Abstract Bis(dithioimidodiphosphinato)nickel(II) chelates, Ni[(SPR2) (SPPh2)N]2 (R = Ph (1), Me (2)) were prepared by methathesis reactions between NiCl2·6H2O and the corresponding potassium dithioimidodiphosphinate, in methanol. Compound 1 crystallizes in the triclinic space group P-1, a = 13.336(2), b = 18.580(2), c = 18.670(2) A , α = 90.10(2), β = 93.00(2), γ = 98.21(2)°, Z = 4 , and contains two independent molecules in the unit cell. Compound 2 crystallizes in the monoclinic space group P2 1 /c, a = 13.161(2), b = 10.737(5), c = 12.101(4) A , β = 108.38(2)°, Z = 2 . In both compounds the 1,3-dithiophosphorus ligands act as symmetrical monometallic biconnective (isobidentate chelating) units and the resulting NiS2P2N rings are non-planar. Compound 1 contains a tetrahedral NiS4 core (mean NiS 2.239 A, SNiS 111.9° (endocyclic), 108.2° (exocyclic)), while compound 2 exhibits a square-planar NiS4 core (mean NiS 2.239 A, SNiS 98.3° (endocyclic), 81.1° (exocyclic)). The structures are discussed in relation to previously reported Ni(II) derivatives of 1,1-dithiophosphorus ligands.