Cook Brian J, Chen Chun-Hsing, Pink Maren, Caulton Kenneth G
Department of Chemistry, Indiana University, 800 E Kirkwood Ave, Bloomington, 47405, IN, USA.
Dalton Trans. 2018 Feb 6;47(6):2052-2060. doi: 10.1039/c7dt04253a.
The behavior of the complex (HL)CoCl, where HL is a bis-(pyrazol-3-yl)pyridine, towards Brønsted bases is studied, to evaluate peripheral NH deprotonation as a route to a dianionic pincer ligand on a d center. Deprotonation is found to also remove chloride from cobalt, and the decreased metal coordination number is then satisfied by bimolecular reaction of the newly formed peripheral deprotonated pyrazolate nitrogen, leading to Co units bridged by some of the pyrazolates, in the analogous species Co(L)(LH) and [Co(L)(HL)][Co(L)], but also occasionally by chloride retention, in LiCoLCl. Reacting LiCoLCl with tBuNC, yields monomeric LCo(tBuNC), shown to be a 17 valence electron species. Use of excess LiN(SiMe) in deprotonation of (HL)CoCl leads to a product containing a Co[N(SiMe)] substructure, which illustrates opening of the CoL dimer in response to an attacking nucleophile.
研究了配合物(HL)CoCl（其中HL为双-(吡唑-3-基)吡啶）对布朗斯特碱的行为，以评估外围NH去质子化作为在d中心生成双阴离子钳形配体的途径。发现去质子化还会使钴上的氯离去，新形成的外围去质子化吡唑氮通过双分子反应满足降低后的金属配位数，从而在类似物种Co(L)(LH)和[Co(L)(HL)][Co(L)]中形成由一些吡唑盐桥连的Co单元，但在LiCoLCl中偶尔也会通过保留氯来满足。LiCoLCl与tBuNC反应生成单体LCo(tBuNC)，显示为17价电子物种。在(HL)CoCl的去质子化反应中使用过量的LiN(SiMe)会导致产物含有Co[N(SiMe)]子结构，这说明了CoL二聚体响应亲核试剂攻击而打开的情况。
