Asymmetric copper complexes of stable mono-tert-butyl monobenzyl dithioether N2S2 ligands
作者:David A. Nation、Max R. Taylor、Kevin P. Wainwright
DOI:10.1039/dt9960003001
日期:——
Attempts to form copper complexes of new N2S2 compounds, in which one sulfur donor is a thiolate and the other a thioether, have been made by protecting the potential thiolate through tert-butylation and benzylating the other. Whereas earlier work with symmetrical bis(tert-butylated thioethers) had shown that de-tert-butylation occurs upon co-ordination to copper, to yield the bis(thiolate) complex, this proves not to be the case with these asymmetric compounds. Thus, complexation of N-[2-(benzylsulfanyl)benzyl]-N′-[2-(tert-butylsulfanyl)benzylidene]ethane-1,2-diamine, L1, and N-[2-(benzylsulfanyl)benzyl]-N′-[2-(tert-butylsulfanyl)benzyl]ethane-1,2-diamine, L2, leads to stable copper(I) complexes and in the case of L1 a stable copper(II) complex as well. The copper(I) perchlorate complexes of L1 and L2 have been characterised by X-ray crystallography and both complex cations are found to have distorted-tetrahedral structures [CuN2–CuS2 dihedral angles of 74.05(9) and 73.5(2)°, respectively] in which the tert-butyl group is retained. The 2-cyanoethyl group has also been investigated as a protecting group for the thiolate moiety in N-[(2-benzylsulfanyl)benzyl]-N′-[2-(2-cyanoethylsulfanyl)benzylidene]-N′-methylethane-1,2-diamine, L3, which forms a stable complex with copper(II) but not with copper(I). Decyanoethylation of [CuL3]2+ could not be induced.
人们尝试通过叔丁基化保护潜在的硫醇盐并将另一个硫醇盐苄基化来形成新的N2S2化合物的铜配合物,其中一个硫供体是硫醇盐,另一个是硫醚。虽然早期对对称双(叔丁基化硫醚)的研究表明,在与铜配位时会发生脱叔丁基化,从而产生双(硫醇盐)络合物,但事实证明这些不对称化合物的情况并非如此。因此,N-[2-(苄基硫基)苯甲基]-N'-[2-(叔丁基硫基)亚苄基]乙烷-1,2-二胺、L1和N-[2-(苯甲基硫基)苯甲基]-的络合N'-[2-(叔丁基硫基)苄基]乙烷-1,2-二胺,L2,产生稳定的铜(I)络合物,并且在L1的情况下也产生稳定的铜(II)络合物。 L1 和 L2 的高氯酸铜 (I) 配合物已通过 X 射线晶体学进行了表征,发现两种配合物阳离子都具有扭曲的四面体结构 [CuN2-CuS2 二面角分别为 74.05(9) 和 73.5(2)° ],其中叔丁基被保留。 2-氰乙基也被研究作为 N-[(2-苄基硫基)苯甲基]-N'-[2-(2-氰基乙基硫基)亚苄基]-N'-甲基乙烷-1 中硫醇盐部分的保护基团, 2-二胺,L3,与铜(II) 形成稳定的络合物,但不与铜(I) 形成稳定的络合物。无法诱导 [CuL3]2+ 的脱氰乙基化。