Spectroscopic, magnetic and crystal structure investigation of a new pseudo-Dawson nano-sized polyoxometalate cluster with mixed addenda

Patrut A, Margineanu D, Lowy DA, Kögerler P, Schmidtmann M, Bögge H. Spectroscopic, magnetic and crystal structure investigation of a new pseudo-Dawson nano-sized polyoxometalate cluster with mixed addenda. JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS. 2007;9(12):3921-3926.A new nano-sized polyoxometalate cluster was synthesized as a neutral salt. The cluster, which corresponds to the formula Na-2(NH4)(6)[(H3SbVW17O60)-V-III-W-IV]center dot 14H(2)O, contains a heteroatom Sb-III with an unshared electron pair and mixed addenda, i.e., W and V-IV. Structural investigation of the new substance was performed by FT-IR, Raman, UV-Vis-NIR spectroscopy, magnetic susceptibility measurements and by X-ray diffraction. Single-crystal X-ray diffraction analysis showed that the [(H3SbVW17O60)-V-III-W-IV](8-) polyoxometalate molecule is made up of two halves, each being of trilacunary Keggin-type, namely B alpha-[SbM9O33] and B alpha-[H3M9O33], linked by corners and edges. The Sb-III heteroatom is statistically distributed between the two halves. The Sb-III heteroatom is tricoordinated, forming an unusual trigonal SbO3 pyramid in the [SbM9O33] unit. The paramagnetic V-IV metal centre is disordered over all 18 addenda positions. It is proposed that this structure, called initially non-Dawson, should be renamed as pseudo-Dawson