Structural characterization of possible intermediates in vanadium-catalysed sulfide oxidation
作者:Hauke Schmidt、Mandana Bashirpoor、Dieter Rehder
DOI:10.1039/dt9960003865
日期:——
Reaction between 3-methoxysalicylaldehyde and (R,R)-1,2-diaminocyclohexane with VO2+ as a template yielded the racemic Schiff-base complex [VO(L1)][H2L1=N,N′-bis(3-methoxysalicylidene)cyclohexane-1,2-diamine] which is converted into trans-[VCl2(L1)] with SOCl2. The crystal structures of both have been determined. The former is a tetragonal-pyramidal complex, whereas the structure of the latter is best described as an octahedron distorted towards a trigonal prism. The complex [VO(acac)2](acac = acetylacetonate) reacted with HN(CH2CH2OH)2 in the presence of oxygen to yield [VO(acac)PhN(CH2CH2O)2}], the crystal structure of which reveals a co-ordination geometry in-between tetragonal-pyramidal and octahedral (provided by a weak vanadium-to-nitrogen bonding interaction). Aeration of a reaction mixture consisting of [VO(acac)2] and the Schiff base (H2L2) formed between H2NCH2CH2OH and o-hydroxynaphthaldehyde afforded [VO(L2)}2O] having a bent and slightly asymmetric oxo-bridge, and an additional weak bridging interaction between one of the V–O (ethanolate) centres and the second vanadium centre (crystal structure). In solution, the inequivalency of the two vanadium centres is offset. The reactivity of the complexes towards Me2SO and/or PhSMe has been studied by EPR and 51V NMR spectroscopy.
以 VO2+ 为模板,3-甲氧基水杨醛和 (R,R)-1,2-环己烷二胺反应生成了外消旋席夫碱复合物 [VO(L1)][H2L1=N,N′-双(3-甲氧基水杨醛基)-1,2-环己烷二胺],该复合物在 SOCl2 的作用下转化为反式 [VCl2(L1)]。这两种物质的晶体结构均已确定。前者是一个四方五面体复合物,而后者的结构最好描述为一个向三棱柱变形的八面体。复合物 [VO(acac)2](acac = 乙酰丙酮)在有氧气存在的情况下与 HN(CH2CH2OH)2 反应生成 [VO(acac)PhN(CH2CH2O)2}],其晶体结构显示出一种介于四方金字塔和八面体之间的配位几何结构(由弱的钒-氮键相互作用提供)。将[VO(acac)2]和 H2NCH2CH2OH 与邻羟基萘甲醛之间形成的希夫碱(H2L2)组成的反应混合物通气后,得到了[VO(L2)}2O],它具有弯曲和轻微不对称的氧桥,而且其中一个 V-O(乙醇酸)中心和第二个钒中心之间还存在着微弱的桥接作用(晶体结构)。在溶液中,两个钒中心的不等价性被抵消。这些复合物对 Me2SO 和/或 PhSMe 的反应性已通过 EPR 和 51V NMR 光谱进行了研究。