Creation of Optically Pure Crystals from a Meso-Type Gold(I) Metalloligand with d- and l-Amino Acids: A Coordination Trick.

A unique example of a coordination system that creates optically pure crystals from a meso compound with d- and l-amino acids is reported. The 1:1 reaction of a newly prepared meso digold(I) complex, [Au (dcpe)(d-Hpen)(l-Hpen)] ([H 1]), with Co(OAc) under aerobic conditions yielded a cationic Au Co trinuclear complex, [Au Co(dcpe)(d-pen)(l-pen)] [2] , in which [1] acts as a hexadentate-N ,O ,S metalloligand to a Co center. Similar reactions with M(OAc) (M=Ni and Zn) produced analogous but neutral Au M complexes, [Au M(dcpe)(d-pen)(l-pen)] ([3 ]). Complexes [2] and [3 ] are chiral (C vs. A) at the octahedral Co and M centers due to the arrangement of the N ,O ,S donor set. In addition, through spontaneous resolution, [3 ] gave optically pure C-[3 ] and A-[3 ] crystals, showing the creation of homochirality from meso-[1] and achiral M through crystallization. Such a phenomenon was not observed for [2] , which gave a racemic compound containing both C-[2] and A-[2] .