Synthesis, spectroscopic, electrochemical, and magnetic properties of dimolybdenum(II,II), diruthenium-(II,III) and -(II,II) complexes containing bridging aspirinate (2-acetoxybenzoate) ligands

Abstract

Carboxylate exchange reactions were used to prepare the dimolybdenum(II,II) tetra-aspirinate complex, [MO₂(µ-asp)₄](1), and the soluble aspirinate/trifluoroacetate, [Mo₂(µ-asp)-(µ-O₂CCF₃)₃]·2H₂O (2)(asp = aspirinate = 2-acetoxybenzoate). Similar metathesis reactions were used for the synthesis of the diruthenium(II,III) complexes, [Ru₂(µ-asp)₄Cl](3), [Ru₂(µ-asp)₂(µ-O₂CC₆H₅)₂Cl]·H₂O (4), and [Ru₂(µ-asp)₄(O₂CCF₃)]·2H₂O (5). A methanolic solution of (3) reacts with an aqueous solution of AgNO₃at 20 °C to give the Ru₂⁵⁺ nitrate/aspirinate, [Ru₂(asp)₄(NO₃)]·H₂O (6). When this reaction is repeated at 70 °C the Ru₂⁴⁺ nitroso/aspirinate, [Ru₂(asp)₄(NO)]·4H₂O (7), is isolated. Complex (7) also formed when a methanolic solution of (6) was either refluxed (70 °C) for 3 h, or allowed to stand (20 °C) for a period of 3–4 weeks. The conversion of (3) and (6) into (7) represents a reduction of both the bimetallic core (Ru₂⁵⁺ to Ru₂⁴⁺) and the nitrate group (NO₃^–; to NO). Infrared absorption spectra, conductivity, cyclic voltammetry, and magnetic susceptibility data are given.