The non-isomorphous crystal structures of NHC—Au—Cl and NHC—Au—Br (NHC is 1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene)

Abstract

Gold monochloride and monobromide can be transformed into monomeric complexes by ligands such as CO, PPh or MeS, and such ligand-stabilized gold monochloride compounds have been investigated as catalysts, luminescent materials and anticancer drugs, especially when coordinated to a lipophilic benzyl-substituted N-heterocyclic carbene (NHC) ligand. The triclinic structures of NHC-Au-Cl {chlorido(1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene)gold, [AuCl(CHN)]} and NHC-Au-Br {bromido(1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene)gold, [AuBr(CHN)]}, determined by X-ray crystallography at 100 K, have one and four molecules, respectively, in their asymmetric units. The chloride compound shows an almost linear C-Au-Cl fragment [179.76 (8)°], with an Au-C distance of 1.976 (3) Å and an Au-Cl distance of 2.3013 (6) Å, while the bromide compound shows surprisingly large geometry deviations, from 1.969 (12) to 2.016 (10) Å for the Au-C distance and from 2.4279 (14) to 2.4796 (12) Å for the Au-Br distance, in the four independent molecules.

Synthesis and Cytotoxicity Studies of Novel NHC*-Gold(I) Complexes Derived from Lepidiline A

“…Bond angles of 108.40(10)° for 12 , 109.44(8)° for 13 , and 108.83(12)° for 14 are observed for the Au–S–C(30) angle. These values are in good agreement with similar compounds reported earlier by the Tacke group [ 25 , 26 ].…”

Synthesis and biological evaluation of Au‐NHC complexes

“…These distances confirm a single-bond character, consonant with their strong σ-donor characteristic, and similar values are related to Au(I) complexes. [61][62][63][64][65][66][67] These distances also correspond with the relatively longer Au-Cl bond lengths, indicating that the carbene ligand has a stronger trans-influence than the chloride ligand, as mentioned in the literature. [63][64][65][66][67] No exceptional values are found for the bond lengths and angles in the benzimidazole ring for both complexes, and these values agree well with those reported for carbene complexes.…”