Crystal structure of 1-(5-amino-2H-tetrazol-2-yl)-2-methylpropan-2-ol

The title compound, C5H11N5O, crystallized with two independent molecules in the asymmetric unit. The two molecules differ in the orientation of the 2-methylpropan-2-ol unit, with the hydroxy H atoms pointing in opposite directions. In the crystal, molecules are linked via O—H⋯O and N—H⋯O hydrogen bonds, forming ribbons propagating along [10-1]. The ribbons are linked via N—H⋯N hydrogen bonds, forming a three-dimensional structure.


S1. Comments
Tetrazole compounds are useful building blocks for the construction of high dimensional metal-organic frameworks, and they have provided various binding modes toward metal centers (Karaghiosoff et al., 2009;Liu et al., 2013). The title compound was easily prepared by the reaction of 5-aminotetrazole and iso-butylene oxide, and introduces an hydroxyl group which we hope will be useful as an additional coordination center.
The title compound, Fig. 1, crystallized with two independent molecules(A and B) in the asymmetric unit. The two molecules differ in the orientation of the 2-methylpropan-2-ol unit, with the hydroxyl H atoms pointing in opposite directions ( Fig. 2).
In the crystal, molecules are linked via O-H···O and N-H···O hydrogen bonds (Table 1) forming ribbons propagating along direction [101]. The ribbons are linked via N-H···N hydrogen bonds forming a three-dimensional structure (Table   1 and Fig. 3).

S2. Synthesis and crystallization
The title compound was synthesized by heating 5-aminotetrazole with an excess amount of iso-butylene oxide, without solvent, at 333 K. Crystals were obtained on cooling the reaction mixture.

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The OH and NH 2 H atoms were located in difference Fourier maps and freely refined. The C-bound H atoms were positioned geometrically and refined using a riding model: C-H = 0.96-0.97 Å with U iso (H) = 1.5U eq (C-methyl) and 1.2U eq (C) for other H atoms.

Figure 1
The molecular structure of the two independent molecules (A and B) of the title compound, with atom labelling.
Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A view of the molecular overlap of molecules A (black) and B (red); calculated using the AutoMolfit routine in PLATON (Spek, 2009  A view along the c axis of the crystal packing of the title compound. The hydrogen bonds are shown as dashed lines (see Table 1). H atoms not involved in hydrogen bonding have been omitted for clarity.