(Methanol-κO)-cis-dioxido{(4Z,N′E)-N′-[(Z)-4-oxido-4-phenylbut-3-en-2-ylidene]isonicotinohydrazidato}molybdenum(VI)

In the title complex, [Mo(C16H13N3O2)O2(CH3OH)], the deprotonated Schiff base (E)-N′-[(Z)-4-oxido-4-phenylbut-3-en-2-ylidene]isonicotinohydrazide coordinates in a meridional fashion through the enolate O-, imine N- and amidate O-atom donors to the Mo atom of a cis-[MoO2]2+ core. The sixth coordination site of molybdenum is occupied by the O atom of a methanol molecule. In this complex, the NO5 coordination sphere adopts a distorted octahedral coordination geometry. The metal atom is shifted by 0.335 (1) Å from the square plane defined by the three donor atoms of the Schiff base ligand and one oxide group towards the second oxide group in the cis position. In the crystal, the complex forms inversion dimers through a pair of O—H⋯N hydrogen bonds involving the methanol –OH group and the pyridine N atom. Additional C—H⋯O contacts stack the molecules along the b axis.

In the title complex, [Mo(C 16 H 13 N 3 O 2 )O 2 (CH 3 OH)], the deprotonated Schiff base (E)-N 0 -[(Z)-4-oxido-4-phenylbut-3en-2-ylidene]isonicotinohydrazide coordinates in a meridional fashion through the enolate O-, imine N-and amidate O-atom donors to the Mo atom of a cis-[MoO 2 ] 2+ core. The sixth coordination site of molybdenum is occupied by the O atom of a methanol molecule. In this complex, the NO 5 coordination sphere adopts a distorted octahedral coordination geometry. The metal atom is shifted by 0.335 (1) Å from the square plane defined by the three donor atoms of the Schiff base ligand and one oxide group towards the second oxide group in the cis position. In the crystal, the complex forms inversion dimers through a pair of O-HÁ Á ÁN hydrogen bonds involving the methanol -OH group and the pyridine N atom. Additional C-HÁ Á ÁO contacts stack the molecules along the b axis.
Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. The coordination chemistry of cis-dioxomolybdenum complexes has acquired significant interest due to their catalytic ability in various organic oxidation reactions (Arzoumanian, 1998). The title complex described here was synthesized as part of our investigation into ligand exchange reactions of [MoO 2 (acac) 2 ] with various Schiff-bases derived from acid hydrazides (Chakravarthy & Chand, 2011). In the present work we have used the Schiff base (E)-N′-((Z)-4-hydroxy-4phenylphenylbut-3-en-2-ylidene)isonicotinohydrazide. In the title complex, the doubly deprotonated Schiff-base is In solid state, charge assisted intermolecular hydrogen bonding involving of methanol-OH (O5) and the pyridine-N (N3) (O-H···N) leads to formation of discrete dimeric units of the title complex ( Fig.2). As a result of our investigation for other short contacts in the crystal lattice, we found five types of C-H···O contacts. In the C-H···O interactions, the H···A distances lie in the range 2.57-2.63 Å, Table 1 and together with the O-H···N hydrogen bond stack the molecules along the b axis.

Experimental
The Schiff-base was prepared according to a literature method (El-Bahnasawy & El-Meleigy, 1993). The title complex was prepared following our previously reported method (Kurapati et al., 2012). Solid [MoO 2 (acac) 2 ] (0.1 mmol) was added to a hot methanol solution of the Schiff-base (0.1 mmol in 25 mL), and the mixture was heated on water bath for 30 minutes. The resulting bright red solution was slowly cooled to room temperature. After one day, red colored block shaped crystals were collected by filtration (Yield: 82%). One of the these crystals was used for the X-ray structural analysis.

Refinement
All non-hydrogen atoms were refined using anisotropic thermal parameters. All hydrogen atoms bound to carbon were positioned geometrically and refined using a riding model. The H5 bound of the methanol OH group was located in a difference Fourier map and its coordinates were refined with U eq = 1.5U eq (O).

Figure 1
ORTEP plot of the title complex with 30% probability ellipsoids and atom-labelling scheme.

Figure 2
A hydrogen-bonded dimer formed through O-H···N hydrogen bonds.

Figure 3
Crystal packing in the title compound viewed along the b axis.

Crystal data
[Mo (C 16  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.