NMR Evidence for the Unprecedented Binding of a Naphthalene Group to Copper(I) in Solution

Abstract

Variable-temperature one- and two-dimensional NMR experiments with [LCu](PF6) (L = N-(2-(1-naphthyl)ethyl)-1-aza-4,8-dithiacyclodecane) reveal solution binding of the pendant naphthalene group, consistent with the η2 binding found in the solid-state structure. The free energy for the barrier to the process that involves coordination/decoordination of the naphthalene group was estimated to be 12−13 kcal/mol.

Tryptophan π‐Electron System Capping a Copper(I) Binding Site—A New Organometallic Bonding Mode in Proteins

“…Solid‐state structures of small‐model complexes are not always preserved in solution,22, 23 but an elaborate 2D 1 H, 13 C NMR study of the model Cu I complex with a hemilabile naphthyl ligand proved invaluable in showing that the solid‐state structure is essentially preserved in solution. The η 2 ‐naphthyl ligand indeed shows dynamic behaviour on the NMR timescale and binds with 12–13 kcal mol −1 29. This type of weak binding supports metal ion exchange between proteins in the specific transport systems.…”

“…Conry et al have developed a copper(I) model system based on the tridentate S,S,N‐macrocyclic ligand 1‐aza‐4,8‐dithiacyclodecane 29–32. Like its bioinorganic analogue, this tridentate ligand binds with two thioether and one tertiary amine entities in S,S,N.…”

Group 6 Dihapto-Coordinate Dearomatization Agents for Organic Synthesis

“…Finally, the metal can be oxidatively removed to provide novel tetrahydropyridines (181 and 183) synthesized from pyridine. [109][110][111]113,114,137,138 In comparison, organic acylpyridinium 16,17 or η 6 -pyridine complexes 18 14). When nitrosobenzene (NOB) was combined with DHP complexes 173, 176, and 177, novel oxadiazabicyclo[2.2.2]octenes were formed (184−186).…”

“…A number of transition metals have shown the ability to bind aromatic molecules in a dihapto fashion, with d 10 Cu­(I), − Ag­(I), Pt(0), , and Ni(0), − d 2 Ta­(III) − and Nb­(III), d 8 Rh­(I) − and Ru(0), and d 6 Ru­(II) , and Re­(I) − complexes having been reported . But if an η 2 -arene complex is to be an effective substrate for organic reactions, it must be substitution-inert, and the ancillary ligand complex (i.e., all but the bound aromatic) must resist decomposition by acids, bases, oxidants, and reductants.…”

“…As with η 2 -arene complexes, these reactions are highly regio- and stereoselective. Finally, the metal can be oxidatively removed to provide novel tetrahydropyridines ( 181 and 183 ) synthesized from pyridine. − ,,,, In comparison, organic acylpyridinium , or η 6 -pyridine complexes typically require strong nucleophiles to overcome the aromatic stabilization of the pyridine ring. Also, without the use of directing groups, such nucleophilic additions can show poor regioselectivity. , …”