51538-76-2Relevant academic research and scientific papers
Synthesis, Structure, and Reactivity of Arylfluoro Platinum(II) Complexes
Nilsson, Patrik,Plamper, Felix,Wendt, Ola F.
, p. 5235 - 5242 (2008/10/09)
Complexes of the type trans-[PtPhFL2], where L = PPh 3 (4), PMe2Ph (5), were synthesized. Complex 4 was characterized by X-ray crystallography. The equilibrium constant for the substitution of the fluoride trans to phenyl in 4 by Cl- and I - was determined, and the stability sequence follows the normal trend seen in "soft" metal centers: i.e., the Pt has a preference for the halide in the order I > Cl > F; the difference is, however, fairly small. The substitution kinetics follow the usual two-term rate law, and the rate constants for the solvolytic (k1) and the direct (k 2) reaction pathways were determined to be k1 = (9.7 ± 2.4) × 10-5 s-1, k2 = (11.7 ± 0.3) × 10-2 M-1 s-1 and k 1 = (7.1 ± 4.9) × 10-5 s-1, k 2 = (23.0 ± 1.3) × 10-2 M-1 s -1 for Cl- and I-, respectively. Activation parameters for the solvolytic and direct pathways with Cl- as incoming ligand are typical for associative processes and were determined to be δHDagger; = 77.8 ± 5.5 kJ mol-1, δS Dagger; = -56 ± 18 J K-1mol-1 and δH? = 67.6 ± 1.8 kJ mol-1, δS? = -37 ± 6 J K-1mol-1, respectively. Complexes 4 and 5 react with Me3SnPh, and within 2-15 min there is a complete conversion to products. 4 gives a single product, trans-[PtPhMe(PPh3)2], which was characterized by X-ray crystallography. 5 gives two products: trans-[PtPhMe(PMe2Ph) 2] and trans- [PtPh2(PMe2Ph)2]. Steric effects on the reactivity speak in favor of an associative mechanism. The surprisingly high reactivity for the transmetalations, compared to the substitution reactions, can be explained in terms of an associative mechanism, where a strong, bridging Sn-F interaction stabilizes the transition state. Furthermore, only trans products are formed; i.e., we have an exclusive F-for-R (R = Me, Ph) substitution at these platinum fluoro complexes. Treatment of 4 with phenylacetylene in benzene at room temperature gives the alkynyl complex trans-[PtPh(CCPh)(PPh3)2] (8).
Reactivity of platinum diolefin complexes. 2. Reactions with bulky and chelating group 5B ligands and studies relating to carbonyl insertion
Anderson,Clark,Davies
, p. 3607 - 3611 (2008/10/08)
Reactions of [PtXY(cod)] (X = Y = Cl, Me, Ph; X = Cl, Y = Ph, COPh) with bulky monodentate and chelating group 5B ligands have been examined by 31P{1H} NMR spectroscopy. The molecularity of the products is a function of steric bulk with monodentate ligands and a function of chelate bite with bidentate ligands. The geometry of the products is controlled largely by the trans influence of both neutral and anionic groups. Where the steric constraints involved in nucleophilic attack of the complexes by bulky ligands are dominant, olefin displacement can be prevented entirely. Reactions of [PtXYL2] (X = Y = Ph, Cl; X = Ph, Y = Cl; L = monodentate ligand, L2 = bidentate ligand) with carbon monoxide have been studied by 31P{1H} and 13C{1H} NMR and infrared spectroscopies. The mechanism of carbonyl insertion at platinum(II) is discussed in terms of the chelate effect and the trans influence of the anionic ligands.
