Antimony Center Research Articles

Synthesis and Characterization of Hypervalent Organoantimony(III) Compounds Containing the [2‐(Me2NCH2)C6H4]2Sb Fragment

AbstractCompounds containing the [2‐(Me2NCH2)C6H4]2Sb moiety were prepared by using R2SbX [X = Cl (1), Br (2)] as starting materials. The reaction of 1 with Me3SiCH2MgCl gave the mixed alkyl–aryl stibine R2SbCH2SiMe3 (3). Reduction of 2 with Mg in thf followed by in situ air oxidation or treatment with S8 resulted in the isolation of (R2Sb)2E [E = O (4), S (5)]. Compound 5 is also formed from R2SbCl and Na2S. The reaction of 4 with [W(CO)5(thf)] gives the unexpected complex [(R2SbOH)W(CO)5] (6). The new compounds were investigated by IR, 1H, and 13C NMR spectroscopy, as well as by mass spectrometry. The structures of 3–6 were determined by single‐crystal X‐ray diffraction. For compounds 3–5, both nitrogen atoms from the pendant arms are involved in intramolecular N→Sb coordination, which results in distorted square‐pyramidal (C,N)2SbC or (C,N)2SbE (E = O, S) cores. By contrast, in 6 only one nitrogen atom is strongly coordinated to the antimony center, whereas the second nitrogen atom is involved in N···H–O bonding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Polyol Metal Complexes. Part 54 Multiply Deprotonated Purine Nucleosides as Ligands in Bismutates and Antimonates

AbstractThe crystal structures of [Co(NH3)6][Bi(Guo1,2′,3′H−3)2] · 9 H2O (1), Na[Sb(Ado2′,3′H−2)2] · H2O (2), and Na2[Bi(Ado2′,3′H−2)(Ado2′,3′,5′H−3)] · 13.5 H2O (3) were determined from single‐crystal X‐ray diffraction data (Guo = guanosine, Ado = Adenosine). The chelate complex anions of all structures consist of a bismuth(III) or antimony(III) center which is coordinated by the 1,2‐diolato group of the ribofuranosyl moiety of the nucleosides. In 1, two guanine moieties belonging to different complexes are linked by two hydrogen bonds of the type N2–H···N3. 13C NMR data obtained from the mother liquors show a coordination‐induced shift for the coordinating alkoxido groups of guanosine and adenosine as well as inosine.

Synthesis and structural characterization of tris(phenolate)amine complexes of antimony derived from [formula omitted

The antimony aryloxide compound [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb may be readily obtained via the reaction of Sb(OEt) 3 with tris(3,5-di- t-butyl-2-hydroxybenzyl)amine, N ( CH 2 Ar Bu 2 t OH ) 3 . [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb forms the adduct [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb ( OSMe 2 ) upon treatment with Me 2SO, and comparison of the molecular structure of [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb ( OSMe 2 ) with that of [κ 4-N( o-C 6H 4O) 3]Sb(OSMe 2) demonstrates that the Sb–OSMe 2 bond length in the former complex is significantly longer than that in the latter. This observation indicates that the [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] ligand engenders a less Lewis acidic antimony center than does [ κ 4 -N ( o – C 6 H 4 O) 3 ] . [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb exhibits diverse reactivity. For example, treatment of [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb with AcOH cleaves one of the Sb–O bonds to give [ κ 3 -N ( CH 2 Ar Bu 2 t O ) 2 ( CH 2 Ar Bu 2 t OH ) ] Sb ( κ 1 - O 2 CMe ) , Br 2 undergoes oxidative addition to give N ( CH 2 Ar Bu 2 t O ) 3 ] SbBr 2 , while Me 3NO · 2H 2O yields the oxo and hydroxo complexes { [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb ( μ -O ) } 2 , [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb ( OH ) 2 , and { [ κ 4 -N ( CH 2 Ar Bu 2 t O ) 3 ] Sb V O } 4 { Sb 4 III O 6 } .

On the structure of liquid antimony pentafluoride

The liquid structure of antimony pentafluoride at room temperature has been investigated using neutron and high-energy X-ray diffraction and subsequently modelled using Empirical Potential structure refinement. The neutron diffraction measurements show that each antimony centre is surrounded by 6 fluorine atoms; four at a non-bridging distance of 1.86 ± 0.03 Å and two bridging fluorines at a distance of 2.03 ± 0.06 Å. The X-ray data show an additional peak at 3.93 ± 0.03 Å attributed to antimony–antimony contacts. The diffraction data were fit to three models; cis-monomer, isolated tetramer and cis-linked chains. The X-ray data rule out the cis-monomer model but good fits are obtained for the isolated tetramer and cis-linked chain models. It is argued that the liquid is comprised of chains of cis-linked tetrameric building blocks when these data and modelling results are considered in light of NMR measurements.

Synthesis of enantiomerically pure Sb-chirogenic organoantimony compounds and their crystal structures

Sb-chirogenic organoantimony compounds (±)- 5a– c bearing heteroatom moieties such as 4,4-dimethyl-2-oxazolinyl, methoxymethyl, and diphenylphosphanyl substituents on the o-position of an aryl group have been prepared by nucleophilic displacement of the ethynyl moiety on (1-naphthyl)(phenylethynyl)( p-tolyl)stibane ( 3) with aryllithium reagents ( 2a– c). The optical resolution of the racemic (±)- 5a, b was attained via separation of a diastereomeric mixture of their palladium complexes ( S)- 7 formed from the reactions of (±)- 5a, b with di-μ-chlorobis[( S)-dimethyl(1-ethyl- α-naphthyl)aminato-C 2, N]dipalladium(II) ( 6). The enantiomerically pure Sb-chirogenic stibanes isolated here were optically stable, and no racemization on the chiral antimony center was observed even when they were allowed to stand at room temperature for over 72 h in chloroform. The structure of 5a, b including the absolute configuration was determined by single crystal X-ray analyses of (+)- 5aB and antimony–palladium complex ( 7bB), respectively. The analyses also revealed the presence of intramolecular interaction between the antimony and sp 2-nitrogen atoms in the molecule Sb( S)-(+)- 5aB.

Chlorination of p-substituted triarylpnictogens by sulfuryl chloride: Difference in the reactivity and spectroscopic characteristics between bismuth and antimony

Competitive oxidative chlorination of p-substituted triarylstibines 3 [( p-XC 6H 4) 3Sb; a: X = OMe, c: Cl, d: CO 2Et, e: CF 3, f: CN, g: NO 2] by sulfuryl chloride was carried out against 3b (X = H) and the electronic effect of these substituents on the chlorination of 3 was compared with that of homologous triarylbismuthanes 1. The relative ratios 4/ 4b (Ar 3SbCl 2/Ph 3SbCl 2) decreased with increasing electron-withdrawing ability of the substituents ( a: 53/47, c: 49/51, d: 46/54, e: 44/56, f: 40/60, g: 37/63), but the tendency was not so pronounced as observed in the chlorination of 1. A Hammett plot of the 4/ 4b ratios against the σ p constants exhibited a good linear relationship with a negative slope, the value of which was almost half of that deduced from the 2/ 2b (Ar 3BiCl 2/Ph 3BiCl 2) ratios. The difference in the reactivity between 1 and 3 may be explained by the effect of the electron-withdrawing substituents in the aromatic rings, which affects the p-character of the lone pair on the pnictogen atoms by increasing the positive metal charge and appears more remarkably in 1 than in 3. The 13C NMR study of 3 revealed that the chemical shifts of the ipso carbons (C1) attached to the antimony show a linear relationship against the σ p constants with a positive slope (14.5). The value was smaller than that deduced from 1 (17.0), suggesting that the antimony center of 3 is less sensitive to the substituent effect. This is in accord with the tendency of the chlorination.

First Introduction of an Azulenyl Group into the Bismuth and Antimony Center. Synthesis and Structure of Azulenylbismuthanes and Their Difluorides

A nonalternant organyl ligand derived from azulene, a 1,3-dichloro-2-azulenyl group, is introduced for the first time into the bismuth and antimony center. Conversion of the azulenylbismuthanes into the pentacoordinated difluorides by xenon difluoride promotes the π-polarization of the azulene nucleus, which is detected as a color change in solution as well as changes in the chemical shifts of the 13C NMR spectra. A similar tendency is observed in the antimony congeners. The X-ray crystallographic study of (1,3-dichloro-2-azulenyl)diphenylbismuth difluoride (20b) reveals that intermolecular π−π stacking takes place between the azulenyl groups through the interaction of the five-membered ring with the seven-membered ring. This may reflect the more polarized azulenyl group of the difluorides, which strengthens the stacking interaction.

Cyclic Voltammetric Study of Intramolecular and Intermolecular Hypervalent Organoantimony Complexes with Sb···N Bonding

The electrochemical behaviors of a series of four intramolecular hypervalent complexes containing Sb···N bonding (antimony (III, V) compounds) and of the relevant common precursors, organonitrogen and (tri- and penta-) substituted stibines, have been investigated using cyclic voltammetry. The shape of the voltammograms is not the simple superposition of the precursors, and the antimony centers of all the complexes undergo an irreversible oxidation process consisting of a charge transfer preceded by the first-order formation−dissociation equilibrium of the complexes. The detailed analysis of the oxidation current, when combined with the theoretical treatment by Nicholson and Shain, provides information on the status of the Sb···N bonding. Good correlations between the electrochemical parameters derived from the oxidation current and the Sb···N bond distance are obtained. Additionally, the cyclic voltammetry of a mixture of the precursors leads to the discovery of their intermolecular hypervalent complexes.

Synthesis and properties of optically active organoantimony compounds

The chemistry of chiral ligands for transition metal-catalyzed asymmetric reactions is an interesting research field in synthetic chemistry and has recently been the focus of much attention. Although a number of chiral ligands containing phosphorus (P) and arsenic (As) have been widely studied and are well documented, asymmetric reactions with optically active organoantimony compounds have not been reported so far. We are interested in the synthesis and utilization of optically active organoantimony compounds for asymmetric synthesis. We present here the synthesis and resolution of Sb-chiral and C2-symmetric compounds containing antimony as well as their physical and chemical properties. Resolution of (+/-)-1-phenyl-2-trimetylsilylstibindole (1), Sb (R/S)-(aryl) [2-(S)-(1-dimethylaminoethyl) phenyl] (p-tolyl) stibane (9), and (+/-)-2,2'-bis(diarylstibano)-1,1'-binaphthyl (13) can be achieved by the separation of a mixture of the diastereomeric antimony-palladium complexes. The optically pure Sb-chiral stibanes (1, 9) isolated here were optically stable, and no racemization on the chiral antimony center was observed even when they were heated under a neutral or a basic condition. Single-crystal X-ray analysis of Sb-chiral triarylstibane 9b-B revealed the presence of an intramolecular interaction between the antimony and nitrogen atoms. The optically active BINASb (13) can be used as powerful chiral ligand for the palladium-catalyzed asymmetric allylic alkylation of racemic 1,3-diphenyl-2-propen-1-yl acetate with dimethyl malonate. We also report the synthesis, molecular structure, and fluxional behavior of the (R)-(-)-7-p-tolyl-dinaphtho [2, 1-b; 1',2'-d] stibole (21c) which is the first isolated example of optically active C2-symmetric group 15 dinaphthoheteroles.

Synthesis of Sb-chiral organoantimony compounds having intramolecular Sb⋯N interaction and their separation into optically pure compounds via ortho-palladated benzylamine complexes

A diastereomeric mixture of Sb-chiral triarylstibanes having an amine moiety on an aryl group, Sb( R/ S)-(aryl)[2-( S)-(1-dimethylaminoethyl)phenyl]( p-tolyl)stibanes ( 4a– c), has been prepared by stepwise nucleophilic displacement of the ethynyl groups on bis(phenylethynyl)( p-tolyl)stibane ( 1) with Grignard reagents 2a– c and 2-[( S)-(dimethylamino)ethyl]phenyllithium. Although direct separation of the diastereomeric mixtures of 4 was unsuccessful, they could be separated with ease via their palladium complexes 6 formed from the reactions of the stibanes 4 with di-μ-dichlorobis(2-dimethylaminobenzyl- C 1, N)dipalladium(II) ( 5). The diastereomerically pure Sb-chiral stibanes isolated here were optically stable, and no racemization on the chiral antimony center was observed even when they were heated at 110 °C over 24 h in toluene or pyridine. The single X-ray crystal analysis of Sb( S)–[2-( S)-(1-dimethylaminoethyl)phenyl](1-naphthyl)( p-tolyl)stibane ( 4b- B) revealed the presence of intramolecular interaction between the antimony and nitrogen atoms.

Two successive single crystal phase transitions involving the coordination sphere of antimony in PhSb(dmit), the first organo-antimony(III) dithiolene complex.

PhSb(dmit) (dmit(2)(-), 4,5-dithiolato-1,3-dithiole-2-thione), the first neutral organo-antimony dithiolene complex, has been synthesized by addition of PhSbCl(2) on a suspension of Na(2)(dmit). The complex was characterized by spectroscopic ((1)H and (13)C NMR and IR) methods and elemental analysis. Its crystal structure was determined by X-ray diffraction at room temperature in the monoclinic P2(1)/c space group, with a = 12.580(3), b = 8.9756(18), c = 15.905(3) A, beta = 109.06(3) degrees, V = 1697.5(6) A(3), Z = 4. A coordinating THF molecule was found in the structure and the coordination geometry around the antimony atom is of distorted pseudopentagonal bipyramid type, if taking into account the Sb.O and secondary Sb.S interactions, as well as the stereochemically active 5s(2) lone pair. The intermolecular Sb.S and S.S contacts, shorter than the sum of van der Waals radii of corresponding atoms, lead to the formation of a three-dimensional polymeric network in the solid state. A second X-ray diffraction experiment, performed at 85 K, revealed a very similar monoclinic unit cell with the noncentrosymmetrical space group P2(1) with a = 12.613(3), b = 8.9876(18), c = 15.109(3) A, beta = 107.01(3) degrees, V = 1637.8(6), Z = 4. The structural differences with the first one are basically due to the rotation of the THF ligand in the coordination sphere of the antimony center, leading to the loss of every inversion center found at room temperature. A temperature variable X-ray diffraction study on a PhSb(dmit) single-crystal allowed the detection, with a remarkable accuracy, of two successive first-order phase transitions, the first occurring at T = 162.5 K, while the second was observed at T = 182.5 K. Subsequently, a third set of X-ray data was collected at 180 K and the resulting structure (monoclinic, P2(1)/c, a = 16.736(3), b = 8.9653(18), c = 33.132(7) A, beta = 91.98(3) degrees, V = 4968.2(17), Z = 12) derives from the two others by a common b axis, a 3-fold cell volume increase, and the presence of only one-third of the inversion centers present at room temperature. A DSC analysis, showing two endothermic peaks at the expected temperatures, confirms the occurrence of the two structural phase transitions, also in agreement with preliminary Raman data.

THE MOLECULAR STRUCTURE O F [{SbEtBr(μ-Br)[SCN(Me)C2Me2N(Me)]}2

[Extract] Prior to this work there were no crystallographically characterised examples of imidazolethione adducts of organoantimony compounds and only 3 exaamples of imidazolethione adducts of antimony trihalides [1-3]. The antimony centre in the present compound has a slightly distorted square based pyramidal geometry and a stereochemically active lone pair. The compound sits on an inversion centre and is dimeric thorugh unsymmetrical Sb-Br-Sb bridges, both the longer and shorter interactions of which oie in the normal region for SB-Br bonds [4]. The geometry of the imidazolethione ligand in the complex is similar to its geometry in the uncoordinated state [5].

Group 15 Complexes with α-Hydroxy Carboxylic Acids: 7. The Preparation and Structure Determination of Sodium (+)-Tartrato Arsenate(III), [Na8As10(C4H2O6)8(C4H3O6)2(H2O)19]n; Silver(I) (+)-Tartrato Arsenate(III), [Ag9As10(C4H2O6)9(C4H3O6)(H4As2O5) (H2O)10]n and Rubidium Citrato Antimonate(III), [Rb2Sb4(C6H5O7)2(C6H6O7)2(C6H7O7)4(H2O)2

The structures of sodium (+)-tartrato arsenate(III),[Na8As10(C4H2O6)8(C4H3O6)2(H2O)19]n(1), silver (+)-tartrato arsenate(III),[Ag9As10(C4H2O6)9(C4H3O6)(H4As2O5)(H2O)10](2) and rubidium citrato antimonate(III)[Rb2Sb4(C6H6O7)6(C6H7O7)2(H2O)2](3) have been determined by X-ray methods and refined to residuals of 0.085(1), 0.072 (2) and 0.065 (3) for 5018, 4487 and 8207 observed reflections,respectively. The (+)-tartrato complexes (1) and (2) are similar instructure to the two known isomorphous silver(I) (+)-tartratoarsenate(III) complexes in that independent anionic[As2(tartrate)2] dimericcages are linked to the sodium or silver counter-cations, respectively,through free carboxyl oxygen atoms. However, the structures are made morecomplex by the presence of labile water molecules in the lattice, resulting insome disorder. Furthermore, charge balance in both (1) and (2) requires thepresence of two and one tri-negative tartrato units, respectively, among theten independent tartrate units in each structure, an unusual feature for Asand Sb complexes with this ligand species. Bond distances within the fivearsenic(III)-(+)-tartrate dimers in each structure are: As–O(hydroxy), 1.75(2)–1.84(2) Å (1); 1.75(3)–1.83(2) Å(2) and As–O (carboxy), 1.94(2)–2.13(3) Å (1);1.95(2)–2.14(2) Å (2). In addition, the structure of (2) has twoshort Ag–As bonds [2.500, 2.524(3) Å] in the terminalsites of two of the f ive independent dimers, as well as an additionalAg–As bond [2.613(4) Å] to an unusual dimeric arseniousacid residue(H4As2O5),part of an As2AgO3 hetero-ringforming the polymeric network structure. The antimony(III) citrate complex (3)is isomorphous and isostructural with the previously reported potassiumanalogue which involves mixed-valence citrato ligands in conventionalbis-chelate four-coordination about the antimony centres, linked by bothseven- and eight-coordinate rubidium ions [Rb–O,2.743(10)–3.102(9) Å]. The arsenic and antimony atoms in allcompounds have typical distorted pseudo-trigonal bipyramidal stereochemistry.

Reactions of an antimony containing cage compound with metal carbonyls: synthesis and structural characterization of [{M(CO)5}2(η1:η1-P4Sb2C4But4)], M = Cr, Mo or W, and [{Fe(CO)4}2{Fe(CO)3(η3:η1-P4Sb2C4But4)}

The antimony containing cage compound, P4Sb2C4But4, was treated with an excess of [M(CO)5(THF)], M = Cr, Mo or W, to produce the 2∶1 adduct complexes, [{M(CO)5}2(η1∶η1-P4Sb2C4But4)], which X-ray crystallographic studies have shown to contain one M(CO)5 fragment co-ordinated to an unsaturated phosphorus centre and one co-ordinated to an antimony centre. In contrast, its reaction with an excess of [Fe2(CO)9] produced [{Fe(CO)4}2{Fe(CO)3(η3∶η1-P4Sb2C4But4)}], which is probably formed by the insertion of an Fe(CO)3 fragment into an Sb–P bond of the cage. Its crystal structure confirms that it contains two η1-co-ordinated Fe(CO)4 groups and a 1,3-diphosphaallyl fragment η3 co-ordinated to an Fe(CO)3 moiety.

Ph4P]2[Sb2S15

The reaction of antimony chloride, sulfur and tetraphenylphosphonium bromide in an aqueous ammonia solution under hydrothermal conditions yields orange crystals of bis(tetraphenylphosphonium) μ-sufido-μ-tetrasulfido-S1:S4-bis[(pentasulfido-S1,S5)antimonate], [(C6H5)4P]2[Sb2S15]. The structure contains tricyclic molecular Sb2S152− anions built up of two distorted ψ-trigonal bipyramidally coordinated antimony centres which are connected by two Sx2− units (x = 1,4) and bound to an additional S52− ligand.

Tetrahydrofuran Adducts of a Chlorobismuthate(III) Anion and Antimony Triiodide

Tetrahydrofuran (thf) adducts of a chlorobismuthate(III) anion and of antimony triiodide have been prepared and characterized by X-ray crystallography. The former compound, bis[tetrakis(tetrahydrofuran-O)lithium(I)] di-μ-chloro-bis[trichloro(tetrahydrofuran-O)bismuthate(III)], [Li(C4H8O)4]2[Bi2Cl8(C4H8O)], contains centrosymmetric edge-shared bi-octahedral dianions with the formula [Bi2Cl6(thf)2(μ-Cl)2]2− in which the thf ligands occupy terminal sites at 90° to the Bi2(μ-Cl)2 plane; the cations are [Li(thf)4]+. The latter structure, triiodo(tetrahydrofuran-O)antimony(III), [SbI3(C4H8O)], comprises a polymeric arrangement of SbI3(thf) units, the antimony centres bridged alternately by pairs of I atoms and pairs of thf ligands.

Polyhetero-ferrocenes and -ruthenocenes derived from the 1,4,2-diphosphastibolyl ring anion [P2SbC2But2

The complex [RuCl 2 (PPh 3 ) 3 ] reacted with the 1,4,2-diphosphastibolyl ring anion [P 2 SbC 2 Bu t 2 ] - (containing ca. 25% of the 1,2,4-triphospholyl anion [P 3 C 2 Bu t 2 ] - ) to produce a cocrystallised mixture (crystal structure) of two isomers of [Ru(η 5 -P 2 SbC 2 Bu t 2 ) 2 ] with [Ru(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -P 3 C 2 Bu t 2 )]. Variable-temperature 31 P-{ 1 H} NMR studies on the mixture show one of the isomers and the last complex to be fluxional at room temperature. It is believed that an interring Sb · · · Sb interaction in the other isomer restricts its fluxionality in solution. The reaction of [P 2 SbC 2 Bu t 2 ] - with FeCl 2 yielded only one isomer of the heteroferrocene complex [Fe(η 5 -P 2 SbC 2 Bu t 2 ) 2 ] which is also non-fluxional in solution and has a similar oxidation potential to that of ferrocene itself. The heteroruthenocene complexes [Ru(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 R 5 )] (R = H or Me) were prepared by treating [Ru(η 5 -C 5 R 5 )(MeCN) 3 ] [PF 6 ] (R = H or Me) with [P 2 SbC 2 Bu t 2 ] - . The analogous ferrocene complex [Fe(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 )] (crystal structure) was synthesized by treating a 1∶1 mixture of [P 2 SbC 2 Bu t 2 ] - and Li(C 5 Me 5 ) with half an equivalent of FeCl 2 . Treatment of [M(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 )] (M = Ru or Fe) with [W(CO) 5 (thf)] (thf = tetrahydrofuran) formed the secondary co-ordination complexes [M(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 ){W(CO) 5 }] (M = Ru or Fe) in which the W(CO) 5 fragment is η 1 ligated to the phosphorus centre adjacent to the ring antimony centre. A diphosphastibolyl-bridged cationic triple-decker complex [(η 5 -C 5 Me 5 )Ru(µ-η 5 : η 5 -P 2 SbC 2 Bu t 2 )Ru(η 5 -C 5 Me 5 )][PF 6 ] was the product of the reaction of [P 2 SbC 2 Bu t 2 ] - with 2 equivalents of [Ru(η 5 -C 5 Me 5 )(MeCN) 3 ] [PF 6 ].

Controlled hydrolysis reactions of the Group 15 element–azamacrocyclic complexes MCl3L (M = As, Sb or Bi; L = 1,4,7-trimethyl-1,4,7-triazacyclononane). Formation and crystal structures of [AsCl2L][As2OCl5], [H2L]2[Sb2OCl6]Cl2, [HL]I and [H2L]2[Sb2Cl9]Cl·MeCN·H2O

Reactions of MCl3(M = As, Sb or Bi) and 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3[9]aneN3= L) gave the respective 1 : 1 adducts as white-yellow microcrystalline solids which were characterised by microanalytical and spectroscopic (IR and 1H NMR) data. Addition of water to AsCl3L under controlled stoichiometry in acetonitrile solution led to the formation of the white crystalline salt [AsCl2L][As2OCl5]1. A crystal structure determination revealed the cation as five-co-ordinate with ψ-octahedral metal geometry featuring a cis-AsCl2+ unit co-ordinated to the three donor nitrogen atoms of the ligand (fac) and a stereochemically active lone pair occupying the sixth site [As–Cl 2.462(7), 2.520(7) and As–N 2.18(2), 2.12(2), 2.10(2)A with the latter directly opposite to the lone pair]. The anion is made up of a dinuclear (µ-oxo) Cl2As–O–AsCl2 unit with a single Cl– anion linked symmetrically to the two separate arsenic atoms [mean As–Clterminal 2.216(8), As–Clbridge 2.795(8)A]. Controlled hydrolysis of SbCl3L in acetonitrile solution provided colourless needle crystals of [H2L]2[Sb2OCl6]Cl22 as identified by X-ray diffraction studies. The structure of the dication shows protonation of two of the three nitrogen atoms with strong intramolecular hydrogen bonding N–H ⋯ N 2.70–2.85 A involving the third amine centre. This is the first structural characterisation of the diprotonated form of L. The structure of the accompanying chlorooxoantimony(III) anion can be described as a single (µ-oxo) Cl2Sb–O–SbCl2 unit linked to two chloride ions via secondary Sb ⋯ Cl bonding involving the two metal centres [mean Sb–Clterminal 2.435(3), Sb–Clbridge 2.863(3)A]. Each of the antimony(III) centres is further associated with a unique chloride anion, Sb ⋯ Cl– 3.550(7)A, which, in turn, forms close contacts with the two protonated nitrogen atoms of the triazamacrocycle Cl ⋯ H–N 3.07, 3.02 A. Treatment of L and SiMe3I in acetonitrile solution provided yellow needle crystals of [HL]I 3. X-Ray (diffraction) crystallographic characterisation revealed a monoprotonated ring (L) in which the single proton is bonded directly to one nitrogen atom and to the remaining two via intramolecular hydrogen N–H ⋯ N 2.71 A. The product isolated from the reaction of L and SiCl4 in the presence of antimony(V) chloride as halide abstractor in acetonitrile was identified by a crystal structure determination as [H2L]2[Sb2Cl9]Cl·MeCN·H2O 4. The structure reveals two [H2L]⋯Cl moieties which have dimensions similar to those found for 2. Conformational analyses have been carried out on free L and its mono-, di- and tri-protonated forms and the results are consistent with the experimental conformations observed in this work and elsewhere.

Preparation and crystal structures of diphenylantimony(III) thiocyanate and bis(2,6-dimethylphenyl)antimony(III) thiocyanate

Diphenylantimony(III) and bis(2,6-dimethylphenyl)antimony(III) thiocyanates have been prepared by metathesis reactions between the appropriate diarylantimony(III) halide and potassium thiocyanate in acetonitrile solution. The second compound was also obtained by thermal decomposition of tris(2,6-dimethylphenyl)antimony(V) dithiocyanate. Crystal structure determinations showed that in SbPh2(NCS) the thiocyanate group bridges between antimony centres to give an infinite polymer, while the 2,6-dimethyl-substituted analogue is an N-bonded monomer. The diphenylantimony structure is probably unique in that the asymmetric unit consists of three formula units and, although each thiocyanate group is bridging, two are primarily N-bonded while the third is primarily S-bonded. Angles at the bridging nitrogens are large (150.4–174.9°) while those at sulfur are close to 90°(85.7–98.6°). These in conjunction with the presence of thiocyanate groups in the axial positions of pseudo-trigonal-bipyramidal arrangements about antimony lead to a curious ‘triangular spiral’ structure for the polymeric chains.

Neutral thiolates of antimony(III) and bismuth(III)

A range of bismuth(III) and antimony(III) thiolates, Bi(SR)3(R = C6F5, 4-MeC6H4, 2,6-Me2C6H3 or 3,5-Me2C6H3) and Sb(SR)3(R = 4-MeC6H4 or 3,5-Me2C6H3) has been synthesised and the structures of the two antimony complexes have been determined. Both structures reveal a trigonal-pyramidal antimony centre bonded to three thiolate groups with, for the 4-MeC6H4 complex, additional intermolecular Sb ⋯ S interactions and, for the 3,5-Me2C6H3 complex, intermolecular arene to antimony interactions. The syntheses and structures of the organotransition-metal complexes [Bi(SC6F5){M(CO)3(η-C5H5)}2](M = Mo or W) are also reported in which the bismuth centre is bonded to one SC6F5 group and two M(CO)3(η-C5H5) fragments with no short intermolecular interactions.