Highly Congested Donor-Acceptor P-B Compound: Synthesis and Properties of a BMes2- and a PPh2-Functionalized 1,8-Naphthalene

초록

A PPh2- and BMes(2)-functionalized (Mes = mesityl) 1,8-naphthalene molecule (1) has been synthesized and fully characterized. Compound 1 is a highly congested molecule with a P B dative bond. NMR studies support that the P B bond in 1 is persistent in solution. Compound 1 is thermally and photochemically stable. It is highly fluxional in solution. The only reactivity it displays is its reactions with halogen molecules (PhI center dot Cl-2 and I-2), leading to the isolation of a hydrolyzed product 2, in which an oxygen atom is inserted between the P and B atom. The crystal structures of 1 and 2, have been determined by single-crystal X-ray diffraction analyses. A DFT computational study established that the open form of 1 has a P-B separation distance of 3.00 angstrom, much longer than the closed one (2.23 angstrom). Furthermore, a computational study showed that the energy difference between the two forms is very small, similar to 1 kcal/mol, which can be attributed to the highly congested nature of the molecule.

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