ISSN:
0947-6539
Keywords:
cations
;
crystal structures
;
phenyl rings
;
supramolecular chemistry
;
tetraphenylphosphonium ions
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Examination of the Cambridge Structural Database reveals that Ph4P+ cations in crystals associate through phenyl-phenyl nonbonded interactions which are attractive, concerted, and widespread. Intermolecular phenyl-phenyl conformations, which are offset-face-to-face (off), edge-to-face (ef) or vertex-to face (vf), combine in five classes of supramolecular motifs for {Ph4P+}2 pairs, namely the sextuple phenyl embrace (SPE) with (ef)6 and offset sextuple phenyl embrace (OSPE) containing (off)1 (ef)2(ef/vf)2, the translational quadruple phenyl embrace (TQPE) with (ef)4, the parallel quadruple phenyl embrace (PQPE) with (off)1(vf)2, and the double phenyl embrace (DPE) with (off)1. Typical intermolecular attractive energies (kJ per mol of {Ph4P+}2) for these motifs are SPE 85, OSPE 57, TQPE 70, PQPE 41, DPE 34. There is strong interpenetration of the cations in these motifs: 489/770 structures in the CSD have P⃛P≤7 Å (spherical Ph4P+ has a van der Waals diameter of 13.6 Å). Of the 812 instances of P⃛P ≤7 Å, 86% are SPE, 10% are OSPE, 2% are TQPE, and only 2% are unclassified, Average P⃛P separations in the PQPE and DPE are 8.3 Å. Centrosymmetry is prevalent in all except the TQPE, which has implications for the engineering of noncentric crystals.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19960020505
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