Inorganic Chemistry
AND M. T. POPE 662 G. M.VARGA,JR., E. PAPACONSTANTINOU,
CONTRIBUTION FROM THE DEPARTMENT O F CHEMISTRY, GEORGETOWN UNIVERSITY, WASHINGTON, D. C. 20007
Heteropoly Blues. IV. Spectroscopic and Magnetic Properties of Some Reduced Polytungstatesl BY GIDEON M. X'ARGA,
JR.,
ELIAS PAPACOXSTANTINOU,
AND
MICHAEL T. POPE2
Received Septembev 8 , 1969 Optical, electron spin resonance, and nuclear magnetic resonance spectra of aqueous solutions of one- and two-electron blues derived from eight 1: 12- and 2 : 18-heteropolytungstates have been measured. Esr g values for the one-electron blues are characteristic of tetragonal W(V) complexes. No hyperfine structure (lS3W,I = I,'%) was observed due to the broadness of the signals (100-200 G a t 77'). According to nmr and esr the two-electron blues are spin-paired a t 77 and 310°K. The optical spectra of the reduced species show broad mixed-valence bands a t 8-20 kK. The one- and two-electron heteropoly blues are regarded as class I1 mixed-valence species with trapped tungsten(V) valences and with intraionic electron transfer occurring a t a rate which is slow on the esr time scale (
