Some oxo-complexes of molybdenum(IV) and (V) with 1,2-bisdiphenylphosphinoethane

Abstract

Complexes formulated [{MoOCl,(diphos)}] (red and brown isomers), MoOCl,(diphos), [MoOCl(diphos),]+. and [MoOCl,(thf) (diphos)] (diphos = Ph,P*CH,*CH,*PPh,, thf = tetrahydrofuran) have been prepared and their structures assigned on the basis of analysis, i.r. and l H n.m.r. spectra, conductivity, and magnetic measurements. Only [MoOCl(diphos),] + forms alkoxy-complexes, [MoO(OR) (diphos),]+, with alcohols in the presence of sodium carbonate.?

Synthesis, properties and structural features of molybdenum(v) oxide trichloride complexes with neutral chalcogenoether ligands

“…19 In order to allow comparisons with the WOCl 4 , WOCl 3 , WSCl 4 and WSCl 3 chemistry, we have examined the chemistry of MoOCl 3 with neutral chalcogenoethers and report here complexes of mono-and bi-dentate thio-, seleno-and telluroethers. Data on diphosphine analogues, which clarifies some of the (inconsistent) earlier studies, [7][8][9] is also presented.…”

“…The spectroscopic data on this complex (Experimental section) are in good agreement with that of the red isomers with other diphosphines. [7][8][9] Notably, the five-membered chelate ring diphosphine complexes are fac isomers, contrasting with the mer-[MoOCl 3 (dichalcogenoether)] described above.…”

“…were reported in the 1970s and confirmed by IR, UV/visible spectroscopy and magnetic measurements as Mo(V) compounds. [7][8][9] No structures were obtained, but EPR spectra supported fac octahedral isomers. 8,9 A second (brown) form with Ph 2 P(CH 2 ) 2 PPh 2 and cis-Ph 2 PCH = CHPPh 2 obtained by refluxing the red form in alcohol for several hours, had similar, but not identical, spectroscopic properties; Isovitsch et al, 10 confirmed the crystal structure of the red form of the Ph 2 P(CH 2 ) 2 PPh 2 complex as the fac isomer.…”

“…The presence of varying amounts of a cocrystallised second species would account for the various (small) differences reported by other workers. 7,8,10 Similar problems, including X-ray structures with a variety of bond lengths for apparently the same complex, led to the proposal…”

“…[4][5][6] Interest in high oxidation molybdenum complexes bearing sulfur donor ligands stems in part from the presence of Mo-S coordination in the molybdenum-containing enzymes, nitrate reductase, sulfite oxidase and Fe-Mo nitrogenases which involve (anionic) cysteine or sulfide ligands. [4][5][6] The chemistry with neutral P-and As-donor ligands with Mo(V) has also been investigated, [7][8][9][10][11] but sulfur-based ligands were mostly represented by charged thiolate and dithiocarbamate ligands. [2][3][4] More recent work has reported a series of extremely moisture sensitive Mo(VI) complexes [MoO 2 X 2 (dithioether)] (X = Cl or Br; dithioether = RS(CH 2 ) 2 SR, R = Me, Et, i Pr), which have distorted octahedral structures with the sulfur donor atoms trans to MovO; 12,13 there are also some thia-macrocyclic analogues.…”