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Two mononuclear cis-[Mo VI O 2 ] complexes with Schiff base ligands, H 4 L 1 (I) and H 4 L 2 (II) (derived from the condensation of 3,5-diformyl-4-hydroxybenzoic acid with isonicotinoylhydrazide and nicotinoylhydrazide) were synthesized using [Mo VI O 2 (acac) 2 ] (Hacac = acetylacetone) and ligand in 1 : 1 molar ratio in methanol. The obtained homogeneous complexes [Mo VI O 2 (H 2 L 1 )] n (1) and [Mo VI O 2 (H 2 L 2 )(MeOH)] (2) were supported on titania functionalized with amine group (APTMS-TiO 2 ) to obtain heterogeneous complexes [Mo VI O 2 (HL 1 )(MeOH)]-@APTMS-TiO 2 (3) and [Mo VI O 2 (HL 2 )(MeOH)]@APTMS-TiO 2 (4), respectively. All the isolated complexes were characterized by various spectral techniques (FT-IR, UV-visible, 1 H and 13 C NMR), elemental (CHN) and thermogravimetric analyses; heterogeneous complexes were additionally characterized by transmission electron microscopy, diffuse reflectance, X-ray photoelectron spectroscopy and Powder-X-ray diffraction studies.The single-crystal X-ray diffraction analysis of complexes 1 and 2 confirms the distorted octahedral geometry for both complexes, where ligands coordinate to the metal centre through O phenolate , N azomethine , and O enolate . Complex 1 has a 3D polymeric structure, where the sixth site of one molecule of Mo is coordinated to the pyridinic nitrogen of the other molecule while 2 is monomeric. These complexes are explored as biomimicking model catalysts for the type II copper site in phenoxazinone synthase. These complexes catalyze the oxidative condensation of o-aminophenol (OAP) into 2-aminophenoxazine-3-one (APX) utilizing aq. H 2 O 2 in the MeCN-MeOH mixture. For complexes 1 and 2, the value of turnover number (k cat ) obtained for phenoxazinone synthase-like activity is 2.14 and 1.76 h À 1 , respectively. Under the optimized reaction parameters, the yield of 2-aminophenoxazine-3-one (APX) obtained is 97 and 92 % for complexes 3 and 4, respectively.

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Mononuclear dioxidotungsten(VI) complex [WVIO2(CH3-hptb)(H2O)] (1) of deferasirox (4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid, H3hptb, I) has been synthesized by the reaction of [WVIO2(acac)2] with I in MeOH and successfully characterized by various spectral techniques...