Crystal growth of four oxovanadium(IV) tartrates prepared via a mild two-step hydrothermal method: observation of spin-dimer behavior and second harmonic generation.

Four new oxovanadium(IV) tartrates, namely, A2[(VO)2(C4H4O6)(C4H2O6)(H2O)2]·(H2O)2, where A = Cs, 1, Rb, 2; K2[(VO)2(C4H2O6)2(H2O)2]·(H2O)2, 3; and Na2[(VO)2(C4H4O6)(C4H2O6)(H2O)7]·(H2O)2, 4, were prepared utilizing a two-step, mild hydrothermal route involving l-(+)-tartaric acid as the reducing agent. All four compounds were structurally characterized by single-crystal and powder X-ray diffraction methods and were found to crystallize in the non-centrosymmetric orthorhombic space groups P212121 for 1, 2, and 4 and C2221 for 3. The temperature dependence of the magnetic susceptibility of these compounds was measured, and 1, 2, and 4 were found to be paramagnetic down to 2 K, while 3 was found to exhibit spin-dimer behavior. Compounds 1, 2, and 3 were found to be second harmonic generation active. All compounds were further characterized by IR and UV-vis spectroscopies.