Synthesis and structural properties of metal complexes of dialkyl alpha-hydroxyiminophosphonates

A range of dialky alpha-hydroxyiminophosphonates R'C=N(OH)P(O)(OR)(2), with substituents of varying bulk (R=Et, R'=Me L-1, Et L-2, Pr-c L-3, 3-heptyl L-4; R=Pr-i, R'=Et L-5, 3-heptyl L-6; R=Bu-n, R'=Pr L-7) have been used to synthesise neutral metal complexes with nickel(II) [Ni(L-1-3,L-5)Cl-2], cob alt(II) [Co(L-1-3,L-5)Cl-2] and lanthanides (La-III with L-1,L-2,L-5, Pr-II I with L-1,L-2,L-4-7, Nd-III with L-5, Gd-III with L-2,L-5 and Dy-III with L-2,L-5) the charge being balanced by anionic ligands chloride or nitrate. Included in this range are two 3-heptyl derivatives which have not previous ly been reported. All the metal complexes have been fully characterised by elemental analysis, IR, electronic and NMR spectroscopy and mass spectromet ry. X-Ray crystallography has been used to establish the structure of six k ey metal complexes and one of the free ligands (L-3). Three different bondi ng modes have been established. The d-block metal chlorides consistently sh ow symmetrical bidentate coordination in [ML2Cl2], the lanthanide chlorides [ML3Cl3] are all asymmetrically bidentate and monodentate coordination was observed in the neodymium nitrate complex [NdL25(NO3)(3)(H2O)].