The reactions of the very bulky phosphine ligands containing both tert-butyl and orthotrifluoromethylphenyl substituents with [PdCl 2 (PhCN) 2 ] have been studied, in order to assess the impact of steric and electronic effects on a ligand's coordination ability. The palladium complexes of tertbutyl(ortho-trifluoromethylphenyl)methyl phosphine and tert-butyl(ortho-trifluoromethylphenyl)(nbutyl)phosphine were characterised by X-ray crystallography and shown to be good precatalysts for the hydroxy-and alkoxycarbonylation of alkenes relative to Pd complexes of tricyclohexylphosphine and triphenylphosphine. A notable feature of Pd complexes of tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine is significantly enhanced regioselectivity relative to previous state-of-the-art catalysts in the hydroxycarbonylation of styrene, even if lithium chloride co-catalysts are not used. These catalysts derived from large cone angle ligands consistently give higher regioselectivity in the alkoxycarbonylation of styrene using ethanol, n-propanol, and i-propanol as nucleophiles. These Pd complexes are also active in the Suzuki coupling of activated aryl chlorides, and in both carbonylation and Suzuki reactions, tertbutyl(ortho-trifluoromethylphenyl)methyl phosphine gives more productive catalysts than its bulkier analogues.