Coordination Chemistry in the Solid State: Reactivity of Manganese and Cadmium Chlorides with Imidazole and Pyrazole and Their Hydrochlorides

Crystalline coordination compounds [MnCl2(Hpz)2] 3, [CdCl2(Hpz)2] 5, [MnCl2(Him)2] 9, and [CdCl2(Him)2] 13 (Him = imidazole; Hpz = pyrazole) can be synthesized in solid state reactions by grinding together the appropriate metal chloride and 2 equiv of the neutral ligand. Similarly, grinding together the metal chlorides with the ligand hydrochloride salts produces the halometallate salts [H2pz][MnCl3(OH2)] 1, [H2pz][CdCl4] 4, [H2im]6[MnCl6][MnCl4] 8, and [H2im]6[CdCl6][CdCl4] 11. In contrast, reacting the metal chloride salt with the ligand in concentrated HCl solution yields a second set of salts [H2pz][MnCl3] 2, [H2im][MnCl3(OH2)2] 7, and [H2im][CdCl3(OH2)]·H2O 12. Compound 5 can be partly dehydrochlorinated by grinding with KOH to form an impure sample of the pyrazolate compound [Cd(pz)2] 6, while recrystallizing 9 from ethanol yielded crystals of solvated [Mn4Cl8(Him)8] 10. The crystal structure determinations of 1, 2, 4, 11, and 12 are reported.