Supramolecular Gold(I) Thiobarbiturate Chemistry: Combining Aurophilicity and Hydrogen Bonding to Make Polymers, Sheets, and Networks

Abstract

The cooperative forces of aurophilic and hydrogen bonding have been used in the self-assembly of phosphine or diphosphine complexes of gold(I) with the thiolate ligands derived from 2-thiobarbituric acid, SC(4)H(4)N(2)O(2), by single or double deprotonation. The reaction of the corresponding gold(I) trifluoroacetate complex with SC(4)H(4)N(2)O(2) gave the complexes [Au(SC(4)H(3)N(2)O(2))(PPh(3))], 1, [(AuSC(4)H(3)N(2)O(2))(2)(micro-LL)], with LL = Ph(2)PCH(2)PPh(2), 2a, Ph(2)P(CH(2))(3)PPh(2), 2b, or Ph(2)PCH=CHPPh(2), 2c, or the cyclic complex [Au(2)(micro-SC(4)H(2)N(2)O(2))(micro-Ph(2)PCH(2)CH(2)PPh(2))], 3. In the case with LL = Ph(2)P(CH(2))(6)PPh(2), the reaction led to loss of the diphosphine ligand to give [Au(6)(SC(4)H(3)N(2)O(2))(6)], 4, a hexagold(I) cluster complex in which each gold(I) center has trigonal AuS(2)N coordination. Structure determinations show that 1 has no aurophilic bonding, 2b, 3, and 4 have intramolecular aurophilic bonding, and 2c has intermolecular aurophilic bonding that contributes to the supramolecular structure. All the complexes undergo supramolecular association through strong NH...O and/or OH...N hydrogen bonding, and complex 3 also takes part in CH...O hydrogen bonding. The supramolecular association leads to formation of interesting polymer, sheet, or network structures, and 4 has a highly porous and stable lattice structure.