HIGHLY SUBSTITUTED TRIS(PYRAZOLYL)METHANE LIGANDS AND SOME ZINC-COMPLEXES THEREOF

Tris(pyrazolyl)methane Ligands in which two or three of the pyrazole c arbon atoms bear organic substituents (L(1)-L(7)) were synthesized fro m chloroform and the corresponding pyrazole under phase transfer condi tions. Their behavior towards zinc salts was found to span the range f rom no reaction at all to hydrolytic destruction. One hydrolysis produ ct isolated and structurally characterized was the perchlorate complex [(HPz(5))(3)Zn-OClO3]ClO4 (1), other ones were the 2:1 complexes (HPz (3))(2)ZnBr2 (2) and (HPz(6))(2)Zn(NO3)(2) (3r HPZ(n) = substituted py razole). Zinc perchlorate and tris(trimethylpyrazolyl)methane (L(2)) f ormed the octahedral binary complex [L(2)(2)Zn](ClO4)(2) (4) as eviden ced by a structure determination. Zinc halides produced the 1:1 comple xes L(1) . ZnBr2 (5), L(4)<bulZnCl(2) (6), and L(4) . ZnBr2 (7), which according to the structure determinations of 6 and 7 contain tetrahed ral ZnN(2)Hal(2) units with only bidentate tris(pyrazolyl)methane Liga nds. In contrast, the zinc nitrate complex L(4) . Zn(NO3)(2) (8) was f ound to have an octahedral structure with mono- and bidentate nitrate and tridentate L(4). The bromide complex 7 was converted by silver per chlorate hydrate into the labile compound [L(4) . ZnBr]ClO4 (9) and th en into the unstable product [L(4) . Zn-OH2](ClO4)(2) (10), both presu med to contain zinc in a tetrahedral ZnN3Br or ZnN3O environment, resp ectively The ease of hydrolytic self-destruction prevented the exploit ation of the reactivity of 9 and 10 in analogy to that of the correspo nding tris(pyrazolyl)borate zinc complexes.