Synthesis and Reactions of Cp-Linked Phosphine Complexes of Rhodium

The linked Cp ligand [C 5 H 4 SiMe 2 CH 2 PPh 2 ] - has been used to synthesize several rhodium derivatives. Reaction with [RhClL 2 ] 2, where L = C 2 H 4, C 8 H 14, or CO, gives (η 5:η 1 -C 5 H 4 SiMe 2 CH 2 PPh 2 )Rh(L) complexes, which have been characterized by single-crystal X-ray diffraction. Reaction of the ethylene complex with CO or PMe 3 gives the carbonyl- and phosphine-substituted derivatives, respectively. Irradiation of the ethylene complex in the presence of hydrogen gives a new binuclear polyhydride, also structurally characterized, in which the chelating ligand spans the two metal centers. Reaction of the ethylene complex with iodine leads to the formation of the diiodide (η 5:η 1 -C 5 H 4 SiMe 2 CH 2 PPh 2 )RhI 2, which in turn can be converted to the dihydride (η 5:η 1 -C 5 H 4 SiMe 2 CH 2 PPh 2 )RhH 2 by reaction with NaAl(OCH 2 CH 2 OCH 3 ) 2 H 2 . The reactivity of the dihydride toward C−H bond activation has been investigated. While benzene does not give a stable oxidative addition adduct, pentafluorobenzene yields (η 5:η 1 -C 5 H 4 SiMe 2 CH 2 PPh 2 )Rh(C 6 F 5 )H, which was structurally characterized as its chloro derivative. Reaction of the dihydride with C 6 F 6 gives the η 2 complex (η 5:η 1 -C 5 H 4 SiMe 2 CH 2 PPh 2 )Rh(η 2 -C 6 F 6 ), also structurally characterized.