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1,2‐Diphosphaacenaphthene 1,2‐Dications: Synthetic, Stereochemical and Computational Study of the Stabilising Role of Naphthalene‐1,8‐diyl Backbone
Author(s) -
Somisara D. M. Upulani K.,
Bühl Michael,
Lebl Tomas,
Richardson Neville V.,
Slawin Alexandra M. Z.,
Woollins J. Derek,
Kilian Petr
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002259
Subject(s) - dication , chemistry , naphthalene , trifluoromethanesulfonate , steric effects , alkylation , crystal structure , tetrafluoroborate , reagent , medicinal chemistry , nap , single crystal , stereochemistry , crystallography , molecule , organic chemistry , ionic liquid , catalysis , neuroscience , biology
Syntheses and full characterisation data (including single crystal diffraction) of three 1,2‐diphosphonium dicationic species with the naphthalene‐1,8‐diyl (Nap) backbone are reported. The oxidation of Nap[P(NMe 2 ) 2 ] 2 with P 2 I 4 to its 1,2‐dication was achieved. meso ‐ and rac‐ forms of “all carbon” 1,2‐diphosphonium dications were obtained in good yields and purity by double alkylation of the parent diphosphine (1,2‐diphenyl‐1,2‐diphosphaacenaphthene) with methyl triflate or trimethyloxonium tetrafluoroborate. Each methylating reagent produces one of the rac ‐ or meso ‐forms of the dication diastereospecifically. Structural parameters of the new dications are discussed with respect to other phosphorus 1,2‐dications. DFT (B3LYP) computations revealed the significant role of the naphthalene backbone in stabilisation of the dicationic motif and helped to assess the energy cost of the steric clash of a variety of groups attached to the peri ‐positions of naphthalene. The synthesis and single crystal X‐ray data of the extremely crowded Nap[P(Se)(O i Pr) 2 ] 2 are discussed, and are contrasted with the unsuccessful synthesis of Nap(P t Bu 2 ) 2 from NapLi 2 and ClP t Bu 2 .