Hexaphenylcarbodiphosphorane is the
organophosphorus compound with the formula C(PPh3)2 (where
Ph = C6H5). It is a yellow, moisture-sensitive solid. The compound is classified as an
ylide and as such carries significant negative charge on carbon. It is isoelectronic with
bis(triphenylphosphine)iminium. The P-C-P angle is 131°.[1] The compound has attracted attention as an unusual ligand in organometallic chemistry.[2]
The pure compound has two crystalline phases: a metastable
monoclinic C2 phase that is
triboluminescent, and an
orthorhombic P222 form that is not. Both polymorphs are
photoluminescent, with respective peak wavelengths at 540 and 575 nm.[3]
Preparation
The compound was originally prepared by deprotonation of the
phosphonium salt [HC(PPh3)2]Br using potassium.[4]
An improved procedure entails production of the same double phosphonium salt from methylene bromide. The double deprotonation is effected with
potassium amide.[5]
^Hardy, Gordon E.; Kaska, William C.; Chandra, B. P.; Zink, Jeffrey I. (March 1981). "Triboluminescence-structure relationships in polymorphs of hexaphenylcarbodiphosphorane and anthranilic acid, molecular crystals, and salts". Journal of the American Chemical Society. 103 (5): 1074–1079.
doi:
10.1021/ja00395a014.
^Ramirez, Fausto; Desai, N. B.; Hansen, B.; McKelvie, N. (1961). "Hexaphenylcarbodiphosphorane, (C6H5)3P:C:P(C6H5)3". Journal of the American Chemical Society. 83 (16): 3539–40.
doi:
10.1021/ja01477a052.
^Gruber, Marco; Bauer, Walter; Maid, Harald; Schöll, Kilian; Tykwinski, Rik R. (2017). "Synthetic and NMR Studies on Hexaphenylcarbodiphosphorane (Ph3P=C=PPh3)". Inorganica Chimica Acta. 468: 152–158.
doi:
10.1016/j.ica.2017.04.018.