AN X-RAY AND C-13 CP MAS NMR-STUDY OF C,C-LINKED BIPYRAZOLES AND BISPYRAZOLYLMETHANES

4,4'-Methylene-bispyrazole (1) crystallizes in the P2(1)/n space group with Z = 4, a = 5.4199(8) angstrom, b = 16.194(6) angstrom, c = 8.381 (5) angstrom, beta = 98.18(5)degrees. 4,4'-Methylene-bis (3,5-dimethyl pyrazole) (2) crystallizes in the Pbca space group with Z = 8, a = 8.3 50(3) angstrom, b = 16.078(3) angstrom and c = 17.154(5) angstrom. Fin ally, 3,3'-bipyrazole (4) crystallizes in the P2(1)/n space group with Z = 2, a = 5.465(2) angstrom, b = 5.491(3) angstrom, c = 10.058(4) an gstrom and beta = 92.88(2)degrees. The packing adopted by molecules 1 and 2 is related to the disposition of the pyrazole rings. In compound 4, all the molecules are joined to their neighbors by two double hydr ogen bond systems forming zig-zag chains. Using solid state C-13 NMR s pectroscopy, no dynamic proton transfer was observed in these crystals , and not on those of 3,5,3',5'-tetramethyl-4,4'-bipyrazole (3) either .