Reactions of tetrachloro(cyclopentadienyl)niobium with arenedithiolates yielded products [NbCp(1,2-S2C6H3R-4)2] (Cp = ?5-C5H5; R = H 1 or Me 2), characterised primarily by analysis, 1H NMR and mass spectroscopy. Cyclic voltammetric studies on 1 and 2 showed two consecutive, quasi-reversible, reduction processes; ESR spectra of the initial products of chemical reduction were typical of those from niobium(IV) species with an unpaired electron largely centred on the metal and assigned to the anions [NbCp(1,2-S2C6H3R-4)2]-. Similar tantalum derivatives were less tractable, although properties of the more soluble species [TaCp'(1,2-S2C6H4)2] (Cp' = ?5-C5H4Me) are reported. Reactions of tetrachloro(methylcyclopentadienyl)-niobium or -tantalum with salts of ethane-1,2-dithiol (H2edt) were very susceptible to hydrolysis and the major isolable products of reactions using the sodium reagent (Na2edt) were [M2(µ-O)(µ-n2:?2-edt)Cp' 2Cl4] (M = Nb 4 or Ta 5), containing oxo and symmetrical dithiolate bridges. Reaction of [NbCp'Cl4] with 2 molar equivalents of TI2edt formed the unsymmetrical compound [Nb2(µ-?1 : ?2-edt)2 Cp'2O(edt)] 6, containing a terminal oxide ligand, one chelating and two unsymmetrically bridging edt groups. Structures of compounds 4 and 6 have been determined in the solid state by X-ray crystallography; 1- and 2-D NMR spectra of the binuclear products support the retention of these structures in solution.
|Number of pages||6|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 7 Oct 1998|