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

trans-Disubstituted diamido/diamine cyclam zirconium complexes

“…As previously reported by some of us, the reaction of ZrCl 4 (THF) 2 with 5 led to (Bn 2 Cyclam)ZrCl 2 , 6, in 40% yield [10]. The relatively low yield obtained by the chloride metathesis reaction impelled us to investigate acid-base reactions as alternative synthetic approaches to 6, avoiding the lithiation of H 2 Bn 2 Cyclam, 3.…”

“…Addition of 2 equiv of LiBu to a Et 2 O or THF solution of (H 2 Bn 2 Cyclam), 3, results in the formation of Li 2 Bn 2 Cyclam(Et 2 O) 2 , 4, or Li 2 Bn 2 Cyclam(THF) 2 , 5, that have been isolated in 65% and 70% yield, respectively [9,10]. The crystal structure of 5 is depicted in Fig.…”

Dinuclear Cationic Zirconium Hydrides Stabilized by the N,N-Dibenzylcyclam Ancillary Ligand

“…Not only are zirconium hydride complexes important reagents in organic synthesis − but they have also been used in the reduction of small molecules such as CO 2 and CO; − in addition, certain zirconium hydride species have been found useful in the preparation of dinitrogen complexes via dihydrogen elimination. , For the vast majority of structurally characterized zirconium hydride complexes, cyclopentadienyl-type ligands are typically found to stabilize these derivatives; in fact, the bis(cyclopentadienyl) motif dominates this chemistry. ,− For some time we have been interested in alternative ligand environments − in an attempt to expand early-transition-metal chemistry and, in particular, to explore the use of group 4 and 5 hydride complexes that can serve as entry points into N 2 activation . For this reason, we investigated the formation of zirconium hydride derivatives stabilized by the N,N -dibenzylcyclam (Bn 2 Cyclam) ancillary ligand, in an effort to build on the alkyl and amido chemistry already reported for complexes of this type. − Herein we report the synthesis and characterization of a unique dinuclear zirconium hydride species that is unexpectedly cationic.…”

Macrocyclic coordination chemistry

“…A, 2007, 103, 264-286 | 269 Zirconium(IV) and hafnium(IV) complexes of cross bridged cyclam where two of the amines have been deprotonated to form an amido/amino ligand, L 17 , have been synthesised. 41 Related bisbenzyl complexes of cyclam were structurally characterised, see Fig. 3.…”

“…75 Despite a longer copper-copper distance (4.5 A ˚) than previously considered ideal, the complex exhibits catecholase type activity and a mechanism was proposed. Another pyrazolic macrocycle with a pendant arm, L 41 , was examined for its coordination properties towards alkali metal ions in transport and extraction experiments, showing particularly favourable properties for potassium. 76 Copper(II) complexes of pyrazole containing macrocycles and cryptands were synthesised, and the redox potentials recorded under physiological conditions were comparable to those observed for Cu/Zn SOD.…”