Through‐Space Spin Coupling in a Silver(II) Porphyrin Dimer upon Stepwise Oxidations: Ag^II⋅⋅⋅Ag^II, Ag^II⋅⋅⋅Ag^III, and Ag^III⋅⋅⋅Ag^IIIMetallophilic Interactions

Abstract

Metallophilic interactions between closed‐shell metal ions are becoming a popular tool for a variety of applications related to high‐end materials. Heavier d8 transition‐metal ions are also considered to have a closed shell and can be involved in such interactions. There is no systematic investigation so far to estimate the structure and energy characteristics of metallophilic interactions in AgII/AgII (d9/d9), AgIII/AgIII (d8/d8), and mixed‐valent AgII/AgIII (d9/d8) complexes, which have been demonstrated in the present study. Both interporphyrinic and intermetallic interactions were investigated on stepwise oxidation by using a rigid ethene‐bridged cis silver(II) porphyrin dimer and the results compared with those for highly flexible ethane‐bridged analogues. By controlling the nature of chemical oxidants and their stoichiometry, both 1e and 2e oxidations were done stepwise to generate AgII/AgIII mixed‐valent and AgIII/AgIII porphyrin dimers, respectively. Unlike all other ethene‐bridged metalloporphyrin dimers reported earlier, in which 2e oxidation stabilizes only the trans form, such an oxidation of silver(II) porphyrin dimer stabilizes only the cis form because of the metallophilic interaction. Besides silver(II)⋅⋅⋅silver(II) interactions in cis silver(II) porphyrin dimer, stepwise oxidations also enabled us to achieve various hitherto‐unknown silver(II)⋅⋅⋅silver(III) and silver(III)⋅⋅⋅silver(III) interactions, which thereby allow significant modulation of their structure and properties. The strength of Ag⋅⋅⋅Ag interaction follows the order AgII/AgII (d9/d9)<AgII/AgIII (d9/d8)<AgIII/AgIII (d8/d8). Single‐crystal XRD, X‐ray photoelectron spectroscopy (XPS), 1H NMR and EPR spectroscopy, and variable‐temperature magnetic investigations revealed various oxidation states of silver and metallophilic interactions, which are also well supported by computational analysis.

Enhanced Metallophilicity in Metal–Carbene Systems: Stronger Character of Aurophilic Interactions in Solution

“…The term aurophilicity was established by Schmidbaur to describe attractive interactions between Au I centers, relyingo n earlier findings and empirical evidence. [1][2][3][4][5][6] Since then, substantial efforts have been made to understandt he nature of such interactions, [7][8][9][10][11][12] furthere xtended to other M···M contacts, such as argentophilicity. [13] In spite of the relatively low stabilization energy,i nt he rank of hydrogen bonds, numerous examples in which metallophilic interactions efficiently modifyc hemical and physicalp roperties of metal-based compounds and materials have been described.…”

Ag(III)···Ag(III) Argentophilic Interaction in a Cofacial Corrole Dyad

“… a Center-to-center distance between the centroids of the N 4 unit. b Interplanar angle, defined as the angle between the mean 23-atom plane (or 24-atom plane in the case of Ag-3 ) of the two macrocycles. c Slip angle (α), defined as the average angle between the vector normal to the N 4 plane and the Ag···Ag vector. d Lateral shift between the two Ag centers, defined as (sin α)­(Ct···Ct distance). e Electronic density at the BCP in atomic units. f Laplacian of the electronic density in atomic units. g Electron delocalization index between Ag centers (i.e., average number of electrons shared between the two Ag ions) from Bader analysis. h Wiberg bond index from NBO analysis. i [SbF 6 ] − salt, CCDC 1536021. j Data reproduced from ref . k [PF 6 ] − salt, CCDC 1536020. l Center-to-center distance between mean 24-atom planes. m Angle between the vector normal to the mean 24-atom plane and the Ct···Ct vector. n Calculated for the DFT-optimized geometry. o Data reproduced from ref . p CCDC 1907233. q CCDC 1907234. r CCDC 1907235. …”

“…Stepwise oxidation resulted in shorter Ag···Ag distances: 3.61 Å for Ag­(II)/Ag­(II), 3.53 Å for mixed-valent Ag­(II)/Ag­(III), and 3.45 Å for Ag­(III)/Ag­(III). A Bader analysis revealed that the strength of the Ag···Ag interaction increases with the oxidation state . Because β-unsubstituted silver corroles are authentic Ag­(III) species, − rather than Ag­(II) complexes with a noninnocent ligand [i.e., a Ag­(II) corrole radical cation], as in the case of copper corroles, − silver corroles offer an ideal platform to observe Ag­(III)···Ag­(III) argentophilic interactions.…”

A Structural Diversity of Molecular Alkaline‐Earth‐Metal Polyphosphides: From Supramolecular Wheel to Zintl Ion

“…The value of electron density 1 and the sign of Laplacian distribution r 2 1(r) at bond critical point (BCP) are closely related to bonding strength and nature of interaction respectively in any pair of interacting atoms. [46] The values of several relevant parameters for selected bond pairs are summarized in Table 1. The strength of such interactions were also determined according to the method proposed by Espinosa et al [41] and Vener et al [42] Based on the crystal structure data and the aforementioned guideline of QTAIM analysis, we found that in complex 3, each Mg atom binds with only two P atoms, whereas each Ca atom binds with three P atoms in complex 4 (Figure 8).…”