Structural diversity and catalytic properties in a family of Ag(I)-benzotriazole based coordination compounds

In this work we study the coordination chemistry of a series of semi-rigid benzotriazole based ligands (L1-L3) along with the low coordination number but versatile AgI ions. This has led to nine new coordination compounds formulated [Ag(L1)(CF3CO2)] (1), [Ag2(L1T)2(CF3SO3)2]·2Me2CO (2), [Ag(L2T)(ClO4)(Me2CO)] (3), [Ag(L2T)(BF4)(Et2O)] (4), [Ag2(L3T)2(ClO4)2]2 (5), [Ag(L3)(NO3)] (6), [Ag2(L3T)2(CF3CO2)2] (7), [Ag2(L3T)(CF3SO3)2] (8) and [Ag2(L3T)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 L1-L3, influencing their variety coordination abilities. Interestingly, certain structures exhibit an isomerism effect (L1T-L3T) 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 A3 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).