Formation of a Dinuclear Mercury(II) Complex with a Regular Bis‐Strapped Porphyrin Following a Tunable Cooperative Process

Abstract

Teamwork: Structural characterization of the first dinuclear mercury(II) complex with a regular porphyrin reveals dissymmetry induced by binding of dimethyl sulfoxide molecules to the metal ions, which form two allosterically connected binding sites (see structure; gray C, orange Hg, blue N, red O, yellow S). The cooperativity of the metal insertion can be tuned, either positively or negatively, by the presence of a base or by the interaction with exogenous ligands.

Formation and Dynamic Behavior of Mono‐ and Bimetallic Cadmium(II) Porphyrin Complexes: Allosteric Control of Coupled Intraligand Metal Migrations

“…All these data suggest the formation of the C 2 ‐symmetric bimetallic complex 1Cd 2 (Scheme , left) according to a highly cooperative process. Such cooperativity was also observed under the same experimental conditions during the formation of a related Hg II bimetallic complex; no intermediate monometallic species were observed during the metallation process 10. An analytical sample of 1Cd 2 was prepared and isolated upon precipitation in a methanol/water mixture, and its elemental analysis confirmed the bimetallic nature of the complex.…”

“…The system involves a bis‐strapped porphyrin ligand functionalized with an overhanging carboxylic acid group on each side of the macrocycle ( 1 , Scheme ) 8. This homoditopic ligand can generate two types of homobimetallic complexes with Pb II and Bi III ions:9 1) C 2 ‐symmetric complexes with both metal ions interacting with the N core and a COO − group of a strap, with the porphyrin acting as a bridging ligand ( 1(BiOAc) 2 and 1Pb 2 , Scheme );10 and 2) dissymmetric complexes in which one cation is bound to the N core (out‐of‐plane coordination mode, OOP) whereas the other one interacts exclusively with the strap on the opposite side (hanging‐atop coordination mode, HAT; 1 Bi ⋅Bi(OAc) 2 and 1 Pb ⋅PbOAc , Scheme ) 11. 12 These latter complexes, present in the form of two degenerate states, undergo a dynamic process in which the metal ions exchange their coordination modes concomitantly (OOP↔HAT) while staying on their respective side of the macrocycle.…”

The overhanging carboxylic acid strategy: an alternative route to the porphyrin core expansion/modification for the coordination of large metal ions

“…An X-ray structure of the complex was solved and revealed a dinuclear complex with a mercury ion located on each side of the macrocycle (Fig. 6) [31]. In contrast to the dinuclear lead complex 5Pb 2 , 5Hg 2 lacks the C 2 symmetry and the two metal ions sit in two different environments.…”

Adaptable Overhanging Carboxylic Acid Porphyrins: Towards Molecular Assemblies through Unusual Coordination Modes

“…Such a structure was obtained by formally grafting one or two straps on the diametrically opposed meso positions, namely 5,15 or/and 10,20 of the macrocycle (Figure , top line). Based on the study of the resulting homo‐ and heterobimetallic complexes, our group has evidenced a new coordination mode,, , new dynamic processes encompassing compartmentalized and non‐compartmentalized translocations taking place during stereoselective metallation reactions, or dynamic constitutional evolution, and recently controlled by (photo)redox processes , , . Most of the properties of these complexes come from the peculiar hanging‐atop coordination mode in which a metal cation is “overhung” to the intramolecular carboxylate group and is stabilized via hydrogen bond(s) between the amide linkage(s) of the strap and its own acetate ligand .…”