Grace J. J. Chen

Studies on the reactivity of oxodihalobis(diethyldithiocarbamato) molybdenum(VI) and tungsten(VI) complexes

Abstract The complexes OMoX 2 L 2 (L = S 2 )CNEt 2 ) 2 react with Na 2 S 2 O 4 to yield OMoL 2 (X = Cl), with PhNCO to yield (PhN)MoX 2 L 2 (X = Cl), with PPh 2 Et to give MoX 2 (PPh 2 Et)L 2 (X = Cl, Br), and with OMol 2 to produce OMoXL 2 (X = Cl, Br). The epr spectra of OMoXL 2 display halogen superhyperfine splitting [A( 35,37 Cl) = ∼3 gauss; A(bb]79,81Br) = 12.3 gauss). Reaction of WCl 6 with NaL in MeOH yields the new complex OWCl 2 L 2 which either does not react at all or gives no characterizable products with the above reagents. The results demonstrate the lack of atom transfer ability of tungsten(VI) relative to its molybdenum analog.

Preparation of OMoCl(acac)2 by a novel oxygen-chlorine atom exchange and its use as a reagent for the synthesis of monomeric molybdenum(V) complexes

Abstract The known monomeric Mo(V) complex OMoCl(acac) 2 has been prepared by a unique new reaction involving an overall oxygen-chlorine atom exchange between MoO 2 (acac) and MoCl 2 (acac) 2 . OMoCl(acac) 2 undergoes substitution reactions with the acid forms of a number of bi- and tetradentate ligands to produce the complexes OMoClL 2 [L = 8-hydroxyquinolinato, 8-mercaptoquininolato, S 2 P(i-Pr) 2 ] and OMoClL′ (L′ = salen, salpn, salphen). Spectral (IR, visible, EPR) characterization data for these complexes and for OMoCl(acac) 2 itself are presented and in some cases are used to assign the stereochemistry of the species.