Structure of the 17-electron Cp *MoCl 2(dppe): an unexpected trans geometry in the solid state

Abstract

Compound Cp *MoCl 2(dppe) crystallizes in the monoclinic space group P2 1/ c, a=16.9063(10), b=11.0118(8), c=18.6128(14) Å, β=111.713(6)°, V=3219.3(4) Å 3, Z=4, D calc=1.445 Mg m −3, μ(Mo Kα)=0.698 mm −1, R1=0.0448, wR2=0.0906 for all data, R1=0.0337, wR2=0.0839 for 4754 data with I>2 σ( I). The geometry of the compound is a four-legged piano stool as typically found for this class of compounds, but the dppe ligand occupies relative trans position whereas the previously reported CpMoBr 2(dppe) has the more common cis geometry. EPR spectroscopic investigations indicate that a mixture of isomers is present in solution and that the relative amounts of the isomers are both solvent and temperature dependent.