Conversion of D-penicillaminato trinuclear to mononuclear palladium(II) structure by diamine ligands: remarkable enantioselectivity toward racemic 1,2-cyclohexanediamine

The reactions of an S-bridged trinuclear palladium(II) complex, [Pd(3)(D-pen-N,O,S)(3)] (D-H(2)pen = D-penicillamine), with ethylenediamine (en) and racemic (R,R/S,S) 1,2-cyclohexanediamine (chxn) in water gave mononuclear palladium(II) complexes, [Pd(D-pen-N,S)(en)] (1) and [Pd(D-pen-N,S)(chxn)] (2), respectively. Of two diastereomers, [Pd(D-pen-N,S)(R,R-chxn)] (2(R)) and [Pd(D-pen-N,S)(S,S-chxn)] (2(S)), possible for 2, 2(S) was exclusively isolated in a high yield.