Making very short O-H center dot center dot center dot Ph hydrogen bonds: the example of tetraphenylborate salts

In crystal structures of tetraphenylborate salts with cationic X-OH donors (choline, triethanolammonium dihydrate, 6-ammonio-n-hexanoic acid monohydra te), the shortest intermolecular O-H . . . Ph hydrogen bonds known as yet h ave been found, both in terms of the H . . .M as well as the O . . .M dista nces (2.17 and 3.07 Angstrom, respectively, for normalized O-H distance; M= midpoint of the aromatic ring). In these interactions the donor H and O ato ms reside roughly over the centroids of the acceptor groups. A supporting d atabase study of very short O-H . . . Ph hydrogen bonds has also been made (using the Cambridge Structural Database).