Coordination and oxidative addition at a low-coordinate rhodium(I) beta-diiminate centre
Willems STH, Budzelaar PHM, Moonen NNP, de Gelder R, Smits JMM, Gal AW
CHEMISTRY-A EUROPEAN JOURNAL
8 (6): 1310-1320 MAR 15 2002


Abstract:
The reaction of 14e [LMeRh(coe)] (1: L-Me = ArNC(Me)CHC(Me)NAr, Ar = 2,6-Me2C6H3 ; coe = cis-cyclo-octene) with phenyl halides and thiophenes was studied to assess the competition between a coordination, arene pi coordination and oxidative addition of a C-X bond. Whereas oxidative addition of the C-Cl and C-Br bonds of chlorobenzene and bromobenzene to LMeRh results in the dinuclear species [{LMeRh(Ph)(mu-X)}(2)] (X=Cl, Br), fluorobenzene yields the dinuclear inverse sandwich complex [{LMeRh](2)(anti-mu-eta(4):eta(4)-PhF)]. Thiophene undergoes oxidative addition of the C-S bond to give a dinuclear product. The reaction of 1 with dibenzo[b,d]thiophene (dbt) in the ratio 1:2 resulted in the formation of the sigma complex [LMeRh(eta(1)-(S)-dbt)(2)], which in solution dissociates into free dbt and a mixture of the mononuclear complex (LMeRh(eta(4)-(1,2,3,4)-dbt)] and the dinuclear complex [(LMeRh](2)(mu-eta(4)- (1,2,3,4):eta(4) -(6,7,8,9)-dbt)]. The latter could be obtained selectively by the 2:1 reaction of I and dbt. Reaction of I with diethyl sulfide produces [LMeRh(Et2S)(2)], which in the presence of hydrogen loses a diethyl sulfide ligand to give [LMeRh(Et2S)(H-2)] and catalyses the hydrogenation of cyclooctene.