Conversion of a Monodentate Amidinate–Germylene Ligand into Chelating Imine–Germanate Ligands (on Mononuclear Manganese Complexes)

The unprecedented transformation of a terminal two-electron-donor amidinate–germylene ligand into a chelating three-electron-donor κ2-N,Ge-imine–germanate ligand has been achieved by treating the manganese amidinate–germylene complex [MnBr­{Ge­(iPr2bzam)tBu}­(CO)4] (1; iPr2bzam = N,N′-bis­(isopropyl)­benzamidinate) with LiMe or Ag­[BF4]. In these reactions, which afford [Mn­{κ2Ge,N-GeMe­(iPr2bzam)tBu}­(CO)4] (2) and [Mn­{κ2Ge,N-GeF­(iPr2bzam)tBu}­(CO)4] (3), respectively, the anionic nucleophile, Me– or F–, ends on the Ge atom while an arm of the amidinate fragment migrates from the Ge atom to the Mn atom. In contrast, the reaction of 1 with AgOTf (OTf = triflate) leads to [Mn­(OTf)­{Ge­(iPr2bzam)tBu}­(CO)4] (4), which maintains intact the amidinate–germylene ligand. Complex 4 is very moisture-sensitive, leading to [Mn2{μ–κ4Ge2,O2-Ge2tBu2(OH)2O}­(CO)8] (5) and [iPr2bzamH2]­OTf (6) in wet solvents. In 5, a novel digermanate­(II) ligand, [tBu­(OH)­GeOGe­(OH)tBu]2–, doubly bridges two Mn­(CO)4 units. The structures of 1–6 have been characterized by spectroscopic (IR, NMR) and single-crystal X-ray diffraction methods.通过使锰基脒基-锗烯配体配合物[MnBr{Ge(iPr₂bzam)ᵗBu}(CO)₄]（记为1；其中iPr₂bzam指N,N'-二异丙基苯甲脒基，N,N′-bis(isopropyl)benzamidinate）与甲基锂（LiMe）或四氟硼酸银（Ag[BF₄]）反应，成功实现了端基双电子给体脒基-锗烯配体（terminal two-electron-donor amidinate–germylene ligand）向螯合型三电子给体κ₂-N,Ge-亚胺-锗酸根配体（chelating three-electron-donor κ₂-N,Ge-imine–germanate ligand）的前所未有的转化。上述两反应分别得到配合物[Mn{κ₂Ge,N-GeMe(iPr₂bzam)ᵗBu}(CO)₄]（2）与[Mn{κ₂Ge,N-GeF(iPr₂bzam)ᵗBu}(CO)₄]（3）；反应中，亲核性阴离子Me⁻或F⁻最终结合于锗原子，同时脒基片段的一个臂从锗原子迁移至锰原子。与之相对，1与三氟甲磺酸银（AgOTf，OTf即三氟甲磺酰基，triflate）反应则得到配合物[Mn(OTf){Ge(iPr₂bzam)ᵗBu}(CO)₄]（4），该配合物中脒基-锗烯配体保持完整。配合物4对水分极为敏感，在含水溶剂中会转化为[Mn₂{μ-κ₄Ge₂,O₂-Ge₂ᵗBu₂(OH)₂O}(CO)₈]（5）与[iPr₂bzamH₂]OTf（6）。在配合物5中，一种新型二锗酸(II)根配体[ᵗBu(OH)GeOGe(OH)ᵗBu]²⁻作为双桥基连接了两个Mn(CO)₄单元。通过光谱学（红外、核磁共振）以及单晶X射线衍射方法对配合物1至6的结构进行了表征。