Synthesis and Structural Characterization of New Hindered Aryl Phosphorus Centers (Aryl = 2,6-Dimesitylphenyl)

Abstract

The new sterically encumbered dichlorophosphine ArPCl₂ (Ar = 2,6-dimesitylphenyl = Dmp,l) has been prepared from the corresponding aryliodide, n-butyllithium, and phosphorus trichloride. DmpPC1₂ served as a precursor for the phosphinic acid DmpP(O)(OH)H (2), primary phosphine DmpPH₂ (3), and diphosphene DmpP = PDmp (4). Compounds 2 and 4 have been crystallographically characterized. The solid state structure of 2 reveals the existence of dimeric phosphinic acids associated by hydrogen bonding in a manner analogous to carboxylic acid dimers. The P–O distances are 1.508(2) and 1.521(2) Å and the O–H and O–H...O distances are 1.06(4) and 1.46(4), consistent with localized hydrogen bonding. The structure of 4 feajures a trans configuration about the P = P bond and short P = P bond length of 1.985 (2) Å. Crystal data for compound 2: a = 9.4552(8) Å, b = 11.174(1) Å, c = 11.711(1) Å, α = 65.775(8) Å, β = 75.735(7)°, γ = 69.621(7)°, triclinic, P–1,Z = 2. Crystal data for compound 4: a = 10.940(1) Å, b = 22.323(2) Å, c = 17.017(2) Å, b =91.085(9)°, monoclinic, P2(l)/c,Z=4.