Hydrogen bonding of 2-tetrazenes. Part 1. First synthesis and investigation of two hydroxyalkyl-substituted 2-tetrazenes.
In: European Journal of Organic Chemistry, (1998) ; Nr. 7, S. 1431-1440
Zeitschriftenaufsatz / Fach: Chemie
The hydroxyalkylated 2-tetrazenes (E)-ROCH2CH2NPhN:NNPhCH2CH2OR (I, R = H) and II were synthesized, and hydrogen bonding of these novel difunctional compds. was investigated by spectroscopic (IR, 1H NMR, 15N NMR) and theor. methods. The structures of I (R = H) and its silyl deriv. I (R = Me3Si) were detd. by X-ray anal. In the cryst. state, mols. I (R = H) are assocd. by OH...O H-bonds that form a 3D network. Ab initio HF and DFT as well as semiempirical SCF calcns. show that OH...N H-bonds of 2-tetrazenes are medium strong. The d-15N data and the quantum chem. calcns. indicate that the amino N atoms of a 2-tetrazene are involved in intermol. H bonding to a larger extent than the azo N atoms. The corresponding energy difference of the 2 types of hydrogen H bonds is .apprx.3 kJ mol-1. The H bonds can either stabilize or destabilize 2-tetrazenes thermodynamically depending on which N atoms are involved. Complexation of 1,1,4,4-tetramethyl-2-tetrazene with MeOH is accompanied by only minor changes in geometric parameters, whereas systematic effects on the electronic structure are more distinct. Transition states for N-N bond cleavage are stabilized to a larger extent making such compds. rather sensitive for thermal decompn.