The crystal and molecular structure of 3,4-quinoxalino-1-telluracyclopentane C10H8N2TeII

The crystal and molecular structure of 3,4-quinoxalino-1-tellura(II)cyclopentane has been determined by X-ray diffraction at room temperature. The crystals are tetragonal, space group I4₁/a with a = b = 25.315(8), c = 6.010(1) Å and V = 3851.38 ų. The density of 1.96 g cm^?3 calculated on the basis of 16 molecules per unit cell is in agreement with the flotation value of 1.91 g cm^?3. The structure has been refined to a conventional R value of 0.0408 using 744 independent observed reflections obtained from four-circle diffractometer measurements. The structure consists of discrete molecules TeC = 2.134 Å (av.), CN = 1.343 Å (av.) and angle CTeC = 80.7° (e.s.d. 0.5) but the intermolecular TeTe bonds (3.791 and 3.998 Å) are less than the sum of the Van der Waals' radii thus indicating the presence of secondary bonding. These short intermolecular contacts in the crystal structure are consistent with the anomalous physical properties observed.