Structural Diversity and Catalytic Properties in a Family of Ag(I)-Benzotriazole Based Coordination Compounds

Abstract

In this work we study the coordination chemistry of a series of semi-rigid benzotriazole based ligands (L 1-L 3) along with the low coordination number but versatile Ag I ions. This has led to nine new coordination compounds formulated [Ag(L 1)(CF3CO2)] (1), [Ag2(L 1T)2(CF3SO3)2]•2Me2CO (2), [Ag(L 2T)(ClO4)(Me2CO)] (3), [Ag(L 2T)(BF4)(Et2O)] (4), [Ag2(L 3T)2(ClO4)2]2 (5), [Ag(L 3)(NO3)] (6), [Ag2(L 3T)2(CF3CO2)2] (7), [Ag2(L 3T)(CF3SO3)2] (8) and [Ag2(L 3T)2(CF3CF2CO2)2]•2Me2CO (9). These compounds show structural diversity including dimers (5, 7, 9), one dimensional (1D) (3, 4, 6) and two dimensional (2D) (1, 2, 8) coordination polymers. The presence of the two-CH2-units between the three rigid backbones, benzotriazole/-C6H4-/benzotriazole, provides a limited, but significant, flexibility in L 1-L 3 , influencing their variety coordination abilities. Interestingly, certain structures exhibit an isomerism effect (L 1T-L 3T) in the benzotriazole unit when in solid state; a series of studies are indicative of the 1,1-form is generally dominant in solution even in cases where the crystal structure does not contain this tautomer. The homogeneous catalytic efficacy of all compounds against the well-known multi component A 3 coupling reaction and the hydration of alkynes were investigated. Compound 4 was identified as the optimal catalyst for both reactions, promoting the multicomponent coupling as well as the alkyne hydration reaction under low loadings (0.5 and 3 mol%, respectively) and in high yields (up to 99 and 93% in each case).

An Efficient A3 Coupling Catalyst Based on a Silver Complex Bearing N‐Heterocyclic Carbene and Homoscorpionate Bis(3‐methyl‐mercaptoimidazolyl)borate Ligands

“…Multiple strategies have been implemented in the literature. Previous studies in A 3 coupling reactions have shown that coinage metals are powerful catalysts for A 3 coupling reactions . Despite great achievements in the past two decades in the field of A 3 coupling, these reactions still suffer from some shortcomings.…”

Metal-Catalysed A3 Coupling Methodologies: Classification and Visualisation

“…We have also attempted to elucidate the reaction mechanism from an inorganic perspective; through a thorough synthesis and study of targeted coordination compounds, we evaluated how factors such as coordination geometry, anion, and ligand tuning affect the catalytic activity. One year later, inspired by the successful Ag-based paradigms described above, we elucidated the efficacy of Ag-benzotriazole compounds in promoting the A 3 coupling [120]. From our studies, we identified compound [Ag(L)(BF4)(Et2O)] (8) as the optimum One year later, inspired by the successful Ag-based paradigms described above, we elucidated the efficacy of Ag-benzotriazole compounds in promoting the A 3 coupling [120].…”

Recent advances in the coordination chemistry of benzotriazole-based ligands

“…Good to excellent yields (67 -95%) of the relevant substrates were generated under the optimal conditions and using only 1 mol% of the catalytic precursor. The next compound in this family of catalysts was generated from the reaction of pbta with the Ru II (p-cymene) chloride dimer, leading to the synthesis of [Ru II (pbta)(pcymene)Cl]•Cl (156) as reported in a following study [126]. In this case, the Ru II centre coordinates to pbta in a bidentate fashion through the N2 atom of the triazole moiety and the pyridine nitrogen (Figure 24, right).…”

“…Having created a library of CPs with catalytic activity using these benzotriazole-based linkers, the next step in our research efforts was to combine this ligand system with the rich chemistry, unique coordination capabilities and superior alkynophilicity of Ag I ions. These attempts are documented in a recent study which reports the synthesis of multiple new compounds using ligands bbpm, bbmm and bbom [156]. The complexes exhibit a large structural diversity of 0D dimers and 1D / 2D CPs with interesting topological features and architectures.…”