Michael A. Paver

Two triorganostannate complexes synthesised from bis(cyclopentadienyl)tin(II); structural variation between [Mg(thf)6]2+2[Sn(η3-C5H5)3]– and [Li(thf)4]+[Sn(C13H9)3]–(thf = tetrahydrofuran, C13H9= fluorenyl)

Nucleophilic addition of Mg(C5H5)2 to Sn(C5H5)2(1 : 2) in tetrahydrofuran (thf) gave [Mg(thf)6]2+ 2[Sn(η3-C5H5)3]21 whereas the reaction of fluorenyllithium (2 or 3 equivalents) resulted in nucleophilic substitution of both C5H5 ligands and in the formation of [Li(thf)4]+[Sn(C13H9)3]–2; the anion of 1 is essentially planar whereas that in 2 has a distorted-pyramidal structure.

Synthesis and structure of [Sb2Li2{N(C6H11)}4]2; a cage complex containing a core of two interlocked ‘broken’ cubes

The imido cage complex [Sb2Li2{N(C6H11)}4]2, synthesised by the condensation reaction of dimeric [Sb(NMe2){µ-N(C6H11)}]2 with [LiNH(C6H11)]n(1 : 1 monomer equiv.) consists of an Sb4Li4N8 polyhedral core which can be viewed as being constructed from two interlocked ‘broken’ cubes.

Synthesis and structure of [Bi2(NtBu)4]2Li2·2THF; a bimetallic cubane fragment containing a [Bi2(NtBu)4]2− anion

Abstract The imido-Bi complex [Bi2(NtBu)4]Li2·2THF (1) has been prepared by the in situ reaction of [(Me2N)Bi(μ-NtBu)]2 with [tBuNHLi] in toluene/THF solution. The complex has been characterised by elemental analysis, solid-state IR spectroscopy, 1H NMR spectroscopy in solution, and by a low-temperature (153 K) X-ray diffraction study. The complex crystallises in the monoclinic space group P21/n, with cell dimensions a = 11.158(2), b = 16.777(3), c = 17.239(3) A , β = 92.45(3)°, V = 3224.2(10) A 3 and Z = 4 . Molecules of 1 consist of discrete [Bi2Li2N4] cubane units in the solid state. Further association of these units into a structure akin to the previously characterised complex [Sb2(NCy)4]2Li4 (2), consisting of a cage of two interlocked ‘broken cubes’, is prevented by Lewis base solvation of Li. Solution NMR and cryoscopic studies of 2 show that the complex is involved in a dissociative equilibrium in which separate cubane units, similar to those identified in 1, are formed.

The next homologue of the bis(cyclopentadienyl)thallate anion; synthesis and X-ray structure determination of [(η5-C5H5)Tl(µ-C5H5)Tl(µ5-C5H5)]–[Li(12-crown-4)2]+·thf

Reaction of (C5H5)Li with (η5-C5H5)Tl (1.2 equiv.) in the presence of 12-crown-4 (2 equiv.) produces the ion-separated complex [(η5-C5H5)Tl(µ-C5H5)Tl(µ5-C5H5)]–[Li(12-crown-4)2]+·thf 1 which contains the first homometallic main group metal triple-decker sandwich as the anion; this anion can be viewed as the first homologue of the thallocene anion [(η5-C5H5)2Tl]a– and is a molecular segment of the polymeric structure of [(η5-C5H5)Tl]∞.

Structure and reactivity of [{Te(NMe2)2}∞]; application to the preparation of metalloorganic tellurium(II) compounds

Condensation of the highly reactive complex [{Te(NMe2)2}∞]1, prepared by the reaction of TeCl4 and Li[NMe2](1 : 4 equivalents), with various organic acids has been used as a route to tellurium(II) metalloorganic complexes. The crystal structures of 1 and of Te(SCPh3)22, formed by the reaction of 1 with Ph3CSH(1 : 2 equivalents), have been determined.

Dimeric antimony complexes capturing dimethylamine as a neutral donor; syntheses and structural characterisation of [SbCl2(NHMe2)(µ-OEt)]2 and [SbCl(NHMe2)(µ-NBut)]2

The two dimeric antimony complexes, [SbCl2(NHMe2)(µ-OEt)]2 and [SbCl(NHMe2)(µ-NBut)]2 have been synthesised by the reaction of SbClx(NMe2)3–x with EtOH (x= 2) or NH2Bu2(x= 1) respectively; both complexes exhibit the co-ordination of a dimethylamine ligand to antimony and intricate intermolecular association in the solid state.

A model intermediate for the nucleophilic substitution of (Cp)2Sn; synthesis and structure of (Cp)(Me3Si)2NSn(µ-Cp)Li·pmdeta [Cp = C5H5, pmdeta =(Me2NCH2CH2)2NMe]

Reaction of LiN(SiMe3)2 with Cp2Sn and pmdeta produces (Cp)(Me3Si)2NSn(µ,-Cp)Li·pmdeta 1 which can be viewed as a model intermediate for nucleophilic substitution of Cp2Sn.

Organo-functionalised arsine and stibine organometallics; syntheses and structural characterisations of 1,3-[(PhCC)2Sb]2(CH2)3, As(CCPh)3, R2AsCH2AsR2 [R=Me3SiCC-, (Me3Si)2N- and 2-SPy] with π-stacking in the latter

A series of dinuclear organo-functionalised stibine and arsine ligands incorporating a range of hard, soft and pi-donor moieties have been synthesised from the reactions of Cl2Sb(CH2)(3)SbCl2 and Cl2AsCH2AsCl2 with a range of organolithium reagents. The X-ray structures of 1,3-[(PhCdropC)(2)Sb](2)(CH2)(3) (1), As(CdropCPh)(3) (2), R2AsCH2AsR2 [R = Me(3)SiCdropC, 3; (Me3Si)(2)N, 4; and 2-SPy 5] have been determined. Compound 5 associates into pseudo dimers as a result of intermolecular pi-pi stacking between the pyridyl groups on one end of two separate diarsine molecules. Whereas the bridging unit remains intact during the syntheses of 1 and 3-5, the formation of the mononuclear trisacetylide species 2, involves the unexplained cleavage of the bridging methylene unit.

Synthesis and structure of [{As(NtBu)3}2Li6] containing an [As(NtBu)3]3− trianion

Abstract Attempts to prepare the [As(NtBu)3]3− trianion by the reaction of As(NMe2)3 with [tBuNHLi]n (1:3 monomer equiv.) proved unsuccessful. However, if the reaction is carried out with an excess of tBuNH2 (3 equiv.) the target complex [{As(NtBu)3}2Li6] (1) is obtained. This is the first example of a complex containing an [As(NR)3]3− trianion.

Intramolecular versus intermolecular bonding in amidoantimony dimers; syntheses and structures of {Sb(NMe2)[µ-N(mpy)]}2(mpy = 4-methylpyridin-2-yl) and [Sb(NMe2){µ-N[C6H2(OMe)3-3,4,5]}]2

The reaction of Sb(NMe2)3 with 2-amino-4-methylpyridine (1 : 1 ratio) produced {Sb(NMe2)[µ-N (mpy)]}2(mpy = 4-methylpyridin-2-yl) which forms unassociated dimers in which relatively weak intramolecular Sb ⋯ N interactions are present [2.891(5)A], whereas a similar reaction with 3,4,5-trimethoxyaniline produced [Sb(NMe2){µ-N[C6H2(OMe)3-3,4,5]}]2in which the dimer units are associated into a loosely linked polymer by intermolecular chelating MoO ⋯ Sb interactions [3.500(5)A].