Liang Qiuming, Song Datong
Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
Inorg Chem. 2017 Oct 2;56(19):11956-11970. doi: 10.1021/acs.inorgchem.7b01918. Epub 2017 Sep 12.
Complexes [MClCp*(HL)] (1[Fe]/1[Ru]) (where HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-2-ylidene) were synthesized from the reaction of in situ generated HL ligand and [FeClCp*(TMEDA)] (where TMEDA is N,N,N',N'-tetramethylethylenediamine) or [RuClCp*], respectively. The deprotonation of 1[Fe]/1[Ru] with 1 equiv of LiHMDS led to cyclometalation through the o-Me of the mesityl group, forming [MCp*(L-κC,κC',κN)] 2[Fe]/2[Ru]. The coordinatively unsaturated compounds [MCp*(HL)]BPh 3[Fe]/3[Ru] were prepared from 1[Fe]/1[Ru] and halide scavenger NaBPh. Complex 3[Ru] showed agostic interactions between the o-Me group of the mesityl moiety and the metal center in solution and the solid state. When the vacant coordination site of 3[Fe]/3[Ru] is occupied by CO, the resulting [MCp*(CO)(HL)]BPh 4[Fe]/4[Ru] can be deprotonated with 1 equiv of KHMDS at the pyridylic position to afford complexes [MCpL'(CO)] 5[Fe]/5[Ru], where the L' ligand chelates to the metal center through the nitrogen donor atom of the dearomatized pyridine ring and the carbene carbon. Complex 2[Fe] reacted rapidly with CO to afford the simple ligand substitution product [FeCp(L-κC,κC')(CO)] 6[Fe], where the L acts as a bidentate chelating ligand through the carbene carbon and benzylic carbon. Under the same condition, the reaction of 2[Ru] with CO forms [RuCpL″(CO)] 7[Ru], where the L″ ligand (an isomer of L and L') chelates to the metal center through the carbene carbon and a pyridyl carbon. Complexes 3[Fe]/3[Ru] reversibly bind dinitrogen to form [MCp(HL)(N)]BPh 8[Fe]/8[Ru]. 3[Ru] reversibly binds dihydrogen to give [MCp*(H)(HL)]BPh 9[Ru], while no reaction was observed between 3[Fe] and H. The reaction of 3[Ru] with dioxygen led to the isolation of a stable side-on O complex [RuCp*(HL)(O)]BPh 10[Ru], while the reaction of 3[Fe] with dioxygen led to an intractable mixture of products.
配合物[MClCp*(HL)] (1[Fe]/1[Ru])（其中HL = 1-均三甲苯基-3-(吡啶-2-基甲基)咪唑-2-亚基）分别由原位生成的HL配体与[FeClCp*(TMEDA)]（其中TMEDA是N,N,N',N'-四甲基乙二胺）或[RuClCp*]反应合成。1[Fe]/1[Ru]与1当量的LiHMDS去质子化，通过均三甲苯基的邻甲基发生环金属化，形成[MCp*(L-κC,κC',κN)] 2[Fe]/2[Ru]。配位不饱和化合物[MCp*(HL)]BPh 3[Fe]/3[Ru]由1[Fe]/1[Ru]与卤化物清除剂NaBPh制备。配合物3[Ru]在溶液和固态中均显示出均三甲苯基部分的邻甲基与金属中心之间的agostic相互作用。当3[Fe]/3[Ru]的空配位位点被CO占据时，生成的[MCp*(CO)(HL)]BPh 4[Fe]/4[Ru]可在吡啶位置用1当量的KHMDS去质子化，得到配合物[MCpL'(CO)] 5[Fe]/5[Ru]，其中L'配体通过去芳构化吡啶环的氮供体原子和卡宾碳螯合到金属中心。配合物2[Fe]与CO迅速反应，得到简单的配体取代产物[FeCp(L-κC,κC')(CO)] 6[Fe]，其中L通过卡宾碳和苄基碳作为双齿螯合配体。在相同条件下，2[Ru]与CO反应形成[RuCpL″(CO)] 7[Ru]，其中L″配体（L和L'的异构体）通过卡宾碳和吡啶基碳螯合到金属中心。配合物3[Fe]/3[Ru]可逆地结合二氮形成[MCp(HL)(N)]BPh 8[Fe]/8[Ru]。3[Ru]可逆地结合二氢生成[MCp*(H)(HL)]BPh 9[Ru]，而3[Fe]与H之间未观察到反应。3[Ru]与 dioxygen的反应导致分离出稳定的侧基O配合物[RuCp*(HL)(O)]BPh 10[Ru]，而3[Fe]与dioxygen的反应导致生成难以处理的产物混合物。
