Synthesis and crystal structure of a new charge transfer salt [NBu4]6H[Fe(C5H5)2][PMoVMo11O40]2

A new charge transfer salt, [NBu4]6H[Fe(C5H5)2][PMo12O40]2, based on Fe(C5H5)2 (ferrocene) and Keggin-type anion [PMo12O40]3− was electrochemically synthesized and its structure was determined by single-crystal X-ray diffraction. Monoclinic, C2/c, M=4068.12, a=50.383(18) Å, b=14.113(5) Å, c=26.554(10) Å, β=115.318°, V=17068(11) Å3, Z=6, R1=0.0759, wR2=0.1744 (I>2σ). The layers of the organic donor and inorganic acceptor in solid state are alternatively arranged in (001) plates and each [Fe(C5H5)2]+ is surrounded by four Keggin-type anions. There are weak interactions between organic and inorganic layers. ESR spectrum at 110 K displays distinct ferrocenyl cation [Fe(C5H5)2]+ and Mo5+ signals, the anion [PMo12O40]3− is reduced by one electron. The CV properties of the complex were also discussed.