Diphosphinito-bridged ruthenium(II) and rhodium(III) complexes with stereogenic metal centers

The bis-4-phosphinito ligands [(p-Ph2POC6H4)(2)X] (X = O, 1; X = CMe2, 2; X = S, 3) react with [Ru(eta(6)-p-cymene)Cl-2](2) to form the binuclear comp lexes {[Ru(eta(6)-p-cymene)Cl-2](2)[mu-(p-Ph2POC6H4)(2)X]} (X = O, 4; X = C Me2, 5; X = S, 6) in good yields as red air stable solids. The crystal stru ctures of 4-6 were determined by X-ray analysis. In acetonitrile and in the presence of AgPF6 (1:1 equiv. with respect to Ru), complexes 4-6 undergo s ubstitution to yield the cationic complexes {[Ru(-eta(6)-p-cymene)Cl(CH3CN) ](2)[mu-(p-Ph2POC6H4)(2)X]}[PF6](2) (X = O, 7; X = CMe2, 8; X = S, 9), whos e stability in solution is very limited. The acetonitrile ligand in complex es 7-9 can be easily replaced by carbon monoxide; the products {[Ru(eta(6)- p-cymene)Cl(CO)](2)[mu-(p-Ph2PoC6H4)(2)X]}[PF6](2) (X = O, 10; X = CMe2, 11 ; X = S, 12) can only be detected in solution under a CO atmosphere and hav e limited stability. The reaction of [Rh(eta(5)-C5Me5)Cl-2](2) with ligands 1-3 results in the formation of the complexes {[Rh(eta(5)-C5Me5)Cl-2](2)[m u-(p-Ph2POC6H4)(2)X]} (X = O, 13; X = CMe2, 14; X = S, 15), which have been isolated as red-orange air stable solids. The cationic complexes {[Rh(-eta (5)-C5Me5)Cl(CH3CN)](2)[mu-(p-Ph2POC6H4)(2)X]}[PF6](2) (X = O, 16; x = CMe2 , 17; X = S, 18), in which the metal atoms are stereogenic centers, have be en obtained from the corresponding complexes 13-15, by treatment in CH3CN w ith AgPF6, and have been characterized only in solution by P-31{H-1} NMR sp ectra and conductivity measurements. On reaction with ligands 1-3, [Rh(eta( 5)-C5H5)(CO)(2)] was converted into the binuclear phosphinito-bridged compl exes {[Rh(eta(5)C(5)H(5))(CO)](2)[mu-(p-Ph2POC6H4)(2)X]} (X = O, 19; X = CM e2, 20; X = S, 21). The reactions of the binuclear complex {[Rh(eta(5)-C5H5 )(CO)](2)[mu-(p-Ph2PC6H4)(2)S]} (21) with CH3I, S-(+)-1-bromo-2-methylbutan e and racemic PhCH(CH3)Br were also studied. The products were the correspo nding acyl derivatives. The reaction of 21 with neat CH3I easily afforded t he complex {[Rh(eta(5)-C5H5)(CoCH3)I](2)[mu-(p-Ph2POC6H4)(2)S]} (23), whose structural determination by X-ray analysis is also reported. (C) 1999 Else vier Science S.A. All rights reserved.