Crystal Structure of bis(O,O′-neopentylene dithiophosphato)nickel(II) Ni[S2 $$\kern2pt\raise12pt\hbox{\vrule height3pt width.5pt depth0pt}\kern-.5pt\raise14pt\hbox{\vrule height.5pt width145pt depth0pt}\hspace*{-147pt}{\rm POCH}_2{\rm CMe}_2{\rm CH}_2{\rm O}\kern-4.2pt\raise12pt\hbox{\vrule height3pt width.5pt depth0pt\kern3pt}]$$ 2 and bis(O,O′-hexylene dithiophosphato)nickel(II) Ni[S2 $$\kern2pt\raise12pt\hbox{\vrule height3pt width.5pt depth0pt}\kern-.5pt\raise14pt\hbox{\vrule height.5pt width164pt depth0pt}\hspace*{-166pt}{\rm POCMe}_2{\rm CH}_2{\rm CHMeO}\kern-4.2pt\raise12pt\hbox{\vrule height3pt width.5pt depth0pt\kern3pt}]$$ 2