The crystal structure of a Di(tetramethylammonium)-bis[R,R-tartrato(2-)]-cis-dioxomolybdate(VI), (NMe4)2[MoO2(C4H4O6)2] · EtOH · 1.5 H2O,with comments on tartrate coordination

Summary In the salt (NMe₄[MoO₂(H₂tart)₂] · EtOH · 1.5 H₂O (H₄tart = R,R-(+)-tartaric acid) the tartrato-ligands are linked to molybdenum through a carboxyl oxygen and the vicinal deprotonated hydroxyl oxygen atom, with carboxyl oxygentrans to terminal oxygen of the MoO₂cis-dioxo core. The configuration about Mo is A. The C-C-C-C torsion angles of the ligands are almost 180°. This enables inter-ligand H-bonding from the uncoordinated hydroxyl groups. The five skeletal atoms from the uncoordinated section of a ligand are nearly co-planar. The probable strong preference fortrans coordination of carboxyl must limit the range of dissolved molybdenum(VI)-tartrate species.