Bis(alkylidynyl)tellurides and ditellurides.

The tellurocarbonylates [M(CTe)(CO)2 (Tp*)]- (M = Mo, W; obtained from [M([triple bond, length as m-dash]CBr)(CO)2 (Tp*)] and Li2 Te or [M([triple bond, length as m-dash]CLi)(CO)2 (Tp*)] and Te) react with an additional equivalent of [M([triple bond, length as m-dash]CBr)(CO)2 (Tp*)] to give bis(alkylidynyl)tellurides, [M2 (μ-CTeC)(CO)4 (Tp*)2 ], whilst oxidation with [Fe(η-C5 H5 )2 ]PF6 affords the corresponding ditellurides [M2 (μ-CTe2 C)(CO)4 (Tp*)2 ]. The unprecedented M[triple bond, length as m-dash]CTeC[triple bond, length as m-dash]M and M[triple bond, length as m-dash]CTe2 C[triple bond, length as m-dash]M bridges are discussed with reference to more conventional but rare alkylidynyltelluroethers [M([triple bond, length as m-dash]CTeR)(CO)2 (Tp*)] (R = Me,n Bu, Ph).