Preparation, crystal structures, EPR and reflectance spectra of two new charge-transfer salts, [CpFeCpCH2N(CH3)3]4[XMo12O40] · nCH3CN (n = 0 for X = P or n = 1 for X = Ge)

Two new charge-transfer salts, [CpFeCpCH2N(CH3)3]4[PMo12O40] · CH3CN (1) and [CpFeCpCH2N(CH3)3]4[GeMo12O40] (2), were synthesized by the traditional solution synthetic method and their structures were determined by single-crystal X-ray analysis. Salt 1 belongs to the triclinic space group P1, and salt 2 belongs to the triclinic space group P1¯. There exist the complex interactions of the cationic ferrocenyl donor and Keggin polyanion in the solid state. The solid state UV–Vis diffuse reflectance spectra indicate the presence of a charge-transfer band climbing from 450 nm to well beyond 900 nm for 1, a charge-transfer band from 460 to 850 nm with λmax = 630 nm for 2.The EPR spectra of salts 1 and 2 at 77 K show a signal at g = 2.0048 and 1.9501, respectively, ascribed to the delocalization of one electron in reduced Keggin ion [PMoVMo11VIO40]4- in salt 1 and the MoVI in [GeMo12O40]4− is partly reduced to MoV owing to the charge-transfer transitions taking place between the ferrocenyl donors and the POM acceptors. The two compounds were also characterized by IR spectroscopy and cyclic voltammetry.

Graphical abstractThe two novel charge-transfer salts, [CpFeCpCH2N(CH3)3]4[XMo12O40] · nCH3CN (n = 0 for X = P or n = 1 for X = Ge) were synthesized in high yields and fully characterized.Figure optionsDownload full-size imageDownload as PowerPoint slide