N‐(2,4,6‐Trimethylborazinyl)‐Substituted Phosphanes, Arsanes, and Stibanes

Abstract

Reaction of the N‐lithioborazine LiH2N3B3Me3·OEt2 (2) in diethyl ether with PCl3 or PBr3 leads to the borazinylphosphanes (Me3B3N3H2)PX2, (Me3B3N3H2)2PX (X = Cl, Br), and (Me3B3N3H2)3P, depending on the initial stoichiometry. The analogous arsane and stibane derivatives were obtained in a similar manner. While (Me3B3N3H2)2PBr is reduced byLiAlH4 in diethyl ether/hexane to give the monophosphane (Me3B3N3H2)2PH (13), the reaction of (Me3B3N3H2)PBr2 (5) with LiAlH4 in diethyl ether/hexane produces the zwitterionic compound [Me3B3N2(HN)]–P+H2Et (14). Dehalogenation of (Me3B3N3H2)2PBr (6) with Na yields the diphosphane (Me3B3N3H2)2PP(H2N3B3Me3)2 (18), while the mixed diphosphane (Me3B3N3H)2PPmes2 (17) is obtained from 6 and LiPmes2. Dehalogenation of Me3B3N3H2PBr2 with Na results in the exclusive formation of (Me3B3N3H2)4P4 (19), while the reaction of 5 with Li2Pmes leads to a mixture of cyclotetraphosphanes (mes)4–n(Me3B3N3H2)nP4 (A–F) along with bicyclic P4mes2. The new compounds have been characterized by NMR and IR spectroscopy and partly by mass spectrometry. X‐ray structures for compounds, 4, 5, 6, 9, 13, 14, 17, 18, 19, and E have been determined. All show different B–N bond lengths within the borazine rings, and some have borazine rings in a half‐chair conformation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

B-substituted group 1 phosphides: synthesis and reactivity

“…19 Discrete B ← P coordinated diphosphine has not yet been structurally characterized. Compounds containing P–P bonds in the presence of a nearby electrophilic boron atom are limited to B-containing cyclooligophosphanes, 20 trimethylborazinyl-substituted phosphanes, 21 carbaborane-substituted 1,2-diphosphetanes 22 or boron-substituted phosphorus cages formed by the P 4 activation of 1,2-diboraallene, 23 where the P–P bond lengths vary in the range from 2.171(4) Å to 2.263(1) Å. Both B1–P1 (2.139(3) Å) and B2–P2 (2.148(3) Å) bond lengths prove the presence of B ← P coordination in 4 , but they are slightly longer than typical B(sp 3 )–P single bonds (1.93–2.06 Å).…”

“…Both B1-P1 (2.139(3) Å) and B2-P2 (2.148(3) Å) bond lengths prove the presence of B ← P coordination in 4, but they are slightly longer than typical B(sp 3 )-P single bonds (1.93-2.06 Å). [20][21][22][23] The B atoms are fourfold coordinated and show a distorted tetrahedral environment with τ = 0.87 in accordance with sp 3 hybridization. The 11 B{ 1 H} NMR spectrum of 4 corroborated the presence of tetra-coordinated boron by the signal resonating at δ −0.4 ppm.…”