SYNTHESIS, STRUCTURE AND CHARACTERIZATION OF AMIDO DERIVATIVES OF [9]ANEN(3) (1,4,7-TRIAZACYCLONONANE)

The amido species OHC[9]aneN(3) (1-formyl-1,4,7-triazacyclononane), [O HC[9]aneN(3)H]BPh(4), (OHC)(3)[9]aneN(3) (1,4,7-triformyl-1,4,7-triaza cyclononane) and (PhOC)(3)[9]aneN(3) (1,4,7-tribenzoyl-1,4,7-triazacyc lononane) have been synthesised, characterised and their crystal struc tures determined. The conformations of these compounds are discussed i n terms of their solid-state structures and of their H-1 and C-13 NMR spectra in solution. Symmetric isomers derived from hindered rotation about the N-C (amide) bond are generally preferred to asymmetric ones, with the N-C(O)R (R = H or Ph) forming a planar unit exo to the triaz amacrocycle. Complexation of Pd-II with OHC[9]aneN(3) confirms the bid entate binding of this ligand and affords [Pd(OHC[9]aneN(3))(2)][B(C6F 5)(4)](2) . 2H(2)O, the single-crystal structure of which shows the Pd atom at an inversion centre with Pd-N 2.057(13) and 2.065(10) Angstro m. The amide functions lie above and below the square-planar metal cen tre with Pd...N (amide) 3.021(12) Angstrom. The retention of planarity within the amide function upon complexation [torsion angle for C(2)-N (1)-C(10)-O(11)-6(2)degrees] suggests that there is no interaction bet ween the amide group and the metal centre.