GERGŐ, É.

MIRONOV, V. F.

NAGY, J.

English

Periodica Polytechnica (Budapest University of Technology and Economics)

STUDIES ON THE BOND STRUCTURE OF THE ORGANIC ALLYL DERIVATIVES OF GROUP IV/I ELEMENTS By J. NAGY, V. F. NlIRONOY and E. GERGO Department for Inorganic Chemistry, Technical University, Budapest Received: July 29, 1971 The vinyl, allyl, benzyl and phenyl derivatives of Group IV/I elements, as well as their structure elucidation have been earlier dealt with [1, 2, 3, 4, 5,6,7]. For the purpose of checking the structure established for allyl derivatives the cyclic form had to be studied too. As the dipole moment of the 1,I-dimethyl-germanium-cyclopentene-3 is equal to zero, only that of 3-trimethyl-germa-nium-cyclopentene-l was determined. Naturally, a further germanium com-pound was also necessary (trimethyl-allyl-germanium) and the work was completed by studies on I-neopentyl-ethylene. All in all, dipole moments of the following .three compounds have been determined: CH=CHo 1. (CH3hGc-CH( 1-CH2-CH2 2. (CH3)aGe-CH2-CH=CH2 3. (CH3)aC-CH2-CH=CH2 The compounds were prepared as published in the literature by the research group directed by V. F. MIRol\"oy. The purity of the compounds 'was checked by comparing molar refrac-tions (iVIRD ) determined at 25°C and calculated from the bond increments, as well as by gas chromatography. Gas chromatography analysis was performed on a G CHF 18.2 Willy Giede apparatus. The packing was Chromosorb W wetted with 18% SE-30, the carrier gas was nitrogen. The dipole moment was determined by the Onsager method [8], as our compounds were liquids at room temperature and did not tend to associate. According to Onsager's theory, the dipole moment at 25°C fi = 0.22123 1 (1) 3 132 J. :VAGY et al. where So is the measured dielectric constant V is the molar volume (ml) 2R V V-R (2) (3) R is the sum of atomic (P A) and electronic polarization (Pd. Its approximate value cau be calculated from the molar refraction at 25°C by means of the following equation: R = iVIRD • 1.05 = PA + PE' (4) The tests were performed at 25 0.02 cC. The temperature was kept constant by an ultrathermostat. The density (d 25) was determined using grad-uated dilatometers, the refractive index with reference to the sodium D line (n~) and the dispersion values (nF - ne) by means of an Abbe refracto-meter. Dielectric constants (S25) were determined at a frequency of 10000 Hz using an apparatus constructed in Dur laboratories [9]. Measurement and calculation results are compiled in Table 1, including recorded refractive indices (n75) , dielectric constants (S25), molar volumes (V25), densities (d 25), molar refractions calculated from bond increments 25 nD S25 dZ5 p5 Table 1 Characteristic physical constants of 1-neopentyl-ethylene, trirnethyl-allyl-germanium and trimethyl-germanium-cyclopentene-1 (CH,),-C-CH,-CH=CH, I (CH,),-Ge-CH,-CH=CH, \ CH=CH (CH,),-Ge-CH<- CH, ;>CH, 1.3887 1.4289 1.4676 1.997 2.400 2.299 0.6771 0.9859 1.0626 145.0249 161.0396 173.9196 J.l!IRD eaIe (ml) 34.114 41.130 48.226 MRD meas (ml) 34.2776 41.5076 48.3110 R 34.2776** 43.5830 50.7266 seif 1.928 2.113 2.235 P* 1.902 7.853 18.357 pD 0.305 0.620 0.948 ** For carbon compounds the atomic polarization can be neglected R = lURD • STUDIES OS THE BOSD STRCCTURE 133 (1\:lRD calc/ml), measured molar refractions (1\:lRD meas/ml), sums R of atomic and electronic polarization calculated by means of Eq. (4), the value of the effective dielectric constant (,seff) calculated using Eq. (3), as well as values of the polarization of orientation (P*) and of the dipole moment (/-l), calculated using Eqs (2) and (1), respectively. In Table 2 the dipole moments of some compounds are presented which are necessary to our studies. Fig. 1 clearly shows the change of the dipole moments of compounds of the type (CH3hlVICH2CH=CH2' where M=C, Si, Ge, Sn. As the electronega-tivity of M decreases, the inductive effect increases, similarly to the analogous benzyl compounds, and the dipole moment increases, too. This is in contrast to the analogous phenyl and vinyl compounds where a -M effect is con-comitant to the +1 effect. Table 2 Dipole moments of the vinyl, allyl, phenyl and benzyl derivatives of the Group IV elements Compound p.D Reference @-CH2 -CCCHah 0.39 [13] @-CH2 -Si(CHah 0.55 [101 (g)-CH~-Ge(CHah 0.632 [7] < 0 )-CHz-Sn(CH3)3 0.91 [10] CH2 = CH - CH2 - Si(CH3h 0.58 [10] < 0 )-C(CH3h 0.425 [6] @-Si(CH3h 0.248 [6] <0 )-Ge(CH3h 0.378 [6] (0 )-Sn(CH3)3 0.51 [10] CH2 = CH - C(CH3)3 0.330 [11] CH2 =CH-Si(CH3)3 0.229 [11] CH2 =CH-Ge(CH3)3 0.319 [11] CHz=CH-Sn(CH3h 0.449 [7] 3* 134 J. ,',"AGY el al. 1,0.----,-----,----,----,----~ )1 (D) ({j)- CHr t1(CH3h CH2 =CH-CH2-H(CH3h 0,6 j----r-o;;;;;;;:::j=----i'--i------j /F0..... 0--H(CH3lJ CH2 = CH-!1(CH3h 0'2r---~-----+----_r----~--~ o 6 10 14 20 C Si 3032 Ge 40 50 z Sn Fig. 1. The change of dipole moment in the vinyl, phenyl, allyl and benzyl derivatives of Group IV elements Test results on allyl compounds are similar to those obtained for benzyl compounds, attributable to their similar bond structures. This is supported, according to the rule of Karapetiantz, also by the fact that a linear correlation exists between the dipole moments of corresponding pairs of compounds (Fig. 2). Hence, the expectable dipole moment of the allyl compound of tin might be about I D. Unfortunately, no such experimental value was ayailable to us. 1,0 J1(benzyl). 0,8 0,6 /' 0,2 0.2 I /r lLr / I ./ 0,4 0,6 0,8 1,0 )1 [allyl) Fig. 2. Correlation between dipole moments of the allyl and benzyl derivatives of Group IY elements STUDIES O.V THE BOSD STRUCTURE 13:1 It is clearly shown by both figures that the values for silicon and germa-nium compounds are very close -what can be explained by the similar electro-negativity and affinity of the two elements. As mentioned earlier [4, 5], in the case of allyl derivatives a d - ;r interaction, so called long bond and the hyperconjugation of the CHz group have to be taken into account. I II But in the case of compound HI there is no long bond, in accordance with the fact that compound H exhibits a marked bathochromic shift in the ultraviolet band relative to compound I, whereas compound HI exhibits a great hypsochromic shift [12]. This prov-es that the long bond lends to com-pound T, and ev-en more to compound H a more conjugated hond system since the degree of freedom of rotation is lO'I-er, whereas in compound HI the double bond is practically localized, as no long bond may occur, since germanium lies in the plane of the cyclopentene ring. This has been stated earlier in connection with silicon compounds [1,2,3,4,5]. The bond orders calculated by the HMO-(I) technique for the three types are as follows: () "~l>O ().O.~O·I / ., 7'~O ./,O.Y6.12 o.!)tj6H C=C------::ii- C=C------Si-/ O.W3S\\ / "--.. L::1.2~{)YI ~ .. l()S~ c 0.07% C 'I' ~.,).)60 I O,9i42 H H" b c The bond order ;r of the long hond is seen to 5.04% for a, 9.68% hence greater for b. Therefore the hond order of the allyl group is 97.98 % for a and 96.42% for b, whereas nearly 100% for c. The isostructural germanium compounds are expected to hehave simi-larly. The fact that dipole moment of the cyclopentenyl compound is much greater than that of the allyl deriv-ative, partly due to the greater electron shift and partly to the lower degree of freedom of rotation is likely to agree with this phenomenon. 136 This latter statement can be proved by the following model calculation: The following values were used in the calculations: 1110 = 0.6 D 1111 = 0.7 D 1112 = 0.2 D 1113 = 0.5 D G e _n_I,::..., ---+) C II Calculations for minimum and maximum limiting values delivered ,u = 0.53 D for I, and ,u = 0.35 D for H. In view of the fact that I-trimethyl-germanium-cyclopentene-2 has only a structure corresponding to I, whereas trimethyl-allyl-germanium can assume all the rotation states between I and H including the limiting states, its dipole moment is expected to be smaller than that of the cyclic compound. Similar statements can be made on the benzyl derivatives of silicon and germanium, as shown earlier [1,2,3,4,5]. Summary 1. Dipole moments of I-neopentyl-ethylene, trimethyl-allyl-germanium and trimethyl-germanium-cyclopentene-l have been determined. 2. Comparison of dipole moments led to the conclusion that a d - :r interaction occurs between the p-carbon of the allyl group and the silicon atom. References 1. NAGY, J., REFFY, J.: J. Organometal. Chem., 22, 565 (1970) 2. NAGY, J., REFFY, J.: J. Organometal. Chem., 22, 573 (1970) 3. NAGY, J., REFFY, J.: J. Organometal. Chem., 23, 71 (1970) 4. NAGY, J., REFFY, J.: J. Organometal. Chem., 23, 79 (1970) 5. NAGY, J., REFFY, J., ELL-I.S, P.: Acta Chimica Acad. Sci. Hung. 63, 403 (1970) STUDIES OZ .... THE BOSD STRC,"CTURE 137 6. NAGY, J., i"EREI'CZI-GREsz, 5., BECKER-PALOSSY, K., BORBELY-Ktisz)L~I'I', A.: Acta Chimica Acad. Sci. Hung. 61, 149 (1969) 7. K~GY, J., FEREI'CZI-GRESZ, 5., NEFIODOY, O. M.: Per. Polytechn. Ch. 10, 319 (1966) 8. OI'SAGER, C. J.: J. Am. Chem. Soc. 58, 1486 (1936) 9. NAGY, J., GRESZ, I., FEREI'CZI-GRESZ, 5.: Per. Polytechn. Ch. 10, 335 (1966) 10. I\..\.GY, J., FEREI'CZI-GRESZ, 5., MIRol'i"oY, V. F.: Acta Chim. Acad. Sci. Hung. 47, 189 (1966) 11. NAGY, J., FEREI~CZI-GRESZ, 5., DURGARL.\.l'i", S. G.: Acta Chim. Acad. Sci. Hung. 60, 357 (1969) 12. PETUKOY, V. A., MIRONOY, V. F., SORIGIl'i", P. P.: Izv. Akad. Nauk. S. S. S. R. OHN 1964, 2203 13. BAKER, J. W., GROVES, L. G.: J. Chem. Soc. 1939, 1144 Dr. J6zsef NAGY } Eva GERGO V. F. :NhRONOV } Budapest XI., Gellert ter 4, Hungary Institut Kremniyorganicheskikh Soedinenii, Moscow E 275, USSR 

STUDIES ON THE BOND STRUCTURE OF THE ORGANIC ALLYL DERIVATIVES OF GROUP IV/I ELEMENTS

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STUDIES ON THE BOND STRUCTURE OF THE ORGANIC ALLYL DERIVATIVES OF GROUP IV/I ELEMENTS

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Periodica Polytechnica (Budapest University of Technology and Economics)