Acta Cryst. (2013). C69, 1051-1054 [ doi:10.1107/S0108270113020647 ]
Abstract: The title compound, C45H70P+·ClO4- or [Tripp3PH+][ClO4-], was produced from the perchlorate salt of the corresponding radical cation Tripp3P·+ through very slow H-atom abstraction reactions in a solution of 1,2-dimethoxyethane (Tripp is 2,4,6-triisopropylphenyl). The H atom on the P atom was located in a difference map and was freely refined with an isotropic displacement consistent with full occupancy [P-H = 1.37 (3) Å]. It is the most sterically congested triarylphosphonium salt yet to be reported and has a `propeller' arrangement of the three Tripp groups around the P atom, with the protonation site located along the molecular threefold axis. There are short contacts between the flanking isopropyl methine H atoms and the P atom [PH = 1.99 (2)-2.17 (2) Å]. The sum of the angles around the P atom [(C-P-C) = 349.9 (6)°] is a convenient index of pyramidality for tricoordinate centres. This value is significantly larger than in analogous Mes3PH+ salts (Mes is mesityl or 2,4,6-trimethylphenyl), for which the average of the three reported structures in the literature is (C-P-C) = 345.3 (6)°. For comparison, in the ubiquitous Ph3PH+ salts, this parameter has a typical average value of only 333.3 (9)°. The value of (C-P-C) in the title compound is midway between that of the neutral phosphane Tripp3P [334.4 (6)°] and the phosphoniumyl radical cation Tripp3P·+ [359.8 (2)°]. This geometrical feature provides additional support for the assignment as a phosphonium salt.
Keywords: crystal structure; triarylphosphonium ions; pyramidality index; phosphoniumyl radical cations.
Chemical Markup Language (CML) file (14.0 kbytes)
To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.
The download button will force most browsers to prompt for a file name to store the data on your hard disk.
Where possible, images are represented by thumbnails.
Copyright © International Union of Crystallography