title: Cationic, linear Au(I) N-heterocyclic carbene complexes: synthesis, structure and anti-mitochondrial activity.
abstract: Six linear, two-coordinate cationic Au(I) N-heterocyclic carbene complexes of the form [(R2Im)2Au]+ (R = Me 1, Me, Et 2, i-Pr 3, n-Bu 4, t-Bu 5 and Cy 6) have been prepared by the reaction of two equivalents of the appropriate dialkylimidazol-2-ylidene (R2Im) with (Me2S)AuCl in dmf. Single crystal structural studies for 1.PF6, 2.PF6), 3.Cl and 4-6.PF6 show that for all six complexes the gold(I) centres have quasi-linear C-Au-C coordination, with quasi-parallel pairs of aromatic imidazole planes, except in 5.PF6 where they are quasi-normal; in the latter, Au-C are 2.038(3), 2.033(3) A, cf. (e.g.) 2.027(2) A. Inter-cation Au...Au are close at 3.487(2), 3.525(2) A in 1PF6 and 2.PF6. The structural studies and low temperature NMR experiments provide no supportive evidence for the presence of pi back-bonding within this series of complexes. The lipophilicities of the six compounds, as estimated from the logarithm of the n-octanol-water partition coefficients (log P), varied across the series within the range -1.09 to 1.73. To investigate their potential as possible anti-mitochondrial anti-tumour agents, five of the compounds have been evaluated for their propensities to induce mitochondrial membrane permeabilization (MMP) in isolated rat liver mitochondria. At concentrations between 1-10 microM compounds 1.Br and 3-6.Cl induced dose-dependent, Ca2+-sensitive mitochondrial swelling at rates that increased with the lipophilicities of the complexes, with the most lipophilic compounds inducing the most rapid onset of swelling. The swelling was completely inhibited by cyclosporin A, the specific inhibitor of the mitochondrial permeability transition pore.
authors.affiliation: Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences, Chemistry M313, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Murray V
authors.initials: MV
authors.lastname: Baker
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barnard
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Berners-Price
authors.forename: Simon K
authors.initials: SK
authors.lastname: Brayshaw
authors.forename: James L
authors.initials: JL
authors.lastname: Hickey
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.forename: Allan H
authors.initials: AH
authors.lastname: White
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D018360:Crystallography, X-Ray; D017612:Gold Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008930:Mitochondria, Liver / Q000187:drug effects*; D051336:Mitochondrial Membranes / Q000187:drug effects; D008933:Mitochondrial Swelling / Q000187:drug effects; D008958:Models, Molecular; D010539:Permeability / Q000187:drug effects; D051381:Rats; D013056:Spectrophotometry, Ultraviolet
chemical_list: D017612:Gold Compounds; D006571:Heterocyclic Compounds; D007202:Indicators and Reagents