Synthesis and X-ray diffraction studies of bis(4-propanoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-onato) dioxomolybdenum(VI) and [4-(1-trichloro-2-ethoxy)propanoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-onato][4-trichloroacetyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-onato] dioxomolybdenum(VI)

Two 4-acyl-2,3-dihydro-5-methyl-2-phenyl-3 H-pyrazol-3-one complexes of mol ybdenum(VI), namely (4-propanoyl-2,3-dihydro-5-methyl-2-phenyl- H-pyrazol-5 -onato) dioxomolybdenum(VI), [MoO2(C26H26N4O4)], 1, and (4-(1-trichloro-2-e thoxy)-propanoyl)-2,4-dihydro-5-methyl-2-phenyl-3 H-pyrazol-3-onato)(4-tric hloroacetyl-2,4-dihydro-5-methyl-2-phenyl-3 H-pyrazol-3-onato) dioxomolybde num(VI), [MoO2(C26H21Cl6N4O5)], 2, have been synthesised from a reaction be tween MoO2II ion and 4-propanoyl and 4-trichloroacetyl derivatives of 2,3-d ihydro-5-methyl-2-phenyl-3 H-pyrazol-3-one respectively. The complexes crys tallized from solution with stereochemistry that have remarkable deviations from each other and modest deviation from octahedral geometry. X-ray diffr action studies revealed that in 2 an ethoxy moiety was introduced to one of the two ligand anions rather than on the molybdenum atom due to a deproton ation reaction between the complex and ethanol solvent. This unusual reacti on in 2 lead to the destruction of the Mo-VI atom as a pseudo two-fold cent re of inversion of the ligands, the non planarity of both the pyrazole ring s and chelate rings of the ligand anions as is observed in 1. The yellow co mplex 1 crystallized in the orthorhombic space group Iba2 with unit cell pa rameters, a = 9.6757(6) Angstrom, b = 19.854(3) Angstrom, c = 13.464(3) Ang strom; Z = 4 and D-x = 1.516 g cm(-3). The yellow complex 2 crystallized in the triclinic space group P (1) over bar with unit cell parameters, a = 8. 706(8) Angstrom, b = 12.3155(15) Angstrom, c = 16.179(2) Angstrom; alpha = 107.268(10)degrees, beta = 95.060(9)degrees, gamma = 104.822(8)degrees; Z = 2 and D-x = 1.709 g cm(-3). The UV, IR and H-1 NMR spectral data of the co mplexes were reported.