Dinuclear molybdenum and gadolinium complexes of new ‘back-to-back’ B–B linked bis[tris(pyrazolyl)borate] ligands

Abstract
Some B–B linked ‘back-to-back’ bis[tris(pyrazolyl)borate] bridging ligands [(Rpz)3B–B(Rpz)3] (where Rpz is 3-R-pyrazolyl) have been prepared: when R=H or Me the ligands have two terdentate compartments, and have been used to prepare a variety of molybdenum complexes; when R=2-pyridyl, the ligand has two B–B linked hexadentate cavities which each bond a lanthanide(III) ion.