Bis[bis(3,5-dimethylpyrazol-1-yl)(dimethylamino)methane]copper(II) perchlorate-bis(dichloromethane), Cu(II)-(1)(2)(ClO4)(2). 2CH(2)Cl(2), 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)N-6 geometry arising from coordination of four pyrazole N atoms and two tertiary amine Id 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) Angstrom] and the second equatorial [Cu-N, 1.995(4) Angstrom]; the cations exhibit crystallographic 2-fold symmetry that relates one ligand to the other. Cu(II)(1)(2)(ClO4)(2). 2CH(2)Cl(2), CuC28H46-Cl6N10O8. 2CH(2)Cl(2), 2CH(2)Cl(2), crystallizes in the monoclinic space group C2/c, with a 26.278(5) Angstrom, b = 8.835(2) Angstrom, c = 20.655(4) Angstrom. beta = 120.73(3)degrees, Z = 4, and R-F (R-wF(2)) = 0.049 (0.122) for 1979 observed reflections with I > 2 sigma(I). Crystals of 2 an stable in dry air but hydrolyze readily to yield dirnethylformamide and 3,5-dimethylpyrazole. A mechanism is proposed for the formation of complex 2 by silane-promoted aminalization tan aminal is the diaza analogue of an acetal) of dimethylformamide.