Herein, we present the synthesis of nickel complexes with tripodal phosphine ligands, CH₃Si(CH₂PPh₂)₃ and CH₃C(CH₂PPh₂)₃, and their application as catalysts in Sonogashira cross-coupling reactions in water. Although both types of nickel complexes are based on similar tripodal ligands, the Si-derived compounds adopt stable tetrahedral coordination geometries, whereas the C-derived counterparts adopt a square-planar coordination environment. This structural and electronic difference has an important effect on the catalytic properties of the complexes. Our study demonstrates that C-derived complexes are catalytically inactive, whereas the complexes [CH₃Si(CH₂PPh₂)₃NiX₂] (X = Cl^–, Br^–) are competent catalysts for cross-coupling reactions of aryl halides with phenylacetylenes. This investigation reveals the importance of structural tuning on catalysis and strongly supports the theory that tetrahedral (PR₃)₂NiCl₂ complexes are the active species in Sonogashira cross-coupling reactions.