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 (ClO 4 ) 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 (ClO 4 ) 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 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 (ClO 4 ) 2 ·2CH 2 Cl 2, CuC 28 H 46 Cl 6 N 10 O 8 ·2CH 2 Cl 2, crystallizes in the monoclinic space group C 2/ c, with a = 26.278(5) Å, b = 8.835(2) Å, c = 20.655(4) Å, β = 120.73(3)°, Z = 4, and R F ( R wF 2 ) = 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.