Substitution and Redox Chemistry of [Bu₄N]₂[Ta₆Cl₁₂(OSO₂CF₃)₆]

Two sequential electrochemical reductions occur for the cluster anion [Ta6Cl12(OSO2CF3)6]2- at 0.89 and 0.29 V vs Ag/AgCl, with the generation [Ta6Cl12(OSO2CF3)6]3- and [Ta6Cl12(OSO2CF3)6]4-. Chemical reduction of [Ta6Cl12(OSO2CF3)6]2- by ferrocene produces [Ta6Cl12(OSO2CF3)6]3- with the concomitant shift of the ν(SO2) stretch from 1002 to 1018 cm-1. Reaction of [Bu4N]2[Ta6Cl12(OSO2CF3)6] (1) with [Bu4N]X (X = Cl, Br, I, NCS) occurs by reduction and substitution, yielding [Bu4N]3[Ta6Cl12X6], where the clusters with X = Br, I, and NCS are new. Spectroscopic (IR and UV−vis) evidence indicates that the reduced cluster core {Ta6Cl12}2+ is produced in reaction mixtures of 1 with the halide and pseudohalide ions. Concomitant substitution of the triflate ligands of 1 by X- occurs and the rates for the overall reduction and substitution increase in the order X- = Cl- < Br- < NCS- < I- < CN-. Reduction of 1 with ferrocene followed by addition of [Bu4N]O2CCH3 produces the new cluster [Ta6Cl12(O2CCH3)6]3- isolated as the tetrabutylammonium salt. Cyclic voltammetry and UV−vis spectroscopy on the new clusters [Bu4N]3[Ta6Cl12X6] (X = Br, I, NCS, and O2CCH3) are reported. Crystal data for [Bu4N]3[Ta6Cl12(NCS)6]·CH2Cl2: monoclinic, space group, P21/c (No. 14); a = 25.855(6) Å, b = 21.843(6) Å, c = 16.423(3) Å; β = 100.03(2)°; V = 9133(3) Å3; Z = 4.簇阴离子[Ta6Cl12(OSO2CF3)6]2-在相对于Ag/AgCl参比电极的0.89 V和0.29 V电位下发生两次连续的电化学还原过程，分别生成[Ta6Cl12(OSO2CF3)6]3-与[Ta6Cl12(OSO2CF3)6]4-。采用二茂铁对[Ta6Cl12(OSO2CF3)6]2-进行化学还原，可得到[Ta6Cl12(OSO2CF3)6]3-，同时SO2的伸缩振动峰从1002 cm⁻¹偏移至1018 cm⁻¹。[Bu4N]2[Ta6Cl12(OSO2CF3)6]（记为化合物1）与[Bu4N]X（X=Cl、Br、I、NCS）发生还原取代反应，生成[Bu4N]3[Ta6Cl12X6]，其中X为Br、I、NCS的簇合物为新型产物。光谱（红外及紫外-可见）表征结果表明，在化合物1与卤离子、拟卤离子的反应体系中生成了还原型簇核{Ta6Cl12}2+；同时化合物1中的三氟甲磺酰配体可被X-取代，整体还原与取代反应的速率按X-=Cl- < Br- < NCS- < I- < CN-的顺序依次升高。先用二茂铁还原化合物1，再加入[Bu4N]O2CCH3，可得到新型簇合物[Ta6Cl12(O2CCH3)6]3-，并以四丁基铵盐的形式分离得到。本文报道了新型簇合物[Bu4N]3[Ta6Cl12X6]（X=Br、I、NCS及O2CCH3）的循环伏安特性与紫外-可见光谱行为。[Bu4N]3[Ta6Cl12(NCS)6]·CH2Cl2的晶体数据如下：单斜晶系，空间群P21/c（编号14）；晶胞参数a=25.855(6) Å，b=21.843(6) Å，c=16.423(3) Å；β=100.03(2)°；晶胞体积V=9133(3) ų；Z=4。