NEW EXAMPLE OF A SYMMETRICAL NHN HYDROGEN-BOND IN PROTONATED 1,8-BIS(DIMETHYLAMINO)NAPHTHALENE (DMAN)

The crystal structure of the adduct of 1,8-bis(dimethylamino)naphthalene (DMAN) with tetrazole (DMAN-THM), containing crystallographically symmetric NHN+ hydrogen bridges, was determined. The crystals of DMAN THM (monohydrate) are orthorhombic, space group P(nma) with Z = 4, a = 9.500(3), b = 10.966(5), c = 15.615(4) angstrom, R(N...N) = 2.573(2), r(N-H) angstrom 1.312(5) angstrom and less than with right parenthesis through NHN = 157(2)-degrees. The symmetry of the DMAN.H+ cations is reflected in an equivalence of the two moieties of the naphthyl ring. In the infrared spectra, the low-frequency nu(NHN) band centred at about 500 cm-1 (half-width of about 250 cm-1) is observed, typical of very strong NHN hydrogen bonds.