Diamido/diamine cyclam-based zirconium and hafnium complexes: Synthesis and characterization

The synthesis and characterization of amido-amine cyclam based metal complexes is described. A novel tetraazamacrocycle ligand precursor (Li2[1,8-Bn2-1,4,8,11-tetraazacyclotetradecane], Li2Bn2cyclam, 2) is reported. Reactions of 2 with MCl4(THF)2 afforded M(Bn2cyclam)Cl2 (M = Zr 3, Hf 4). The two complexes show trigonal prismatic metal coordination geometries in the solid-state molecular structures. The cross-bridged cyclam 1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (CB-H2cyclam 5) was used to prepare the lithiated ligand precursor (CB-Li2cyclam 6) and (CB-(Me3Si)2cyclam 7). M(CB-cyclam)Cl2 (M = Zr 8, Hf 9) were synthesized from reactions of MCl4(THF)2 with 6. The structures of 3 and 4 are compared with those of zirconium and hafnium complexes derived from cyclam and unsaturated tetraazamacrocyclic ligands.