Syntheses and Crystal Structures of Copper(II) and Copper(I) dpp Complexes, [Cu(dpp)Br2] and [Cu(dpp)2][CuBr2] (dpp = 2,9‐diphenyl‐1,10‐phenanthroline)

Abstract The complexes [Cu(dpp)Br 2 ] ( 1 ) and [Cu(dpp) 2 ][CuBr 2 ] ( 2 ) (dpp = 2,9‐diphenyl‐1,10‐phenanthroline) were synthesized and characterized by single‐crystal X‐ray diffraction methods. Reaction of copper(II) bromide with the dpp ligand in dichloromethane at room temperature afforded 1 , which is a rare example of non‐square planar four‐coordinate copper(II) complexes. Complex 1 crystallizes in the monoclinic space group C2/c with a = 15.352(3), b = 13.192(3), c = 11.358(2) Å, β = 120.61(3)°, V = 1979.6(7) Å 3 , Z = 4, D calc = 1.865 g cm −3 . The coordination geometry about the copper center is distorted about halfway between square planar and tetrahedral. The Cu‐N distance is 2.032(2) Å and the Cu‐Br distance 2.3521(5) Å. Heating a CH 2 Cl 2 or acetone solution of 1 resulted in complex 2 , which consists of a slightly distorted tetrahedral [Cu(dpp) 2 ] + cation and a linear two‐coordinate [CuBr 2 ] − anion. 2 crystallizes in the triclinic space group ${\rm P}{\bar 1}$ with a = 10.445(2), b = 11.009(2), c = 18.458(4) Å, α = 104.72(3), β = 94.71(3), γ = 103.50(3)°, V = 1973.3(7) Å 3 , Z = 2, D calc = 1.602 g cm −3 . The four Cu(1)‐N distances are between 2.042(3) and 2.067(3) Å, the distance of Cu(2)‐Br(1) 2.2268(8) Å, and the disordered Cu(3)‐Br(2) distances are 2.139(7) and 2.237(4) Å, respectively. Complex 2 could also be prepared by directly reacting CuBr with dpp in CH 2 Cl 2 .