Synthesis and characterization of bistropolonato oxovanadium(IV and V) complexes

Abstract

Oxovanadium(IV) and oxovanadium(V) complexes of tropolone (Htrp, 2-hydroxy-2,4,6cycloheptatrien-1-one), of stoichiometry VO(trp) 2 and VO(trp) 2 Cl, were characterized by electronic, infrared, and Raman spectroscopies. Their electrochemical behavior was investigated by cyclic voltamperommetry in dimethylsulfoxide solutions. The magnetic susceptibility of VO(trp) 2 was investigated between 2 and 300 K. The vibrational spectra of the related Co(trp) 2 , Cu(trp) 2 , and Zn(trp) 2 complexes were also analyzed for comparative purposes.

Synthesis and characterisation of zirconium complexes for cell tracking with Zr-89 by positron emission tomography

“…Electronic absorptions for free tropolone in methanol were in accord with those previously observed in DMSO 16. The absorptions are due to π→π* transitions and analogous transitions are observed in Zr(tropolonate) 4 with increased extinction coefficients attributed to the presence of four tropolone rings with enhancement by the contribution of a charge transfer transition 16. Zr(tropolonate) 4 was also successfully prepared from of ZrCl 4 in 1M HCl or K 4 [Zr(C 2 O 4 ) 4 ] in 1M oxalic acid if the acidic solutions were first neutralised (Method 5).…”

“…The previously reported crystal structure contained 2.25 CHCl 3 . 12 IR and Raman spectra were assigned by comparison with bistropolonato vanadium, cobalt, copper and zinc complexes, 16 and tristropolonato lanthanum, neodymium, samarium and ytterbium complexes. 17 Electronic absorptions for free tropolone in methanol were in accord with those previously observed in DMSO.…”

Coordinating Properties of Pyrone and Pyridinone Derivatives, Tropolone and Catechol toward the VO2+ Ion: An Experimental and Computational Approach

“…[41] With vanadium, non-oxido complexes have been studied, [42] and recently a pentacoordinate species, [VO(trop) 2 ], has been characterized by Baran and co-workers. [43] Values of pK a for the -OH group in the range of 6.7-7.0 have been reported in the literature, much smaller than those of Hma, Hema and Hkoj. [44] However, to the best of our knowledge, no study in aqueous solution has been published to date.…”

“…The stretching frequency of V=O group falls at 986 cm -1 , which is in agree- ment with what reported in the literature. [43] When the solid compound was dissolved in a coordinating solvent such as DMSO and DMF, only one species was formed, which can be revealed by EPR spectroscopy ( Figure S4, traces a [16] The values of A z for the cis-octahedral complexes formed by Hma and Htrop in DMSO (and that for the square-pyramidal species) have been simulated with DFT methods and reported in Table 3; it can be seen that the agreement between experimental and calculated values is very good.…”

Synthesis and reactivity of oxygen ligated molybdenum(II) carbonyl complexes

“…Moving to an oxygen based chelate will eliminate these undesirable side reactions and stabilize the metal with stronger field oxygen donor atoms. Despite the widespread use of chelating oxygen ligands, particularly acetylacetonate, across the periodic table [23][24][25][26][27][28], their substitution for dithiocarbamates on low valent group VI metals has only recently been reported for tungsten and is mostly unexplored for molybdenum [29][30][31][32][33][34], though a few mono ligand species are known [35]. The unusual ability of (acac) 2 W complexes to coordinate nitriles in a p-bound fashion and subsequently derivatize them in a stoichiometric fashion is a substantial difference from dtc chemistry and provides further motivation to explore the chemistry of low valent Mo complexes of acetylacetonate (acac) and tropolonate (trop) [30][31][32][33][34]36].…”