A Heterodinuclear Co^IICu^I Complex with Co(salen) in a Macrocyclic Framework. Oxygenation Studies in Comparison with Analogous Cu^IICu^I and Co^IIPb^II Complexes

Abstract

A di(μ-phenoxo)CoIICuI complex, [CoCu(L)]ClO4·0.5DMF, has been prepared where (L)2- is a macrocyclic dinucleating compartmental ligand derived from the 2:1:1 condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and 3-thia-1,5-pentanediamine, having a salen-like N2O2 metal-binding site (salen = N,N‘-ethylenedisalicylideneaminate) and an N2O2S site sharing the phenolic oxygens. It crystallizes in the monoclinic space group P21/n, a = 7.087(1) Å, b = 19.593(6) Å, c = 19.447(3) Å, β = 96.29(1)°, V = 2684(1) Å3, and Z = 4. The CoII resides in the salen-like site and assumes a planar geometry. The CuI in the N2O2S site has a planar four-coordinate geometry with two phenolic oxygens and two imine nitrogens; the thioether sulfur on the lateral chain is situated at an axial site of the CuI, but the Cu--S separation is very large (3.08 Å). In the {CuN2O2} chromophore, the two Cu−O bond distances (2.333(5) and 2.385(5) Å) are significantly long relative to the two Cu−N bond distances (1.984(6) and 1.929(4) Å). Further, the N−Cu−N angle is very large (128.2(2)°), whereas the O−Cu−O angle is very small (65.2(2)°). Analogous CuIICuI and CoIIPbII complexes of (L)2-, [CuIICuI(L)]ClO4 and [CoPb(L)](ClO4)2, have been prepared. The DMF adduct of [CuIICuI(L)]ClO4, [CuIICuI(L)]ClO4·0.5DMF, crystallizes in the monoclinic space group P21/n, a = 6.957(2) Å, b = 23.774(2) Å, c = 7.758(3) Å, β = 94.72(3)°, V = 1278.8(6) Å3, and Z = 4. The dinuclear core resembles that of the CoIICuI complex and shows distortions about the CuI similar to those found for the CoIICuI complex. The di-DMF adduct of the CoIIPbII complex, [CoPb(L)(DMF)2](ClO4)2, crystallizes in the monoclinic space group P21/n, a = 16.265(2) Å, b = 12.640(2) Å, c = 18.584(3) Å, β = 90.43(1)°, V = 3820.5(8) Å3, and Z = 4. The CoII in the N2O2 site has a square-pyramidal geometry together with a DMF oxygen at the apical site. The PbII in the N2O2S site has a six-coordinate geometry with the further coordination of a DMF molecule. The reactivity of the CoIICuI complex toward dioxygen has been studied in comparison with the CuIICuI and CoIIPbII complexes. The CoIICuI complex in DMF is very sensitive to dioxygen and is oxidized at −50 °C. The CuIICuI complex is inert to dioxygen. The CoIIPbII complex is oxygenated at 0 °C to form a peroxo dimer (PbIICoIII−O−O−CoIIIPbII). The high sensitivity of the CoIICuI complex to dioxygen is explained by the irreversible oxidation to a CoIIICuII species through an intramolecular-type peroxo complex (CoIII−O−O−CuII).

Synthesis, crystal structures and yeast RNA-binding properties of copper(II) and nickel(II) complexes with a bidentate Schiff base

“…1. The Cu-N 2.005(3) Å and Cu-S 2.289(2) Å distances are similar to reported values [11][12][13][14][15]. The angle between the furan and phenyl rings is 39.158.…”

(Acetylacetonato-κ2O,O′)(dimethylformamide-κO)[2-phenoxyethanal (2-oxidobenzylidene)hydrazonato-κ3O,N,O′]cobalt(III)

“…The Co-O and Co-N bond lengths of the title complex are in agreement with the corresponding values found in similar cobalt complexes (Lin et al, 2002;Sun et al, 2005;Muller et al, 2000;Shinoura et al, 2000). The Co-O(DMF) bonds are somewhat longer than typical values (Shinoura et al, 2000), which indicates a somewhat weaker attachment of the DMF ligand.…”

“…The Co-O and Co-N bond lengths of the title complex are in agreement with the corresponding values found in similar cobalt complexes (Lin et al, 2002;Sun et al, 2005;Muller et al, 2000;Shinoura et al, 2000). The Co-O(DMF) bonds are somewhat longer than typical values (Shinoura et al, 2000), which indicates a somewhat weaker attachment of the DMF ligand. The C-O(coordinated phenolate) bond lengths are consistent with values reported for an analogous cobalt complex (Sun et al, 2005), but shorter than the C-OH(uncoordinated phenolate) bond length of 1.36 Å (Rao et al, 1999).…”

Synthesis, Structure, and Reactivity of Dinuclear Nickel Amino-Thiophenolate Complexes Bearing Bridging VO2(OH)2–and VO2(OR)2– Coligands

“…We and others are interested in the coordination chemistry of metal complexes with deep binding pockets, one reason being the unusual reactivities associated with confinement effects exerted by the binding cavity. − The Robson type − hexaaza-dithiophenolate ligand H 2 L supports dinuclear transition metal complexes with a bioctahedral N 3 M­(μ-S 2 ) 2 (L′)­MN 3 core embedded in a bowl-shaped “calixarene-like” binding pocket. − Several unusual transformations within the pocket of the [M 2 L­(μ-L′)] + complexes have been reported. , These include fixation of carbon dioxide, cis -bromination of α,β-unsaturated carboxylate ligands, highly diastereoselective Diels–Alder reactions, and reduction of S 8 to S 6 2– by encapsulated BH 4 – . , …”