William P. Griffith

Studies on transition metal peroxo complexes—X. The nature of peroxovanadates in aqueous solution☆

Abstract The nature of the species formed in solutions of [VO4]3−, in excess H2O2 from pH 14 to acid, has been studied by Raman spectroscopy and 51V NMR; polymerization processes are far simpler in the presence than in the absence of H2O2. The principal species present are likely to be [V(O2)4]3−, [VO(O2)3]3−, [V(OH)(O2)3]2−, cis-[VO2(O2)2(H2O)]3−, [V2O3(O2)4]4− or [V2(OH)O2(O2) 4]3−, [VO(O2)2(H2O)]− and [VO(O2)(H2O)4]−. A brief Raman study is also reported of spectra of [M(O2)4]3− (M = Nb, Ta) in excess H2O2 from pH 11 to 7.

Oxo complexes of ruthenium(VI) and (VII) as organic oxidants

Oxidation of a variety of saturated and unsaturated primary and secondary alcohols by tetraoxoruthen-ate(VI), [RuO4]2–, tetraoxoruthenate(VII), [RuO4]–, barium trans-trioxodihydroxoruthenium(VI), trans-Ba[Ru(OH)2O3], dioxotrichlororuthenate(VI), [RuO2Cl3]–, and dioxodichlorobipyridylruthenate(VI), [RuO2(bipy)Cl2], has been studied; [RuO4]2–may be used catalytically in conjunction with [S2O8]2– under basic aqueous conditions. For some of these systems, the oxidation of several aldehydes and amines were also examined. Both [RuO4]2–and [RuO4]– oxidise primary alcohols to carboxylic acids and secondary alcohols to ketones; the reactivity of these reagents towards unsaturated alcohols was studied in particular. The new species [PPh4][RuO2Cl3] and also [RuO2(bipy)Cl2] cleanly oxidise a wide range of alcohols to aldehydes and ketones without attack of double bonds. Ba[Ru(OH)2O3] functions as a heterogeneous oxidant in dichloromethane, oxidising only the most reactive alcohols to aldehydes.

Tropolonato complexes of osmium, iridium, platinum, molybdenum and tungsten, and the X-ray crystal structure of MoO2trop2

The new tropolonato (trop) complexes Os(trop) 3 , Ir(trop) 3 , [Pt(trop)(PPh 3 ) 2 ] BPh 4 , OsO 2 (trop) 2 , MoO 2 (trop) 2 and W 2 O 5 (trop) 2 are reported. The vibrational, 1 H and 13 C NMR spectra of the complexes have been measured and the X-ray crystal structure of MoO 2 trop 2 has been determined. The crystals are monoclinic with α = 15.485(3), b = 13.583(3), c = 14.211(3)A, β = 117.74(1)°, space group C 2/ c , Z = 8; and the structure has been refined to R = 0.033.

Studies on transition metal peroxo complexes. IX: carboxylato peroxo complexes of niobium (V), tantalum (V), zirconium (IV) and hafnium (IV)

Abstract The new complexes K3[M(O2)3(tart)] · H2O (M = Nb, Ta; tart = tartrate), K3[M(O2)3(L)] · 2H2O [M = Nb, Ta; L = glycollate (glyc), citrate (cit)], K3[Nb(O2)3 (mal)] · 2H2O (mal = malate), K[M(O2)2(dipic)(H2O)] · 2H2O (M = Nb, Ta; dipic = dipicolinate), K6[M2(O2)6(tart)] · 2H2O (M = Nb, Ta), K2[M(O2)(ox)2] · 2H2O (M = Zr, Hf) and K2[M(O2)2(cit)] · H2O (M = Zr, Hf) have been prepared and characterized on the basis of the Raman and IR spectra of the solids, the Raman spectra of their aqueous solutions and, in some cases, their 13C NMR spectra. They are likely to contain eight-coordinate metal atoms with the peroxo groups side-bonded to the metal atoms.

Complexes of naphthalene-2,3-diol (H2ND) with group VI and group VIII metals, and the X-ray crystal structure of cis-(NH4)2[Mo2O5(ND)2]·2H2O

Abstract The new naphthalene-2,3-diolato (2 — ) (ND) complexes cis-[M2O5(ND)2]2−, cis-[MO2(ND)2]2− (M = Mo, W), trans-UO2(ND)·3H2O, trans-[OsO2(ND)2]2− and cis-M′(PPh3)2(ND) (M′= Pd, Pt) have been isolated. The X-ray crystal structure of cis-(NH4)2[MO2O5(ND)2]·2H2O has been determined. The crystals are orthorhombic, space group Pbca, a = 9.084(4), b = 13.625(4), c = 39.512(18) A, Z = 8, R = 0.041 from 2554 observed reflections. The naphthalene-2,3-diolato ligands function as bidentate bridges, one oxygen atom of each spanning two cis-MoO2 units while the other lies trans to a symmetric Moue5f8Oue5f8Mo bridge. The two naphthalene units are splayed by ca 18° and sheared by ca 24° with respect to each other. Raman, IR, 1H and 13C NMR spectra of the complexes have been recorded.

On the existence of peroxocarbonates in aqueous solution

The presence of a peroxocarbonate species, likely to be HCO4– in pH-dependent equilibrium with CO42–, in solutions of HCO3– in an excess of H2O2 is inferred from Raman and 13C n.m.r. spectroscopy; similar evidence is presented for the presence of CO42– in solutions prepared by dissolving solid peroxocarbonates (NaHCO4·H2O and K2C2O6) in aqueous alkali.

Tetraphenylphosphonium perosmate(VII) as an oxidant: comparison of [OsO4]− with [RuO4]−

SummaryThe osmium(VII) salt (Ph4P)[OsO4] functions as a stoichiometric oxidant for benzylic and allylic alcohols, oxidising primary alcohols to aldehydes and secondary alcohols to ketones. Its vibrational spectra and cyclic voltammetric behaviour are compared with those of the perruthenate ion, [RuO4]−.

X-Ray structure of K4[Mo2O2(O2)4(C4H2O6)]·4H2O, a novel peroxo complex containing a single tetradentate bridging tartrate

The single crystal X-ray structure of the title complex (1) shows that two MoO(O2)2 moieties are spanned by a tartrato ligand which is bidentate at each end, giving pentagonal bipyramidal co-ordination to the molybdenum atoms; spectroscopic data (13C, 95Mo n.m.r., Raman) show that this structure is maintained in aqueous solution.

Tetrabutylammonium perruthenate: a new mild oxidant for alcohols

Ce nouveau sel relativement facile a preparer, soluble dans les solvants organiques, permet une oxydation selective des alcools primaires en aldehydes et des alcools secondaires en cetones

Complexes of pyrogallol with molybdenum, tungsten, osmium, palladium and platinum

Salts of the new complexes cis-[MO2(PG)2]2− (M=Mo, W), trans-[OsO2(PG)2]2−, trans-OsO2py2(PG), trans-UO2(PG)·3H2O and cis-M′(PPh3)2(PG) (M′=Pd, Pt) with pyrogallol (H2PG) have been prepared. Their Raman, infrared, 1H and 13C NMR spectra are reported.