Phosphine and isonitrile complexes of η 5-tetramethylcyclopentadienylrhodium chlorides; crystal structures of (η 5-C 5Me 4H)RhCl 2(PPh 2R) (R=Ph or C 6F 5)

Abstract

The reaction between [(η 5-C 5Me 4H)RhCl(μ-Cl)] 2 and the phosphines PPh 2R (R=Ph or C 6F 5) or cyclohexylisonitrile yields the complexes (η 5-C 5Me 4H)RhCl 2L ( 1, L=PPh 3; 2, L=PPh 2(C 6F 5); 3, L=CNC 6H 11). The structures of complexes 1 and 2 have been determined by single-crystal X-ray diffraction. Both exhibit three-legged piano stool geometry about the rhodium atom. Unlike the structures of (η 5-C 5Me 5)RhCl 2L complexes, the rhodium atoms of 1 and 2 do not lie on axes normal to the C 5 centroids, but are displaced towards the CH carbon atoms. Treatment of 1 with cyclohexylisonitrile or 3 with PPh 2(C 6F 5) in the presence of NaBF 4 yield the chiral-at-metal salts [(η 5-C 5Me 4H)RhCl(PPh 2R)(CNC 6H 11)] +·BF 4 − as racemic mixtures. The bis(isonitrile) complex, [(η 5-C 5Me 4H)RhCl(CNC 6H 11) 2] +·BF 4 −, is formed similarly from 3. Treatment of [(η 5-C 5Me 4H)RhCl(μ-Cl)] 2 with dppe in the presence of NaBF 4 yields [(η 5-C 5Me 4H)RhCl(dppe)] +·BF 4 −.