https://doi.org/10.1351/goldbook.K03366
An affix in the name of a polydentate chelate complex indicating single ligating atom attachments of a polyatomic ligand to a coordination centre. A right superscript numerical index indicates the number of such attachments.
Example: $\ce{Ni[(CH3)2PCH2CH2P(CH3)2]Br2}$,
$\ce{dibromobis[1,2-ethanediylbis(dimethylphosphine){-}\upkappa^{2}\!\textit{P}]nickel(II)}$.
$\ce{dibromobis[1,2-ethanediylbis(dimethylphosphine){-}\upkappa^{2}\!\textit{P}]nickel(II)}$.