Synthesis and characterization of triphenyltin(IV) complexes of azocarboxylates. Crystal structures of a ligand, HO2CC6H4{N=N(C6H3-4-OH(C(H)=NC6H4CH3-4))}-o hemihydrate, and triphenyltin complexes Ph3Sn[O2CC6H4{N=N(C6H3-4-OH(C(H)=NC6H4X-4))}-o] (X = Br, Me (polymeric) and OMe (dimeric))