The Methanol−Methanolate CH₃OH···OCH₃^- Bridging Ligand: Tuning of Exchange Coupling by Hydrogen Bonds in Dimethoxo-Bridged Dichromium(III) Complexes^†

Two bis(μ-methoxo)dichromium(III) complexes, [LSe2Cr2(μ-OCH3)2(CH3OH)2] 1 and [LSe2Cr2(μ-OCH3)2(CH3OH)(CH3O)]- 2, where LSe represents the dianion of 2,2‘-selenobis(4,6-di-tert-butylphenol), have been reported to demonstrate the effect of hydrogen bonding on the exchange coupling interactions between the chromium(III) centers. The corresponding sulfur analogue of the ligand, i.e., 2,2‘-thiobis(4,6-di-tert-butylphenol), also yields the analogous [LS2Cr2(μ-OCH3)2(CH3OH)2] 3 and [LS2Cr2(μ-OCH3)2(CH3O)(CH3OH)]- 4, which exhibit similar exchange coupling parameters. An acid−base dependent equilibrium between 1 and 2 or 3 and 4 has been established by electronic spectral measurements.本文报道了两种双(μ-甲氧基)二铬(III)配合物，分别为[LSe₂Cr₂(μ-OCH₃)₂(CH₃OH)₂]（化合物1）与[LSe₂Cr₂(μ-OCH₃)₂(CH₃OH)(CH₃O)]⁻（化合物2），其中LSe代表2,2'-硒代双(4,6-二叔丁基苯酚)的二阴离子。上述配合物被用于探究氢键对铬(III)中心间交换耦合相互作用的影响。该配体的硫代类似物，即2,2'-硫代双(4,6-二叔丁基苯酚)，同样可得到结构类似的配合物[LS₂Cr₂(μ-OCH₃)₂(CH₃OH)₂]（化合物3）与[LS₂Cr₂(μ-OCH₃)₂(CH₃O)(CH₃OH)]⁻（化合物4），二者展现出相似的交换耦合参数。通过电子光谱测量，已确证1与2或3与4之间存在酸碱依赖的平衡。