Addition of Cr(CO)5 to the M(η2- S2) moiety of Cp2 M(S2H (Cp′ = tBuC5H4 : M = Ta; CpX = C5Me4Et: M = Nb) and crystal structures of Cp′2TaS2H · [Cr(CO)5]n (n = 1, 2)

Abstract Reaction of Cp′ 2 TaS 2 H (Cp′ = t BuC 5 H 4 ) or Cp 2 x NbS 2 H (Cp x = C 5 Me 4 Et) with an excess of Cr(CO) 5 THF gives the adducts Cp′ 2 TaS 2 H · Cr(CO) 5 1 , Cp′ 2 TaS 2 H · 2Cr(CO) 5 2 , and Cp 2 x NbS 2 H · Cr(CO) 5 3 respectively. 1 and 2 are separated by fractional crystallisation. The crystal structures show the Cr(CO) 5 fragment in 1 to be coordinated to the ‘outer’ sulfur, and in 2 both Cr(CO) 5 fragments are coordinated to each sulfur of the S 2 ligand in a trans fashion. In all cases approximate sp 3 hybridisation of the S atoms is observed. The new compounds are thermally labile and give CO-free, trinuclear compounds of the type Cp 4 M 2 S 4 Cr upon heating their solutions.