The interaction of manganese phthalocyanine with F4-TCNQ is accompanied by the transformation of the acceptor molecule into a new organic ligand, the 4-(dicyanomethanido)tetra-fluorobenzoate dianion, resulting in the formation of a unique Mn III charge-transfer complex, in which two Mn phthalocyanine moieties are bridged by the dianion, with parallel arrangement of all aromatic fragments and an interplanar distance of 3.30 Å. The formation of the complex takes place in a 2:1 ratio, with the two electrons transferring from two donor molecules to an acceptor molecule. Magnetic measurements [a] A. E. ported so far; however, several complexes with structurally similar metal-porphyrin derivatives are known. They involve charge-transfer complexes with π-stacking interactions between the donor and acceptor molecules [12] and those with metal-N≡C coordination bonds between metal-porphyrins and TCNQ derivatives. [13] Similar results should possibly be expected for metal-phthalocyanine complexes.Our attempts to grow mixed single crystals of MnPc and F4-TCNQ from solution resulted in a quite unexpected reaction between the components and a new type of complex. Herewith, we report these new complexes, their structure, and their electrochemical and magnetic properties.
Results and Discussion
SynthesisThe main problem of growing CT multicomponent single crystals from solution is the poor solubility of phthalocyanines. [14] We chose N-methyl-2-pyrrolidone (NMP) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidin-7-one (DMPU) as solvents suitable for both the donor and acceptor components.The first step to grow bicomponent crystals was naturally performed in the moisture-free conditions that are most consistent with those used for the preparation of thin films. [10] However, no single crystals suitable for single-crystal X-ray diffraction study could be grown from dry solvents. Instead, the crystallization appeared to be possible by slow diffusion of water into the reaction mixtures. The reaction products obtained in the two solvents NMP and DMPU are quite different.The crystallization from NMP produces two types of crystals, 1 and 2. Their structure was studied by single-crystal X-ray diffraction. The results appear to be quite unexpected (Scheme 1).Both compounds contain the Mn III Pc framework, as well as the aromatic 4-(dicyanomethanido)tetrafluorobenzoate dianion, obviously being transformed from pristine F4-TCNQ. The first compound (1) has a salt-like structure, composed of Mn III Pc, coordinated by the 4-(dicyanomethanido)tetrafluorobenzoate dianion, and the cation of Mn III Pc, coordinated by two water molecules.Scheme 1. Interaction of MnPc with F4-TCNQ in NMP.
