VIBRATIONAL-SPECTRA OF COPPER FORMATE TETRAHYDRATE, COPPER FORMATE DIHYDRATE AND 3 ANHYDROUS FORMS OF COPPER FORMATE

The infrared and Raman spectra of the two hydrated and three anhydrous forms of copper formate have been recorded. Based on x-ray structures previously published for several of these species it was determined that formate groups bridging copper atoms in the anti-anti configuration can be distinguished from those which bridge in the anti-syn configuration on the basis of C = O stretching modes. Anti-syn structures have absorption between 1585 and 1610 cm-1 as well as at almost-equal-to 1560 cm-1. The almost-equal-to 1560 cm-1 frequency is present in both anti-anti and anti-syn structures. The dehydrated form of copper formate dihydrate was found to exist in a double layered form with alternate layers made up of formate bridges of the two different types. Only when copper is bridged by anti-anti configuration formates in square planar arrangement are the magnetic moments of these species depressed. No magnon scattering was observed in the Raman spectrum of the antiferromagnetic ordered phase of the tetrahydrate.