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Issue 27, 2011
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Diphosphanes derived from phobane and phosphatrioxa-adamantane: similarities, differences and anomalies

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Abstract

The homodiphosphanes CgP–PCg (1) and PhobP–PPhob (2) and the heterodiphosphanes CgP–PPhob (3), CgP–PPh2 (4a), CgP–P(o-Tol)2 (4b), CgP–PCy2 (4c), CgP–PtBu2 (4d), PhobP–PPh2 (5a), PhobP–P(o-Tol)2 (5b), PhobP–PCy2 (5c), PhobP–PtBu2 (5d) where CgP = 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-9-yl and PhobP = 9-phosphabicyclo[3.3.1]nonan-9-yl have been prepared from CgP(BH3)Li or PhobP(BH3)Li and the appropriate halophosphine. The formation of 1 is remarkably diastereoselective, with the major isomer (97% of the product) assigned to rac-1. Restricted rotation about the P–P bond of the bulky meso-1 is detected by variable temperature 31P NMR spectroscopy. Diphosphane 3 reacts with BH3 to give a mixture of CgP(BH3)–PPhob and CgP–PPhob(BH3) which was unexpected in view of the predicted much greater electron-richness of the PhobP site. Each of the diphosphanes was treated with dimethylacetylene dicarboxylate (DMAD) in order to determine their propensity for diphosphination. The homodiphosphanes 1 and 2 did not react with DMAD. The CgP-containing heterodiphosphanes 4a–d all added to DMAD to generate the corresponding cisalkenes CgPCH(CO2Me)[double bond, length as m-dash]CH(CO2Me)PR2 (6a–d) which have been used in situ to form chelate complexes of the type [MCl2(diphos)] (7a–d) where M = Pd or Pt. The PhobP-containing heterodiphosphanes 3 and 5a–d react anomalously with DMAD and do not give the products of diphosphination. The X-ray crystal structures of the diphosphanes 2, 3, 4a, and 5a, the monoxide and dioxide of diphosphane 1, and the platinum chelate complex 7c have been determined and their structures are discussed.

Graphical abstract: Diphosphanes derived from phobane and phosphatrioxa-adamantane: similarities, differences and anomalies

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Publication details

The article was received on 26 Feb 2011, accepted on 11 Apr 2011 and first published on 06 Jun 2011


Article type: Paper
DOI: 10.1039/C1DT10335K
Citation: Dalton Trans., 2011,40, 7137-7146
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    Diphosphanes derived from phobane and phosphatrioxa-adamantane: similarities, differences and anomalies

    D. L. Dodds, J. Floure, M. Garland, M. F. Haddow, T. R. Leonard, C. L. McMullin, A. G. Orpen and P. G. Pringle, Dalton Trans., 2011, 40, 7137
    DOI: 10.1039/C1DT10335K

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