Crystal chemistry of tetraradial species. Part 6. Embarras de richesses: lithium cation coordinated by eight O—H … phenyl bonds

Abstract

Lithium tetraphenylborate tetrahydrate, [Li(OH2)4]BPh4 (LiTBw; tetragonal, I41/a, a = 27.566(2) Å, c = 12.228(2) Å, Z = 16) is remarkable in that the four H2O molecules coordinating the Li+ ion all form O—H …π hydrogen bonds to the phenyl groups of the anion. LiTBw thus appears to be the first reported example of such an exhaustive O—H …π coordination and can be described as a 3-dimensional, completely H-bonded polymer in which all the H2O hydrogens are bonded to phenyl groups and all the phenyl groups are involved in O—H … phenyl bonds. Six of the O—H … phenyl bonds are essentially normal and two are highly bent, possibly bifurcated. The existence of the H-bonds has been corroborated from variable-temperature FT-ir spectra of weakly deuterated LiTBw. The O—Li—O angles in the LiO4 coordination tetrahedron (of symmetry C1) exhibit large departures from the tetrahedral angle, two of the angles bisected by a quasi-S4 axis being 118.3° and 122.5°, respectively. An ab initio (6-31G*) investigation of the Li(OH2)4+ and Be(OH2)42+ cations has shown that such large O—M—O angles are to be expected even in the free ions and are thus not necessarily the result of packing effects. A detailed comparison with several Li(OH2)4+ and Be(OH2)42+ salts provides a rationale for the observed M(OH2)4n+ (M = Li, Be) geometries.

Komplexe der Alkalimetalltetraphenylborate mit makrocyclischen Kronenethern

“…Die präparativen Arbeiten wurden in Reagenzgläsern unter Luft durchgeführt. Lithiumtetraphenylborat wurde nach bekannter Literatur hergestellt [38]. Natriumtetraphenylborat konnte käuflich erworben werden.…”

Short N+—H...Ph hydrogen bonds in ammonium tetraphenylborate characterized by neutron diffraction

“…Knop and co-workers studied salts with various cations containing N + ÐH groups and reported statistical data on the many N + ÐHÁ Á ÁPhÐB À interactions found (Bakshi, Linden et al, 1994). OÐHÁ Á ÁPhÐB À bonds formed by water molecules were reported for several hydrated tetraphenylborates (Aubry et al, 1977;Bakshi, Linden et al, 1994;Bakshi, Sereda et al, 1994). C CÐHÁ Á ÁPhÐB À bonds were found in propargylammonium tetraphenylborate and also studied by IR spectroscopy (Steiner, Schreurs et al, 1997).…”

Retention of -4 Symmetry in Compounds Containing MAr4 Molecules and Ions

“…Several ionic MAr q salts crystallize in structures that can be viewed as superstructures of the more common arrangements. Crystals of [Li(H20)z][BPh4] (Bakshi, Sereda, Knop & Falk, 1994) have ions on general positions in space group 141/a. The hydrogen-bonding requirements of the cations apparently preclude their being located on ?~ sites, but the columnar motif of the anions is retained.…”