THE INFRARED SPECTRA OF TRIMETHYL ALUMINUM, DIMETHYL ALUMINUM CHLORIDE, METHYL ALUMINUM DICHLORIDE, METHYL TITANIUM TRICHLORIDE, DIMETHYL TITANIUM DICHLORIDE, AND SOME DEUTERIUM DERIVATIVES

The vapor phase infrared spectra to 300 cm −1 are discussed and assignments made for the compounds (CH 3 ) 6 Al 2 , (CD 3 ) 6 Al 2 , (CH 3 ) 4 Al 2 Cl 2 , (CD 3 ) 4 Al 2 Cl 2 , (CH 3 ) 2 Al 2 Cl 4 , CH 3 TiCl 3 , CD 3 TiCl 3 , and (CH 3 ) 2 TiCl 2 . The assignments differ significantly from those previously published, but are consistent throughout the series of aluminum compounds and with related spectra. The data are in agreement with a bridged structure for trimethyl aluminum of D 2h or C 2h symmetry and with a bridged structure of dimethyl aluminum chloride with chlorine bridging. The dimer (CH3) 2 Al 2 Cl 4 is shown to exist in the trans configuration. Evidence is presented indicating that an impurity is commonly found in spectra of dimethyl aluminum chloride which is identified as the mixed dimer (CH 3 ) 3 Al 2 Cl 3 , aluminum sesquichloride. A number of anomalies observed in the spectra of the methyl titanium compounds are pointed out and discussed.