HYDROGEN-BONDING OF 2-TETRAZENES, 1 - FIRST SYNTHESIS AND INVESTIGATION OF 2 HYDROXYALKYL-SUBSTITUTED 2-TETRAZENES

Two members of previously unknown hydroxyalkyl-2-tetrazenes (1a, 2a) h ave been synthesized and hydrogen bonding of these novel difunctional compounds has been investigated by spectroscopic (IR, H-1 NMR, N-15 NM R) and theoretical methods. The structures of la and its bis(trimethyl silyl) derivative Ib were determined by X-ray analysis. In the crystal line state, molecules la are associated by O-H ... O hydrogen bonds th at form a three-dimensional network. Ab initio HF and DFT as well as s emiempirical SCF calculations show that O-H ... N hydrogen bonds of 2- tetrazenes are medium strong. The delta-N-15 data and the quantum chem ical calculations indicate that the amino nitrogen atoms of a 2-tetraz ene are involved in intermolecular hydrogen bonding to a larger extent than the azo nitrogen atoms; the corresponding energy difference of t he two types of hydrogen bonds is about 3 kJ mol(-1). The hydrogen bon ds can either stabilize or destabilize 2-tetrazenes thermodynamically depending on which nitrogen atoms are involved. Complexation of 1,1,4, 4-tetramethyl-2-tetrazene with methanol is accompanied by only minor c hanges in geometric parameters whereas systematic effects on the elect ronic structure are more distinct. Transition states for N-N bond clea vage are stabilized to a larger extent making such compounds rather se nsitive for thermal decomposition.