The trivalent fluorophosphine (+/-)-PFPh(i-Pr), (+/-)-1, has been prepared by halogen exchange of the corresponding chlorophosphine with sodium fluoride in hot sulfolane. The neat fluorophosphine rapidly decomposes by equilibrium redox disproportionation into PF(3)Ph(i-Pr) and (R*,R*)/(R*,S*)-Ph(i-Pr)PPPh(i-Pr), but in benzene, (+/-)-1 has considerable thermodynamic stability. The resolution of (+/-)-1 was achieved by a fractional crystallization of the diastereomers (R,Rp)- and (R,Sp)-chloro[1-[1-(dimethylamino)ethyl]-2-naphthalenyl-C,N](fluorophenylisopropylphosphine)palladium(II), (R,Rp)- and (R,Sp)-5, whereby the less soluble (R,Rp) diastereomer selectively crystallized in 64% yield in a typical second-order asymmetric transformation. Optically pure (S)-(-)-1, [alpha](20)(D) -210 (c 0.59, C6H6), was liberated from (R,Rp)-5 with (R*,S*)-1,2-phenylenebis(methylphenylphosphine). The optically active phosphine in benzene racemizes over 6 h without significant redox disproportionation. The methoxyphosphine (+/-)-P(OMe)Ph(i-Pr), (+/-)-9, was also resolved by the method of metal complexation. Thus, fractional crystallization of (R,Rp)- and (R,Sp)-chloro[1-[1-(dimethylamino)ethy1]-2-naphthalenyl-C,N](methoxyphenylisopropylphosphine)palladium(II), (R,Rp)- and (R,Sp)-8, followed by liberation of the respective optically active methoxyphosphines from the separated diastereomers with 1,2-bis(diphenylphosphino)ethane, gave (R)(+)- and (S)-(-)-9 of 92% and 96% ee, respectively. The barrier to unimolecular inversion for (+/-)-9 was determined to be >82.9 +/- 0.5 kJ mol(-1) by variable temperature H-1 NMR spectroscopy. The substitution of fluoride in (R,Rp)-5 by methoxide proceeds with predominant inversion of the configuration at phosphorus to give (R,RP)- and (R,Sp)-8 with (R,Sp)/(R,Rp) = 1/5. The crystal structures of (R,Rp)-5 and (R,Rp)-8 have been determined : (R,Rp)-5 (C23H28ClFNPPd) crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 9.967(2) Angstrom, b = 10.998(4) Angstrom, c = 21.324(3) Angstrom, Z = 4, and R = 0.031; (R,Rp)-8 (C24H31ClNOPPd) crystallizes in the space group P2(1)2(1)2(1) with a = 10.444(3) Angstrom, b = 12.146(3) Angstrom, c = 19.047(2) Angstrom, Z = 4, and R = 0.026.