Interplay between Metal⋅⋅⋅π Interactions and Hydrogen Bonds: Some Unusual Synergetic Effects of Coinage Metals and Substituents

Abstract

The ternary systems of C(2)H(4) (C(2)H(2) or C(6)H(6))-MCN-HF (M=Cu, Ag, Au) and the respective binary systems were investigated to study the interplay between metal⋅⋅⋅π interactions and hydrogen bonds. The metal⋅⋅⋅π interactions in C(2)H(4)-MCN become stronger with the irregular order Ag<Cu<Au, while the hydrogen bonds in MCN-HF become weaker following the same order. The metal⋅⋅⋅π interactions are weakened as the H atoms in the π system are replaced with electron-withdrawing groups and enhanced by electron-donating groups. Type 1 of these ternary systems, in which MCN acts as Lewis base and acid simultaneously, is more stable than type 2, in which C(2)H(4) acts as a double Lewis base. Negative cooperativity is present in type 2 ternary systems with a weakening of the metal⋅⋅⋅π interactions and the hydrogen bonds. Positive cooperativity is found in type 1 ternary systems with an enhancement of the metal⋅⋅⋅π interactions and the hydrogen bonds, except for C(2)(CN)(4)-AuCN-HF-1. The weaker metal⋅⋅⋅π interaction in C(6)H(6)-AuCN has a greater enhancing effect on the hydrogen bond in AuCN-HF than those in C(2)H(4)-AuCN and C(2)H(2)-AuCN. These synergetic effects were analyzed with the natural bond orbital and energy decomposition.

Synergistic and Diminutive Effects between Regium and Aerogen Bonds

“…The total interaction energy ranges from −43.81 kcal/mol in C 2 H 2 −AgCN−XeF 2 O to −68.44 kcal/mol in C 2 H 4 −AuCN−XeF 2 O (Table 5), and it has a consistent change with the regium bonding interaction energy since the regium bond is much stronger than the aerogen bond. C 2 H 4 is a better electron donor to form a regium bond with AgCN and AuCN than C 2 H 2 , while an opposite result is found for CuCN due to the larger distortion of C 2 H 2 when it binds with CuCN [52] . The total interaction energy of MCN−C 2 H 4 −XeF 2 O is smaller 11 kcal/mol than that of C 2 H 4 −MCN−XeF 2 O.…”

“…In this manuscript, we studied the binary complexes of C 2 H 2 −MCN, C 2 H 4 −MCN, C 2 (CN) 4 −MCN, C 2 H 4 −XeF 2 O, and MCN−XeF 2 O, in which M is a coinage metal atom including Cu, Ag, Au. The C 2 H 2 −MCN, C 2 H 4 −MCN, and C 2 (CN) 4 −MCN complexes have been studied in the previous studies [51–54] . By comparing with HCN−XeF 2 O, we can unveil the M substitution effect on the strength of coinage‐metal bond.…”

“…When the strong electron‐withdrawing −CN groups are present in C 2 (CN) 4 , its π‐electron density is greatly decreased and the C=C bond is surrounded by the positive MEPs, but it still binds with the σ‐hole of AuCN [51] . The coinage‐metal bond also has cooperativity with hydrogen, halogen, chalcogen, pnicogen, tetrel, and triel bonds [51–56] …”

Synergistic and diminutive effects between triel bond and regium bond: Attractive interactions between π‐hole and σ‐hole

“…We are also interested in comparing different types of non‐covalent interactions involving MCN. It was found that MCN engages in a hydrogen bond with HF, a halogen bond with ClF, and a tetrel bond with SiF 4 . Moreover, the corresponding interaction is stronger from SiF 4 to ClF to HF to ZX 3 (Z = B, Al; X = H, F).…”

Interaction between Trinuclear Regium Complexes of Pyrazolate and Anions, a Computational Study

“…Furthermore, using atoms in molecules (AIM) and natural bond orbital (NBO) methods, the nature of the complexes between H 2 O and H 2 S acting as the Lewis basis and AuCl as a Lewis acid was characterized [38], and the intermolecular interaction between phosphines (XH 2 P with X = H, CH 3 , F, CN and NO 2 ) and MY molecules (M = Cu, Ag, Au and Y = F, Cl, Br and I) [39]. Cooperativity in ternary complexes involving the regium bond was also explored [40][41][42][43]. The properties of complexes of Au(I) and Au(III) were compared using the CCSD(T)/CBS computational level [44].…”