Monocrystals and powders of some binuclear Cu(I1) carboxilates which EPR spectra cannot be described by the usual S = 1 spin Hamiltonian were investigated. It is shown that all the peculiarities of their spectra can be interpreted taking temperature dependent intermolecular exchange into account. The observed effects are discussed assuming that the triplet exciton is able to migrate through the crystal lattice.Einkristalle und Pulver einiger binuklearer Cu(I1)-Carboxilate werden untersucht, deren EPR-Spektren mit dem gewohnlichen S = 1 Spinhamiltonoperator nicht beschrieben werden konnen. Es wird gezeigt, daB alle Besonderheiten ihrer Spektren mit der Annahme einer temperaturabhingigen, intermolekularen Austauschwechselwirkung erkliirt werden konnen. Die beobachteten Effekte werden mit der Annahme eines durch das Kristallgitter wandernden Triplett-Exzitons diskutiert.The presence of an exchange interaction between copper atoms in Cu(I1) carboxilates allows to consider such compounds as binuclear ones whose molecules are constructed similarly to the copper acetate monohydrate [l]. Their general formula can be written as (RCOO),Cu, -2 L. The exchange interaction between copper atoms in binuclear molecules gives rise to the formation of a ground singlet state with S = 0 and an excited triplet state with S = 1, which is responsible for the paramagnetism of dimeric Cu(1I) carboxilates. I n this case the following spin Hamiltonian can be used for the interpretation of the EPR spectra:

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