Coordination Compounds

$[\mathrm{NiC}{\mathrm{l}}_4{]}^{2-}$ ($\mathrm{N}{\mathrm{i}}^{2+}$, $d^8$, weak-field tetrahedral) has two unpaired electrons; so does $[\mathrm{Ni}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$ (octahedral $d^8$). $\mathrm{Ni}(\mathrm{CO}{)}_4$ and $\mathrm{Ni}(\mathrm{PP}{\mathrm{h}}_3{)}_4$ contain Ni(0), $d^{10}$; $[\mathrm{Ni}(\mathrm{CN}{)}_4{]}^{2-}$ is square planar $d^8$, all paired. Paramagnetic: A and D.