- Substitution and cyclometallation reactions on Pt(II) phosphite complexes
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This paper describes the formation of newseries of platinum(II) complexes with phosphite and phosphine ligands. Treatment of cis,cis-[Me2Pt(μ-SMe2)2PtMe2] with 2 equimolar of L, L = P(OiPr)3/sub
- Jamshidi, Mahboubeh,Samouei, Hamidreza,Esmaeilbeig, Ahmad R.
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- Organoplatinum(II) complexes with phosphite ligands
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The phosphite complexes cis-[PtMe2L(SMe2)] in which L = P(OiPr)3, 1a, or L = P(OPh)3, 1b, were synthesized by the reaction of cis,cis-[Me2Pt(μ-SMe2)2PtMe2] with 2 equiv. of L. If 4 equiv. of L was used the bis-phosphite complexes cis-[PtMe2L2] in which L = P(OiPr)3, 2a, or L = P(OPh)3, 2b, were obtained. The reaction of cis-[Pt(p-MeC6H4)2(SMe2)2] with 2 equiv. of L gave the aryl bis-phosphite complexes cis-[Pt(p-MeC6H4)2L2] in which L = P(OiPr)3, 2a′, or L = P(OPh)3, 2b′. Use of 1 equiv. of L in the latter reaction gave the bis-phosphite complex along with the starting complex in a 1:1 ratio. The complexes failed to react with MeI. The reaction of cis,cis-[Me2Pt(μ-SMe2)2PtMe2] with 2 equiv. of the phosphine PPh3 gave cis-[PtMe2(PPh3)2] and cis-[PtMe2(PPh3)(SMe2)] along with unreacted starting material. Reaction of cis-[PtMe2L(SMe2)], 1a and 1b with the bidentate phosphine ligand bis(diphenylphosphino)methane, dppm = Ph2PCH2PPh2, gave [PtMe2(dppm)], 8, along with cis-[PtMe2L2], 2. The reaction of cis-[PtMe2L(SMe2)] with 1/2 equiv. of the bidentate N-donor ligand NN = 4,4′-bipyridine yielded the binuclear complexes [PtMe2L(μ-NN)PtMe2L] in which L = P(OiPr)3, 3a, or L = P(OPh)3, 3b. The complexes were fully characterized using multinuclear NMR (1H, 13C, 31P, and 195Pt) spectroscopy.
- Esmaeilbeig, Ahmad R.,Samouei, Hamid R.,Rashidi, Mehdi
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p. 2519 - 2526
(2008/09/20)
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- Binding of specialty phosphines to metals: Synthesis, structure, and solution calorimetry of the phosphirane complex [PtMe2(iPrBABAR-Phos)2]
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The complex [PtMe2(iPrBABAR-Phos)2] (3) was prepared in a clean and quantitative ligand substitution reaction from [PtMe2(cod)] (1; cod = η4-1,5-cyclooctadiene) and the phosphirane iPrBABAR-Phos (2). The structure of 3 was determined by X-ray diffraction. The Pt-P bonds (~2.26 A) lie in the shorter range of PtII-P bonds, although the 1J(195Pt31P) coupling (1840 Hz) is quite small. The enthalpy for this ligand substitution reaction was measured by solution calorimetry and found to be exothermic by 11.8 kcal/mol, a relatively low exothermicity for a reaction involving a tertiary phosphine in this Pt system. Calculations using density functional theory (DFT) on the B3LYP level were applied using the simplified model reaction [PtH2(cod)] + 2(H2N)PC2H4 → [PtH2{(H2N)PC2H4}2)] + cod, and these also gave a rather low substitution enthalpy (-17 kcal/mol). A charge decomposition analysis (CDA) was performed for Pt(II) and Pt(0) complexes with the simple P-amino phosphirane (H2N)PC2H4 and PH3 as ligands. Contrary to expectations, it is found that the phosphirane acts as a relatively good electron donor, while its electron-acceptor properties are not significantly different from those of other phosphines. The particularly low reaction enthalpy may thus be due to a low directionality of the donor orbitals toward the metal center.
- Laporte, Cecile,Frison, Gilles,Gruetzmacher, Hansjoerg,Hillier, Anna C.,Sommer, William,Nolan, Steven P.
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p. 2202 - 2208
(2008/10/08)
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