Influence of free and chelating phosphine on the NiS2P2 planar chromophore. Synthesis and single crystal structure determination of bis(triphenylphosphine) (N,N′-iminodiethylenebis(phthalimide)-dithiocarbamato)nickel(II) perchlorate, methanol and water solvate.

Article abstract of DOI:10.1016/s0020-1693(96)05447-3

Syntheses and crystal structures of [Ni(padtc)(PPh³)₂]ClO₄·CH ₃OH·H₂O (1) and [Ni(padtc)(dppe)]BPh₄·H₂O (2) (padtc=N-N′-iminodiethylenebis(phthalimide)dithiocarbamate, dppe=1,2-bis(diphenylphosphino)ethane) are reported. Crystal parameters; complex 1, space group P2/n, a=26.388(3), b=12.862(4), c=17.815(2) A?, β=106.03(3)°, V=5811.3(2) A?³, Z=4, R=0.067 for 4150 reflections with I>2σ(I); complex 2, space group P2₁/c, a=19.722(2), b=34.931(3), c=20.373(3) A?, β=114.54(3)°, V=12767.4(4) A?³, Z=8, R=0.069 for 12012 reflections with I>2σ(I). The bulky dithiocarbamate padtc is an umbrella shaped molecule flanking the NiS₂P₂ chromophore. Complex 2 is a molecule with the chelating phosphine dppe. Both the complexes have planar NiS₂P₂ chromophores in keeping with the observed diamagnetism. A relatively short Ni-P distance is observed in the dppe complex 2. The chelating dppe forces the Ni-S distances to be symmetric (2.200(2), 2.204(2) A?) unlike PPh₃ which induces asymmetry (2.227(3), 2.198(2) A?). Shortening of the thioureide C-N bonds (1.307(10) A? in 1, 1.323(7) A? in 2, 1.359(3) A? in free padtc^-) in the complexes is a clear indication of the localisation of the nitrogen electrons between C and N. Thioureide stretching bands in Ni(padtc)₂, [Ni(padtc)(PPh₃)₂]⁺ and [Ni(padtc)(dppe)]⁺ occur at 1494, 1509 and 1512 cm^-1, respectively, in keeping with the significant reduction in C-N bond distances.