Room-temperature Single-crystal X-ray Structure Determinations Research Articles

Syntheses, structures and vibrational spectroscopy of some 1:1 and 1:2 adducts of silver(I) oxyanion salts with 2,2′-bis(pyridine) chelates

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of 1:1 stoichiometry of silver(I) oxyanion salts (perchlorate, nitrate, trifluoroacetate (‘tfa’) (increasing basicity)) with 2,2′-bis(pyridine) ligands (2,2′-bipyridyl, ‘bpy’; 2,2′-biquinolyl, ‘bq’; 2,2′-dipyridylketone, ‘dpk’; 2,9-dimethylphenanthroline, ‘dmp’). The adducts take two forms: (a) neutral mononuclear molecules, in which the 2,2′-bis(pyridine) ligand behaves as a chelate, with the silver coordination number dependent on the denticity of the anion; these are Agtfa:bpy (1:1) and AgClO 4:bq (1:1) (and various (ionic) acetonitrile or pyridine solvates AgClO 4:bq/dmp:MeCN/py (1:1:1), in which the solvent molecules are coordinated); and (b) one-dimensional polymers. The latter are diverse: in AgClO 4:bpy, dpk (1:1), the anion is discrete, the polymer made up of an array of two-coordinate silver atoms linked by bpy ligands twisted about their central connecting element. In AgNO 3:bpy, bq (1:1), the bpy ligands are chelating with the oxyanions bridging, cf. previously reported AgNO 3:dpk (1:1), in which the nitrate chelates the metal, with the dpk bridging, chelating N,O to one silver, while the other nitrogen bridges to the next. With Agtfa, a novel binuclear adduct has been isolated in conjunction with the hydrated ligand, Agtfa:dpk:(dpk · H 2O) (1:1:2). The far-IR spectra of several of these complexes show bands that can be assigned to the ν(AgN) modes, the positions of these bands correlating well with the relative Ag–N bond lengths. Syntheses and single-crystal X-ray structural characterizations are also reported for various adducts of silver(I) perchlorate, nitrate and trifluoromethanesulfonate with bpy, bq, ‘phen’ (= 1,10-phenanthroline), and ‘dmp’, of stoichiometry AgX:L (1:2). In each case the complex is ionic [AgL 2]X; the silver atom is four-coordinate, but diverse and remarkable variations in stereochemistries associated with changes in the interligand N–Ag–N angles, presumably influenced by the different packing arrangements, are observed.

Trans-5-(4-Bromobenzoyloxy)-2-phenyl-1,3-dioxane

The structure of the major product from the treatment of benz­aldehyde with glycerol, derivatized as its crystalline 4-bromo­benzoate, is shown to be the title compound, C17H15BrO4, by a room-temperature single-crystal X-ray structure determination, providing a rare example of a structurally characterized 1,3-dioxane system.

Synthesis and Structural Characterization of Some Adducts of 1,4-Dithian and -Oxathian with Silver(I) Nitrate and Perchlorate

Despite its relatively high melting point of 112◦C, 1,4-dithian (S(CH2CH2)2S=L) sublimes readily and malodorously at ambient temperatures, a factor possibly influential in the limited use it has found as a ligand despite its simplicity; the disposition of the sulfur atoms also may be such as to encourage the formation of perhaps uncongenial oligomers/polymers, rather than chelating to the same atom, even in ‘boat’ conformation. Its crystal structure was determined in 1955[1] and there appears to be no subsequent redetermination using improved techniques, or, until recently, seemingly very few metal complexes. Accordingly, we have initiated a minor foray into this area with a redetermination of the structure of the parent ligand and two complexes obtained by co-crystallization with silver(i) oxyanion salts (nitrate and perchlorate) from acetonitrile solution. We record this work herein. Contemporaneous studies[2–4] have recently recorded the structural characterization of a number of AgX/dithian adducts of various stoichiometries, but neither of the present, although a synthesis of the nitrate is reported[3] and the tetrafluoroborate is isomorphous with the perchlorate.[2] We also report a redetermination of enhanced precision for the adduct of 1 : 1 stoichiometry of silver(i) nitrate with 1,4oxathian (O(CH2CH2)2S),[5] with a reinterpretation in terms of a two-dimensional sheet structure. In terms of stoichiometry and connectivity, the results of the room-temperature single-crystal X-ray structure determinations are consistent with the above descriptions of the pleasantly crystalline colourless substances examined. The results for 1,4-dithian (L), i.e., the present ligand molecule, are harmonious with those of the previous record,[1] and its two complexes with silver(i) nitrate and perchlorate were determined to be AgNO3/L (1 : 1) and AgClO4/L (1 : 1.5), respectively, the latter being isomorphous with the recently determined tetrafluoroborate counterpart.[2] In the ligand, one-half of the formula unit, disposed about a crystallographic inversion centre, comprises the asymmetric unit of the structure, in the nitrate, the full formula unit, and in the perchlorate, one sixth of the formula unit. Molecules of the parent ligand are shown disposed within the unit cell in Figure 1; the geometry, defined with useful precision (Table 1), persists without Fig. 1. Unit cell contents of the ligand projected down b.

α-Sulfonyl Radical Initiated Intramolecular Tandem Radical Cyclization: Stereochemistries of a Pair of Doubly Cyclized Products

Room-temperature single-crystal X-ray structure determinations are recorded for trans-1,2,3,3a,9,9a-Hexahydro-cyclopenta[b]-1-benzothiapyran-4,4-dioxide and its 3a-methyl analogue, minor products of the α-sulfonyl radical-initiated intramolecular tandem radical cyclization of H2C=CH(CH2)CRBrSO2Ph (R = H, CH3), confirming the assigned structures and rigorously establishing the trans relationship at the ring junctions.

Synthesis and Structure of the Binuclear 1 : 1 Silver(I) 2-Hydroxy-3,5-dinitrobenzoate/Triphenylphosphine Complex

A room-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of silver(I) 2-hydroxy-3,5-dinitrobenzoate/triphenyl-phosphine (AgL/PPh3) was recorded, showing it to be a binuclear centrosymmetric system with the silver atoms bridged by one of the carboxy oxygen atoms of each ligand, [(PPh3)Ag(μ-O)2Ag(PPh3)] as in the parent acetate; the phenolic oxygen, retaining its protonation, is hydrogen bonded within the ligand to the other feebly chelating carboxylate oxygen.

2beta-Hydroxy-4'-demethyldesoxy-podophyllotoxin.

A room-temperature single-crystal X-ray structure determination of the title compound, C21H20O8, confirms the stereochemical assignment made previously on the basis of spectroscopic studies [Shaari & Waterman (1994). J. Nat. Prod. 57, 720–724].

Structural Systematics of Rare Earth Complexes. XV Tris(2,2′:6′,2″-terpyridine)lanthanoid(III) Tris(perchlorate) Complexes

Room-temperature single-crystal X-ray structure determinations of the 1 : 3 adducts of the trivalent lanthanoid perchlorates with 2,2′:6′,2″-terpyridine (‘tpy’) as crystallized from acetonitrile are recorded. The Ln = La complex is the only one of its structural type, being modelled as La(ClO4)3/tpy/MeCN/H2O (1 : 3 : 2 :2/3), trigonal P 3c1, Z = 6, a 13·063(7), c 53·04(4) Å, recorded on an interim basis, with conventional R on |F| 0·081 for No 2889 ‘observed’ (I >3σ(I)) reflections. For Ln = Ce, (Pr, Sm,) Eu and, by presumption, other intermediate members, a monosolvate is found, monoclinic P 21/n, a ≈ 9·3, b ≈ 21·1, c ≈ 24·7 Å, β ≈ 91°, Z = 4, R being 0·045, (0·060, 0·049,) 0·047 for No 4420, (4199, 3931,) 3713. The Ln = Eu adduct has also been obtained unsolvated in a form representative of Ln = Eu, Lu and, by presumption, intermediate members, as well as Y, which is monoclinic C 2/c, Z = 4, R being 0·051, 0·044, 0·061 for No 4386, 4407, 3713. All monoclinic systems are of the form [Ln(tpy)3] (ClO4)3(.S), Ln being nine-coordinate, and in the case of the C 2/c phase lying on a crystallographic 2 axis. The Ln = La adduct was modelled with three independent cations, all with crystallographic 3 symmetry, two with their coordination number augmented by the approach of solvent along the 3 axis.

Structural Systematics of Rare Earth Complexes. XIV Hydrated 1 : 1 Adducts of Lanthanoid(III) Nitrates with 2,2′:6′,2″-Terpyridine

Room-temperature single-crystal X-ray structure determinations are recorded for (hydrated) lanthanoid(III) nitrate/2,2′:6′,2″-terpyridine (‘tpy’) (1 : 1) complexes; all are of the form Ln(NO3)3/tpy/H2O(1 : 1 :x), [(tpy)Ln(O2NO)2(OH2)y](NO3)(.z H2O), and form two series of compounds. For Ln = La(-)Gd, the complexes are [(tpy)Ln(O2NO)2(OH2)3](NO3), the lanthanoid atom being ten-coordinate; crystals are triclinic, P 1, a ≈ 11·8, b ≈ 11·3, c ≈ 8·9 Å, α ≈ 75, β 69, γ ≈ 89°, Z = 2 f.u., conventional R on |F| 0·045, 0·062 for No 4513, 2710 independent ‘observed’ (I > 3σ(I)) diffractometer reflections for Ln = La, Gd respectively. For Ln = Tb(-)Lu, a different form is found: monoclinic, P 21/c, a ≈ 8·8, b ≈ 11·5, c ≈ 23·8 Å, β ≈ 111°, Z = 4, R 0·055, 0·037, 0·056 for No 2427, 3079, 1857 for Ln = Tb, Lu, Y respectively, the form of the complex being [(tpy)Ln(O2NO)2(OH2)2](NO3).2H2O, with nine-coordinate lanthanoid. Crystallization of the Ln = La adduct from methanol yields an adduct of La(NO3)3/tpy/MeOH (1 : 1 : 2) [(tpy)La(O2NO)3(HOMe)2] stoichiometry with 11-coordinate lanthanum. Crystals are triclinic, P 1, a 12·361(2), b 12·244(3), c 7·753(2) Å, α 96·56(2), β 103·22(2), γ 91·16(2)°, Z = 2, R 0·037 for No 6597.

Structural Systematics of Rare Earth Complexes. XI (‘Maximally’) Hydrated Rare Earth(III) Trifluoro- and Trichloro-acetates

Room-temperature single-crystal X-ray structure determinations carried out on ‘maximally’ hydrated rare earth(III) trifluoroacetates, Ln(tfa)3.x H2O, crystallized at room temperature, show the Ln = La, Ce adducts to be isomorphous and monoclinic, P 21/c, a ≈ 11·9, b ≈ 12·8, c ≈ 9·8 8 Å, β ≈ 103·7°, Z = 4; they are trihydrates. The Ln = Pr, Lu (and, implicitly, intermediate Ln) adducts are also monoclinic, P 21/c, Z = 4, and trihydrates, but of a different polymorph, with a ≈ 9·2, b 18·8, c ≈ 9·8 Å, β ≈ 114°. For the four determinations, conventional R values on |F| were 0·038, 0·032, 0·036, and 0·034 for No 2952, 4821, 4544, and 4092 independent ‘observed’ (I > 3σ(I)) diffractometer reflections respectively. The Ln = La, Ce adducts are two-dimensional polymers, the sheets parallel to the bc plane; the other systems are binuclear, the two metal atoms being linked by four bridging carboxylate O-tfa-O′ ligands. In both structural types, the metal atoms are eight-coordinate, but differ in the number of water molecules (2 cf. 3) in the O8 array. Extension of previous studies by single-crystal X-ray methods on the structural characterization of trivalent rare earth trichloroacetates, ‘maximally’ hydrated at local ambience, Ln(tca)3.x H2O, suggests the following arrays to be prevalent. The Ln = La adduct is a pentahydrate, monoclinic, P21/c, a 5·636(7), b 22·454(4), c 16·58(1) Å, β 90·52(8)°, Z = 4 f.u., R 0·035 for No 4154. The compound is a linear polymer along a, successive nine-coordinate La (separated by a) being linked by three O-tca-O′ bridging ligands at the opposite faces of a tricapped trigonal prismatic array, the equatorial sites being filled by water molecules. The Ln = Ce adduct is a trihydrate, monoclinic, P 21/c, a 10·071(2), b 22·973(2), c 20·222(5) Å, b 119·48(2)°, Z= 8 f.u., R 0·050 for No 5019. The array is also linear polymeric, but with successive Ce being linked alternately now by sets of two and then four O-tca-O′ bridging carboxylates along b, the Ln = Ce coordination number being diminished (relative to La) to eight with the coordination of two water molecules to each metal. Ln = Pr, Lu (and, presumptively, intermediate Ln) are dihydrates, triclinic, P 1, a ≈ 11·70, b ≈ 12·8, c ≈ 15·3 Å, α ≈ 71, β ≈ 77·85, γ ≈ 65·5°, Z = 4 f.u., R 0·056, 0·059 for No 5650, 5398. The array is a linear polymer, similar to that of the Ln = Ce adduct but alongside the bridging acetate pair one of the water molecules now bridges, resulting in a stepped Ln 1 array (along c) rather than a quasi-straight one as is found for the Ln = Ce (and La) adduct. Structure determinations are also recorded for rare earth(III) trichloroacetate ethanol trisolvates, Ln(tca)3.3EtOH. Adducts of Ln = La, Yb (and, implicitly, intermediate Ln) are isomorphous, triclinic, P 1, a ≈ 12, b ≈ 11·8, c ≈ 11·4 Å, α ≈ 114, β ≈ 100, γ ≈ 104°, Z = 2 f.u., R 0·056, 0·050 for No 3843, 4171. The complexes are centrosymmetric dimers [(EtOH)3(tca-O)Ln(O-tca-O′)4Ln(O-tca)(HOEt)3], the two metal atoms being linked by four O-tca-O′ bridging carboxylate groups; the metal atoms are eight-coordinate, the other four sites being occupied by four oxygen atoms from unidentate ethanol and carboxylate moieties. Bis(bis(2-pyridyl)aminium) bis(diaquatetrakis(trichloroacetato)lanthanate(III)), 2(dpaH+) [(H2O)2-(tca-O)(tca-O,O′)2La(O-tca-O′)2La(O,O′-tca)2(O-tca)(OH2)2]2-, is triclinic, P 1, a, 13·901(2), b 13·764(3), c 10·073(2) Å, α 104·04(2), β 108·93(2), γ 101·50(2)°, Z = 1 binuclear f.u., R 0·045 for No 4999. The anion is binuclear, the two nine-coordinate lanthanum atoms being linked by a pair of bridging O-carboxylate-O′ groups. The other seven sites of the LaO9 array are occupied by a pair of O,O′ -chelating and one O-unidentate carboxylate groups and a pair of water molecules.

Structural Systematics of Rare Earth Complexes. XII Solvated 1 : 1 Adducts of Some Lanthanoid(III) Carboxylates with 1,10-Phenanthroline and 2,2′:6′,2″-Terpyridine

A room-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of 1,10-phenanthroline (`phen") with lutetium(III) acetate (as its dihydrate) is recorded. Crystals are triclinic, P 1, a 12·430(8), b 10·681(4), c 8·134(8) Å, α 74·76(6), β 84·81(7), γ 74·29(4)°, Z = 2 f.u.; conventional R on |F| was 0·031 for No 3939 independent ‘observed’ (I > 3σ(I)) diffractometer reflections. The complex [(N,N′-phen)(O,O′-ac)Lu(O-ac-O′)4Lu(O,O′-ac)(N,N′-phen)].2H2O is binuclear, the lutetium being eight-coordinated by bidentate phen and ac (acetate) ligands and four oxygen atoms from the bridging acetate ligands. Also recorded is the structural characterization of 1 : 1 Lu(ac)2Cl/tpy (tpy = 2,2′:6′,2″-terpyridine) as its pentahydrate; this complex is triclinic, P 1, a 12·410(3), b 11·559(4), c 9·976(4) Å, α 85·19(3), β 70·30(3), γ 65·70(2)°, Z = 2, R 0·049 for No 4717. The complex is shown to be [(tpy)(H2O)2Lu(O2CCH3)2]Cl.3H2O, with the lutetium nine-coordinated by tridentate tpy, a pair of bidentate acetates and two unidentate water molecules, with the chloride uncoordinated. Structural characterizations of a number of 1 : 1 adducts of variously solvated lanthanoid(III) trichloroacetates, Ln(tca)3, with tpy are also recorded. Yb(tca)3/tpy/MeOH (1 : 1 : 1) is triclinic, P 1, a 14·016(4), b 12·951(5), c 9·604(3) Å, α 73·89(3), β 76·56(3), γ 69·20(3)°, Z = 2 f.u., R 0·057 for No 4465. The complex is mononuclear, the eight-coordinate N3YbO5 array containing tridentate tpy, unidentate methanol, and two unidentate and one bidentate chelating anions. 1 : 1 : 1 Ln(tca)3/tpy/OH2 adducts for Ln = La(-)Nd are triclinic, P 1, a ≈ 13·4, b ≈ 12·47, c ≈ 11·5 Å, α ≈ 114·5, β ≈ 89·9, γ ≈ 115·6°, Z = 1 binuclear array, R 0·061, 0·071 for No 3240, 2394. The two Ln atoms are O,O′-bridged by a pair of anions, the N3LnO6 nine-coordinate lanthanoid environment being completed by a tridentate tpy, one water, one unidentate and one bidentate anion. A 1 : 1 : 1 Lu(tca)3/tpy/OH2 array, by contrast, is triclinic, P 1, a 16·569(8), b 14·815(5), c 14·375(6) Å, α 62·05(3), β 81·35(4), γ 77·97(3)°, Z = 4 ‘mononuclear’ f.u., R 0·067 for No 6710. The array, remarkably, contains species of both of the above types in a 1 : 2 binuclear-to-mononuclear ratio, but with water replacing methanol in the mononuclear array.

Structural Systematics of Rare Earth Complexes. XVI (‘Maximally’) Hydrated Rare Earth(III) Bromides

Room-temperature single-crystal X-ray structure determinations carried out on rare earth bromides crystallized from water at room temperature define three series of hydrates LnBr3.nH2O. For Ln = La, Ce, a heptahydrate phase (n = 7) is defined, triclinic P 1, a ≈ 8·6, b ≈ 9·4, c ≈ 8·3 Å, α ≈ 108, β ≈ 99, γ ≈ 72°, isomorphous with the array described for the ‘early’ (Ln = La-Pr) rare earth chlorides, being binuclear [(H2O)7Ln(-Br)2Ln(OH2)7] Br4, Z = 1 dimer; conventional R on |F| were 0·051, 0·042 for 2323, 3451 independent ‘observed’ (I > 3σ(I)) diffractometer reflections respectively. For Ln = Pr(-)Dy, a hexahydrate phase is defined, monoclinic P 2/n, a ≈ 10·0, b ≈ 6·8, c ≈ 8·2 Å, β ≈ 93·5°, Z = 2 f.u., isomorphous with the array defined for the heavier (Ln = Nd, Lu, Y) rare earth chlorides, being [(H2O)6LnBr2] Br, with R 0·029, 0·034 for No 1590, 1388 respectively. For Ln = Ho(-)Lu, Y, an octahydrate is defined for the first time, monoclinic P 21/n, a ≈ 8·1, b ≈ 16·0, c ≈ 10·1 Å, b ≈ 94·0°, Z = 4 f.u., a new array of the form [Ln(OH2)8] Br3 emerging, with R 0·061, 0·048, 0·042 for No 1191, 2402, 1674 respectively, the metal environment being square antiprismatic.

Structural Systematics of Rare Earth Complexes. XVIII (Hydrated) Mononuclear 1 : 1 Adducts of Lanthanoid(III) Chlorides with 2,2′-Bipyridine

Room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of hydrated lanthanoid(III) chlorides with 2,2′-bipyridine, ‘bpy’, crystallized from water/ethanol solutions, which contain mononuclear arrays with 1 : 1 Ln/bpy stoichiometry. Extended isomorphous series have been defined pertinent to the heavy end of the Ln series: crystals of LnCl3/bpy/H2O (1 : 1 : 6) ([(bpy)Ln(OH2)6]Cl3), seemingly inclusive of (at least) the range Ln = Ho(-)Lu and Y, are monoclinic, P 21/n, a ≈ 14·2, b ≈ 7·7, c ≈ 17·4 Å, β ≈ 91°, Z = 4, with an eight-coordinate LnN2O6 array; conventional R values on |F| were 0·043, 0·029, 0·057 for No 2435, 3120, 1846 independent ‘observed’ (I > 3σ(I)) diffractometer reflections (Ln = Ho, Lu, Y). Crystals of LnCl3/bpy/H2O (1 : 1·5 : 8) ([(bpy)Ln(OH2)6]Cl3.½bpy.2H2O), seemingly encompassing (at least) the range Ln = Er(-)Lu and Y, are triclinic, P 1, a ≈ 11·7, b ≈ 11·0, c ≈ 10·1 Å, α ≈ 85·8, β ≈ 74·7, γ ≈ 79·5°, Z = 2, R 0·038, 0·033, 0·048 for No 3897, 4377, 3130, and contain similar [(bpy)Ln(OH2)6]3+ cations as does HoCl3/bpy/H2O (1 : 2 : 7), [(bpy)Ho(OH2)6]Cl3.bpy.H2O, orthorhombic, Pbca, a 18·02(2), b 20·06(2), c 15·051(9) Å, Z = 8, R 0·057 for No 3009. By contrast, only sporadic, diverse and unrelated forms are thus far defined among the lighter Ln: EuCl3/bpy/H2O(1 : 1 : 5) ([(bpy)Eu(OH2)4Cl2]Cl.H2O), triclinic, P 1, a 11·506(7), b 11·098(5), c 6·974(8) Å, α 77·35(7), b 85·1(1), γ 89·54(4)°, Z = 2, R 0·063 for No 4633, also contains a mononuclear [(N,N′-bidentate)Ln(unidentate)6] array. PrCl3/bpy/H2O(1 : 1 : 3)(× 4) is a remarkable compound, being 2[(bpy)Pr(OH2)3Cl3] [(bpy)(H2O)2Cl2Pr(µ-Cl)2PrCl2(OH2)2(bpy)].2H2O, triclinic, P 1, a 13·490(4), b 11·121(2), c 10·162(1) Å, α 96·06(1), β 90·08(2), γ 96·43(2)°, Z = 2 f.u., R 0·045 for No 4127, with a mononuclear species of PrCl3/bpy/H2O (1 : 1 : 3) stoichiometry and a binuclear species of 1 : 1 : 2 stoichiometry. A binuclear ethanol solvated array has been characterized for LaCl3/bpy/EtOH (1 : 1 : 2) [(bpy)(EtOH)2Cl2La(µ-Cl)2LaCl2(HOEt)2(bpy)], with eight-coordinate lanthanum; this complex is triclinic, P 1, a 11·426(8), b 10·673(7), c 10·453(7) Å, α 109·60(5), β 113·10(5), γ 105·80(5)°, Z = 1 dimer, R 0·046 for No 2786.

Structural Systematics of Rare Earth Complexes. XIII (‘Maximally’) Hydrated (Heavy) Rare Earth Nitrates

Room-temperature single-crystal X-ray structure determinations are known for a number of ‘maximally hydrated" nitrates of, in particular, the lighter lanthanoid elements; in all cases, all nitrates coordinate as O,O′-bidentate ligands so that the series may be represented at the outset as Ln(O2NO)3.x H2O. Two distinct triclinic P 1 hexahydrate phases of similar cell dimensions are recognized, the most distinctive distinguishing feature being that in the La, Ce phase the 11-coordinate Ln is surrounded by three O,O′-bidentate nitrate and five O-unidentate water molecule ligands; the domain of the other, with four coordinated water molecules, extends from Ln = Pr to Ln = Dy (inclusive of Y). At local ambience, we have crystallized heavier members of the series as pentahydrates, isomorphous with the previously characterized Ln = Eu example, also containing a molecule of the form [Ln(O2NO)3(OH2)4] (with a molecule of water of crystallization), but a different stereoisomer to that found in the Ln = Pr(-)Dy array. Structure determinations are recorded for Ln = Dy, Er, Yb, conventional R on |F| 0·042, 0·034, 0·029 for No = 3858, 3980, 3935 independent ‘observed’ (I > 3σ(I)) diffractometer reflections. For Ln = Lu a new tetrahydrate phase is described, monoclinic P21/n, a 7·379(7), b 10·364(5), c 14·26(1) Å, β 96·09(7)°, Z = 4, R 0·048 for No 2324, together with a new triclinic P 1 trihydrate, a 12·591(4), b 12·144(3), c 7·355(2) Å, α 80·22(2), β 77·68(3), γ 62·30(2)°, Z = 4, R 0·051 for No 4552. In both of the latter, Lu is nine-coordinate, with three bidentate nitrate groups and three coordinated water molecules; remarkably, the two independent molecules of the asymmetric unit in the triclinic phase are distinct isomers, one having the water molecules fac, derivative of the 10-coordinate array of the Pr(-)Yb series with quasi-3 symmetry, while the other, like that in the monoclinic phase, is mer.

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. VII Acid Salts of the 4-Nitrophenoxides of Group 2

Room-temperature single-crystal X-ray structure determinations are recorded for a number of Group 2 4-nitrophenoxide acid salts, variously hydrated M(4-np)2.x(4-npH).yH2O. Ca(4-np)2.2(4-npH).8H2O is monoclinic, P 21/n, a 30·52(1), b 10·027(1), c 23·65(2) Å, β 116·3(5)°, Z = 8, conventional R on |F| being 0·058 for No 5092 independent ‘observed’ (I > 3s(I)) reflections. Sr(4-np)2.2(4-npH).8H2O, based on a subcell of the former, is monoclinic, P 21/c, a 15·576(5), b10·081(6), c 24·20(2) Å, β 117·99(5)° , Z = 4, R 0·054 for No 2908. Ba(4-np)2.2(4-npH).4H2O is orthorhombic, Fdd2, a 28·01(1), b 19·90(1), c 10·692(7)Å, Z = 8, R 0·028 for No 1967. The strontium array (and that of the calcium salt developed from it) may be represented as [(H2O)6Sr(4-npH.4-np)] (4-npH.4-np), a neutral ligand being unsymmetrically chelated to the strontium through the nitro group, with a quasi-parallel counter ion hydrogen-bonded to it by phenoxide confrontation. The other two 4-np residues make up a similar phenoxide-confronting pair (4-npH.4-np), the hydrogen being more intimately associated with one moiety. The barium salt is also an interesting array: the 10-coordinate barium lies on a crystallographic 2 axis, in an environment of two pairs of symmetry-related nitro-chelating ligand anions, and a pair of nitro-O coordinating neutral 4-npH ligands; the whole [(H2O)4Ba(4-np)2(4-npH)2] array may be envisaged as a single neutral (super)molecule. Hydrogen bonds between confronting phenoxides of the neutral 4-npH components of the parent and the 4-np- components of neighbouring molecules link the whole into a three-dimensional array.

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. VI 4-Nitrophenoxides of Group 2

Room-temperature single-crystal X-ray structure determinations are recorded for 4-nitrophenolate (4-np-) salts of Group 2 metal ions, variously hydrated, M(4-np)2.xH2O, M = Mg, Ca, Sr, Ba. Mg(4-np)2.8H2 O is monoclinic, P21/c, a 12·402(3), b 6·673(7), c 11·833(6) Å, β 93·70(3)°, Z = 2; conventional R on |F| was 0·041 for No 1995 independent ‘observed’ (I > 3σ(I)) reflections. Ca(4-np)2.4H2O is monoclinic, P21/c, a 13·109(8), b 3·644(1), c 21·181(8) Å, β 125·55(3)°, Z= 2, R 0·050 for No 1371. Sr(4-np)2.8H2O is monoclinic, P21/n, a 7·934(1), b 10·658(1), c 23·602(2) Å, β 91·36(1)°, Z = 4, R 0·038 for No 2050. Ba(4-np)2.8H2O is monoclinic P21/c, a 15·990(8), b 6·337(3), c 25·634(8) Å, β 126·1(3)°, Z = 4, R 0·021 for No 3115. The magnesium salt is ionic with [Mg(OH2)6]2+ cations and interleaved anion stacks up b. The calcium salt is a one-dimensional polymer with ... Ca(µ-O)2Ca(µ-O)2Ca ... spine, the bridges being phenolic oxygen atoms.trans-Coordinated water molecules make up six-coordination about the calcium, the anion planes stacking at the b spacing. The strontium adduct is also a one-dimensional polymer with a similar spine, but with water molecule oxygen atoms bridging, the nine-coordinate strontium environment being made up by a chelating nitro group and three unidentate water molecules. Coordinated anions stacked up a are interleaved by free anions. The barium salt is simply [Ba(4-np)(OH2)8]+ (4-np-), the ligand anion (semi)chelated through the nitro pair of oxygen atoms, again with interleaving anion/ligand stacking.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXV Synthesis, Spectroscopy and Structural Systematics of Some 1 : 3 Adducts of Copper(I) Compounds with Triphenylarsine, [(Ph3As)3CuX], X = Cl, Br, I, ONO2

Crystallization of some copper(I) salts, CuX, with triphenylarsine in 1 : 3 stoichiometry from acetonitrile has yielded an array of adducts, [(Ph3As)3CuX], characterized by room-temperature single crystal X-ray structure determinations. [(Ph3As)3CuCl] (1) has been characterized in two unsolvated phases, α and β, the second form previously recorded as monoclinic, P21/n, Z = 8. The ‘α’ phase, like the bromide (2) and iodide (3), adopts the trigonal P3 array, widespread among many [(Ph3E)3MX] adducts with a ≈ 19, c ≈ 11 Å; conventional R on F was 0·037, 0·041, 0·056 for No 3458, 3259, 3434 independent ‘observed’ (I > 3σ(I)) reflections for these three adducts respectively. A further form, γ, is a toluene hemisolvate, monoclinic, P21/c, a 21·490(5), b 10·218(7), c 24·901(6) Å, β 117·53(2)°, Z = 4, R 0·057 for No 7207. The nitrate (4), obtained as a monosolvate from methanol, is monoclinic, P21/n, a 15 ·115(9), b 23·201(9), c 14·170(14) Å, β 92·56(7)°, Z = 4, R 0·049 for No 5476. In all compounds, the copper atom is four-coordinate, E3CuX, the nitrate in (4) being -ONO2 unidentate. The CuX bond lengthsr(CuX) in [(Ph3E)3CuX] (X = Cl, Br, I) show a decrease from the Ph3P to the corre3sponding Ph3As compound, and this is consistent with the observed increase in the v(CuX) wavenumbers in the far-infrared spectra. These trends are both consistent with an increase in the CuX bond strength from the Ph3P to the Ph3As complexes, and possible reasons for this are discussed.

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. 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.

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. XVII. Synthetic and Structural Studies of Some 1:1 Adducts of 2,2':6,2'-Terpyridine With Lead(II) Salts

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 1:1 adducts of 2,2':6',2"-terpyridine (' tpy ') with the lead(II) oxoanion salts perchlorate, nitrate and nitrite, ( tpy ) Pb ( oxoanion )2. All structures are monoclinic, C2/c, Z = 4, with approximate ranges a from 9 to 11 Ǻ, b from 16 to 20 Ǻ, c from 9.8 to 13.8 Ǻ, β from 113 to 130° and V from 1650 to 1850 Ǻ3. In all cases the lead(II) atoms are disposed on crystallographic 2 axes which also pass through the axis of the central tpy ring; a pair of symmetry related oxoanions link successive lead atoms in a one-dimensional polymeric chain parallel to the ac cell diagonal, one pair of oxygen atoms functioning as an O,O'-bidentate with another oxygen (replaced by the nitrogen in the nitrite) bridging to the adjacent lead atom; the third anionic oxygen atom in the nitrate is replaced by a water molecule in the nitrite, which thus becomes a monohydrate. Residuals were 0.030, 0.034 and 0.040 for 2122, 1564 and 2059 independent 'observed' (I > 3σ(I)) reflections respectively. Also recorded are the syntheses and room-temperature single-crystal X-ray structure determinations for 1:1 aducts of 2,2':6',2"-terpyridine with lead(II) chloride, bromide and iodide, the chloride and bromide being hydrated. ( tpy )PbCl2.H2O is monoclinic, P 21/c, a 8.938(1), b 15,210(7), c 13.414(3) Ǻ, β 115.17(1)°, Z = 4 f.u .; R was 0.036 for No = 3346 independent, 'observed' reflections. The complex is centrosymmetric, binuclear [( tpy ) (H2O)( Cl ) Pb (μ- Cl )2Pb( Cl )(OH2)( tpy )], with the two lead atoms linked by bridging chlorine atoms; the lead atoms are seven-coordinate N3,O,ClPb(μ- Cl )2. The bromide ( tpy )PbBr2.2/3H2O, triclinic, Pī, a 12.360(6), b 12.452(4), c 18.372(6) Ǻ, α 108.31(3), β 109.44(3), γ 90.56(3)°, Z = 6 f.u ., R being 0.046 for No 7282, is in fact trinuclear [Pb3Br6( tpy )6].2H2O, a novel and elegant oligomer with quasi-2 symmetry in which a central lead atom (on the quasi-2 axis) is seven-coordinated [( tpy ) Pb (μ-Br)4] with the associated bromides bridging to a pair of peripheral lead atoms, also seven coordinated, [( tpy )(Br) Pb (μ-Br)3]. Unsolvated ( tpy )PbI2, triclinic, Pī , a 10.834(3), b 9.023(3), c 8.906(2) Ǻ, α 80.34(2), β 89.40(2), γ 79.78(2)°, Z = 2 f.u ., R 0.031 for No 2347 is, like the chloride, centrosymmetric binuclear, [( tpy )(I) Pb (μ-I)2Pb(I)( tpy )], but with the lead(II) now six-coordinate N3(I) Pb (μ-I)2. In both chloride and iodide, the tpy plane is approximately normal to the Pb ... Pb line with the water molecule of the chloride approximately trans to the central tpy nitrogen; in the iodide that site is occupied by the terminal halide.