Diastereoselective Synthesis of the First Enantiomerically Pure (Triazolinylidene)ruthenium(ii) and ‐rhodium(iii) Chelate Complexes

Abstract

Abstract The chloro bridges of the dinuclear complexes [(. 65 ‐cymene)‐RuCl 2 ] 2 and [(. 5 ‐C 5 Me 5 )RhCl 2 ] 2 can be cleaved by reaction wht an N ‐phenyltriazolium perchlorate ( 1 ) and a base, resulting in the formation of (carbene)metal complexes. In this manner, abstraction of one ortho ‐proton of the phenyl group and elimination of HCl leads to pseudo ‐tetrahedral ruthenium ( 2 ) and rhodium ( 3 ) complexes, thereby creating a stereogenic center at the transition metal. By using enantiomerically pure triazolium perchlorates, the diastereoselective synthesis of these complexes with diastereomeric excesses of up to 95% can be achieved, with the possibility of separating the two diastereomers by column chromatography. The relative, and therefore also the absolute configuration of the ruthenium complex ( R Ru )‐ 2b could be determined by X‐ray structure analysis. A stereospecific substitution of chlorine by iodine or acetonitrile to form the diastereomerically pure complexes 4, 5 and 6 (the latter as cationic ruthenium complexes) allows a further variation of the ligands.