Mn(CO)₂ Complexes of Cyclopentadienyl/Scorpionate Hybrid Ligands

Rare examples of complexes featuring a chelating cyclopentadienyl/scorpionate hybrid ligand are reported. The compounds are obtained by photolytic decarbonylation of K[(OC)3Mn(C5H4-B(pz)(R)R‘)] (1: R = R‘ = Me; 2: R = Me, R‘ = pz; 3: R = R‘ = pz; pz = pyrazol-1-yl), which leads to the constrained-geometry complexes K[(OC)2Mn(C5H4-B(μ-pz)(R)R‘)] (4−6) in quantitative yields. In 4−6, the Mn-coordinating pyrazolyl ring is tethered to the cyclopentadienyl ligand via a borate bridge. According to X-ray crystallography, the molecular frameworks of 4−6 are largely unstrained. The ligand scaffold is thus well adapted to the coordination requirements of the Mn(I) ion. The crystal lattices of 2, 3, and Li[(OC)3Mn(C5H4-BPh3)] (7) contain dimeric aggregates held together by K+-OC σ adducts, K+-pz σ adducts, and K+-pz π interactions (2, 3) as well as Li+-OC σ adducts and Li+-phenyl π interactions (7). In none of these cases does the π-electron cloud of the cymantrenyl substituent take part in alkali metal ion complexation.本文报道了一类罕见的含有螯合环戊二烯基（cyclopentadienyl）与蝎型配体（scorpionate）杂合结构的配合物实例。目标化合物通过对K[(OC)₃Mn(C₅H₄-B(pz)(R)R')]（其中1：R=R'=甲基；2：R=甲基，R'=吡唑-1-基（pyrazol-1-yl，简写为pz）；3：R=R'=吡唑-1-基）进行光解脱羰反应（photolytic decarbonylation）制得，以定量产率（quantitative yields）得到具有受限几何构型（constrained-geometry）的配合物K[(OC)₂Mn(C₅H₄-B(μ-pz)(R)R')]（4~6）。在4~6号配合物中，与锰配位的吡唑环通过硼酸桥（borate bridge）与环戊二烯基配体相连。经X射线晶体学（X-ray crystallography）表征，4~6号配合物的分子骨架整体无明显张力，表明该配体骨架可很好适配Mn(I)离子的配位需求。2号、3号配合物以及Li[(OC)₃Mn(C₅H₄-BPh₃)]（7）的晶体晶格中存在由多种相互作用维系的二聚体聚集体（dimeric aggregates）：其中2、3号配合物通过钾离子-羰基σ加合物（σ adducts）、钾离子-吡唑σ加合物以及钾离子-吡唑π相互作用（π interactions）结合；7号配合物则通过锂离子-羰基σ加合物与锂离子-苯基π相互作用维系。在上述所有体系中，锰茂基（cymantrenyl）取代基的π电子云均未参与碱金属离子（alkali metal ion）的配位过程。