Product of a DMF Aminalization, Bis[bis(3,5-dimethylpyrazol-1-yl)(dimethylamino)methane]copper(II) Perchlorate−Bis(dichloromethane)

Bis[bis(3,5-dimethylpyrazol-1-yl)(dimethylamino)methane]copper(II) perchlorate−bis(dichloromethane), Cu(II)(1)2(ClO4)2·2CH2Cl2 , 2, is the unanticipated product of the reaction of tris(3,5-dimethylpyrazol-1-yl)methylsilane,
3, with Cu(II)(DMF)4 (ClO4)2. In the title complex, the Cu(II)(1)2 cations exhibit a tetragonal Cu(II)N6 geometry
arising from coordination of four pyrazole N atoms and two tertiary amine N atoms from two bis(3,5-dimethylpyrazol-1-yl)(dimethylamino)methane ligands, 1. The tridentate (N)3 ligands 1 coordinate copper facially
with one Cu−N (pyrazole) axial [Cu−N, 2.407(4) Å] and the second equatorial [Cu−N, 1.995(4) Å]; the cations
exhibit crystallographic 2-fold symmetry that relates one ligand to the other. Cu(II)(1)2(ClO4)2·2CH2Cl2, CuC28H46Cl6N10O8·2CH2Cl2, crystallizes in the monoclinic space group C2/c, with a = 26.278(5) Å, b = 8.835(2) Å, c =
20.655(4) Å, β = 120.73(3)°, Z = 4, and RF (RwF2) = 0.049 (0.122) for 1979 observed reflections with I > 2σ(I).
Crystals of 2 are stable in dry air but hydrolyze readily to yield dimethylformamide and 3,5-dimethylpyrazole. A
mechanism is proposed for the formation of complex 2 by silane-promoted aminalization (an aminal is the diaza
analogue of an acetal) of dimethylformamide.