Phosphinoarylthiolato molybdenum and iron complexes [M{(SC6H4-2-PPh2)-κ2S,P}2(CO)2] (M = Mo, Fe): Analogous composition – Different structure

The molecular structures of the phosphinoarylthiolato molybdenum and iron complexes [Mo{(SC6H4-2-PPh2)-κ2S,P}2(CO)2] (1) and [Fe{(SC6H4-2-PPh2)-κ2S,P}2(CO)2] (2) are reported. They both have a central hexacoordinate metal(II) cation, but compound 1 has a trigonal-prismatic geometry with both CO and both thiolato groups in cis arrangement, while iron(II) complex 2 displays a pseudo-octahedral structure with both CO, both phosphino and both thiolato groups in trans arrangement. This is in a good agreement with DFT calculations, which showed that the different coordination geometry of molybdenum and iron in complexes 1 and 2 is a consequence of the number of d electrons (electronic factor) combined with the geometrical factors.