Reactions of the Dirhenium(II) Complexes Re<sub>2</sub>X<sub>4</sub>(μ-dppm)<sub>2</sub> (X = Cl, Br; dppm = Ph<sub>2</sub>PCH<sub>2</sub>PPh<sub>2</sub>) with Isocyanides. 18. The Isolation and Characterization of Isomers of the [Re<sub>2</sub>Cl<sub>2</sub>(μ-dppm)<sub>2</sub>(CO)(CNXyl)<sub>3</sub>]<sup>2+</sup> Cation and Its Monocationic and Neutral Congeners
收藏资源简介：
The reactions of the multiply bonded dirhenium(II) complexes Re2Cl4(μ-dppm)2(CO), Re2Cl4(μ-dppm)2(CO)(CNXyl), and [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]O3SCF3 (dppm = Ph2PCH2PPh2; Xyl = 2,6-dimethylphenyl) with the requisite number of equivalents of TlO3SCF3 and XylNC lead to three, non-interconvertible, structural isomers of the complex [Re2Cl2(μ-dppm)2(CO)(CNXyl)3](O3SCF3)2 (4a, 5a, and 6a; a signifies a triflate salt). Each of these complexes undergoes two reversible one-electron reductions which afford the redox pairs 4a‘/4‘ ‘, 5a‘/5‘ ‘, and 6a‘/6‘ ‘, respectively. While 4a‘ and 4‘ ‘ have structures which are very similar to that of 4a, the complexes 5a‘/5‘ ‘ and 6a‘/6‘ ‘ have structures which differ from 5a and 6a, thereby establishing the existence of coupled redox/isomerization reactions. Solutions of 6a‘ in acetonitrile and 6‘ ‘ in benzene slowly convert to the new isomers 7a‘ and 8‘ ‘, respectively, which are in turn found to be members of the redox series 7‘/7‘ ‘ and 8/8‘/8‘ ‘. In all, the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]n+ species (n = 2, 1, or 0) have been found to exist in seven distinct structural forms which possess Re−Re bond orders of 3, 2, 1.5, 1, or 0 depending on the specific bioctahedral structure which is assumed and the charge on the complex. Single-crystal X-ray structure determinations have been carried out on the seven complexes 4‘ ‘, 5a, 6a, 6a‘, 6‘ ‘, 7a‘, and 7‘ ‘.
