Dipyrromethane-Based PGeP Pincer Germyl Rhodium Complexes

A family of germyl rhodium complexes derived from the PGeP germylene 2,2'-bis(di-isopropylphosphanylmethyl)-5,5'-dimethyldipyrromethane-1,1'-diylgermanium(II), Ge(pyrmP(i)Pr(2))(2)CMe2 (1), has been prepared. Germylene 1 reacted readily with [RhCl(PPh3)(3)] and [RhCl(cod)(PPh3)] (cod=1,5-cyclooctadiene) to give, in both cases, the PGeP-pincer chloridogermyl rhodium(I) derivative [Rh{kappa P-3,Ge,P-GeCl(pyrmP(i)Pr(2))(2)CMe2}(PPh3)] (2). Similarly, the reaction of 1 with [RhCl(cod)(MeCN)] afforded [Rh{kappa P-3,Ge,P-GeCl(pyrmP(i)Pr(2))(2)CMe2}(MeCN)] (3). The methoxidogermyl and methylgermyl rhodium(I) complexes [Rh{kappa P-3,Ge,P-GeR(pyrmP(i)Pr(2))(2)CMe2}(PPh3)] (R=OMe, 4; Me, 5) were prepared by treating complex 2 with LiOMe and LiMe, respectively. Complex 5 readily reacted with CO to give the carbonyl rhodium(I) derivative [Rh{kappa P-3,Ge,P-GeR(pyrmP(i)Pr(2))(2)CMe2}(CO)] (6), with HCl, HSnPh3 and Ph2S2 rendering the pentacoordinate methylgermyl rhodium(III) complexes [RhHX{kappa P-3,Ge,P-GeMe(pyrmP(i)Pr(2))(2)CMe2}] (X=Cl, 7; SnPh3, 8) and [Rh(SPh)(2){kappa P-3,Ge,P-GeMe(pyrmP(i)Pr(2))(2)CMe2}] (9), respectively, and with H-2 to give the hexacoordinate derivative [RhH2{kappa P-3,Ge,P-GeMe(pyrmP(i)Pr(2))(2)CMe2}(PPh3)] (10). Complexes 3 and 5 are catalyst precursors for the hydroboration of styrene, 4-vinyltoluene and 4-vinylfluorobenzene with catecholborane under mild conditions.