V 71)S u m m a r y . The adduct 1,4-benzoquinone.TiCl~ has been prepared in CH,Cl, solution at about -6OD. Its I K . spectrum has been recorded a t the same temperature. The experimental study of the vibrational frequencies has been completed by the calculation of the fundamental vibrations in the molecular plane, using Wilson's FG method, with slightly simplified models of 1,4-benzoquinone. TiC1, (13 masses) and 1,4-bcnzoquinone.2TiCI, (14 masses) ; analysis by use of internal and symmetry coordinates. .4n assignnient of most of thc obscrved bands is proposed and the conclusion is rcached that the complex, when solid, is (1,4-benzoquinone.TiC1,),.The force constants F(C=O) are 9,85 . lo5 dync/cm for the quinone and 8,8 . lo5 dyne/cm for the disturbed carbonyl bond of the polymerizcd complex in the model proposed.At ordinary temperature in benzene solution of the components the adduct 1,4-benzoquinone. TiCl,.benzene precipitated; with thc hclp of the models, thc fundamental vibrations of its IR. spcctruni have been assigncd.

Solid stoichiometric adducts of 9, 10‐anthraquinone with SbCl5, ZrCl4, TiCl4 SnCl4, AlCl3, have been prepared. The very important lowering Δω of the IR. carbonyl frequency, ranging from −175 cm−1 for SbCl5 to −117 cm−1 for SnCl4, shows that the acceptor is linked by a dative bond to the carbonyl oxygen atom acting as a donor; an assignment of most of the fundamental IR. frequencies is proposed for anthraquinone and the mentioned adducts. Similar assignments and interpretation have been made for anthrone and its solid adduct with SbCl5, ZrCl4, TiCl4, SnCl4, AlCl3 and ZnCl2, where the CO lowerings range from −164 cm−1 for SbCl5 to −97 cm−1 for ZnCl2.

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