The matrix reaction of lithium atoms and carbon tetrachloride produces the CCl3radical followed by secondary reaction of Li with CCl3to yield a sufficient concentration of dichlorocarbene for infrared spectral study. Natural chlorine isotopes, carbonhyphen;13 and bromine substitution, and loss of CCl2absorptions accompanied by growth of C2Cl4absorptions on sample warming furnish convincing evidence that dichorocarbene is isolated in the argon matrix. Assignments of the Chyphen;Cl stretching vibrations for the12C35Cl2,12C35Cl37Cl, 13C35Cl2, and12C35Cl37Cl species are supported by normal coordinate calculations. For the most abundant isotopic species,ngr;1thinsp;equals;thinsp;719.5andngr;3thinsp;equals;thinsp;745.7cmminus;1, andngr;2, the weak bending mode, was not detected. The stretching force constantsFtgr;thinsp;equals;thinsp;2.86mdynthinsp;sol;thinsp;Aring;andFtgr;tgr;thinsp;equals;thinsp;0.27mdynthinsp;sol;thinsp;Aring;indicate that Chyphen;Cl single bonds are present in dichlorocarbene, making it unlikely that the electron deficiency of the carbon atom is relieved by pi bonding with chlorine.
展开▼
