A unique pair of stereoisomers: synthesis and structures of cis-Mo2(μ-acetate)2[η2-N,N′-bis(trimethylsilyl)benzamidinate]2 and trans-Mo2(μ-acetate)2[μ-N,N′-bis(trimethylsilyl)benzamidinate]2

The reaction between lithium bis(trimethylsilyl)benzamidinate and dimolybdenum tetraacetate yields a mixture of two stereoisomers: trans- (2a) and cis-Mo2(O2CCH3)2[PhC(NSi(CH3)3)2]2 (2b). While the acetates coordinate to the Mo2 core via bridging mode in both compounds, the benzamidinates are bridging in 2a and chelating in 2b. The MoMo bond lengths are 2.0692(4) and 2.1241(3) Å for 2a and 2b, respectively.