Asymmetric functionalisation of aza macrocycles. Syntheses, crystal structures and electrochemistry of [Ni(Bz[9]aneN(3))(2)][PF6](2) and [Pd(Bz[9]aneN(3))(2)][PF6](2)center dot 2MeCN (Bz[9]aneN(3)=1-benzyl-1,4,7-triazacyclononane)

1-Benzyl-1,4,7-triazacyclononane (Bz[9]aneN(3)) has been prepared and its co-ordination chemistry with Ni-II and Pd-II investigated. The crystal structure Df the complex [Ni(Bz[9]aneN(3))(2)] [PF6](2) revealed Six independent Ni-N distances, affording a distorted-octahedral co-ordination geometry. Four lie in the range 2.089(4)-2.123(4) Angstrom, while the distances to the benzyl amine N-donors are significantly longer at 2.262(4) and 2.251(4) Angstrom. The benzyl amine N-donors occupy adjacent sites at the metal centre affording a syn geometry. Cyclic voltammetry of [Ni(Bz[9]aneN(3))(2)][PF6](2) in MeCN at a platinum electrode showed a reversible Ni-II-Ni-III oxidation at E(1/2) = +0.76 V vs. ferrocene-ferrocenium at 235 K. This process was irreversible at higher temperatures. The ESR spectrum of [Ni(Bz[9]aneN(3))(2)](3) c exhibits an axial signal, with g(parallel to) = 2.03 and g(perpendicular to) = 2.15, consistent with a tetragonally elongated octahedral co-ordination geometry at Ni-III. The crystal structure of [Pd(Bz[9]aneN(3))(2)] [PF6](2) . MeCN revealed the Pd atom on an inversion centre with the ligands bound via two N-donors from each, Pd-N 2.0588(19) and 2.0605(19) A. The benzyl amine N-donors do not interact with the metal centre, Pd ... N 3.402(4) Angstrom. Cyclic voltammetry of [Pd(Bz[9]aneN(3))(2)][PF6](2) in MeCN showed a reversible Pd-II-Pd-III couple at E(1/2) = +0.36 V at 298K. The ESR spectrum of [Pd(Bz[9]aneN(3))(2)](3+) exhibits an axial signal, with g(parallel to) = 2.007 and g(perpendicular to) = 2.117. Superhyperfine coupling (A (parallel to); = 26.9 G) is observed to two N-donors in the axial component consistent with a tetragonally elongated octahedral co-ordination geometry at the Pd-III.