UDC 543.51 + 541.49 + 541.57

Chemistry

Academician A. N. Nesmeyanov, V. A. Dubovitskii,
O. V. Nogina, V. N. Bochkarev

Mass Spectra of Some Monocyclopentadienyl Derivatives of Titanium

The assumption that, in certain cyclopentadienyl derivatives of titanium, there is to a considerable degree an ionic bond between titanium and the cyclopentadienyl ring, which we advanced earlier (¹), was confirmed by an investigation of the IR (²) and NMR (³) spectra.

Fig. 1. Mass spectra of \( \mathrm{C_5H_5TiCl_3} \) (I), \( \mathrm{C_5H_5Ti(OC_2H_5)Cl_2} \) (II),
\( \mathrm{C_5H_5Ti(OC_2H_5)_2Cl} \) (III), \( \mathrm{C_5H_5Ti(OC_2H_5)_3} \) (IV)

The present work is devoted to the study of the mass spectra of compounds
\( \mathrm{C_5H_5Ti(OC_2H_5)_{3-n}Cl_n} \), where \( n = 0, 1, 2, 3 \) (see Fig. 1).

For the spectra of all the monocyclopentadienyl derivatives of titanium studied by us, the following features are characteristic: the presence of a molecular ion; formation of the ions \( (\mathrm{M} - \mathrm{A})^+ \) and \( (\mathrm{M} - 2\mathrm{A})^+ \), where \( \mathrm{A} = \mathrm{Cl} \) or \( \mathrm{OC_2H_5} \); formation of the ion \( \mathrm{C_5H_5^+} \). In those cases where \( n = 1 \) and \( 2 \), the ion \( (\mathrm{M} - \mathrm{HCl})^+ \) was recorded, and when \( n = 0, 1, 2 \), the ion \( \mathrm{C_5H_5Ti^+} = \mathrm{O} \).

The ratios \(I_{\mathrm{M}-\mathrm{C}_5\mathrm{H}_5}/I_{\mathrm{M}}\) in the spectra of the titanium derivatives studied by us are given in Table 1. As can be seen, this ratio increases in the series: \(\mathrm{C}_5\mathrm{H}_5\mathrm{TiCl}_3\), \(\mathrm{C}_5\mathrm{H}_5\mathrm{Ti}(\mathrm{OC}_2\mathrm{H}_5)\mathrm{Cl}_2\), \(\mathrm{C}_5\mathrm{H}_5\mathrm{Ti}(\mathrm{OC}_2\mathrm{H}_5)_2\mathrm{Cl}\), \(\mathrm{C}_5\mathrm{H}_5\mathrm{Ti}(\mathrm{OC}_2\mathrm{H}_5)_3\). It was shown earlier \((^4)\) that in the mass spectra of cyclopentadienyl derivatives of various metals the ratio of the peaks \(I_{\mathrm{M}-\mathrm{C}_5\mathrm{H}_5}/I_{\mathrm{M}}\) increases as the ionic character of the metal—cyclopentadienyl bond increases.

Table 1

The fragments \((\mathrm{M}-\mathrm{C}_5\mathrm{H}_5)^+\) and \(\mathrm{C}_5\mathrm{H}_5^+\) arise upon cleavage of the \(\mathrm{Ti}-\mathrm{C}_5\mathrm{H}_5\) bond in the molecular ion. It was to be expected that, in compounds with a more ionic character of the titanium—cyclopentadienyl bond, the probability of formation of the titanium-containing fragment \((\mathrm{M}-\mathrm{C}_5\mathrm{H}_5)^+\) would increase. Indeed, the value of the ratio \(I_{\mathrm{M}-\mathrm{C}_5\mathrm{H}_5}/I_{\mathrm{C}_5\mathrm{H}_5}\) increases in the same series (see Table 1).

Thus, from consideration of the mass spectra of \(\mathrm{C}_5\mathrm{H}_5\mathrm{Ti}(\mathrm{OC}_2\mathrm{H}_5)_{3-n}\mathrm{Cl}_n\), where \(n = 0, 1, 2, 3\), it may be concluded that the degree of ionicity of the \(\mathrm{Ti}-\mathrm{C}_5\mathrm{H}_5\) bond increases with decreasing \(n\). The data obtained are in complete agreement with the chemical behavior, infrared spectra, and NMR spectra of the substances studied by us \((^{1-3})\).

The mass spectra were recorded on an MX-1303 mass spectrometer, \(U = 40\) V, \(t = 175^\circ\).

Institute of Organoelement Compounds
Academy of Sciences of the USSR

Institute of the Chemistry of Natural Compounds
Academy of Sciences of the USSR

Received
12 V 1965

References Cited

1. A. N. Nesmeyanov, O. V. Nogina, V. A. Dubovitskii, Izv. AN SSSR, OKhN, 1962, 1481.
2. T. G. Dvoryantseva, Yu. N. Sheinker, A. N. Nesmeyanov, O. V. Nogina, N. A. Lazareva, V. A. Dubovitskii, DAN, 161, 603 (1965).
3. A. N. Nesmeyanov, E. I. Fedin, P. V. Petrovskii, V. A. Dubovitskii, O. V. Nogina, N. A. Lazareva, DAN, 163, No. 3 (1965).
4. L. Friedman, A. P. Irsa, G. Wilkinson, J. Am. Chem. Soc., 77, 3689 (1955).