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 CMe 2 (1), has been prepared. Germylene 1 reacted readily with [RhCl(PPh 3 ) 3 ] and [RhCl(cod)(PPh 3 )] (cod=1,5-cyclooctadiene) to give, in both cases, the PGeP-pincer chloridogermyl rhodium(I) derivative [Rh{κ 3 P,Ge,P-GeCl(pyrmP i Pr 2 ) 2 CMe 2 }(PPh 3 )] (2). Similarly, the reaction of 1 with [RhCl(cod)(MeCN)] afforded [Rh{κ 3 P,Ge,P-GeCl(pyrmP i Pr 2 ) 2 CMe 2 }(MeCN)] (3). The methoxidogermyl and methylgermyl rhodium(I) complexes [Rh{κ 3 P,Ge,P-GeR(pyrmP i Pr 2 ) 2 CMe 2 }(PPh 3 )] (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{κ 3 P,Ge,P-GeR(pyrmP i Pr 2 ) 2 CMe 2 }(CO)] (6), with HCl, HSnPh 3 and Ph 2 S 2 rendering the pentacoordinate methylgermyl rhodium(III) complexes [RhHX{κ 3 P,Ge,P-GeMe(pyrmP i Pr 2 ) 2 CMe 2 }] (X=Cl, 7; SnPh 3 , 8) and [Rh(SPh) 2 {κ 3 P,Ge,P-GeMe(pyrmP i Pr 2 ) 2 CMe 2 }] (9), respectively, and with H 2 to give the hexacoordinate derivative [RhH 2 {κ 3 P,Ge,P-GeMe(pyrmP i Pr 2 ) 2 CMe 2 }(PPh 3 )] (10). Complexes 3 and 5 are catalyst precursors for the hydroboration of styrene, 4-vinyltoluene and 4-vinylfluorobenzene with catecholborane under mild conditions.