Moira-Ann Rennie

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.

A comparison of the reactions of PPh2CH2SR (R = Me, Ph) with alkyne-bridged dicobalt carbonyl complexes and with an iron dicobalt μ3-thioxo carbonyl complex

Abstract The reactions of Ph 2 PCH 2 SR (R = Me, Ph) in toluene with the dicobalt complexes [Co 2 (μ-R 1 CCR 2 (CO) 6 ] (R 1 = R 2 = CO 2 Me and R 1 = H, R 2 = CO 2 Me) give the monosubstituted complexes [Co 2 (μ-R 1 CCR 2 )(CO) 5 PPh 2 CH 2 SMe] 1 and [Co 2 (μ- R 1 CCR 2 (CO) 5 PPh 2 CH 2 SPh] 2 . On heating 1 and 2 in toluene solution, loss of CO leads to the bridged species [Co 2 (μ-R 1 CCR 2 )(μ- PPh 2 CH 2 SMe)(CO) 4 ] 3 and [Co 2 (μ -R 1 CCR 2 )(μ-PPh 2 CH 2 SPh)(CO) 4 ] 4 . This transformation is readily reversed by treatment of 3 and 4 with CO, showing the Co-S bond in these complexes to be relatively weak. Similar reactions of Ph 2 PCH 2 SR (R = Me, Ph) with [Co 2 Fe(μ 3 -S)(CO) 9 ], however, give only the ligand bridged species [Co 2 Fe(μ 3 -S)(μ-Ph 2 PCH 2 SR)(CO) 7 ] (R = Me 5 and R = Ph 6 ). Treatment of 5 and 6 with CO causes cleavage of the Co-S bond but, in contrast to 3 and 4 , the ligand bridged species readily reform when the CO purge ceases. The structures of 3a and 6 have been confirmed by single-crystal X-ray analysis.

Synthesis and structure of [{(Me3Si)2N}2Cd{(PhN)3C}Li2·3thf]; an unusual heterobimetallic co-complex containing three different metal coordination environments

Dilithio-1,2,3-triphenylguanidide, [{(PhN)3C}Li2], reacts with [Cd{N(SiMe3)2}] to give [{(Me3Si)2N}2Cd{(PhN)3}Li2·3thf] 1; a novel co-complex containing three different metal coordination environments.

Syntheses and structural studies of two adducts of cadmocene, [CdCp2. TMEDA] and [CdCp2. PMDETA] (TMEDA Me2NCH2CH2NMe2, PMDETA (Me2NCH2CH2)2NMe)

Abstract Cp 2 Cd.TMEDA 1 and Cp 2 Cd.PMDETA 2 have been synthesized and characterized by spectroscopic studies and by X-ray diffraction studies at low-temperature (153 K). The adducts are present in the crystals as mononuclear complexes. When the denticity of the Lewis base ligands in these adducts is increased (from two in 1 to three in three in 2 ) the Cd 2+ centre requires less electron density from the Cp ligands and the hapticity changes from η 2 − in 1 to η 1 − in 2 . Complexes 1 and 2 are the first compounds for which π-bonding of Cp ligands to Cd 2+ has been observed in the solid state.

Step-wise nucleophilic substitution of bis(cyclopentadienyl)-tin(II); synthesis and structural characterisation of [{Sn(η3-C5H5)[µ-NC(NMe2)2]}2] and [{Sn[S(CH2)3SC(R)][µ-NC(NMe2)2]}2](R = H or SiMe3)

Nucleophilic substitution of Sn(C5H5)2 with LiNC(NMe2)2 led to the monosubstitution of only one C5H5 ligand yielding dimeric [{Sn(η3-C5H5)[µ-NC(NMe2)2]}2] in which the remaining C5H5 group can be further substituted by reactions with lithiated 1,3-dithianes to give the dimeric mixed-ligand imino–1,3-dithiane complexes [{Sn[[graphic omitted](R)][µ-NC(NMe2)2]}2](R = H or SiMe3).

Syntheses and structures of trans-[ReX(CO)(Ph2PCH2PPh2)2] (X Cl, OReO3), including a rhenium(I)-rhenium(VII) complex

Reduction of Re2Cl10 or NH4ReO4 by NaBH4 in the presence of Ph2PCH2PPh2, dppm, and CO provides a simple route to the complexes trans-[ReX(CO)(dppm)2], 1, X  Cl or 2, X  ReO4 respectively. Both complexes have been characterised by an X-ray diffraction study. In each complex the Ph2PCH2PPh2 ligands adopt the chelating bonding mode and the coordination geometry around the rhenium(I) centre is distorted octahedral. Complex 2 contains both rhenium(I) and rhenium(VII) centres, and a ReO ReO3 linkage with ReIO and ReVIIO distances of 2.207(3) A and 1.754(3) A, respectively.

Synthesis and structure of the mixed anion sandwich complex {[(C5H5)9Pb4]–[(C5H5)5Pb2]–[Li(12-crown-4)2]+2}

The title compound, {[(C5H5)9Pb4]–[(C5H5)5Pb2]–[Li(12-crown-4)2]+2}1, is synthesised by the reaction of [(C5H5)2Pb] and [(C5H5)Li] and 12-crown-4 (3:1:2 equiv. ), and is shown by X-ray diffraction to contain both a quintuple-decker and a triple-decker sandwich anion; in contrast, the corresponding reaction with [(C5H5)2Sn](which possesses no such polymeric lattice of its own) in place of [(C5H5)2Pb]∞ yields the simple ‘paddlewheel’ molecule {[(C5H5)3Sn]–[Li(12-crown-4)2]+}2.

Facile synthesis of Sn4N4 cubanes; syntheses and structures of [Sn(NC6H11)]4 and [Sn(2-NCH2C5H4N)]4

The low-temperature reaction of Sn(NMe2)2 with primary amines (NH2R)(1 : 1 equivalents) is a general route by which imido tin(II) cubanes [Sn(NR)]4 can be prepared. It has been exemplified by the direct reactions of the relatively non-acidic primary amines NH2(C6H11) and 2-H2NCH2C5H4N, producing the cubanes [Sn(NC6H11)]41 and [Sn(2-NCH2C5H4N)]42. The structures of both complexes have been established by X-ray crystallography.