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 KOtBu and subsequent protonation of the azolyl intermediates with NH4PF6. Several NHCâmanganese(I) complexes bearing an NâH 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 = PPh3, 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(PPh3)]+ as carbene acceptor no transmetallation process occurred but instead inverse tautomerization of the NHC to the corresponding imidazole ligand was observed.
                                    通过配合物 fac-[Mn(L)(CO)3(dppe)]+ (L = N-苯基
咪唑)和 fac-[Mn(L)(CO)3(bipy)]+(L = N-甲基
苯并咪唑、和 fac-[Mn(L)(CO)3(bipy)]+(L = N-甲基
苯并咪唑、
苯并恶唑、
苯并噻唑)与 KOtBu 反应,然后用 NH4PF6 使唑基中间体质子化。一些含有通式为 fac-[Mn(NHC)(CO)3(dppe)]+ 和 fac-[Mn(NHC)(CO)3(bipy)]+ 的 NHCâmanganese(I) 复合物带有 NâH 残基,已作为碳烯转移剂对
金片段 [Au(L)]+ (L = PPh3、CNPh、CNXylyl)进行了测试、CNXylyl)的碳烯转移剂,从而可以分离或通过光谱检测各种含有偶氮桥
配体的 Mn(I)/Au(I)杂
金属中间体,这些中间体通过酸
水解作用释放出
金(I)碳烯配合物 [Au(NHC)(L)]+。与此相反,当使用
银(I)片段 [Ag(PPh3)]+ 作为碳烯接受体时,并没有发生透
金属化过程,而是观察到 NHC 反向共聚成相应的
咪唑配体。