Synthesis, Structure, and Cytotoxicity Studies of Oxidovanadium(IV and V) Complexes bearing Chelating Phenolates

Abstract The interaction of [VO(acac) 2 ] with 2,6-bis(hydroxymethyl)-4-methylphenol ( L 1 H 3 ) or 6,6 / -methylenebis(4- tert -butyl-2-(hydroxymethyl)phenol) ( L 2 H 4 ) in refluxing toluene afforded, following work-up in ethanol, the complexes [VO L 1 ] 2 ( 1 ) and {[VO(acac)(HOEt)](VO) L 2 ]} 2 ( 2 ), respectively. Use of 4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzoic acid ( L 3 H 2 ) or 4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzosulfonic acid ( L 4 H 2 ) with [VOCl 3 ] in refluxing acetonitrile, followed by methanol and THF work-up, afforded the complexes [Et 3 NH][VO(OMe) L 3 ] 2 ( 3 ) and [Et 3 NH][VO(OMe) L 4 ] 2 ( 4 ), respectively. The interaction of [VOSO 4 ] and L 3 H 2 in refluxing acetonitrile afforded, with extraction into methanol, the complex [VO(OMe) L 3 ] 2 ( 5 ). The molecular structures of 2 , 3 and 5 have been determined; the structure of 1 has been reported previously. The complexes in this study have been determined to be of low toxicity using in vitro cell assays with 50% cytotoxicity values (CC 50 ) values in the range 56 – 126 µM.