(1,3-Bis(2'-pyridylimino)isoindolinato)nickel(II) complexes of phenylcyanamido ligands: Crystal structure, solution and spectroscopic propertie

A series of 4-coordinate, neutral, approximately square planar (1,3-bis(2$sp prime$-pyridylimino)isoindolinato)Ni(II)(phenylcyanamido) complexes (i.e.(PVP)Ni(pcyd)) have been prepared and characterized by $sp1$H NMR, electronic absorption, and infrared spectroscopies and X-ray crytallography. Increasing the $pi$-donating ability of the phenylcyanamido ligand results in a diamagnetic to paramagnetic change in magnetic properties of the complexes. Tetrahedral distortion from the square plane is demonstrated by a crystal structure of (PVP)Ni(2-Clpcyd) which also shows ordered molecular stacking in the crystal lattice.;The PVP$spominus$ centered $pi$-$pispddagger$ electronic transitions of the (PVP)Ni (pcyd) complexes in low donating solvents shows a " mixing" effect attributed to an extension of conjugation resulting from $pi$ donation of the phenylcyanamido ligand mediated by a common Ni(II) $pi$ symmetry orbital within a square planar geometry.;Temperature dependent, reversible solvent coordination equilibria exist for the (PVP)Ni(pycd) complexes. The proportions of non-solvated and solvated complexes are characterized by changes in the apparent $pi$- mixing effect from which thermodynamic parameters are derived.