Macrocyclic dimer of Fc(NHC(O)PPh2-AuCl)2 induced by aurophilic interactions, and chirality induction into Fc core

Abstract

The reaction of 1,1′-bis(diphenylphosphinecarboxamidyl)ferrocene, Fc(NHC(O)PPh2)2 L, with chloro(tetrahydrothiophene)gold(I), [AuCl(tht)], was found to afford the macrocyclic dimer gold(I) complex, {Fc(NHC(O)PPh2-AuCl)2}21, induced by aurophilic interactions. The macrocyclic dimer gold(I) complex 1 gave needle 1needle and plate 1plate crystals. The single-crystal X-ray structure determination of 1 was demonstrated to reveal the self-association properties of the gold(I) and the phosphinecarboxamide moieties in the solid state. The macrocyclic dimer gold(I) complex 1needle crystallized in the space group C2/c with P- and M-helical chirality of the ferrocene (Fc) core. Both conformational enantiomers were found to form homochiral PP and MM macrocyclic dimers, respectively, through intermolecular aurophilic Au(I)–Au(I) interactions and hydrogen bonds between the NH of the phosphinecarboxamide moiety and the Cl of AuCl of the other molecule, wherein PP and MM macrocyclic dimers induced S- and R-conformational enantiomers based on the torsional twist about the Au(I)–Au(I) axis, respectively. The macrocyclic dimer gold(I) complex 1plate crystallized in the space group P21/c with heterochiral PM macrocyclic dimer through aurophilic Au(I)–Au(I) interactions with R- and S- conformational enantiomers. The macrocyclic dimer gold(I) complex 1 was found to bind halide ion of ammonium salt by using the phosphinecarboxamide binding sites. The addition of l-proline methyl ester hydrochloride to the solution of 1 was demonstrated to induce the P-helical chirality of the Fc core.