Probing the nature of gold–carbon bonding in gold–alkynyl complexes

Abstract

Homogeneous catalysis by gold involves organogold complexes as precatalysts and reaction intermediates. Fundamental knowledge of the gold–carbon bonding is critical to understanding the catalytic mechanisms. However, limited spectroscopic information is available about organogolds that are relevant to gold catalysts. Here we report an investigation of the gold–carbon bonding in gold(I)–alkynyl complexes using photoelectron spectroscopy and theoretical calculations. We find that the gold–carbon bond in the ClAu–CCH− complex represents one of the strongest gold–ligand bonds—even stronger than the known gold–carbon multiple bonds, revealing an inverse correlation between bond strength and bond order. The gold–carbon bond in LAuCCH− is found to depend on the ancillary ligands and becomes stronger for more electronegative ligands. The strong gold–carbon bond underlies the catalytic aptness of gold complexes for the facile formation of terminal alkynyl–gold intermediates and activation of the carbon–carbon triple bond.

Probing the electronic structure and Au–C chemical bonding in AuC2− and AuC2 using high-resolution photoelectron spectroscopy

“…The strong Au-C bond in ClAu-CCH − was shown to be due to the polarization effect of the electronegative Cl: the Au-C bond in FAu-CCH − was shown to be even stronger, while that in IAu-CCH − was weaker. 10 The calculated Au-C distance of 1.95 Å in AuC 2 − (Table IV) is the same as that in ClAu-CCH − . But the Au-C stretching frequency in AuC 2 − is lower than that in ClAu-CCH − .…”

“…10 The Au-C bond strength in ClAu-CCH − was shown to be extremely high (5.01 eV for ClAu-CCH − to dissociate to ClAu + CCH − calculated at the CCSD(T) level), even higher than that in ClAuCN − . More surprisingly, it was found that the single Au-C bond in ClAu-CCH − was stronger than the Au=C and Au≡C multiple bonds, revealing an inverse correlation between bond strength and bonder order.…”

Ill‐defined chemical concepts: The problem of quantification

“…Although these problems are well known, the literature is full of examples where dissociation energies are used as bond strength descriptors for the stable, nondissociated molecule. In a recent publication Lai‐Sheng Wang and coworkers studied the nature and strength of the gold–carbon bond in several gold catalysts ).…”

Immobilization and electrocatalysis of Ru(III) ions on phosphonate functionalized gold nanoparticles

“…In addition, P-Au-NPs don't show stretching vibration peak of =C-H at 3040 cm À1 compared with VPA sample, confirming that the reduction of HAuCl 4 originates from the reduce capability of C¼C bond in VPA. The organogold chemistry have demonstrate the existence of Au-C bond [30]. Thus, we infer that the weak peak at 289 eV maybe originate from Au-C bond (Fig.…”