Dioxygen Oxidation of Coordinated Nitrosyl to Nitro on Dmf-Bridged Dinuclear CoPb Complex

Abstract

Abstract The CoIIPbII complex [CoPb(L)(CH3OH)(ClO4)2] reacts with nitrogen monoxide to give the nitrosyl complex [CoPb(L)(NO)(dmf)2(ClO4)]ClO4 (1), where H2L is a dinucleating macrocycle derived from the [2 : 1 : 1] condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and diethylenetriamine and has a “salen”- and a “saldien”-like metal-binding site sharing the phenolic entities. 1 crystallizes in the triclinic space group , a = 12.729(4), b = 17.103(6), c = 10.548(4) Å, α = 107.42(4)°, β = 106.18(2)°, γ = 101.33(3)°, V = 2003(1) Å3, and Z = 2. The refinement converges with R = 0.045 and Rw = 0.049 for 3768 reflections with I > 3.00σ(I). The Co resides in the “salen” site and the Pb in the “saldien” site. The metal ions are bridged by the two phenolic oxygens of L2− and a dmf oxygen, in the Co–Pb intermetallic separation of 3.511(2) Å. The Co–O(dmf) and O(dmf)–Pb bond distances are 2.14(1) and 3.072(8) Å, respectively. The NO coordinates to the Co at the axial site trans to the bridging dmf oxygen, providing a six-coordinate geometry about the metal; the Co–N(nitrosyl) distance is 1.92(1) Å and the Co–N–O angle is 117(1)°. The Pb has an eight-coordinate geometry together with the bridging dmf oxygen, a terminal dmf oxygen and a perchlorate oxygen. The nitrosyl complex 1 is oxidized with molecular oxygen to the nitro complex [CoPb(L)(NO2)(dmf)2(ClO4)]ClO4 (2). 2 crystallizes in the triclinic space group , a = 12.748(4), b = 17.139(5), c = 10.359(3) Å, α = 106.34(3)°, β = 106.44(3)°, γ = 101.42(3)°, V = 1986(1) Å3, and Z = 2. The refinement converges with R = 0.039 and Rw = 0.042 based on 6202 reflections with I > 3.00σ(I). 2 has a dinuclear core very similar to that of 1, bearing an NO2 group instead of an NO group. The Co–N(nitro) bond distance is 1.889(6) Å. 1H NMR, 13C NMR, and 13C–1H COSY spectroscopies indicate that the dmf-bridged dinuclear cores of 1 and 2 are retained in solution.