Syntheses and characterization of a new class of vanadia precursors of oxime-modified oxovanadium(V) isopropoxide, crystal and molecular structure of [VO{ONC 10 H 16 } 3 ]

Modification of [VO(OPr i ) 3 ] with oximes in different molar ratios, yielded new class of vanadia precursors, [VO{OPr i } 3−n {L} n ] {where, n = 1–3 and LH = C 9 H 16 C=NOH ( 1–3 ) and (CH 3 ) 2 C=NOH ( 4 – 6 )}.All the products are yellow in colour. ( 1 ) and ( 2 ) are liquid/viscous liquid, while others are solids. Molecular weight measurements of all these derivatives and the ESI-mass spectral studies of ( 1 ), ( 2 ), ( 3 ) and ( 5 ) indicate their monomeric nature. 1 H and 13 C{ 1 H} NMR spectra suggest that the oximato moieties are monodentate in solution which was further confirmed by the 51 V NMR signals, appeared in the region expected for tetra-coordinated oxo-vanadium atoms. On ageing, a disproportionation reaction occurs in ( 1 ) and some crystals appeared. Single crystal X-ray diffraction analyses of the crystals obtained from ( 1 ) as well as from ( 3 ) were found to be the same and indicate the presence of side-on {dihapto η 2 -(N, O)} binding modes of the oximato ligands, leading to the formation of seven coordination environment around the vanadium atom. Thermogravimetric curve of ( 1 ) exhibits multi-step decomposition with the formation of V 2 O 5 as the final product at ~850 °C. Sol–gel transformation of ( 3 ) yielded ( a ) VO 2 sintered at 300 °C and ( b ) V 2 O 5 at 600 °C. Similarly, sol–gel transformations of ( 1 ) and ( 2 ) yielded V 2 O 5 ( c ) and ( d ) at 600 °C, respectively. Formation of monoclinic phase in ( a ) and orthorhombic phase in ( b ), ( c ) and ( d ) were confirmed by powder XRD patterns.