NHC-manganese(i) complexes as carbene transfer agents

• Published in: Dalton transactions : an international journal of inorganic chemistry no. 35; p. 6999
• Main Authors: Ruiz, Javier, Berros, Angela, Perandones, Bernabé F, Vivanco, Marilín
• Format: Journal Article
• Language: English
• Published: England 01-01-2009
• Subjects: Crystallography, X-Ray; Gold - chemistry; Heterocyclic Compounds - chemistry; Ligands; Manganese - chemistry; Methane - analogs & derivatives; Methane - chemistry; Models, Molecular; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Silver - chemistry; Stereoisomerism
• ISSN: 1477-9234
• DOI: 10.1039/b906450h

Tautomerization of coordinated azoles to their corresponding N-heterocyclic carbenes (NHCs) has been carried out by reaction of complexes fac-[Mn(L)(CO)(3)(dppe)](+) (L = N-phenylimidazole) and fac-[Mn(L)(CO)(3)(bipy)](+) (L = N-methylbenzimidazole, benzoxazole, benzothiazole) with KO(t)Bu and subsequent protonation of the azolyl intermediates with NH(4)PF(6). Several NHC-manganese(i) complexes bearing an N-H residue of general formula fac-[Mn(NHC)(CO)(3)(dppe)](+) and fac-[Mn(NHC)(CO)(3)(bipy)](+) have been tested as carbene transfer agents to the gold fragments [Au(L)](+) (L = PPh(3), CNPh, CNXylyl), allowing isolation or spectroscopic detection of various Mn(i)/Au(i) heterometallic intermediates containing azolyl bridging ligands, which liberate the gold(i) carbene complexes [Au(NHC)(L)](+) by means of acid hydrolysis. By contrast, when using the silver(i) fragment [Ag(PPh(3))](+) as carbene acceptor no transmetallation process occurred but instead inverse tautomerization of the NHC to the corresponding imidazole ligand was observed.