Syntheses and reactivity of ‘sulfur rich’ Re(iii) and Tc(iii) complexes containing trithioperoxybenzoate, dithiobenzoate and dithiocarbamate ligands
作者:Nicolas Lepareur、Franck Mévellec、Nicolas Noiret、Fiorenzo Refosco、Francesco Tisato、Marina Porchia、Giuliano Bandoli
DOI:10.1039/b503938j
日期:——
Reductionâsubstitution reactions of [M(O)Cl4]â
(M = Re, 99Tc) precursors with an excess of substituted dithiobenzoate ligands (R-PhCS2)â in dichloromethane/methanol mixtures afford a series of six-coordinated neutral mixed-ligand complexes of the type MIII(R-PhCS3)2(R-PhCS2)
(M = Re; Re1â9; M =
99Tc; Tc1â9). The coordination sphere is entirely filled by sulfur donor atoms, and the complexes adopt a distorted trigonal prismatic arrangement, as assessed by the X-ray crystal structure analysis of Re(4-Me-PhCS3)2(4-Me-PhCS2), Re2. These compounds show sharp proton and carbon NMR profiles, in agreement with the diamagnetism typical of low spin d4 trigonal prismatic configurations. The red-ox processes involve reduction of the metal from Re(V) to Re(III) and oxidation of dithiobenzoate to trithioperoxybenzoate. M2â9 complexes contain a substitution-inert [M(R-PhCS3)2]+ moiety including the metal and two trithioperoxybenzoate fragments, while the third dithiobenzoate ligand is labile. The latter is efficiently replaced by reaction with better nucleophiles such as diethyldithiocarbamate giving a further class of mixed ligand complexes of the type MIII(R-PhCS3)2(Et2NCS2)
(M = Re; Re10â18; M =
99Tc; Tc10â18), which retain the trigonal prismatic arrangement, as determined by the X-ray analyses of the representative compounds Re(PhCS3)2(Et2NCS2), Re10 and 99Tc(PhCS3)2(Et2NCS2), Tc10.
在二氯甲烷/甲醇混合物中,[M(O)Cl4]â(M = Re、99Tc)前体与过量的取代二硫代苯甲酸配体(R-PhCS2)â发生还原置换反应,得到了一系列六配位中性混合配体配合物,其类型为 MIII(R-PhCS3)2(R-PhCS2)(M = Re;Re1â9;M = 99Tc;Tc1â9)。根据对 Re(4-Me-PhCS3)2(4-Me-PhCS2), Re2 的 X 射线晶体结构分析,这些配合物的配位球完全由硫供体原子填充,并呈扭曲的三棱柱排列。这些化合物显示出尖锐的质子和碳 NMR 曲线,与低自旋 d4 三棱柱构型的典型二磁性相一致。氧化还原过程包括金属从 Re(V) 还原成 Re(III) 以及二硫代苯甲酸酯氧化成三硫代苯甲酸酯。M2â9 复合物含有一个取代惰性的[M(R-PhCS3)2]+分子,其中包括金属和两个三硫代苯甲酸酯片段,而第三个二硫代苯甲酸酯配体是易变的。后者可以通过与更好的亲核剂(如二乙基二硫代氨基甲酸盐)反应而被有效取代,从而产生出更多的 MIII(R-PhCS3)2(Et2NCS2) 型混合配体复合物(M = Re; Re10â18;M=99Tc;Tc10â18),根据对代表性化合物 Re(PhCS3)2(Et2NCS2),Re10 和 99Tc(PhCS3)2(Et2NCS2),Tc10 的 X 射线分析确定,它们保留了三棱柱排列。