Aldridge Simon, Rossin Andrea, Coombs Deborah L, Willock David J
Centre for Fundamental and Applied Main Group Chemistry, School of Chemistry, Cardiff University, PO Box 912, Park Place, Cardiff, UKCF10 3TB.
Dalton Trans. 2004 Sep 7(17):2649-54. doi: 10.1039/B405027D. Epub 2004 Aug 9.
A series of DFT calculations has been carried out with the aim of characterizing the metal-group 13 element interaction in the novel cationic borylene complex [(eta5-C2Me5)Fe(CO)2(BMes)]+ (1) and related species of the type [eta5-C5R5)M(L)2(EX)]n+. In addition, comparisons have been made with charge neutral borylene complexes and with related group 14 based ligand systems (e.g. cationic metal carbonyls, carbenes and vinylidenes) for which models of bonding have previously been established. In this regard particular attention has been focused on the interpretation of (i) molecular orbital composition; (ii) bond dissociation energies (BDEs) and the ratio of ionic to covalent contributions (DeltaEelstat/DeltaEorb); and (iii) sigma and pi symmetry covalent contributions. The molecular orbital compositions for the prototype borylene complex 1 and for related cationic and neutral systems [e.g.[(eta5-C5H5)Fe(PMe3)2(BMes)]+ and (eta5-C5H5)Mn(CO2(BMes)]] are consistent with the presence of bonding interactions between metal and borylene fragments of both sigma and pi symmetry. Furthermore, on the basis of BDEs, DeltaEorb values and sigma/pi covalent ratios, the bonding in cationic terminal borylene complexes such as 1 appears to have as much right to be termed a M=E double bond as does that in archetypal Fischer carbene and related complexes such as [(eta5-C5R5)Fe(CO)2(CCMe2)]+ and [(eta5-C5R5)Fe(CO)2(CH2)]+.
为了表征新型阳离子硼烯配合物[(η5-C2Me5)Fe(CO)2(BMes)]+(1)以及[η5-C5R5)M(L)2(EX)]n+类型的相关物种中金属-第13族元素的相互作用，进行了一系列密度泛函理论(DFT)计算。此外，还与电荷中性硼烯配合物以及之前已建立键合模型的相关第14族配体体系(如阳离子金属羰基化合物、卡宾和亚乙烯基)进行了比较。在这方面，特别关注以下方面的解释：(i)分子轨道组成；(ii)键解离能(BDEs)以及离子贡献与共价贡献的比率(ΔEelstat/ΔEorb)；(iii)σ和π对称性共价贡献。原型硼烯配合物1以及相关阳离子和中性体系[例如[(η5-C5H5)Fe(PMe3)2(BMes)]+和(η5-C5H5)Mn(CO)2(BMes)]]的分子轨道组成与金属和硼烯片段之间存在σ和π对称性的键合相互作用相一致。此外，基于键解离能、ΔEorb值和σ/π共价比率，阳离子末端硼烯配合物(如1)中的键合似乎与典型的费舍尔卡宾及相关配合物(如[(η5-C5R5)Fe(CO)2(CCMe2)]+和[(η5-C5R5)Fe(CO)2(CH2)]+)中的键合一样，有充分的理由被称为M=E双键。
