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 (Li-2[1,8-Bn-2-1,4,8,11-tetraazacyclotetradecane], Li(2)Bn(2)cyclam, 2) is reported. Reactions of 2 with MCl4(THF)(2) afforded M(Bn(2)cyclam)Cl-2 (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-H(2)cyclam 5) was used to prepare the lithiated ligand precursor (CB-Li(2)cyclam 6) and (CB-(Me3Si)(2)cyclam 7). M(CB-cyclam)Cl-2 (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. (c) 2006 Elsevier B.V. All rights reserved.