((Diaryl- and Dialkylphosphino)alkyl)cyclopentadienyl Ligands and Their Use in the Preparation of Heterobinuclear Ti/Mo and Zr/Mo Complexes

The syntheses of a series of bifunctional ligands, in which a cyclopentadienyl and a phosphine group are linked by either a CH 2 or a C 2 H 4 fragment ( - C 5 H 4 (CH 2 ) n PR 2; n = 1, 2; R = Me, Ph), are reported, as is that of the related ligand, Li 2 [Me 2 C(C 5 H 3 CMe 2 PPh 2 ) 2 ], in which both substituted cyclopentadienyl rings are linked by the CMe 2 group. The metallocene dichloride complexes Cp‘ 2 MCl 2 (M = Ti, Zr; Cp‘ 2 = 2C 5 H 4 (CH 2 ) n PPh 2 ( n = 1, 2), Me 2 C((C 5 H 3 )C(Me) 2 PPh 2 ) 2 ) have also been prepared, and the X-ray structure of (η 5 -C 5 H 4 (CH 2 ) 2 PPh 2 ) 2 ZrCl 2 ( 7 ) has been determined. This complex has the pendent phosphinoalkyl arms close to eclipsed on the two C 5 H 4 groups and bisecting the ZrCl 2 angle, but bent in opposite directions away from the ZrCl 2 plane. Reaction of 7 and its Ti analogue with (COD)Mo(CO) 4 yields the heterobinuclear complexes [(μ-η 5:η 1 -C 5 H 4 (CH 2 ) 2 PPh 2 ) 2 MCl 2 Mo(CO) 4 ] (M = Ti, Zr). Structure determinations of these bimetallic complexes show the expected cis arrangement of phosphine moieties at Mo, M−Mo separations of 6.895 Å (M = Ti) and 6.945 Å (M = Zr), and MCl 2 moieties aimed at right angles to the M−Mo vectors.