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The mixed-valence iron (I1, 111,111) acetates [Fe@(CH3C02)&3], where L = water or pyridine, have been prepared and studied by M&bauer, infrared, and optical spectroscopy and magnetic susceptibility methods. Variabletemperature magnetic susceptibility data for the aquo complex are interpreted on the basis of an HDVV S2 = 2, SI = S3 = 5 / 2 spin-exchange model with JI2 = JZ3 = -50.0 cm-I and J13 = -14.5 crn-'. An intervalence-transfer band is observed at 13 800 cm-' in the room-temperature electronic spectrum of the aquo complex. MBssbauer spectra of these compounds are markedly temperature dependent. At 17 K absorptions due to distinct Fe(I1) and Fe(II1) sites are observed while at 300 K a single absorption is observed. Spectra at intermediate temperatures are modeled by assuming intratrimer electronic relaxation between pairs of iron ions. The activation energy for relaxation derived from this model is 470 cm-' for the aquo complex. This energy is equal to the barrier to intramolecular, intervalence thermal electron transfer. IntroductionMany transition-metal ions form carboxylate complexes

A stable fluorosilicate glass (FSG) has been fabricated from the chemical vapor deposition of SiF4/tetraethylorthosilicate (TEOS)/02 and C2FjrEOS/02. Films were subjected to a temperature and humidity stress for water absorption studies and were thermally stressed for fluorine diffusion studies. Fourier transform infrared spectrometry (FTIR) and secondary ion mass spectrometry (SIMS) indicate films produced from SiF4 absorb less water and diffuse less fluorine into SIO than films produced from C2F6. The activation energies of fluorine diffusion were calculated to be 1.00 and 0.82 eV for SiF4 and C2F9 FSG, respectively.

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