REGIOSELECTIVE CARBON FLUORINE BOND-CLEAVAGE REACTIONS FROM THE INTERACTION OF TRANSITION-METAL FLUOROCARBON COMPLEXES WITH NUCLEOPHILES

The use of fluoro substituents has been tested as a means to stabilize the amide bond to divalent platinum. Products have been obtained which show that complexed fluoroalkyls and fluoroaryls have a high reactivity to nucleophiles. The complex transPtCF3Cl(PPh3)2 reacts with LiN(CH3)2 to give products derived from Pt(PPh3)2. The complex trans-[PtCH3(THF)-(PPh2C6F5)2]ClO4, prepared from trens-PtCH3Cl(PPh2C6F5)2 and AgClO4 in THF solvent, reacts with hydroxide ion to give the cyclometalated complex trans-PtCH3(2-OC6F4PPh,)(PPh2C6F5). The crystal structure of trans-PtCH3(2-OC6F4PPh2)(PPh2C6F5) has a monoclinic P21/c cell with a = 12.437 (2) Å, b = 25.749 (8) Å, c = 10.788 (2) Å, β = 102.35 (1)°, Z = 4. Reaction of this complex with HCl results in ring opening to give trans-PtCH3Cl(2-HOC6F4PPh2)(PPh2C6F5). Reacting irani-[PtCH3-(THF)(PPh2C6F5)2]ClO4 with methoxide ion gives trans-PtCH3(OCH3)(PPh2C6F3(OCH3-2,6)2)2, where all the fluorines in the 2-positions of the fluorophenyl rings have been replaced by methoxide. Treating this complex with water gives trans-PtCH3(2-OC6F3(OCH3-6)PPh2)(PPh2C6F3(OCH3-2,6)2). Heating a mixture of triphenylphosphine, bromopentafluorobenzene and nickel bromide at 200 °C, followed by hydrolysis of the melt, gives the phosphonium salt [Ph3(C6F4H-4)P]Br. The use of D2O in the hydrolysis yields [Ph3(C6F4D-4)]Br. Hydroxide ion reacts with the phosphonium salt to give P-C cleavage. 1,2,4,5-Tetra-fluorobenzene is formed from [Ph3(C6F4H-4)]Br and OH-, 1,2,4,5-tetrafluorodideuteriobenzene is formed from [Ph3(C6F4D-4)]Br and OD-, and 1,2,4,5-tetrafluoro-3-deuteriobenzene is formed from either [Ph3(C6F4H-4)]Br and OD- or [Ph3(C6F4D-4)]Br and OH-. © 1990, American Chemical Society. All rights reserved.