Heteronuclear multiple-quantum correlation N-15-H-1, cross-polarized magicangle spinning C-13, N-15 nuclear magnetic resonance and infrared spectroscopic studies of 1,2,4-triazolo-[1,5 alpha]-pyrimidine and its Zn(II) halide and thiocyanate complexes

1,2,4-Triazolo-[1,5 alpha]-pyrimidine (tp) was studied by gradient heteronu clear multiple-quantum correlation N-15-H-1 NMR and by cross-polarized magi c angle spinning C-13, N-15 NMR. The N-15 signals were unambiguously assign ed. The assignments of some LR absorption bands were proposed by comparison to purine and adenine spectra. The obtained results were used for the inve stigation of Zn(tp)(2)X-2-type complexes (X = Cl, Br, I, NCS), suggesting a pseudo-tetrahedral configuration around the Zn(II) ion with unidentately N (3) bonded heterocycles and halides or thiocyanates (N bonded) in terminal positions. A slight shielding effect on the N(3) nucleus upon the formation of Zn(II)-N coordination bonding was observed. (C) 2000 Elsevier Science L td All rights reserved.