Bis{diacetylpyridinebis(benzoylhydrazonato)}thorium(IV) – a novel thorium chelate with co-ordination number 10

The potentially five-dentate ligand diacetylpyridinebis(benzoylhydrazone), H2ac2py(benzhyd)2, reacts with Th(NO3)4·5H2O in methanol under formation of the neutral bis-chelate [Th{ac2py(benzhyd)2}2)]. The co-ordination polyhedron of the 10-coordinate metal ion can best be described to be intermediate between a bicapped cube and a bicapped square antiprism. Bond length between 2.390(3) and 2.398(3) Å have been found for the Th–O bonds, whereas the Th–N distances are in the range between 2.644(3) and 2.781(4) Å.