Reactions of the homoleptic and heteroleptic antimony ligands Sb Pr, Sb PrPh, SbMePh, and SbMePh with NiI generate rare Ni stibine complexes in either square planar or trigonal bipyramidal (TBP) geometries, depending on the steric size of the ligands. Tolman electronic parameters were calculated (DFT) for each antimony ligand to provide a tabulated resource for the relative strengths of simple antimony ligands. The electronic absorbance spectra of the square planar complexes exhibit characteristic bands [λ ≈ 560 nm (17 900 cm), ε ≈ 4330 M cm] at lower energies compared to the reported phosphine complexes, indicating the weak donor strength of the stibine ligands and resultant low-energy ligand field d→ d transitions. The square planar complex Ni(I)(Sb Pr) reacts with CO to form the TBP complex Ni(I)(Sb Pr)(CO). Lastly, the complexes were investigated for nickel metal deposition on Si|Cu(100 nm) substrates. The complexes with the strongest donating ligand, Sb Pr, deposited the purest layer of NiCu alloy according to the balanced reaction Ni(I)(SbPr) → Ni + Sb( Pr)I; the iodinated Sb byproduct was unambiguously detected in the supernatant by H NMR and mass spectrometry. Complexes with weaker ligands (poor I acceptors/scavengers) resulted undesired deposition of iodine and CuI on the surface. This work thus serves as a guide for the design and synthesis of 3 d metal complexes with neutral, heavy main-group donors that are useful for metal deposition applications.