M. D. Fitzroy, G. Fallon, K. Murray
Mar 15, 1989
Citations
1
Influential Citations
15
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract The reactions of bis(acetylacetonato)dioxomolybdenum(VI), MoO2(acac)2, with benzoylhydrazine have been investigated using a number of different solvent conditions. A 1:2 ratio of MoO2(acac)2 to benzoylhydrazine in dry methanol yields red crystals of a six-coordinate oxomolybdenum complex [OMo(MeC(O)CHC(Me)(NNC(O)Ph))(NHNC(O)- Ph)] (1). In ordinary ‘wet’ methanol the same reaction yields white crystals of the octamolybdate (C5H9N2)4[Mo8O26] (2) formed by hydrolysis. C5H9N2+ is the 3,5-dimethylpyrazolium cation which has been produced in situ by a cyclization reaction of acetylacetone and benzoylhydrazine. The tetrahydrate of 2, (C5H9N2)4[Mo8O26]·4H2O (4), is formed in a 1:2 reaction in 95% ethanol. A second white crystalline by-product, 3, tentatively formulated as Mo2O4(NHNHC(O)Ph)2·2H2O, is also formed in this reaction. Crystals of (C5H9N2)4- [Mo8O26]·4H2O (4) are triclinic, space group P 1 , a = 12.029(6), b = 10.181(5), c = 12.193(6) A; α = 97.04(9)°, β = 127.00(12)°, γ = 95.51(9)°; V = 1156.1 A3, Z = 1. The final refinement gave R = 0.043 and Rw = 0.043 for 3610 observed reflections. The structure contains the β-octamolybdate anion and an organic-base 3,5-dimethylpyrazolium cation. The 1H NMR spectra of 4 show the presence of two lines for both the C(4)H and CH3 protons in the 3,5-dimethylpyrazolium rings. The same intensity ratio is observed for each proton. Unusual temperature dependent effects on both the line positions and intensity ratios are observed between 291–385 K. The possibility of N-bonding of 3,5-dimethylpyrazole to Mo in solution is discussed.