Synthesis, chirooptical properties and catalytic activity of diene-rhodium(I) and -iridium(I) cationic complexes containing binaphthyl, C-2-symmetric diamine ligands

New cationic rhodium(I) and iridium(I) complexes [M(diene)(diamine)]BF4 containing chiral C-2-symmetric diamines [M = rhodium; diamine = 2,2'-diamino-1,1'-binaphthyl (BNDA), diene = cycloocta-1,5-diene (GOD), 1a, bicyclo[2,2,1]hepta-2,5-diene (NBD), 1b, hexa-1,5-diene (HEX), 1c; diamine = N,N'-dimethyl-2,2'-diamino-1,1'-binaphthyl (DMBNDA), diene = COD, 1d. M = iridium; diamine = BNDA, diene = COD, 2a; diamine = DMBNDA, diene = COD, 2b] have been prepared by the reaction of [MCl(diene)](2) with AgBF4 and further treatment with the diamine, Using N,N,N',N'-tetramethyl-2,2'-diamino-1,1'-binaphtyl (TMBNDA), no cationic complex was obtained. With the exception of the complex Ic, complexes 1 and 2 are stable in solution under inert atmosphere. Acetonitrile removes bonded DMBNDA but not BNDA from the metal; KOH removes both the diamines but not the diene. Complexes 1a, 1b, and 2a, containing (+)(R)-BNDA, catalyze the enantioselective hydrogenation of (Z)-alpha-acetamidocinnamic acid to acetamidodihydrocinnamic acid (o.p. = 9%; room temperature; hydrogen pressure, 35 arm).