An Unstable Ligand‐Unsupported Cu^IDimer Stabilized in a Supramolecular Framework

Abstract

A stable environment: A [Cu(NH3)2]22+ dimer with weak cuprophilicity is stabilized in the cavities of a supramolecular framework (see structure). This CuI dimer is otherwise unstable, so stabilization within a supramolecular matrix offers an unprecedented opportunity for systematic studies of the isolated dimeric species, either in the ground state or the excited state.

Cuprophilic Interactions in and between Molecular Entities

“…As cuprophilic interactions are weak forces, the unsupported Cu I –Cu I interactions in aggregates are usually accompanied by other forces, such as packing in crystal lattices, hydrogen bonding, anion–cation columbic attractions, or π–π stacking interactions between supporting ligands etc., which render the weak Cu I –Cu I interactions not always readily discernible. In light of the impact that metallophilic interactions may have on macroscopic properties of bulk materials, it is thus of critical importance for corroborating cuprophilic interactions by spectroscopic investigations, such as absorption and vibration spectroscopy, in addition to X‐ray crystallography .…”

“…and Kraus et al. reported the characterization of [{Cu(NH 3 ) 2 } 2 ] 2+ stabilized in supramolecular frameworks with the empirical formulae [{Cu(NH 3 ) 2 } 2 ][H 2 THPE] 2 ⋅ 3.25 H 2 O ( 120 ) (H 2 THPE: tris(hydroxyphenyl)ethane anions), and {[Cu(NH 3 ) 3 ] 2 [Cu 2 (NH 3 ) 4 ]}F 4 ⋅ 4 NH 3 ( 121 ), respectively. Compound 120 was prepared from the reaction of Cu(OH) 2 and H 3 THPE in the presence of aqueous NH 3 , whereas 121 was obtained from the reaction of CuF 2 and Cu with the addition of liquid NH 3 .…”

“…2019, 25,8936 -8954 www.chemeurj.org tigations. By comparing the Raman spectra of the dimeric 126 and 127,monomeric 107 and 108,and the supporting ligands, the stretching frequency of the unsupported Cu-Cu interactions in 126 and 127 were located at ñ = 204 cm À1 .Noteworthy is that the lack of secondaryi nteractions, such as face-to-face p-p interactions or hydrogen bonding, [165,166,172,179,185] in 126 and 127 indicates that the formation of these two dimers was mainly driven by the unsupported cuprophilic interactions.…”

Perspective: On the relevance of slower-than-femtosecond time scales in chemical structural-dynamics studies

“…A contraction of the molecule on excitation, resulting from a promotion of an electron from an anti-bonding to a weakly bonding orbital, was observed when the first results on the 50  μ s lifetime 16 K excited state structure of [Pt 2 (P 2 O 5 H 2 ) 4 ] 4− became available (Novozhilova et al , 2003; Kim et al , 2002). Contractions of binuclear complexes on excitation have since been observed in several systems (Coppens et al , 2004; Zheng et al , 2005; and Makal et al , 2011). Structural modifications have been determined for spin-crossover systems, which can be switched between low- and high-spin states by light irradiation, temperature variation, and other external perturbations, with parallel changes occurring in magnetic and optical properties (Cailleau et al , 2010).…”

Highly Luminescent Linear Complex Arrays of up to Eight Cuprous Centers

“…[10,11] Because of the decreaseo fr elativistic effects with ad ecreasing nuclear charge, Ag I ···Ag I argentophilic bondingi sl ess pronounceda nd Cu I ···Cu I cuprophilic interactions are considered to be very weak or not significant at all. [12,13] Exceptf or rare examples of unsupported Cu I ···Cu I contacts, [14][15][16] multinuclear Cu I complexese xhibiting cuprophilic interactions usually require as uitable ligand framework to incorporate the cuprous ions in close proximity to each other. The large family of amidinate andg uanidinate bridging ligands [17] has resulted in as eries of binuclear Cu I complexes becoming available, whicho riginally served as model systems for studies of closed-shell d 10 ···d 10 contacts.…”