Crystal structure of tri(p-biphenylyl)aminium perchlorate

Abstract

Crystals of tri(p-biphenylyl)aminium perchlorate, (p-C/sub 6/H/sub 5/C/sub 6/H/sub 4/)/sub 3/N/sup +/ClO/sub 4//sup -/, are monoclinic (space group P2/sub 1//n), with a = 9.842 (1), b = 24.442 (1), c = 12.501 (1) A, ..beta.. = 106.77 (1)/sup 0/, Z = 4,d/sub calcd/ = 1.322 g/cm/sup 3/(lambda(CuK..cap alpha../sub 1/) = 1.54051 A). With Cu K..cap alpha.. radiation, 6085 reflections were recorded to 161.5/sup 0/ 2theta and corrected for absorption. The structure solution was achieved with Long's multisolution direct-method program. In final least-squares refinement all atoms, including hydrogen atoms, were given the usual six anisotropic thermal parameters, and the five atoms of the ClO/sub 4//sup -/ ion were each given the ten extra thermal parameters of Johnson's three-cumulant model. Corrections for slight extinction were applied. The final R(F) value was 0.051, and the final standard deviation of fit was 1.55 (all data included). The three N--C bonds are almost exactly coplanar, the N atom being displaced only 0.014 A from the plane of its three carbon neighbors. The three N--C bonds have lengths of 1.421, 1.418, and 1.386 A. The twist angles about these bonds from the hypothetical configuration with each six-membered ring attached to N coplanar with the central triangle ofmore » C atoms are -43.5, -45.3, and -26.5/sup 0/, respectively (sign convention as for the Klyne-Prelog torsion angle). The inter-ring C--C bonds in the biphenylyl groups (in same order as the N--C bonds and the angles above) are 1.487, 1.481, and 1.476 A in length. The twists about these bonds from the coplanar configuration for the two rings are +36.4, -14.5, and +23.0/sup 0/. The radical cation is generally like a propeller, but each of the six rings has its own pitch. The average Cl--O intermode distance, 1.444 A, calculated from the third-cumulant parameters, agrees well with Cl--O bond lengths from recent low-temperature determinations of the perchlorate ion structure.« less