The first alternating Mn II –Mn III 1D chain: structure, magnetic properties and catalytic oxidase activities

An unprecedented one-dimensional mixed-valence chain, [{Mn III (L) 2 }{Mn II (bpy) 2 }(ClO 4 )(H 2 O) 0.5 ] ∞ (H 2 L = N -salicylidene- l -alanine and bpy = 2,2′-bipyridine), has been synthesized. The complex has been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, and variable-temperature magnetic measurements. The structural analysis reveals that the [Mn(bpy) 2 ] 2+ unit is linked to the pendent carboxylate arm of the [Mn III (L) 2 ] − unit to produce a unique syn – anti carboxylate bridged 1D coordination polymer. Variable-temperature (2–300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interaction between the Mn III and Mn II centres with J = −0.98(2) cm −1 . Using 3,5-di- tert -butylcatechol (3,5-DTBC) and o -aminophenol (OAPH) as the substrates, the catecholase-like activity and phenoxazinone synthase-like activity of the complex have been studied; the turnover numbers ( k cat ) for these oxidase reactions have been calculated to be 126.9 and 738.0 h −1 , respectively.