Metallophilicity versus π–π Interactions: Ligand‐Unsupported Argentophilicity/Cuprophilicity in Oligomers‐of‐Dimers [M₂L₂]_n (M=Cu^I or Ag^I, L=tridentate ligand)

Abstract

To verify whether attractive metallophilic interactions exist in the dimer-of-dimers [Cu(2)(ophen)(2)](2) (Hophen=1H-[1,10]phenanthrolin-2-one) (1), we designed and synthesized a series of such [M(2)L(2)](2) structures by varying the d(10) metal and/or the ligand (M=Cu(I) or Ag(I), L=ophen or obpy; Hobpy=1H-[2,2']bipyridinyl-6-one), and have successfully obtained three dimers-of-dimers: [Ag(2)(ophen)(2)](2).6 H(2)O (2), [Cu(2)(obpy)(2)](2) (3), and [Ag(2)(obpy)(2)](2).4.5 H(2)O.0.5 DMF (4). X-ray analyses of these structures show that interdimer M-M separations in [Ag(2)-(ophen)(2)](2) (3.199 A) are remarkably shorter than those in [Cu(2)(ophen)(2)](2) (3.595 A). Shorter interdimer M-M separations are found in the structures of [M(2)(obpy)(2)](2) (2.986 and 2.993 A in [Cu(2)(obpy)(2)](2), 3.037 to 3.093 A in [Ag(2)(obpy)(2)](2)), in which the pi systems are smaller than in the complexes with the ophen ligand. Detailed structural comparison of these dimers-of-dimers indicates that the interdimer, face-to-face pi-pi interactions repulse rather than support the interdimer metal-metal attractive interactions. This study also yields qualitative comparison of the strengths between argentophilic, cuprophilic, and face-to-face pi-pi interactions. DFT calculations on the four dimers-of-dimers further support the above deduction. The structure of a trimer-of-dimers [Ag(2)(obpy)(2)](3) (Ag-Ag 3.171 to 3.274 A) is further evidence that the oligomerization of the [M(2)L(2)] molecules is favored by stronger metallophilic and weaker face-to-face pi-pi interactions.

A comparative study between post-Hartree–Fock methods and density functional theory in closed-shell aurophilic attraction

“…Moreover, a significant number of studies have discussed the aurophilic interactions coexisting with H-bonding, M-p or p-p attractions, all of which can participate in generating extended, supramolecular structures and nanochemistry [31][32][33][34][35]. The experimental results in many works are explained with theoretical models described at the density functional theory (DFT) level due to the size of the system.…”

Crystal structure of (bis(4-((1H-imidazol-1-yl)-methyl)benzoato)zinc(II), Zn(C11H14N2O2)2

“…Metal coordination polymers have been studied extensively in the recent years due to their unusual structures as well as interesting network topologies and material properties [1][2][3][4][5][6][7][8]. But surprisingly coordination polymers with 4-aminobenzoate ligands, containing neutral donor groups, are rather rare.…”

Ligand-directed copper(І) azide coordination polymers bridged by N-donor ligands with different lengths: azide exhibits a rare μ−1, 1, 3, 3 bridging mode

“…In the complexes (2) and (3), there are ligand unsupported Cu(I)-Cu(I) bonding interactions with the distances of 3.027(1) and 3.035(1)Å , which are slightly longer than those in complex of Cu 2 (obpy) 2 {Hobpy = 6-hydroxyl-2,2 0 -bipyridine; Cu-Cu, 2.986 and 2.993 Å } [37], and are close to those in complex of [Cu 3 (pzc) 2 (CN) 2 (H 2 O) 2 Á 2H 2 O] n {pzc = pyrazinecarboxylic acid; Cu-Cu, 3.051Å } [38]. The ligand-unsupported Cu(I)-Cu(I) distances in (2) and (3), however, are shorter than that of 3.375Å observed in complex Cu 2 (ophen) 2 {Hophen = 2-hydroxyl-1,10-phenanthroline} [8].…”