Bach, H. J. and Brunner, Henri and Wachter, Joachim and Kubicki, Marek M. and Leblanc, J. C. and Moise, C. and Volpato, F. and Nuber, B. and Ziegler, M. L.
Metallocene sulfide chemistry of niobium and tantalum: new insights into the formation of niobium-polysulfido complexes and synthesis, structure, and reactivity of Cp2'Ta(.eta.2-S2)H (Cp' = tert-BuC5H4).
Organometallics 11 (3), pp. 1403-1407.
The previously described reaction of Cp'2NbH3 (Cp' = t-BuC5H4) with S8 was investigated with regard to the kinetic stabilization of as yet elusive intermediates during the formation of the polysulfide complex Cp'4Nb2S9 (1). Therefore, the permethylated complex Cp*2NbS3H (2; Cp* = C5Me5) and the Ta complex Cp'2TaS2H (3) were synthesized in a related reaction and structurally investigated. Despite the problematic localization of the hydride atom during X-ray crystallographic studies, the molecules can be described in a proper manner: Characteristic of 2 and 3 are M(eta(2)-S2) cores to which either an SH (2) or a H (3) ligand is attached. Complex 3 is the first known tantalocene sulfide. It readily loses sulfur upon reaction with PR3 (R = C6H5, OCH3) and CH3I to form compounds 4 and 5, which both contain the Ta = S moiety. Attempts to prepare `'classical'' metallocene sulfides by metathesis reaction of Cp'2NbCl2 and Li2S5 gave the polynuclear compounds Cp'3Nb3S10O (6) and Cp'4Nb4S13 (7).