The Synthesis and Structural Characterization of Mesityldiphenylphosphine, Dimesitylphenylphosphine and Trimesitylphosphine

Abstract

The synthesis and structural characterization of the tertiary phosphines mesityldiphenylphosphine [PPh₂( mes )], dimesitylphenylphosphine [ PPh ( mes )₂] and a new phase of trimesitylphosphine [P( mes )₃] have been carried out. Crystals of PPh₂( mes ) are monoclinic, space group P2₁/c, with a 10.252(10), b 9.847(11), c 17.444(7) Ǻ, β 99.78(6)°, Z 4; R 0.059 for 2102 'observed' reflections. Crystals of PPh ( mes )₂ are also monoclinic, space group P 2₁/c, with a 8.964(9), b 22.99(1), c 10.228(4) Ǻ, β 107.98(5)°, Z 4; R 0.058 for 2350 'observed' reflections. The new phase of P( mes )₃ is monoclinic, Cc, a 11.390(5), b 12.034(4), c 17.564(9) Ǻ, β 104.22(4)°, Z 4 (R 0.060 for 1046 'observed' reflections), in which the molecule is disordered. A full report is given for the phase previously studied (triclinic), Pī , a 8.191(3), b 16.447(5), c 18.667(6) Ǻ, α 104.82(3), β 97.74(3), γ 100.07(3)°, Z 4; R 0.065 for 4964 'observed' reflections. The P-C bond distances are similar for the whole series of compounds with an average value of 1.833(1)Ǻ. Introduction if the mesityl groups results in an increase of the C-P-C angles from c. 103 to c. 110° with a concomitant flattening of the PC₃ pyramid.