Toward Understanding the Bonding Character in Complexes of Coinage Metals with Lone-Pair Ligands. CCSD(T) and DFT Computations

Abstract

We present CCSD(T) interaction energies and the bonding analysis for complexes of Cu, Ag, and Au with the lone-pair ligands H2O, OF2, OMe2, NH3, NF3, NMe3, H2S, SF2, SMe2, PH3, PF3, PCl3, and PMe3 (ML complexes). Both electron correlation and relativistic effects are crucial in the bonding of all complexes. AuPH3, AuPF3, and AuPCl3 (AuPX3) complexes exhibit particularly large relativistic effects, 30-46 kJ/mol. Upon neglecting relativistic effects, the Au-P bonds almost vanish aside from weak long-range van der Waals interactions. Highest binding energies are computed for complexes with Au, followed by Cu and Ag. For all coinage metals the strongest interactions are computed for PX3 ligands followed by SX2 and NX3 OX2 ligands. Upon methylation the interaction energy rises significantly. Metal-thiol complexes, particularly AuSCH3, form a separate class. Exceptional stability of gold complexes is due to large relativistic enhancement of the electron affinity of Au. Along with the electron affinity of a metal, we link the pattern of interaction energies in ML complexes with ionization potentials (IPs) of ligands. Strong interaction with P containing ligands is attributed to their lower IP and the lone pair → metal electron donation accompanied with the back-donation characteristic for P containing ligand. Energy data are accompanied with the natural bond orbital analysis. Computationally less demanding DFT computations with the PBE0 functional provide correct pattern of interaction energies when compared with benchmark CCSD(T) results.

Step-by-step transformations of ferrocenyltellurium complexes of Group VIB metal carbonyls

“…The TeeTe bond length in this complex (2.7538(13) A) is greater than that in free diferrocenylditelluride Fc 2 Te 2 (2.7086(10) A) [4] because of the substantial contribution of metal(HOMO)-toligand(LUMO (TeeTe localized)) back donation [5].…”

“…The reactions of the photochemically generated M(CO) 5 Bimetallic 4, 5 and 6 could be converted back to the corresponding monometallic 1, 2 and 3 if kept in THF or CH 2 Cl 2 /hexane solutions overnight.…”

“…It was demonstrated earlier that the interaction of M(CO) 5 (THF) (M ¼ Cr, Mo, W) with diphenyl ditelluride (Ph 2 Te 2 ) afforded mononuclear complexes M(CO) 5 (Ph 2 Te 2 ) with terminal Ph 2 Te 2 ligand as well as Ph 2 Te 2 e bridged bimetallic complexes [M(CO) 5 ] 2 (m-Ph 2 Te 2 ) depending on the specific ratio of reagents. The stepwise procedure also led to the formation of mixed metal (e.g.…”

“…In 2006 Burgess et al reported the formation of similar metale metal bonded tungsten(I)-ferrocenylselenolate "butterfly" complex [W 2 (m-SeFc) 2 (CO) 8 ] upon the treatment of [W(CO) 5 (THF)] with diferrocenyl diselenide (Fc 2 Se 2 ) at room temperature. However, attempts to prepare the corresponding ferrocenyl-tellurium derivative proved unsuccessful [4].…”

Density functional theory approach to gold-ligand interactions: Separating true effects from artifacts

“…Another way to achieve an analogous covalency would be by the interaction of benzenethiyl radical with odd-number Au n clusters. Indeed, such a possibility was investigated by Pasteka et al 50 between CH 3 S• and a single Au atom on the singlet and triplet surfaces. Their all-electron scalar-relativistic Douglas-Kroll (DK) result for the singlet state bonding is −56.8 kcal/mol.…”