- Mono- and dinuclear complexes of platinum(II) with chiral diphosphines: Pt(P-P′)Cl2 and [Pt(P-P′)(μ-OH)]2[BF4]2 (P-P′ = prolophos, N-(diphenylphosphino)-2-((diphenylphosphinoxy)methyl)pyrrolidine, and butaphos, 1-(diphenylphosphinoxy)-2-(N-ethyl-N-(diphenylphosphino)amino)butane). Crystal and molecular structure of ...
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Full title: Mono- and dinuclear complexes of platinum(II) with chiral diphosphines: Pt(P-P′)Cl2 and [Pt(P-P′)(μ-OH)]2[BF4]2 (P-P′ = prolophos, N-(diphenylphosphino)-2-((diphenylphosphinoxy)methyl)pyrrolidine, and butaphos, 1-(diphenylphosphinoxy)-2-(N-ethyl-N-(diphenylphosphino)amino)butane). Crystal and molecular structure of Pt{S-prolophos-P,P′}Cl2. The mononuclear complexes Pt(P-P′)Cl2, 1 and 2, where P-P′ are the chiral ligands (S)-N-(diphenylphoshino)-2-((diphenylphosphinoxy)methyl)pyrrolidine, S-prolophos, and (R)-1-(diphenylphosphinoxy)-2-(N-ethyl-N-(diphenylphosphino)amino)butane, R-butaphos, respectively, were prepared and characterized in solution by 1H, 13C, 31P, 195Pt, and two-dimensional correlation spectra. Only one conformer is observed in solution at room temperature. The structure of complex 1, Pt{S-prolophos}Cl2, was solved by X-ray diffraction: C29H29Cl2NOP2Pt, orthorhombic, space group P212121, a = 16.557 (6) A?, b = 15.697 (6) A?, c = 10.948 (5) A?, Z = 4, and V = 2845 (2) A?3. The structure was refined to a conventional R factor of 0.040 (Rw = 0.049) for 2700 observed reflections with I > 3σ(I). The ligand P-P′ is coordinated in an endobidentate fashion to the platinum atom, which exhibits a slightly distorted square-planar geometry. The seven-membered ring adopts a twist-boat conformation. Treatment of complexes 1 and 2 with silver tetrafluoroborate in methanol solution afforded the dinudear species [(P-P′)Pt(μ-OH)2Pt(P-P′)][BF4]2 (3, P-P′ = prolophos, and 4, P-P′ = butaphos). The dinuclear unit is maintained even in the gas phase, as shown by the MS-FAB spectrum of complex 4. Complex 1, in the presence of tin(II) chloride, was found to catalyze the hydroformylation of styrene to (R)-(-)-2-phenylpropanal with 37% optical purity.
- Bandini, Anna Laura,Banditelli, Guido,Cesarotti, Edoardo,Minghetti, Giovanni,Bovio, Bruna
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p. 391 - 398
(2008/10/08)
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