The structural and electrochemical properties of new bis-imido transition metal salen complexes
作者:Majid Motevalli、A. Duro Oduwole、Bernardetta C. Parkin、Ramkrishna Ramnauth、Alice C. Sullivan、Nikolas Kaltsoyannis
DOI:10.1039/b304627c
日期:——
The reaction between [M(NtBu)2(NHtBu)2]
(M = Mo or W) and dianionic N2O2 coordinating salen ligands afforded new bis-imido salen Mo(VI) and W(VI) transition metal complexes [W(NtBu)2(3,5-tBu2)2salen}]
1, [W(NtBu)2(3-MeO)2salen}]
2, [W(NtBu)2(4-MeO)2salen}]
3, [W(NtBu)2(5-MeO)2salen}]
4, [W(NtBu)2(salen)]
5, [Mo(NtBu)2(3,5-tBu2)2salen}]
6, [Mo(NtBu)2(4-MeO)2salen}]
7 and [Mo(NtBu)2(salen)]
8. Compounds 1–8 were characterised by NMR, IR and FAB mass spectrometry while compound 6 was additionally characterised by X-ray crystallography. Both the Mo and W series adopt structures having the Schiff bases in the strained β-cis configuration and the structural parameters suggest that this is dictated by steric rather than electronic factors while the cis configuration of the imido groups results from expected electronic preferences. The redox chemistry of all these compounds has been studied by cyclic voltammetry and additionally by chemical routes and controlled current electrolytic routes in the case of 1. EPR and density function calculations on oxidised 1 confirmed that the oxidation process is imido centred.
[M(NtBu)2(NHtBu)2](M = Mo或W)与二阴离子N2O2配位的salen配体反应生成了新的双氟亚胺salen Mo(VI)和W(VI)过渡金属配合物:[W(NtBu)2(3,5-tBu2)2salen}] 1,[W(NtBu)2(3-MeO)2salen}] 2,[W(NtBu)2(4-MeO)2salen}] 3,[W(NtBu)2(5-MeO)2salen}] 4,[W(NtBu)2(salen)] 5,[Mo(NtBu)2(3,5-tBu2)2salen}] 6,[Mo(NtBu)2(4-MeO)2salen}] 7 和 [Mo(NtBu)2(salen)] 8。化合物1-8通过NMR、IR和FAB质谱进行了表征,而化合物6还通过X射线晶体学进行了进一步表征。Mo和W系列的结构均呈现Schiff碱在受限的β-顺式构型,结构参数表明这一点是由立体因素而非电子因素决定的,而亚胺基的顺式构型则是由预期的电子偏好导致的。通过循环伏安法研究了所有这些化合物的氧化还原化学,1的情况下还通过化学途径和控制电流电解法进行了研究。对氧化态1的EPR和密度泛函计算确认了氧化过程以亚胺为中心。