Bimetallic coordination networks based on Al(acacCN)3: a building block between inertness and lability

Abstract

The Al(III) complex of 3-cyanopentane-2,4-dionate (acacCN) features peripheric nitrile groups which may coordinate to silver cations. As the Al(acacCN)₃ building block ranges between inertness and lability, its reactivity towards Ag(I) salts depends on the solvent and the weakly or non-coordinating counter anions; an impressive range of different extended structures has been encountered. With AgPF₆, the original building block is retained and hexafluorophosphate remains uncoordinated. A highly symmetric 3D crystalline solid forms in the presence of trichloromethane, and with benzene a tetrasolvate with large solvent-filled voids is obtained. Two different classes of reaction products with silver triflate have been observed. In addition to networks incorporating Al(acacCN)₃, partial solvolysis may lead to a dinuclear methoxide-bridged derivative. The resulting Al₂(μ-OMe)₂ core may be perceived as a four-connected node in a self-interpenetrating 3D network. Earlier studies reported transmetalation for the reaction of Al(acacCN)₃ with AgNO₃ and we find the same reactivity for silver tetrafluoroborate. Full degradation of the Al(III) building block with formation of [Ag(acacCN)] is observed.