXVIII Synthesis and Structural Systematics of Some 1 : 3 Adducts of Silver(I) Compounds with Triphenylstibine, [(Ph3Sb)3AgX], X = Cl, I, SCN, NCS, CN, ONO2

The syntheses and room-temperature single-crystal X-ray structural characterization of 1 : 3 adducts formed between silver(I) (pseudo-) halides, AgX, and triphenylstibine, SbPh3, are described for X = Cl, I, SCN, NCS, CN, NO3 (1)-(6). The chloride, as its methanol solvate (1a), is isomorphous with the arsine analogue: triclinic, P-1, a 13·373(4), b 14·48(6), c 14·702(3) Å, α 83·49(3), β 87·76(2), γ 76·45(3)°; Z = 2, conventional R on F being 0·046 for No 5514 independent ‘observed’ reflections (I > 3σ(I )). A new form (1b) of the chloride has also been authenticated: monoclinic, P 21/c, a 12·832(2), b 54·24(1), c 18·519(8) Å, β 129·68(3)°; Z = 8 (R 0·065 for No 5672). No bromide has been obtained; the iodide (2) is described as monoclinic, P 21/n, a 19·611(4), b 14·473(6), c 17·74(1) Å, β 98·28(3)°; Z = 4 (R 0·036 for No 6769). The thiocyanate crystallizes from acetonitrile or pyridine as an S-bonded form (3) isomorphous with the arsine analogue: monoclinic, P 21/n, a 19·143(7), b 14·288(5), c 18·694(6) Å, β 98·81(2)°; Z = 4 (R 0·037 for No 4482). From 2-methylpyridine, remarkably, a solvate is obtained in which the thiocyanate is N-bonded (4): triclinic, P-1, a 27·261(5), b 14·767(3), c 13·319(1) Å, α 91·53(1), β 101·58(1), γ 92·29(2)°; Z = 4 (R 0·045 for No 6900). The cyanide is also monoclinic, P 21/n, a 19·442(7), b 14·267(3), c 17·741(6) Å, β 97·63(3)°, z = 4; R 0·057 for No 2487. The unsolvated 1 : 3 nitrate complex (6a) is monoclinic, P 21/n, a 19·602(5), b 14·455(1), c 17·727(2) Å, β 97·19(2)°, Z = 4; R was 0·034 for No 6522. The complex is isomorphous with the arsenic and phosphorus analogues, being mononuclear [(Ph3Sb)3Ag(O2NO)]. The ethanol solvate (6b) is triclinic, P-1, a 13·352(5), b 14·548(9), c 14·701(4) Å, α 81·64(4), β 84·45(3), γ 75·32(4)°, Z = 2; R was 0·058 for No 4702. Ag-Sb range between 2·6980(8) and 2·843(3) Å in the precise determinations; Ag-X are 2·481(4) and 2·52(1) Å (the two chlorides), 2·757(1) (I), 2·533(3) (SCN), 2·21(1) (NCS), 2· 09(3) (CN), 2·377(7) Å (unidentate ONO2)

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXIV Synthesis and Structure of the 1 : 1 Adduct of Silver(I) Nitrate with Triphenylstibine

The synthesis and room-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of silver(I) nitrate with triphenylstibine, AgNO3/SbPh3 (1 : 1), is recorded, being monoclinic, Cc,a 12·824(2), b 15·794(4),c 9·796(2) Å, β 117·50(1)°, Z= 4; conventional R on F was 0·030 for 2881 independent ‘observed’ (I > 3σ(I)) reflections. The complex is a one-dimensional polymer with bridging nitrate groups, resembling in this respect its phosphine and arsine analogues. The completion of this study, along with related species recorded in accompanying papers, means that full structural data are now available for the complete array AgNO3/EPh3 (1 : n), E = P, As, Sb, n = 1–4, with the one exception of E = Sb, n = 2.

Structural Characterization of Some Novel Oxidation Products of Triphenylstibine

Room-temperature single-crystal X-ray structural characterizations of two oxidation products of triphenylstibine of the form XPh3SbOSbPh3X are recorded for X = Cl, NO3. ClPh3SbOSbPh3Cl is monoclinic, P 21/c, Z = 4 f.u., a 9·109(4), b 19·809(8), c 19·30(2) Å, β 109·27(5)°, conventional R on F being 0·038 for No 4431 ‘observe’ (I > 3σ(I)) independent reflections. In this complex, Sb-O-Sb is quasi-linear, 173·1(3)°, in contrast to the previously recorded benzene solvate, in which it is 139·0(3)°; in the nitrate, [(O2NO)Ph3SbOSbPh3(ONO2)], triclinic, P-1, Z = 2 f.u., a 15·609(5), b 13·238(4), c 10·140(2) Å, α 87·11(2), β 88·46(7), γ 72·93(2)°, R 0·036 for No 5275, it is also bent (137·0(2)°). The anionic substituent is opposed to the oxo bridge in the trigonal bipyramidal five-coordinate array about the metal in both complexes. A redetermination of the structure of Ph8Sb4O6 is recorded, presenting a non-disordered model in a triclinic P-1 cell, a 19·98(3), b 11·635(2), c 9·739(2) Å, α 92·28(1), β 98·98(1), γ 99·74(1)°, Z = 2 f.u., R 0·046 for No 3578. A new (‘β’) phase of triphenylstibine, crystallized from hexane/toluene is also recorded: monoclinic, P 21/c, a 15·386(8), b 11·304(5), c 19·078(8) Å, β11·64(4)°, Z = 8, R 0·045 for No 3393.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXIII Synthesis, Spectroscopy and Structural Systematics of New 1 : 1 'Cubane' Tetramers of Copper(I) and Silver(I) Halides with Triphenylarsine

Syntheses and room-temperature single-crystal X-ray structural characterization of a number of 1 : 1 ‘cube tetramer’ adducts of copper(I) and silver(I) halides, MX, with triphenylarsine, AsPh3, are recorded, being [XM(AsPh3)]4. The CuBr adduct, obtained unsolvated from toluene, orthorhombic Pbcn, a 17·844(5), b 20·778(8), c 18·430(4) Å, Z = 4 tetramers, conventional R on |F| 0·058 for No 1309 independent ‘observed’ reflctions (I > 3σ(I)), is isomorphous with previously recorded [ClAg(PPh3)]4, the tetramer having crystallographically imposed 2 symmetry. The CuI adduct, previously recorded as a monobenzene solvate, has been isolated unsolvated from toluene, monoclinic, P 21/n, a 19·70(5), b 27·110(7), c 13·59(2) Å, β 98·84(9)°, Z = 4 tetramers, R 0·087 for No 4359, isomorphous with previously recorded [ICu(PPh3)]4, as a 6½ benzene solvate, triclinic, P-1 a 26·688(2), b 15·180(7), c 13·090(1) Å, α 85·41(2), β 87·580(7), γ 77·63(2)°, Z = 2 tetramers, R 0·049 for No 11485, and as a chloroform disolvate, triclinic, P-1 a 22·584(9), b 13·979(2), c 13·892(2) Å, α 68 ·99(2), β 77·31(3), γ 75·65(3)°, Z = 2, R 0·041 for No 8701. An unsolvated AgI complex, monoclinic, P 21/c, a 25·26(1), b 12·506(5), c 25·228(9) Å, β 113·54(4)°, Z = 4 tetramers, R 0·054 for No 5520, isomorphous with previously recorded [IAg(PPh3)]4 (denoted ‘α’), was obtained from methanol/saturated potassium iodide solution, while a second ‘β’-form obtained from 2,4,6-trimethylpyridine, rhombohedral R3c, a 17·048(7) Å, α 61·15(5)°, Z = 2 tetramers, R 0·037 for No 1622, is isomorphous with previously recorded [BrAg(PPh3)]4, for which a redetermination is described (R 0·039 for No 1289); the latter has also been obtained in the common orthorhombic Pbcnarray: a 18·10(1), b 2·08(1), c 18·39(1) Å, Z = 4, R 0·041 for No 2877. A new ‘step’ form of [IAg(PPh3)]4, monoclinic, C 2/c, a 26·14(2), b 16·340(9), c 18·64(2) Å, β 114·04(8)°, R 0·058 for No 2107, obtained from acetonitrile and isomorphous with [BrCu(PPh3)]4 (step), is also recorded. In the far-infrared spectra of [(Ph3As)4Cu4X4] bands which have been assigned to vibrations of the Cu4X4 core are: 166, 150, 135, 114 (X = Br); 136, 85 cm-1 (X = I; 2CHCl3 solvate). The 166, 150, 135 cm-1 bands in the bromide are only partially resolved. These, and the 136 cm-1 band in the iodide are assigned to the T2 v(CuX) mode of the Cu4X4 core; the bands at 114 and 85 cm-1 are assigned to the next highest frequency T2 mode of the cluster. The splitting of the highest frequency T2 band for the bromide is consistent with the greater degree of distortion of the Cu4X4core from ideal Td symmetry in this complex relative to the iodide.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXVI Synthesis, Spectroscopy and Structural Systematics of Some 1 : 3 Adducts of Copper(I) Compounds with Triphenylstibine, [(Ph3Sb)3CuX], X = Br, I, ONO2

The syntheses of adducts, [(Ph3Sb)3CuX], X = Br, I, NO3, obtained by crystallization of 1 : 3 CuX/SbPh3 mixtures from appropriate solvents are described, together with their room-temperature single-crystal X-ray structure determinations. The bromide, obtained as a chloroform monosolvate from that solvent, is triclinic, P-1, a 13·861(4), b 14·306(4), c 14·347(4) Å, α 84·40(2), β 86·93(2), γ 75·56(2)°, Z = 2 f.u., conventional R on F being 0·053 for No = 4136 independent ‘observed’ (I > 3σ(I)) reflections; this solvate is isomorphous with its previously recorded chloride counterpart. The iodide is triclinic, P-1, a 14·55(1), b 14·385(2), c 23·626(6) Å, α 91·78(1), β 90·77(4), γ 92·54(5)°; Z= 4, R 0·050 for No 6917, and isomorphous with its phosphorus counterpart. The nitrate, although a methanol sesquisolvate, is also isomorphous with the chloride and bromide, a 13·369(9), b 14·398(3), c 14· 504(12) Å, α 82·29(5), β 84·39(6), γ 75·11(4)°, R 0·052 for No 5672. Cu-X are (2·235(5) (Cl)), 2·366(3) (Br), 2· 556(2) ( 2 ) (I), 1·98(1) Å (ONO2), appreciably shorter than in their previously recorded EPh3, E = P, As counterparts. The far-infrared spectra of [(Ph3Sb)3CuX] showed no clear v(CuX) bands, in contrast to the situation reported previously for the corresponding Ph3P and Ph3As compounds. It is likely that v(CuCl) is masked by a strong band at 270 cm-1 due to the Ph3Sb ligand. However, the region below 250 cm-1 in which the v(CuX) bands are expected for the X = Br, I complexes contains no strong ligand bands. Possible reasons for the absence of v(CuX) bands in these complexes are considered.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXII Synthesis, Spectroscopy and Structural Systematics of Some 1 : 2 Binuclear Complexes of Silver(I) Halides with Triphenylstibine, [(Ph3Sb)2Ag(μ-X)2Ag(SbPh3)2], X = Cl, Br, I

Syntheses and room-temperature single-crystal X-ray structural characterization of binuclear 1 : 2 adducts formed between silver(I) halides, AgX (X = Cl, Br, I), and triphenylstibine, SbPh3, are described. The three complexes are isomorphous, being triclinic, P-1, a ≈ 18·5, b ≈ 14·6, c ≈ 14·5 Å, α ≈ 62·5, β ≈ 74, γ ≈ 77°, Z = 2 centrosymmetric dimers. Conventional R on F were 0·043, 0·038 and 0·046 for 4984, 8479 and 4166 independent, ‘observed’ (I > 3σ(I)) reflections respectively. In [(Ph3b)2Ag(µ-X)2Ag(SbPh3)2], Ag–Sb range between 2·702(1) and 2·744(2) Å, lengthening slightly from chloride to iodide; Ag–X are 2·567(5)–2·628(4) (Cl), 2·684(1)–2·737(1) (Br) and 2·826(3)–2·869(3) Å (I). The far-infrared spectra of [(Ph3Sb)2Ag(µ-X)2Ag(SbPh3)2] show v(AgX) bands at 178, 158 (X = Cl), 121 (X = Br) and 110 cm-1 (X = I). The splittings and band widths reflect a decrease in the degree of distortion of the Ag(µ-X)2Ag units from a symmetrically bridged structure from X = Cl to I.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXVII Synthesis, Spectroscopy and Structural Systematics of Some 1 : 3 Adducts of Silver(I) Compounds with Triphenylarsine, [(Ph3As)3AgX], X = Cl, Br, I, SCN

The syntheses and room-temperature single-crystal X-ray structure determination of 1 : 3 adducts formed between silver(I) (pseudo-)halides, AgX, and triphenylarsine, AsPh3, are described (X = Cl, Br, I, SCN), [(Ph3As)3AgX], (1)–(4). The chloride (1) has been previously described as its acetone hemisolvate; other solvates (1a–d) (0·75 MeCN, MeOH, 1·5 pyridine, 0·75 2,6-dimethylpyridine) are isomorphous, being triclinic, P-1, a ≈ 13·5, b ≈ 14·0, c ≈ 14·25 Å, α ≈ 83, β ≈ 87, γ ≈ 76°, V ≈ 2600 Å3, Z = 2 f.u. The bromide (2), iodide (3) and thiocyanate (4) are isomorphous with [(Ph3P)3AgI], monoclinic, P21/n, a ≈ 19·1, b ≈ 14·0, c ≈ 17·7 Å, β ≈ 97°, Z = 4 f.u. In the chlorides, Ag–Cl are 2·494(5)–2·525(6) Å, with appreciably different Cl–Ag–As ranges (99·7(1)–114·3(1)° in the acetonitrile solvate; 104·8(2)–110·2(1)° in the 2,6-dimethylpyridine solvate) and more compact As–Ag–As distributions (overall range: 109·93(8)–113·26(3)°). For the bromide and iodide, Ag–X are 2·627(1) and 2·779(1) Å respectively, while for the thiocyanate Ag–S is 2·550(5) Å with Ag–S–C 104·2(3)°; the latter complexes also display wide ranges for many of the associated bonding parameters about the silver atom. The far-infrared spectra of [(Ph3As)3AgX] (X = Cl, Br, I) show v(AgX) bands at 217, 145 and 124 cm-1 respectively. The relationship between the v(AgX) wavenumbers and the Ag–X bond length r (AgX) is found to be the same as that for a range of AgX complexes with phosphine ligands, and is similar to that observed previously for analogous CuX complexes.

Spectroscopic and structural studies on 1 : 2 adducts of silver(I) salts with tricyclohexylphosphine

Adducts of a number of silver(I) salts, AgX, with tricyclohexylarsine, of 1∶1 AgX∶As(C6H11)3 stoichiometry have been synthesized for X = Cl, Br, I, NO3, NCO or CN and subjected to room temperature single crystal X-ray determinations and studies of their low frequency vibrational spectra. The chloride is binuclear [{(C6H11)3As}Ag(µ-Cl)2Ag{As(C6H11)3}], isomorphous with its previously recorded P(C6H11)3, X = Cl, Br counterparts, the silver environment being quasi-planar, trigonal AsAg(µ-Cl)2; the nitrate is isomorphous, with a central planar Ag(µ-O)2Ag array, a pair of oxygen atoms, one from each of a pair of symmetry-related nitrate groups, bridging the two silver atoms. The present bromide, unlike its P(C6H11)3 counterpart, is not a dimer, but, like the iodide, a ‘cubane’ tetramer; the iodide is isomorphous with its P(C6H11)3 analogue, a crystallographic 2 axis passing through a pair of opposed faces of the tetramer, but the bromide is of a new type, rhombohedral space group R. Remarkably, the cyanate is also of the cubane form, the first recorded (other than an organometallic) incorporating a first-row atom, obtained unsolvated and bis(pyridine) solvated. The cyanide is a linear polymer . . . {(C6H11)3As}2AgNCAgCN{As(C6H11)3}2AgNC . . . (‘α’ phase, from 2-methylpyridine); a second ‘β’ phase was obtained from 2,4,6-trimethylpyridine, of similar form, while from pyridine, a solvate of 3∶4∶2 AgCN∶As(C6H11)3∶py stoichiometry [{Ag[As(C6H11)3]2(py)}2(CN)][Ag(CN)2] was obtained. The structure of the E = Px = CN unsolvated 1∶1 analogue was also determined, also being a linear polymeric array like its E = As counterpart. The far-IR spectra of the halide complexes exhibit bands due to ν(AgX) vibrational modes at 229, 148 cm–1 (X = Cl), 167, 151, 125, 109 cm–1 (X = Br) and at 111, 86 cm–1 (X = I). These spectra were interpreted in terms of idealised C2h Ag2Cl2 and Td Ag4X4 structures of the silver halide cores.

Synthesis, Characterization and Reactions of the Chiral Transfer Agent Dicarbonyl(triphenylphosphine)-[(4r)-phenyl-(1'r)-(1'-phenylethyl)-1-azabuta-1,3-diene]iron(0)

The synthesis and room temperature single-crystal X-ray structural characterization of the title compound [( PhCH =CHCH= NCHMePh )Fe(CO)2(PPh3)] are described, the first optically pure 1-azabuta-1,3-diene adduct of iron(0) to be so recorded. Crystals are orthorhombic, P212121, a 20.197(6), b 14.09(1), c 11.094(5) Ǻ, Z 4; conventional R on |F| was 0.061 for 2217 independent 'observed' (I> 3σ(I)) reflections. This compound has been employed to transfer the Fe(CO)2(PPh3) moiety to cyclic 1,3-dienes to give new complexes, including the first example of optically active dicarbonyl ( triphenyl - phosphine )(η4-1-methoxycyclohexa-1,3-diene)iron.

Lewis-Base Adducts of Lead(II) Compounds. XII. Synthetic, Spectroscopic and Structural Studies of Some 1:1 Adducts of Lead(II) (Pseudo-)Halides With Aromatic Bidentate Ligands

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for some 1 : 1 adducts of lead(II) (pseudo-)halides with 1,10-phenanthroline (' phen ') and 2,2'-bipyridine (' bpy '). [( phen )PbX2](∞|∞), X = Cl , Br, I, have been refined in a common monoclinic C2/c setting, a ≈ 16.2, b ≈ 10.6, c ≈ 8.25 Ǻ, β 105°, Z = 4 f.u .; (conventional R on |F| 0.034, 0.046, 0.043 for No = 1694, 1626, 1387 independent, 'observed' (I > 3σ(I)) reflections respectively); [( bpy )PbI2](∞|∞) is isomorphous with similar cell dimensions (R 0.035 for No 1263), but, in its chloride counterpart, the symmetry is degraded to P21/c, a 15.336(5), b 9.476(5), c 8.191(3) Ǻ, β 92.81(3)�, Z = 4 (R 0.041 for No 2849). In the C2/c model the lead atoms are disposed on crystallographic 2 axes, as also are the associated N,N′- bidentate ligands, with the six-coordinate (cis-N2) Pb (μ-X)4 environments linked in an infinite …(μ-X)2Pb(μ-X)2Pb… one-dimensional polymeric chain by bridging halogen atoms. A somewhat similar, albeit more complex, array is found in [( bpy ) Pb (SCN)2](∞|∞), monoclinic, C2/c, a 17.655(6), b 12.027(3), c 6.794(1) Ǻ, β 107.03(2)°, Z = 4 (R 0.028 for No 1064), isomorphous with its previously studied phen analogue, in which a web of bridging SCN units is found. Stacks of successive strands up b have interleaving arrays of ligands and (pseudo-)halide atoms. The far-infrared spectrum of [( phen )PbCl2] shows four strong, broad bands at 152, 144, 116 and 96 cm-1 which are assigned as vPb-Cl. The corresponding bands in the bromo and iodo complexes are shifted to below 100 cm-1, revealing sharper bands at about 120 and 150 cm-1 which are assigned to vPb -N modes. The low wavenumbers of the vPb-X bands are indicative of weak Pb-X bonding. The far-infrared spectrum of the previously reported [( phen ) Pb (NCS)2] complex is similar to that of the chloro complex, consistent with its similarity in structure.

Lewis-Base Adducts of Lead(II) Compounds. XVIII. Synthetic and Structural Studies of Some 1:1 and 2:1 Adducts of 2,4,6-Tris (2-pyridyl)-1,3,5-triazine With Lead(II) Nitrate

Adducts of lead(II) nitrate with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (' trz ') have been synthesized and structurally characterized by room-temperature single-crystal X-ray studies, for 1:1 and 1:2 stoichiometry. Crystals of [( trz ) Pb (NO3)2](∞|∞) are monoclinic, P 21/c, a 10.531 (1), b 12.856(2), c 16.874(3) Ǻ, β 102.83(1)°, Z = 4 f.u .; R was 0.027 for No = 2773 'observed' (I > 3σ(I)) reflections. The complex is an infinite polymer; the plane of the tridentate trz ligand lies normal to the polymer axis ( Pb -N(central; distal) 2.523(5); 2.594(5), 2.568(5) Ǻ) with unsymmetrically bidentate nitrate groups to either side ( Pb -O 2.598(6), 2.928(7); 2.556(6), 2.911(7) Ǻ). The third oxygen of each nitrate group bridges to the next lead atom in the polymer chain ( Pb -O 3.008(5), 3.083(6)Ǻ). [( trz )2Pb(NO3)2] is monoclinic, C 2/c, a 15.723(5), b 10.034(2), c 24.379(15) Ǻ, β 106.84(4)°, Z = 4 f.u .; R was 0.038 for No 3030. The compound is a methanol monosolvate. The complex species is mononuclear, with the lead atom located on a crystallographic 2 axis and 10-coordinated by pairs of symmetry-related tridentate trz ( Pb -N(central; distal) 2.779(4); 2.800(5), 2.818(5) Ǻ) and bidentate nitrate ligands ( Pb -O 2.796(6), 2.689(5)Ǻ). A hexahydrate has also been obtained (triclinic, Pī a 23.580(9), b 10.147(4), c 9.762(4)Ǻ, α 113.14(3), β 92.11(3), γ 101.60(3)°, Z = 2 f.u ; R 0.041 for No 5633); although metal-ligand distances are similar to those found in the methanol solvate, and quasi-2 symmetry is retained, a very different stereochemistry is evident in respect of the relative dispositions of the ligands about the (quasi)-2 axis, involving a substantial twist of the two nitrate ligands relative to the triazines, and a flattening of the latter. The coordination polyhedron is different in the two 1:2 adducts. In the methanol solvate the stereochemistry is pentagonal antiprismatic whereas in the hexahydrate it is bicapped square antiprismatic.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. X. Some Mixed-Ligand Complexes of Group 2 Metal Halides With 2,2':6',2"-Terpyridine and Oxygen Donors

Room-temperature single-crystal X-ray structural characterizations are recorded for a variety of adducts of Group 2 metal halides with 2,2':6',2?-terpyridine ( tpy ) from various hydroxylic solvents. [Mg( tpy )2][Mg( tpy )(OH2)3] Br4.PriOH (1) is triclinic, Pī, a 19.352(6), b 12.852(5), c 11.463(3) Ǻ, α 110.95(3), β 99.04(2), γ 98.81(3)°, Z = 2 f.u .; conventional R on ׀ F ׀ at convergence was 0.056 for No 4398 independent 'observed' (I > 3σ(I)) reflections. In the [Mg( tpy )2]2+ ion, Mg-N(central; distal) are 2.099(9), 2.09(1); 2.152(9)-2.212(8) Ǻ, while in [Mg( tpy )(OH2)3]2+, Mg-N(central; distal) are 2.139(7); 2.206(9), 2.222(9) Ǻ, while Mg-O trans to these are 2.042(6); 2.082(9), 2.097(8) Ǻ. [Mg( tpy )(OH2)2( MeOH )] Cl2 (2) is triclinic, Pī, a 14.049(7), b 8.354(4), c 8.301(2) Ǻ, α 74.25(3), β 73.05(3), γ 80.37(4)°, Z = 2 f.u., R 0.064 for No 2417. In the cation, Mg-N(central; distal) are 2.125(4); 2.203(4), 2.218(4) Ǻ; Mg-O( MeOH ) is trans to Mg-N(central), being 2.013(4) Ǻ; Mg-O(OH2) are 2.067(4) and 2.063(4) Ǻ. [CaCl2( tpy )( dmf )2 (3) ( dmf = N,N- dimethylformamide ) is monoclinic, C2/c, a 23.27(2), b 11.225(6), c 16.517(8) Ǻ, β 109.56(5)°, Z = 4 centrosymmetric dimers, R 0.061 for No 985. The calcium atoms are linked by a pair of μ-chlorines, CaCl2Ca, and are seven-coordinate, N3Ca(μ-Cl )4 being broadly coplanar in the equatorial plane of a pentagonal bipyramidal array, with the other chlorine and the dmf oxygen trans and axial.

Lewis-Base Adducts of Lead(II) Compounds. X. Synthetic and Structural Studies of Some 1:1 Adducts of 'tet-b' With Lead(II) (Pseudo-)Halides

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 1 : 1 adducts of (7R*,14R*)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (' tet -b') with a variety of lead(II) salts. [( tet -b)PbCl2] is monoclinic, P 21/c, a 7.183(3), b 12.425(2), c 24.418(2) Ǻ, β 95.32(3)°, Z = 4; conventional R on |F| was 0.044 for 3188 independent, 'observed' (I > 3σ(I)) reflections. [( tet -b)PbI2] is monoclinic, P 21/c, a 19.920(5), b 7.772(5), c 15.605(6) Ǻ, β 108.39(2)°, Z = 4; R 0.051 for No 2507. [( tet -b) Pb (NCS)2] is orthorhombic, P 212121, a 36.99(1), b 8.996(5), c 6.964(3) Ǻ, Z = 4; R 0.043 for No 2100. All are discrete mononuclear [( tet -b)PbX2] entities in which the macrocyclic N4 ligand occupies one 'face' of the N4PbX2 coordination sphere, the thiocyanate ligands being N-bonded, with Pb -N-C angles of 116(2) and 118(1)°; interesting hydrogen-bonding interactions are found, columns of molecules being formed by way of hydrogen bonding between the coordinated (pseudo-)halides and the NH hydrogen atoms which project to the 'rear' face of the ligand of the next molecule, opposite the metal. In contrast to these, the bromide analogue, monoclinic, P21, a 9.342(3), b 12.720(5), c 18.845(5) Ǻ, β 103.17(2)°, Z = 4, R 0.035 for No 3593, is best formulated as [( tet -b) PbBr ] Br, one only of the bromide entities being bound to the lead, the other being fully dissociated by hydrogen bonding/ion pairing to the 'rear' side of adjacent ligands , forming hydrogen-bonded sheets rather than columns. This formulation has been extended to provide a description of an analogous mixed chloride- perchlorate 'double salt', [( tet -b) PbCl ] (ClO4).CH3OH, which is orthorhombic, P 212121, a 19.475(2), b 18.73(1), c 6.820(2) Ǻ, Z = 4, R 0.054 for No 3075. However, another double salt, modelled in refinement as Pb ( tet -b)Cl0.5(ClO4)1.5.H2O, orthorhombic Pnma , a 20.640(5), b 26.16(1), c 8.937(4) Ǻ, Z = 4 dimers , R 0.074 for No 1769, is in this case more appropriately described as [( tet -b) Pb (OClO2O)2Pb( tet -b)] (ClO4) Cl.H2O with perchlorate rather than halide coordinated, and an incipiently dimeric cation, as in the parent [( tet -b) Pb (OClO3)]2 (ClO4)2.2H2O.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. IX. Some Complexes of Group 2 Metal Halides With 2,2':6',2"-Terpyridine

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of MX2.ntpy stoichiometry of salts of Group 2 metals, MX2, with 2,2':6',2"-terpyridine ( tpy ). ' Homoleptic' adducts, [M( tpy )3] X2, are found in space groups with trigonal symmetry, with M located on a site of at least 3 symmetry, the structures being derivative of the P 62c array found in [ Pb ( tpy )3] (ClO4)2, but with variations in anion and cation stackings . [M( tpy )3] I2.~1.7MeOH, M = Ca (1), Sr (2), are trigonal , P3c1, a ≈ 13, c ≈ 15.3 Ǻ, Z = 2 f.u., conventional R on ׀ F ׀ being 0.050, 0.086 for No 894, 865 independent 'observed' (I > 3σ(I)) reflections respectively. [ Sr ( tpy )3] Br2.2MeOH (3), although similar, is modelled in space group P3c1, a 13.040(4), c 15.13(1) Ǻ, Z = 2 f.u ., R 0.041 for No 447. [( tpy )2BaI2] (4) is monoclinic, P 21/c, a 10.812(4), b 16.740(5), c 17.458(4) Ǻ, β 109.39(2)°, Z = 4 f.u ., R 0.042 for No 3256. [( tpy )2Ba(O2ClO2)2] (5) is triclinic, Pī , a 14.220(4), b 11.212(2), c 10.511(2) Ǻ, α 65.66(2), β 87.32(2), γ 88.92(2)°, Z = 2 f.u ., R 0.029 for No 4676.

Lewis-Base Adducts of Lead(II) Compounds. XIV. Synthetic and Structural Studies of Some 2:1 Adducts of 2,2'-Bipyridine With Lead(II) Oxoanion Salts

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 2: 1 adducts of the N,N′-bidentate aromatic base 2,2′-bipyridine (' bpy ') with lead(II) nitrate and perchlorate. [( bpy )2Pb(NO3)2]2 is triclinic, Pī , a 14.609(6), b 9.400(4), c 8.396(4) Ǻ, α 71.10(3), β 83.53(3), γ 81.72(3)°, Z = 1 dimer; R was 0.037 for No = 3001 independent, 'observed' (I > 3σ(I)) reflections. [( bpy )2Pb(ClO4)2] is monoclinic, P21/c, a 9.8806(6), b 12.198(6), c 19.924(2) Ǻ, β 106.80(1)°, Z = 4, R 0.040 for No 4456. Unlike the two 1,10-phenanthroline (' phen ') systems which are mononuclear with eight-coordinate PbN4O4 environments incorporating a pair of O,O′;- bidentate anions, the bpy systems are centrosymmetric dimers; in each case the coordination environment incorporates a pair of N,N′- bidentate aromatic bases and an O,O′- bidentate anion, but the other anion is not only O,O′- bidentate, but also bridges by a third oxygen atom to the other lead atom so that it is nine-coordinate PbN4O5. Syntheses and room-temperature single-crystal X-ray structure determinations are also recorded for a pair of 2:1 adducts of 2,2?-bipyridine with lead(II) salts of mixed anion stoichiometry , viz. ( bpy )2PbX(ClO4), X = acetate ('ac'), chloride. [( bpy )2Pb(ac)(ClO4)] is triclinic, Pī , a 15.910(6), b 9.067(5), c 8.588(3) Ǻ, α 102.91(4), β 93.64(3), γ 103.41(4)°, Z = 2, R 0.039 for No 5283. [( bpy )2PbCl(ClO4)2 is monoclinic, P 21/c, a 12.923(2), b 8.759(2), c 19.650(2) Ǻ, β 94.776(9)°, Z = 2 dimers (R 0.037 for No 4433). Like the 1:2 oxoanion/phen adducts, the acetate is a discrete molecular species with an eight-coordinate PbN4O4 lead environment, the oxygen array comprising a pair of O,O′- bidentate perchlorate and acetate ligands. The chloride adduct, however, is like the 1:2 oxoanion/bpy adducts, being centrosymmetric binuclear, a pair of μ-chloride ions linking the two lead atoms which have seven-coordinate PbN4(μ- Cl )2O lead environments, the perchlorate species being O-unidentate.

Lewis-Base Adducts of Lead(II) Compounds. XIX. Synthetic and Structural Studies of Some 1:1 Adducts of 2,4,6-Tris (2-pyridyl)-1,3,5-triazine With Lead(II) (Pseudo-)Halides

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 1:1 adducts of 2,4,6-tris(2-pyridyl) 1,3,5-triazine (' trz ') with lead(II) chloride, bromide, iodide and thiocyanate, the chloride and bromide being methanol monosolvates. [( trz )PbCl2](∞|∞). MeOH is monoclinic, P 2/c, a 9.178(2), b 14.833(3), c 7.347(8) Ǻ, β 93.89(2)°, Z = 2 f.u .; R was 0.042 for No = 1451 'observed' (I > 3σ(I)) reflections; the bromide is related, having a derivative triclinic cell, Pī, a 9.259(3), b 15.153(6), c 7.428(2) Ǻ, α 90.28(3), β 94.62(2), γ 91.15(3)°, Z = 2 f.u .; R was 0.047 for No 2729. [( trz )PbI2](∞|∞), also solvated, is triclinic, Pī , a 15.266(9), b 8.9448(8), c 8.148(11) Ǻ, α 80.60(6), β 77.05(7), γ 83.45(3)°, Z = 2; R was 0.032 for No 3222. In all three compounds an infinite PbX2PbX2Pb polymer is found with the plane of the tridentate trz lying quasi normal to the polymer axis. Pb -N distances lie between 2.63(1) and 2.803(8) Ǻ; Pb-Cl are 2.848(3) and 3.074(3), Pb -Br 2.963(2)-3.257(2) and Pb-I 3.192(3)-3.466(2) Ǻ. The thiocyanate, monoclinic, C 2/c, a 16.974(6), b 6.410(2), c 39.49(2) Ǻ, β 96.33(4)°, Z = 8, R 0.13 for No 2465, is a column of dimeric units stacked up b, successive lead atoms being bridged by thiocyanate sulfur atoms packed in between them, and quasi-parallel to a, and by thiocyanates parallel to b which link pairs of lead atoms in each dimer with the same b coordinate by pairs of bridging nitrogens and bridging sulfurs from the adjacent pair.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. VIII. Some Mixed-Ligand Complexes of Group 2 Metal Halides With Aromatic N,N'-Bidentate and Oxygen Donors

Room-temperature single-crystal X-ray structural characterizations have defined an interesting array of species obtained by variously crystallizing Group 2 halides with 2,2'-bipyridine ( bpy ) and 1,10-phenanthroline ( phen ) from hydroxylic solvents. [( phen )2Ca(OH2)3]Br2 (1) is monoclinic, P21/c, a 16.896(5), b 8.620(2), c 17.814(5) Ǻ, β 97.05(2)°, Z = 4 f.u .; conventional R on ׀ F ׀ was 0.057 for 1707 � independent 'observed' (I > 3σ(I)) reflections No, the complex � containing seven-coordinate Ca(N2)2O3 calcium. [( bpy )2CaBr(OH2)( HOPri )] � Br (2) is monoclinic, P21/c, a 9.674(4), b 18.236(8), c 14.716(8) Ǻ, β 90.83(4)°, Z = 4 f.u ., R 0.044 for No 2349, with seven-coordinate [CaBr (N2)2O2] calcium. [( bpy )2CaBr2( HOPr )] (3), [( bpy )2CaBr2( HOBu )] (4) and [( bpy )2SrBr2( HOPr )] (5) are all isomorphous, triclinic, Pī, a ≈ 17, � b ≈ 9.6, c ≈ 7.7 Ǻ, α ≈ 105, β ≈ 94, γ ≈ 95°, Z = 2 f.u .; R 0.055, 0.037, 0.061 for No 3111, 3102, 2424 respectively; all have a seven-coordinate [MX2(N2)2O] metal environment. A similar array is found in [(phen)2CaBr(OH2)( HOMe )] Br (6), triclinic, Pī , a 16.761(8), b� 10.647(6), c 7.376(6) Ǻ, α 75.78(6), β 82.47(5), γ 75.86(5)°, Z = 2 f.u ., R 0.057 for No 3216. With bpy , from aqueous methanol, however, [(bpy)2Ca(OH2)2( HOMe )2] Br2 (7) was obtained, monoclinic, C2/c, a � 17.645(7), b 10.899(4), c 16.071(5) Ǻ, β 118.88(2)°, Z = 4 f.u ., R 0.044 for No 1448, containing eight-coordinate Ca(N2)2O4 calcium; the calcium is disposed on a twofold axis. [( bpy )2SrBr2( HOMe )2] (8) is triclinic, Pī , a 13.784(5), b 10.605(4), c 9.653(1) Ǻ, α 115.78(2), β 96.87(3), γ 96.67(3)°, Z = 2 f.u ., R 0.045 for No 2754; the� strontium is eight-coordinate [SrBr2(N2)2O2]. [( phen )2Sr(OH2)4] I2.2phen (9), triclinic, Pī , a 13.314(4), b 12.311(3), c 7.066(2) Ǻ, α 99.77(2), β 92.43(2), γ 77.27(2)°, Z = 1 f.u ., R 0.049 for No 2703, is isomorphous with the previously studied perchlorate analogue, the strontium being disposed on a centre of symmetry. Species (1)-(9) are all mononuclear; the barium adducts (10) and (11) are binuclear: [( phen )2Ba(OH2)2Cl(μ-OH2)2Cl(H2O)2Ba( phen )2] Cl2.2phen.4H2O (10) is triclinic, Pī , a 14.590(3), b 14.109(4), c 10-862(2) Ǻ, α 74.56(2), β 65.87(2)°, γ 63.59(2)°, Z = 1 centrosymmetric dimer, R 0.027 for No 5249, with nine-coordinate Ba (N2)2ClO2(μ-O)2 barium. [( bpy )2Ba(I/OH2)(μ- I)3(I/OH2) Ba ( bpy )2] (11) is monoclinic, P 2/c, a 13.988(2), b 11.00(2), c 20.900(7) Ǻ, β 127.59(2)°, Z = 2 dimers , R 0.069 for No 3353, with eight-coordinate Ba (N2)2(I/OH)(μ-I)3 barium. All of (1)-(11) contain M(N2)2 arrays with diverse associations of solvent oxygen atoms, and in some cases halogens. Species (12), [( bpy )BaBr2( HOMe )2] (∞ ׀ ∞), is polymeric, monoclinic, C 2/c, a 17.119(2), b 13.844(1), c 7.489(1) Ǻ, β 111.21(1)°, Z = 4 f.u ., R 0.057 for No 2326; the barium lies on a twofold axis in an eight-coordinate [ Ba (N2)(O)2(μ-Br)4] environment. An adduct (13) of barium iodide with 4,4'-bipyridine, BaI2/(4,4'-bpy)/ PrOH (1:2½:2), monoclinic, P 21/c, a l5.467(5), b 12.639(7), c 21.004(5) Ǻ, β 118.99(3)°, Z = 4, R 0.059 for No 2.003, is a one-dimensional polymer, linked by two of the 4,4'-bpy ligands , one of these being centrosymmetric; the third ligand occupies a lattice site, so that the complex is [(4,4′-bpy)(4,4′-bpy)½Ba( HOPr )2](∞ ׀ ∞).(4,4'-bpy). The barium environment is seven-coordinate pentagonal bipyramidal, the two iodines occupying the axial/trans sites and the two oxygens non-adjacent in the pentagonal plane.

Lewis-Base Adducts of Lead(II) Compounds. XX. Synthesis and Structure of the 1:1 Adduct of Pyridine With Lead(II) Thiocyanate

The synthesis and room-temperature single-crystal X-ray structure determination are recorded for a 1:1 adduct of lead(II) thiocyanate with pyridine (' py '). [( py ) Pb (SCN)2](∞|∞) is triclinic, Pī , a 10.544(1), b 7.3729(7), c 6.705(2) Ǻ, α 103.91(2), β 95.99(2), γ 100.51(1)°, Z = 2 f.u .; R was 0.041 for 3226 'observed' (I > 3σ(I)) reflections. The structure is a two-dimensional polymer in the be plane with eight-coordinate ( py -N)PbN3S4 linked by the familiar four- membered Pb2S2 and eight-membered Pb2(NCS)2 motifs by way of bridging thiocyanate groups; one of the latter, unusually, has a bifurcating bridging nitrogen atom leading to the introduction of Pb2N2 motifs. The structure of the parent lead(II) thiocyanate is also discussed.