Flourine containing phosphine complexes of the platinum metals.
thesisposted on 19.11.2015, 08:45 by Michael John. Hacker
While an extensive chemistry exists for the chloro, and, to a lesser extent, the bromo and iodo phosphine, and related organometallic complexes of the platinum metals the corresponding fluoro complexes are virtually unknown; and as a consequence, have received little attention. In this study we have attempted to synthesise such complexes by various routes and to study and compare their chemistry with that of the other halogen complexes. There has been some controversy concerning the formulation of the product obtained from the reaction of tetrakis (triphenylphosphine) platinum (0) with liquid hydrogen fluoride. We have reinvestigated this reaction and provided conclusive evidence for the presence of a cationic species[ptF(PPh3).;containing a platinum-fluorinebond, into which, as a crystal study has shown, the carbon disulphide molecule can be inserted; the first reported insertion reaction into a M-F bond of this type. The fluoro derivative of Vaska's complex, and its rhodium analogue,have been synthesised by simple halide exchange using silver fluoride; as a consequence of these reactions we have found a simple high yield route to hitherto unknown mixed donor ligand complexes of the type RhX(C0)LL' CX= Cl,Br; L= PPh3,AsPh3; L*= PPh3, AsPh3, SbPh3, P(0Ph)3 ) by halogen bridge cleavage of the dimeric precursors.;RhX(C0)Lj The inability to synthesise the corresponding fluorinebridged complex precluded investigation of similar reactions to obtain fluoro complexes of that type. The iridium-fluorine bond in fluorocarbonylbis -(triphenylphosphine)iridium(I) has been shown to readily undergo halide exchange, either directly or simultaneously,and in compet.;ition with,oxidative addition of addenda containing other halogensand, in polar solvents, displacement. The adduct with sulphur dioxide appears to be less stable than the corresponding chloro, bromo, and iodo adducts. However, as a quantitative thermodynamic study has shown, the adducts with tetrafluoroethylene and hexafluorobut-2-yne are more stable than those of the other halogen derivatives; the trend for the stabilities of reversible decomposition for the complete series of these compounds IrX (CO) (PPh.;)(X=F,Cl, Br; L*= C.;Fg) is in the opposite direction to that predicted on the basisof series of related compounds. Attempts to isomerise the tt bonded tetrafluoro -ethylene in complexes of the type PtL2(C2F.;) (L= PPh.;AsPh.;) to yield trifluorovinylcomplexes containing a platinum-fluorine bond, in an analagous reaction to that observed for the fluoro -chloro/bromo olefins* were unsuccessful;but led to the invesitigation of the chemistry of carbonatobis (triphenylarsine) platinum(II) as a clean easy precursor of bis(triphenylarsine) platinum(0) for the synthesis of olefin and acetylene complexes of the type Pt (AsPh.;)2.;f; (Cf"olefin r acetylene). A kinetic study pf the.oxidative addition ofmethylfluorosulphonate to Yaska's complex has been made and compared with data obtained for other molecules.