Synthesis and structural studies of amido, hydrazido and imido zirconium(IV) complexes incorporating a diamido/diamine cyclam-based ligand.
The preparation, characterisation and structural analysis of a series of zirconium(IV) complexes that incorporate the diamido/diamine macrocyclic ligand Bn2Cyclam (Bn2Cyclam = 1,8-dibenzyl-1,4,8,11-tetraazacyclotetradecane) are described. The reaction of one or two equivalents of the appropriate LiNHR reagents with [(Bn2Cyclam)ZrCl2] give the corresponding amido-chloride [(Bn2Cyclam)ZrCl(NHR)] (R = tBu, (2,6-iPr)Ph) or bis(amido) [(Bn2Cyclam)Zr(NHR)2] (R = iPr, tBu, (2,6-Me)Ph) complexes, respectively. Treatment of [(Bn2Cyclam)ZrCl(NH(2,6-iPr)Ph)] with one equiv. of MgClMe gives the base-free, monomeric imido complex [(Bn2Cyclam)Zr(N(2,6-iPr)Ph)]. The reaction of the tBu analog with MgClMe generates a dimeric bridging imido species [{(Bn2Cyclam)Zr}2(mu-NR)2], which can also be obtained by thermal decomposition of [(Bn2Cyclam)Zr(NHtBu)2] in toluene. The bis(hydrazido) complex [(Bn2Cyclam)Zr(NHNPh2)2] was obtained by reaction of [(Bn2Cyclam)ZrCl2] and two equiv. of LiNHNPh2. A hydrazido-chloride compound [(Bn2Cyclam)ZrCl(N(Ph)NBu(Ph))] was generated in a one-pot reaction between [(Bn2Cyclam)ZrCl2], LiBu and azobenzene. DFT calculations on [(Bn2Cyclam)ZrXY] complexes indicate that the coordination geometry adopted by these species is dictated by the steric bulk of the ligands X and Y, varying between six-coordinate prismatic and four-coordinate tetrahedral.
Munhá
Rui F
RF
Centro de Química Estrutural, Instituto Superior Técnico, Av. Rovisco Pais No. 1, 1049-001, Lisboa, Portugal.
Veiros
Luis F
LF
Duarte
M Teresa
MT
Fryzuk
Michael D
MD
Martins
Ana M
AM