Manabendra N. Bhattacharjee

Some aspects of pyridinium fluorochromate, C5H5NhCrO3F (pfc), oxidations. stoichiometry of oxidation of alcohols, evidence for oxygen transfer, and the identity of the reduced chromium species

Abstract Molar stoichiometry of the oxidation of n -butanol, iso -propanol, benzyl alcohol, or cyclohexanol involving pyridinium fluorochromate, C5H5NHCrO3F ( PFC ), in dichloromethane, has been evaluated to be 1:1. The facile oxidation of triphenyl-phosphine oxide by PFC in acetonitrile provides a clear-cut example of an oxygen transfer reaction. The reduction product of PFC , isolated after such oxidations, has been identified from the results of chemical analyses, chemical determination of the oxidation state of chromium, magnetic susceptibility, ESR and IR spectral studies as C5H5NHCrO2F, a chromium(IV) species.

Alkali-metal trifluoromonosulphatomanganates (III) A2[MnF3(SO4)] (A = NH4, Li, Na or K)

Abstract Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A 2 [MnF 3 (SO 4 )] (A = NH 4 , Li, Na or K), have been synthesised in high yields by reacting KMnO 4 or MnO(OH) with 40% HF and A 2 SO 4 or by the reaction of MnO(OH) with 40% HF and A 2 S 2 O 8 (A = NH 4 or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH 4 ) 2 [MnF 3 (SO 4 )] on being pyrolysed at 340°C yields MnSO 4 .

Direct synthesis of bis(acetylacetonato)nickel(II) dihydrate and isolation of α,α,β,β-tetra-acetylethane as the oxidation product of acetylacetone

NiO(OH) undergoes a facile reaction with acetylacetone affording a very high yield of bis(acetylacetonato)nickel(II) dihydrate, [Ni(acac)2]·2H2O, and giving α,α,β,β-tetra-acetylethane as the oxidation product of acetylacetone.

Synthesis and structural assessment of new mixed (n-heteroligand)fluoro complexes of cobalt(II). Evidence for ligand synthesis at the metal site

Abstract Mixed-ligand fluorocobaltates(II), with N-donor co-ligands [Co(N2H4)2F2] · 2H2O, [Co(dmpz)F2(H2O)2] · 2H2O, [phenH[CoF3(phen)] · 8H2O and [bipyH][CoF3 (bipy)] · 6H2O (dmpz = 3,5-dimethylpyrazole, phen = 1,10-phenanthroline and bipy 2,2′-bipyridine) have been synthesized from the reaction of a solution of Co(OH)2 in 40% HF with hydrazine at pH ⩽ 5. Attempts to synthesize the CoII-dmpz-F complex with simultaneous synthesis of the ligand 3,5-dimethylpyrazole (dmpz) on a cobalt(II) centre involving reactions among Co(acac)2, F− and N2H4 or CoF2(N2H4)2, F− and acacH (acacH = acetylacetone) resulted in the formation of [Co(dmpz)F2(H2O)2] · 2H2O and CO(dmpz′)2 (dmpz′ = dmpz — H), respectively, demonstrating the formation of the ligand on the metal. The comparative strength of the CoN and CoO bonds is discussed. The compounds have been characterized by elemental analyses, chemical determination of the oxidation state of cobalt, conductance and magnetic susceptibility measurements, pyrolysis, IR and electronic spectral studies. The complex ion in each case has a distorted octahedral structure, but discrete in [Co(N2H4)2F2], and polymeric containing F− as the bridging ligand in other cases. Some of the differences of the fluorocomplexes from those of the other halides have been highlighted.

Mass spectrometry of metal compounds. IV. Electron ionisation mass spectra of bis(acetylacetonato)dioxouranium(VI), UO2(C5H7O2)2, and a comparison with those of bis(acetylacetonato) complexes of first row transition metals, M(C5H7O2)2 (M Mn, Fe, Co, Ni, or Cu)

Abstract Electron ionisation mass spectra are reported for the first time for UO 2 (C 5 H 7 O 2 ) 2 , 1 , and the results compared with those of M(C 5 H 7 O 2 ) 2 (M  Mn, Fe, Co, Ni or Cu) recorded under identical experimental conditions. The EI mass spectra of 1 showed a molecular ion signal at m/z 468 without indicating any association in the gaseous state. The molecular ion [UO 2 (C 5 H 7 O 2 ) 2 ] +· loses either CH 3 · and C 4 H 4 O 2 , or OCCH 2 and C 3 H 5 O · to produce [UO 2 (C 5 H 7 O 2 )] + , which undergoes internal reduction to give [UO 2 (C 5 H 7 O 2 )] +· . The radical ion [UO 2 (C 5 H 7 O 2 )] +· suffers a sequential loss of CH 3 · and C 4 H 4 O 2 to produce ultimately the bare species [UO 2 ] + . A comparative account of the results of mass spectrometric studies of 1 and M(C 5 H 7 O 2 ) 2 is presented.

Synthesis and structural assessment of ammonium and caesium difluorodioxoperoxouranates(VI), A2[UO2(O2)F2](A = NH4 or Cs), and alkali-metal difluorodioxoperoxouranate(VI) monohydrates, A2[UO2(O2)F2]·H2O (A = K or Rb)

The product obtained by treating an aqueous solution of UO2(NO3)2·6H2O with NH4OH or KOH reacts with AF (A = NH4, Rb, or Cs) or KF, 30% H2O2, and a very small amount of 40% HF, in the mol ratio UO2(NO3)2·6H2O:AF:H2O2 of 1:4:110.8, at pH 6.5–7 to afford ammonium and caesium difluorodioxoperoxouranates(VI), A2[UO2(O2) F2](A = NH4 or Cs), and potassium and rubidium difluorodioxoperoxouranate(VI) monohydrates, A2[UO2(O2)F2]·H2O (A = K or Rb). The i.r. spectra suggest that the peroxo-ligand is bonded to the UO22+ centre in a triangular bidentate (C2v,) manner.

Direct synthesis of tris(acetylacetonato)manganese(III)

A concentrated solution of K[MnO4] undergoes a ready reaction with acetylacetone, in the absence of any buffer, giving a very high yield of the title compound, [Mn(acac)3]. The pH of the solution, recorded immediately after the formation of crystalline [Mn(acac)3], was found to be ca. 5. Electron impact induced mass spectrometry showed the compound to be monometric.

A convenient method for the synthesis of alkali metal pentafluoromanganates(III)

Abstract Reaction of MnO(OH) and a concentrated solution of AHF2 (A = NH4 +, Na+, K+ or Cs+) in 40% hydrofluoric acid gives instantaneously rose-pink coloured alkali metal pentafluoromanganate(III), A2MnF5 (A = NH4 + or Na+), and alkali metal pentafluoromanganate(III) monohydrate, A2MnF5.H2O (A = K+ or Cs+). Li2MnF5 has been synthesised by reacting lithium carbonate with a solution of MnO (OH) in 40% hydrofluoric acid followed by addition of a small amount of alcohol. Characterisation of the compounds and assignment of molecular structure were made from the elemental analyses, chemical determination of oxidation state of manganese in the compounds, magnetic susceptibility measurements and infra red spectral studies.

Fluoro and mixed-ligand fluoro complexes of copper(II). A new synthesis of KCuF3, and synthesis and physico-chemical studies of new mixed-ligand fluorocuprates(II), A[CuF(SO4)]·nH2O (A = Na, n=2; A=K or NH4, n=3)

Abstract White crystalline KCuF3 has been synthesized from the reaction of Cu(OH)2 with KHF2 and a small amount of 40% HF at pH ⩽ 4, while the synthesis of blue fluoro(sulphato)cuprates(II), Na[CuF(SO4)]· 2H2O, K[CuF(SO4)]·3H2O and NH4[CuF (SO4)]·3H2O, has been accomplished by reacting Cu(OH)2 with AF and A2SO4 (A = Na, K or NH4), in the ratio of 1:1:1, in the presence of a small amount of 40% HF. Alternative synthesis of the latter involving reactions among Cu(OH)2, F−, and SCN−, and H2O2 or SO2(g) and H2O2 gave CuSCN and Cu11[Cu1SO3]2· 2H2O, respectively, instead of the desired product. The compounds have been characterized by elemental analyses, chemical determination of the oxidation state of copper, magnetic susceptibility and ESR measurements, IR, laser Raman (LR), and electronic spectroscopic studies. The complex [CuF(SO4)]− species has a distorted octahedral polymeric structure containing both F− and SO42− as bridging ligands.

Direct synthesis of alkali trifluorocobaltate(II) monohydrates, A[CoF3]·H2O (A = NH4, Na, or K). First synthesis and structural assessment of mixed-ligand fluoro complexes of cobalt(II), [Co(NH3)4F2] and A[CoF(SO4)(H2O)2](A = NH4, Na, or K)

Alkali trifluorocobaltate(II) monohydrates, A[CoF3]·H2O (A = NH4, Na, or K), have been synthesised directly from the reaction of Co(OH)2 and alkali fluorides in 40% HF followed by precipitation with ethanol at pH <3. While a higher pH (5–6), maintained by the addition of AOH, contaminates the product for A = Na or K, a molecular complex [Co(NH3)4F2] is formed in the case where aqueous ammonia is used to raise the pH. The synthesis of mixed fluorocobaltates(II) of the type A[CoF(SO4)(H2O)2](A = NH4, Na, or K) has been achieved by reacting Co(OH)2 with AF and A2SO4, in the ratio 1 : 2 : 1, in the presence of a very small amount of 40% HF at a steam-bath temperature. The compounds were isolated by the addition of ethanol. The compounds have been characterised from the results of elemental analyses, pyrolysis at 120 °C, magnetic susceptibility measurements, i.r., laser Raman, and electronic spectroscopic studies. While the magnetic moments and electronic spectra of [Co(NH3)4F2] and [CoF(SO4)(H2O)2]– suggest an octahedral or a distorted-octahedral environment for cobalt(II), i.r. and laser Raman spectra provide evidence for the occurrence of a bridging bidentate sulphate ligand in the latter.