In the title co-crystal, [Mo(C(14)H(9)ClN(2)O(4))O(2)(CH(3)OH)]·C(10)H(8)N(2), the deprotonated Schiff base O,N,O'-chelates to the Mo(VI) atom, the three atoms involved in chelation comprising the fac sites of the octa-hedron surrounding the methanol-coordinated metal atom. The methanol mol-ecule forms an O-H⋯N hydrogen bond to an N atom of the 4,4'-bipyridine solvent mol-ecule; the hy-droxy group of the Schiff base forms an O-H⋯N hydrogen bond to the other N atom of another mol-ecule. The two hydrogen bonds leading to the formation of a helical chain running along the b axis.
The Mo(VI) atom in the title co-crystal, [Mo(C(14)H(12)N(2)O(4))O(2)(H(2)O)]·0.5C(10)H(8)N(2), is O,N,O'-chelated by the deprotonated Schiff base and coordinated by the oxide and water O atoms in an octa-hedral geometry. The five-membered chelate ring is planar (r.m.s. deviation = 0.019 Å), but the six-membered chelate ring is puckered (r.m.s. deviation = 0.108 Å). Two mononuclear mol-ecules are linked across a center of inversion by an O-H(water)⋯O hydrogen bond; adjacent dinuclear units are linked by an water-4,4'-bipyridine O-H⋯N hydrogen bond, generating a linear chain structure. The 4,4'-bipyridine mol-ecule is disordered over two positions in a 1:1 ratio.
The coordination geometry at the Mo(VI) atom in the title compound, [Mo(C(16)H(14)N(2)O(4))O(2)(C(2)H(6)OS)], is distorted octa-hedral. The phenolate O, imino N, oxide O from the enolized carbonyl group and one of the terminal O atoms form the equatorial plane; the axial positions are occupied by the other terminal O atom of the dioxidomolybdenum group and the donor O atom of DMSO. The O=Mo=O angle is 105.31 (6)°. An intra-molecular O-H⋯N hydrogen bond and weak inter-molecular C-H⋯O hydrogen bonds are present in the structure.