Tuning low-coordinate metal environments: high spin d5–d7 complexes supported by bis(phosphinimino)methyl ligation
作者:David J. Evans、Michael S. Hill、Peter B. Hitchcock
DOI:10.1039/b210467a
日期:2003.2.11
Treatment of FeCl2 with the lithium derivative of [CH2(Ph2PNC6H2Me3-2,4,6)2] in THF and crystallisation from Et2O gave the âateâ complex [CH(Ph2PNC6H2Me3-2,4,6)2}Fe(μ-Cl)2Li(THF)(OEt2)] in which the iron is four-coordinate and the chlorides bridge to lithium. Treatment of [MN(SiMe3)}2]
(M = Mn, Fe, Co) with [CH2(Ph2PNC6H2Me3-2,4,6)2] in toluene afforded the complexes [CH(Ph2PNC6H2Me3-2,4,6)2}MN(SiMe3)2] which all feature essentially planar N(1)âN(2)âN(3)âM coordination. The carbanionic character of the bis(phosphinimino)methyl ligand results in close C(1)âM contacts in both the Mn and Co complexes effectively raising the coordination number to four. The analogous iron compound is strictly three-coordinate as demonstrated by X-ray crystallography and 57Fe Mössbauer. However protonolysis of this compound with Ph3COH yields the iron alkoxide [CH(Ph2PNC6H2Me3-2,4,6)2}FeOCPh3] that features a close C(1)âFe contact of 2.375 Ã
. Although the iron centre in this complex is only marginally pyramidalised by this contact, its 57Fe Mössbauer spectrum indicates a significant perturbation to the local electronic environment at the metal.
用THF处理FeCl2与[CH2(Ph2PNC6H2Me3-2,4,6)2]的锂衍生物,并从乙醚中结晶,得到了‘ate’复合物[CH(Ph2PNC6H2Me3-2,4,6)2}Fe(μ-Cl)2Li(THF)(OEt2)],其中铁是四配位的,氯离子桥接至锂。将[MN(SiMe3)}2](M = Mn, Fe, Co)与[CH2(Ph2PNC6H2Me3-2,4,6)2]在甲苯中反应,得到复合物[CH(Ph2PNC6H2Me3-2,4,6)2}MN(SiMe3)2],这些复合物均表现出基本平面的N(1)–N(2)–N(3)–M配位。双(膦亚氨基)甲基配体的羧阴离子特性导致在Mn和Co复合物中C(1)–M距离接近,有效地将配位数提升到四。类似的铁化合物则严格为三配位,X射线晶体学和57Fe Mössbauer谱图均表明这一点。然而,这种化合物的质子解离与Ph3COH反应生成铁烷氧化物[CH(Ph2PNC6H2Me3-2,4,6)2}FeOCPh3],其C(1)–Fe接触距离为2.375 Å。尽管该复合物中铁中心由于这一接触仅稍微呈金字塔形,但其57Fe Mössbauer谱表明金属局部电子环境发生了显著扰动。