Copper complexes of multidentate carboxamide ligands

Abstract

The copper coordination chemistry of two multidentate carboxamido ligands derived from HL 1 (offering two quinolyl and one carboxamide donor) and H 4 L 2 (with two pyridine(dicarboxamido) units linked by naphthalene spacers) was explored. The former was chosen because upon deprotonation it would provide a monoanionic mer-coordinating N-donor set that would model the putative deprotonated form of the His-brace in copper monooxygenases, while the latter was designed to bind two copper ions and enable comparisons to other systems with different ligand spacers. Upon reaction with Cu(I)-mesityl, HL 1 yielded a symmetric dimer (L 1 Cu) 2 in which each bis(quinolyl)amide ligand binds via two N-donors to one Cu(I) ion and via the third to the other Cu(I) center. Monomeric Cu(II) complexes [L 1 Cu(H 2 O) 2 ](OTf) and L 1 2 Cu were also characterized. Treatment of H 4 L 2 with Cu(OTf) 2 and excess Me 4 NOH (in CH 3 CN, pyridine/H 2 O, or MeOH) yielded complexes with anions of general formula [L 2 Cu 2 (X)] n-, where X = CH 3 CONH -(n = 1), CO 3 2-(n = 2), or MeO -(n = 1). X-ray structures of these complexes revealed the (L 2 ) 4ligand binding to two Cu(II) ions in an open paddle-wheel geometry, with an additional bridging ligand (X) completing the square planar coordination sphere of each metal ion. The open paddlewheel motif differs from the more 'open' puckered geometry seen with related ligands with different spacer units.

Try Another Crystal: Crystal-Dependent Disorder of Pentaphosphaferrocene within the Same Crystallization

“…One of the most interesting cases, in our opinion, is the complex of copper­(II), [CuL 2 ] ( 6 ), where L = multidentate carboxamido ligand, C 20 H 12 N 3 O 2 (Figure S9 in the Supporting Information). , The first study (crystal 6A , CSD: MIMDOE) revealed the crystal structure disordered over the pseudo-mirror plane perpendicular to the b axis, with the relative weight of the components amounting to ∼0.992/0.008. In the other structural determination, no disorder was found (crystal 6B , CSD: MIMDOE01).…”

Mimicking the Cu Active Site of Lytic Polysaccharide Monooxygenase Using Monoanionic Tridentate N-Donor Ligands

“…Numerous examples of both mononuclear and carboxylate-bridged dimers of Cu exist in the literature. 45 , 112 − 115 …”

“…The Cu­(I) ions adopt distorted trigonal planar geometries. The Cu–N lengths are typical for similar Cu­(I) complexes, ,,, and the Cu–Cu distance is 2.7509(7) Å, which is too long for significant bonding interactions between the two metals …”

“…Ultimately, however, our efforts to generate reactive copper–oxygen species were thwarted. Nonetheless, the fundamental advances in coordination chemistry we describe through the development of new ligands and complexes provides a foundation for future work, as literature examples of Cu complexes with monoanionic N,N′,N′′ ligands employing a central anionic group are fairly limited. − We are hopeful that further modifications of the scaffolds we have studied here could yield future successes with copper–oxygen chemistry.…”

Oxygen Transfer from Trimethylamine N‐Oxide to CuI Complexes Supported by Pentanitrogen Ligands

“…European Journal of Inorganic Chemistry coworkers, [16] although in that case it was obtained from a Cu(I) carboxamide dimer. Both solid-state structures share the C2/c space group, although with different cell parameters.…”