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BuSCH2CH2CH2S n Bu, MeSCH2CH2CH2SMe, MeSeCH2CH2SeMe n BuSeCH2CH2CH2Se n Bu) have been synthesised and isolated in good yield as powdered solids by the reaction of TaCl5 with the appropriate chalcogenoether in a 1:1 molar ratio in anhydrous CH2Cl2 solution at room temperature, followed by the addition of a CH2Cl2 solution containing one mol. equiv. of S(SiMe3)2. The isolated complexes were characterised by IR, 1 H and 77 Se{ 1 H} NMR spectroscopy, as appropriate, and elemental analysis. Single crystal X-ray structure analyses for [TaSCl3(MeSCH2CH2SMe)], [TaSCl3(MeSeCH2CH2SeMe)], [TaSCl3(i PrSCH2CH2S i Pr)] and [TaSCl3(n BuSCH2CH2CH2S n Bu)] have been obtained. The data are compared with the previously described Nb(V) analogues. In contrast to the corresponding [NbSCl3(E n Bu2)] (E = S, Se), attempts to isolate [TaSCl3(E n Bu2)] were unsuccessful. Low pressure chemical vapour deposition (LPCVD) experiments using [TaSCl3(n BuSCH2CH2CH2S n Bu)] did not lead to any deposition, whilst similar experiments using [TaSCl3(n BuSeCH2CH2CH2Se n Bu)] produced only elemental Se films, with no evidence for any deposition of tantalum sulfide or selenide films.

The reaction of [GeF4L2], L = dmso (Me2SO), dmf (Me2NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh3, OPMe3, with Me3SiO3SCF3 (TMSOTf) and monodentate ligands, L, in a 1:1:1 molar ratio in anhydrous CH2Cl2 formed the monocations [GeF3L3][OTf]. These rare trifluoro-germanium (IV) cations were characterised by microanalysis, IR, 1H, 19F{1H} and, where appropriate, 31P{1H} NMR spectroscopy. The 19F{1H} NMR data show that in CH3NO2 solution the complexes exist as a mixture of mer and fac isomers, with the mer isomer invariably having the higher abundance. The X-ray structure of mer-[GeF3(OPPh3)3][OTf] is also reported. The attempts to remove a second fluoride using a further equivalent of TMSOTf and L were mostly unsuccessful, although a mixture of [GeF2(OAsPh3)4][OTf]2 and [GeF3(OAsPh3)3][OTf] was obtained using excess TMSOTf and OAsPh3. The reaction of [GeF4(MeCN)2] with TMSOTf in CH2Cl2 solution, followed by the addition of 2,2′:6′,2”-terpyridine (terpy) formed mer-[GeF3(terpy)][OTf], whilst a similar reaction with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-tacn) in MeCN solution produced fac-[GeF3(Me3-tacn)][OTf]. Dicationic complexes bearing the GeF22+ fragment were isolated using the tetra-aza macrocycles, 1,4,7,10-tetramethyl-1,4,7,10-tetra-azacyclododecane (Me4-cyclen) and 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (Me4-cyclam), which reacted with [GeF4(MeCN)2] and two equivalents of TMSOTf to cleanly form the dicationic difluoride salts, cis-[GeF2(Me4-cyclen)][OTf]2 and trans-[GeF2(Me4-cyclam)][OTf]2. The 19F{1H} NMR spectroscopy shows that in CH3NO2 solution there are four stereoisomers present for trans-[GeF2(Me4-cyclam)][OTf]2, whereas the smaller ring-size of Me4-cyclen accounts for the formation of only cis-[GeF2(Me4-cyclen)][OTf], and is confirmed crystallographically. New spectroscopic data are also reported for [GeF4(L)2] (L = dmso, dmf and pyNO). Density functional theory calculations were used to probe the effect on the bonding as fluoride ligands were sequentially removed from the germanium centre in the OPMe3 complexes.

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