Gas-phase structures of 1-adamantylphosphines, PH n (1-Ad)3−n (n = 1–3)

Abstract

The gas-phase structure of 1-adamantylphosphine has been determined by electron diffraction, supplemented with data from ab initio and DFT calculations. The adamantyl fragment was modeled with local C 3v symmetry and the phosphino group was found to be in a position almost bisecting a mirror plane of the adamantyl group, giving the molecule overall approximate C s symmetry. There is a small displacement of the C-P bond from the local threefold axis of the adamantyl group. Geometry optimizations were also performed for bis-(1-adamantyl)phosphine (C 1 point-group symmetry) and tris-(1-adamantyl)phosphine (C 3 symmetry), demonstrating extremely crowded environments around the phosphorus atoms leading to adamantyl groups that were much less symmetric. The adamantyl groups were also found to twist by a significant amount to minimize the strain.

Electrophilic Routes to Tertiary Adamantyl and Diamantyl Phosphonium Salts

“…The reaction of 1-diamantyl bromide (7) with AgOTf in 2,2,-dimethylbutane was examined as above. AgBr was precipitated more rapidly than in the 1-adamantyl case, and the triflate 10 was formed as colourless crystals when the solvent was removed at 0 °C after cannula filtration.…”

“…6 QM analysis of the structure of Ad 3 P confirms the presence of a high level of steric strain. 7 The chemistry employed in synthesis of tert-butyl and 1-adamantyl phosphines is generally distinct (Scheme 1). For t-Bu 3 P, tert-butyllithium or the corresponding Grignard reagent are employed in a one-step or two-step synthesis starting from PCl 3 .…”

Interplay of thermochemistry and Structural Chemistry, the Journal (volume 22, 2011, issues 1–3) and the discipline

“…Wann et al [71] in their paper report on the experimental and DFT calculations of the 1-adamantylphosphines, PH n (1-Ad) 3-n (n = 1-3) gas-phase structures. Crowded environment around the phosphorus atoms leads to lower symmetry of the adamantyl groups.…”