Crystal structure of 3-diethylaminomethyl-2,2′-biphenol

Crystals of 3-diethylaminomethyl-2,2′-biphenol were examined using X-ray diffraction and FT-IR spectroscopy. Their space group is P2₁/c with a=7.305(1), b=13.816(2), c=29.232(4) Å, β=92.411(3)° and Z=8. The unit cell contains two symmetry-independent zwitterions. The hydrogen atom of the protonated diethylaminomethyl group is linked to the negatively charged phenolate oxygen atom, which in turn is linked to the hydroxyl group by a short hydrogen bond (molecule a: NO=2.604(3), OO=2.512(3) Å; molecule b: NO=2.593(4), OO=2.489(4) Å). The OHO^?H⁺N bifurcated intramolecular hydrogen bonds are crystallographically asymmetric. The IR spectrum of the crystals confirms very well the results obtained by the X-ray study. Instead of continuous absorption, only broad bands are found indicating relatively low proton polarisability in the two types of intramolecular hydrogen bonds.