Reaction of amino derivatives of silicon, germanium, tin and titanium with ketones

J. inorg, nucl, Chem., 1972, Vol. 34, pp. 2449-2454.

Pergamon Press.

Printed in Great Britain

REACTION OF AMINO DERIVATIVES OF SILICON, GERMANIUM, TIN AND TITANIUM WITH KETONES G. E. M A N O U S S A K I S and J. A. TOSSIDIS Laboratory of Inorganic Chemistry, University of Thessaloniki, Greece (Received 11 August 1971) Abstract-Some diethylamino derivatives of tin and titanium and pyrrolidino derivatives of silicon, germanium, tin and titanium react with diethyiketone forming the corresponding amine, the oxide of the element and the enamines, namely 3-(N)-diethylamino-penten-2 and 3-(N)-pyrrolidino-penten-2. The corresponding enamines and oxides were obtained, as well, by directly mixing the metal chlorides with ketone (methylethylketone or diethylketone) and amine (pyrrofidine or diethylamine), with the exception of SiCl4, which does not react with diethylamine and these ketones. Another exception is GeCI4, which does not react in the case of diethylamine with methylethylketone. The formulae of these products were established by means of i.r. and proton N M R spectra as well as by elemental analysis. A reasonable mechanism of the overall reaction is given.

INTRODUCTION

THIS paper deals with a study of the reaction of some diethylamino and pyrrolidino derivatives of-silicon, -germanium, -tin and titanium with diethylketone. This type of reaction is similar to those which were described by other authors with a series of amino derivatives of certain elements; Nelson and Pelter [ 1] using tris (dialkylamino) boranes, Hirsch[2] and Manoussakis [3] using arsenic amino compounds. The reaction with tetrakis amino derivatives of titanium is described by Weingarten and White [4, 5]. EXPERIMENTAL I.R. spectra were recorded in a Beckman Model-IR-4 spectrometer. N M R spectra were recorded on a Varian Associates A-60A (60 Mc/sec) instrument (TMS internal standard). Preparation o f aminoderivatives The preparation of pyrrolidino derivatives was described in a previous paper [ 10]. Preparation o f tris( diethylamino )-c hlorosilane Diethylamine (13.20 g, 180.5 mmoles) and silicon tetrachloride (3.40 g, 20 mmoles) were sealed in a tube. The mixture allowed to react and was treated as described in the preparation of the pyrrolidino derivatives. The products were tris(diethylamino)-chlorosilane (I) a pale yellow liquid, b.p. 255-257°C

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

P. Nelson and A. Pelter, J. chem. Soc. 5142 (1965). H . V . Hirsch, Chem. Ber. 100, 1289 (1967). G. E. Manoussakis, J. inorg, nucl. Chem. 30, 3100 (1968). H. Weingarten and W. A. White, J. A m. chem. Soc. 88, 850 (1966). H. Weingarten and W. A. White, J. org. Chem. 31, 4041 (1966). K. Jones and M. F. Lappert, Organometal. Chem. Rev. 1, 67 (1966). H. H. Anderson, J. Am. chem. Soc. 74, 1421 (1952). R.T. Cowdell and G. W. Fowles, J. chem. Soc. 2522 (1960). H. Breederveld and H. I. Watermann, Research 5, 537 (1952). G. Manoussakis andJ. Tossidis, lnorg, nucl. Chem. Lett. 5, 733 (1969). 2449

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G . E . M A N O U S S A K I S and J. A. TOSSIDIS

(2.69 g, 9.6 mmoles, 48%). (This compound was prepared by Breederveld and Waterman[9] from SiC12(NEtz)e and EtzNH in benzene b.p. 131-136°C/13 mmHg, yield 35%.) The chief i.r. bands were at 2980 vs. 1460 s, 1380 vs. 1360 m, 1300 m, 1215 vs. 1175 vs. 1105 m, 1030 vs. 945 vs. 795 vs. and 700 vs. cm -1. The proton N M R spectrum (in CDC13) gave a quartet at 7.10 and a triplet at 8.98~ (intensities 2:3). The residue of the reaction was diluted in chloroform. On reducing the solubility by addition of acetone Et2NHzCI was isolated (5.76 g, 52.5 mmoles, 87%). The Et2NH~C1 was identified by comparison with an authentic sample.

Preparation of tetrakis(diethylarnino)-germane Diethylamine (7.35 g, 100-5 mmoles) and germanium tetrachloride (2-14 g, 10 mmoles) were mixed in a sealed tube and allowed to react as before. The products were characterized as tetrakis(diethylamino)-germane (II), a pale yellow liquid, b.p. 264-265°C (2.24 g, 6.2 mmoles, 62%). (This compound was prepared by Anderson[7] from GeBr4 and Et2NH in cycloexane, b.p. 266°C, yield 45%.) The chief bands in the i.r. spectrum were at 2980 vs. 2880 s, 1460 m, 1380 s, 1300 m, 1185 vs. 1100 w, 1060 w, 1020 vs. 905 s and 790 m cm -j. The residue identified as Et~NH2CI (3.95 g, 35-9 mmoles, 90%).

Preparation of tetrakis(diethylamino)-tin tetrahydrochloride Diethylamine (14.63 g, 200 mmoles) and tin tetrachloride (5.21 g, 20 mmoles) were sealed in a tube and treated as before. The main product was tetrakis(diethylamino)-tin tetrahydrochloride (III), white solid, m.p. 163°C (10.05g, 18.2mmoles, 91%). (Found: C, 34.34; H, 8.30; N, 10.90; Sn, 21.44; CI, 24.90%. Calc. for ClsH44N4SnCI4: C, 34.75; H, 8.02; N, 10.13; Sn, 21.46; CI, 25-64%.) The main i.r. peaks were at 2570 m, 1170 m, 1070-1055 w (doublet) and 810 m cm -~. The proton N M R spectra (in nujol) showed a quartet at 6-87 and a triplet at 8.55r (intensities 2 : 3).

Preparation of dichloro(diethylamino)-tin dihydrochloride Diethylamine (11-00 g, 150 mmoles) and tin tetrachloride (3-94 g, 15 mmoles) were sealed and treated as before. The main products were dichloro(diethylamino)-tin dihydrochloride (IV), white crystals, m.p. 127-128°C (5.61 g, 13.8 mmoles, 92%). (Found: C, 23.54; H, 5-57; N, 6.78; Sn, 29.10; CI, 34.92%. Calc. for CsH22N2SnCI4: C, 23-62; H, 5-45; N, 6.89; Sn, 29.18; C1, 34.86%.) The chief bands in the i.r. spectrum (in nujol) were at 2525 w, 1160 m, 1065 m, 1035 m, 890 w, 805 w and 765 m cm -j. The proton N M R spectrum (in CDCI3) gave a quartet at 6-93 and a triplet at 8"53z (intensifies 2 : 3).

Preparation of tetrakis(diethylamino)-titanium tetrahydrochloride Diethylamine (14.63 g, 200 mmoles) and titanium tetrahydrochloride (3.8 g, 20mmoles) were sealed and treated as usual. The product was tetrakis(diethylamino)-titanium tetrahydrochloride (V), white solid, m.p. 177-178°C (8"68 g, 18 mmoles, 90%). (Found: C, 39.80; H, 9.24; N, 11.50; Ti, 10.01; CI, 29-30% Calc. for CleI-L~N4TiCI4: C, 39.85; H, 9.19; N, 11 "62; Ti, 9.93; CI, 29.40%.)

Reaction of aminoderivatives with diethylketone The aminoderivatives of silicon, germanium, tin or titanium (2 10 mmoles), the diethylketone (2 20 mmoles) and the amines (= 30 mmoles), cooled in liquid nitrogen, were sealed in ampoules. (In the case of the aminoderivatives I, II and X the addition of amine is omitted.) The mixture was brought slowly to room temperature and the ampoule was heated at 80°C (24 hr). The reaction mixtures were extracted with dried ether and filtered. The filtrates were distilled and gave: (i) In the case of diethylamine, 3-(n)-diethylamino-penten-2, CHsCH=C(NEtz)CH2CH3 (VI), a pale yellow liquid which turned to yellow, b.p. 145-147°C. The i.r. spectrum 0iquid phase) of enamine (VI) showed the following principal pea.ks 3000 vs, 1650 s, 1465 s, 1380 s, 1270 w, 1240 m, 1200 m, 1120 m, 1090-1070-1055 m (triplet), 955 w and 790 m cm -1. The proton N M R spectrum (in CDC13) showed a quartet at 5.76, two multiplets at 7-10 and 7-90, a doublet at 8.40 and a multiplet at 9.00r (intensities 1:4: 2 : 3 : 9). (Found: C, 76.30; H, 13.62; N, 9.80%. Calc. for CgH19N: C, 76.53; H, 13-56; N, 9.91%.) (ii) In the case of the use of pyrrolidine 3-(N)-pyrrolidino penten-2, CHsCH=C(NC4Hs)CH2CH3 (VII) a pale yellow liquid, which turned yellow, b.p. 173-175°C (0.56 g, 4 mmoles, 25%). (Found: C, 77.44; H, 12.23; N, 10.17%. Calc. for CgHI:N: C, 77.64; H, 12.30; N, 10.06%.) The i.r. spectrum (in liquid phase) of this enamine (VII) showed the following main peaks 2980 vs. 1640 vs. 1465 s,

Reaction of amino derivatives

2451

1380 s, 1355 s, 1325 s, 1245 m, 1180 s, 1110 m, 1080 m, 1035 w, 955 w and 775 s cm -1. The proton N M R spectrum, in CDCIa (TMS internal standard) gave a quartet at 5"92, a triplet at 6.98 and two multiplets at 8.20 and 8-96r. In the ampoules the residues of the reactions were identified as the corresponding metal oxides, in both cases, by elemental analysis. The yields of the products are summarized in Table 1. Table 1. Results of the reaction between aminoderivatives and diethylketone Metal Enamine dioxide (%) (%) (Et~N)3SiC1 (I) (Et2N)4Ge (II) (Et2N)4Sn. 4HCI ( l i d (Et2N)2SnCI~. 2HCI (IV) (Et2N)4Ti. 4HCI (V)

VI (29) VI (30) VI (27)

(41) (43) (40)

Enamine (%) (C4HsN)4Si (X) (C4HsN)4Ge. 4HCI (XI) (C4HaN)2SnCI2.2HCI (XII) (C4HsN),Sn. 4HCI (XIII) (C4HsN)4Ti. 4HCI (XIV)

VII VII VII VII VII

(25) (26) (31) (32) (30)

Metal dioxide (%) (44) (47) (54) (53) (52)

Reactions of metal chlorides, amines and ketones The reaction of SiCI4, GeC14, SnCI4 and TiCl4 with amines, (diethylamine and pyrrolidine) and ketones (diethylketone and methylethylketone) took place under the same conditions as described above. The products were again the corresponding oxides, amine hydrochlorides and enamines namely VI, VII, 2-(N)-diethylamino-buten-2, CHzC(NEt2)=CHCH3, (VIII) and 2-(N)-pyrrolidinobuten-2, C H a C = ( N C 4Hs)CHCH3 (IX). The results of these reactions are given in Table 2. The i.r. spectra (in liquid phase) of enamine VIII and IX showed the following main peaks 2960 vs. 1640-1620 s (doublet), 1450 s, 1380 s, 1240 s, 1090 m, 1070 m, 1030 m and 790 s cm -j and 2980 vs. 1630 s, 1460 s, 1380 s, 1310 m, 1170 m, 1085 w, 865 w and 775 w cm -1 respectively. The proton N M R spectra of the above enamines (VIII and IX) gave a quartet at 5-62, a doublet at 6-36, two multiplets at 7.00 and 7"82, a triplet at 8.30 and a multiplet at 8.94z; and a quartet at 5-92, a triplet at 7.12 and two multiplets at 8.30 and 9.96z. RESULTS AND DISCUSSION

The necessary aminoderivatives of the elements of group IV were prepared in sealed tubes according to the reactions MCI4 + MCI4 +

2xNHR2 xNHR2

-~ M(NR2)xCI4-x + -~ M(NR2)xCI4-x

xNHzR2CI

• xHC1

(1) (2)

where M = Si, Ge, Sn or Ti; R = Et or Rz = C 4 H s . These reactions are similar to those which were suggested by Lappert-Jones [6] and Anderson [7] between group IV halides and amines. Aminolysis of covalent metal halides is probably proceeding initially by coordination of a molecule of amine followed by a base-catalyzed elimination of hydrogen halide. This type of aminolysis is suggested by Cowdell and Fowles [8] for the reaction between NH3 and TIC14. The replacement of chlorine atoms proceeds stepwise; as replacement proceeds the remaining M-C1 bonds become increasingly resistant to further aminolysis. Diethylamine reacts with S i C I 4 a n d G e C 1 4 according to reaction (1), forming tris(diethylamino)-chlorosilane, SiCI(NEt2)3 (I) and tetrakis(diethylamino)germane, Ge(NEt2)4 (II) respectively. Compounds I and II are known corn-

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G . E . M A N O U S S A K I S and J. A. TOSSIDIS

pounds [7, 9] but in this work they were prepared in a different way and with an increase of yield. The fact that under the same conditions the fourth chlorine atom of SIC14 is not replaced by an Et2N- group is attributed to steric hinderance. Diethylamine reacts with SnC14 and TiCI4 according to Equation (2). The product aminoderivatives were tetrakis(diethylamino)-tin tetrahydrochloride, Sn(NEt2)4.4HCI (III), dichloro(diethylamino)-tin dihydrochloride, SnC12(NEt2)2.2HCI (IV) and tetrakis(diethylamino)-titanium tetrahydrochloride Ti(NEt2)4.4HCI (V). The formation of hydrochlorides of the aminoderivatives instead of simple aminoderivatives is probably due to the lower basicity of Et2NH in comparison to Sn(NEt2)4 and Ti(NEte)4. The i.r. spectra of these compounds show the characteristic peaks at 30002800 cm- 1 due to stretching and 1480-1300 cm-1 due to deformation of the C-H bond. The peaks in the region 1240-1030 cm -1 are due to stretching of C-N and C-C bonds. A peak at 700 cm-1 in the spectrum of compound I is associated with the Si-N bond. The corresponding peak in the spectra of the aminoderivatives of the other elements is probably shifted to lower frequencies. The spectra of the hydrochloride salts showed a peak in the region 2550-2450 cm -1 which is due to N+-H bond. The proton NMR spectra of compounds I, II, III, IV and V showed a quartet at z = 6.88-7.10 (CH3-C) and a triplet at r = 8.50-8.97 (-CH2-N). The preparation and characterization of the pyrrolidino derivatives is described in a previous paper [ 10]. Most of these diethylamino and pyrrolidino derivatives of silicon, germanium, tin and titanium (Table 1) react with diethylketone with deamination leading in all cases to the formation of enamine and oxide of the element according to the general equation M(NR2)4 + 2(C2H5)2CO --~ 2CH3CH=C(NR2)CH2CH3 + MO~ + 2R2NH.

(3)

Compounds I and II do not react. This is presumably due to steric hinderance. It seems likely that reaction (3) is initiated by nucleophilic attack on the carbon atom of the carbonyl group by basic compounds with a M - N bond forming the intermediate product A (Fig. 1). This product under deamination gives enamine and the compound B. Repetition of the sequence on the species B gives finally amine, enamine and the dioxide of the element. This type of mechanism is supported by the fact that Si-N, G e - N and Sn-N bonds undergo fission with hexafluoroacetone[11] producing compounds of type - M - O - G - N , analogous to product A (Fig. 1). In this case the next step of deamina~ion does not proceed because of the strongly electrophilic character of the -CF3 group. The preparation of aminoderivatives and their reaction with ketones was also carded out in one step with a mixture of amine, metal chloride and ketone in sealed tubes according to the overall reaction MC14 + 2C2H~C(O)R' + 6NHR2 ~ 2CHaCH=C(NR2)R ' + MO~ + 2R~NH2CI. (4) 11. E. W. Abel and J. P. Crow, J. chem. Soc. (A) 1361 (1968).

Reaction of amino derivatives

2453

CH3~H2

I N

/\ H

I

v

H /C~" \ 0 "-~M--N< CH3CHa,~ ~X (A)

CH3CH C--N~ I CH3CH2

+ O=M--N< + >NH i N (B) A Fig. 1.

F o r R = Et, M = Ge, Sn, Ti; R' = Me. F o r R = Et, M = Sn, Ti; R' -- Et. F o r R = C4H8, M = Si, Ge, Sn, Ti; R' = Me, Et. T h e results o f this reaction are given in Table 2. T h e formulae o f the producted enamines which are n e w c o m p o u n d s , were established by m e a n s o f i.r. and proton N M R spectra as well as by elemental analysis. T h e i.r. spectra s h o w a characteristic peak at 1640 c m -1 due to stretching o f the C = C bond. Proton N M R spectra s h o w a quartet at r = 5-76-5.92 which Table 2. Results of the reaction of metal chlorides, amines and ketones

Metal chlorides SiCI4 GeCI4 TiCl4 SnCl4 SiCL GeCI4 TIC14 SnCL SIC14 GeCI4 TIC14 SnCI4 SiCI4 GeC14 TiCI4 SnCL

Amine

Ketone

Enamine (%)

Metal oxide (%)

Diethylamine Diethylamine Diethylamine Diethylamine Pyrrolidine Pyrrolidine Pyrrolidine Pyrrolidine Diethylamine Diethylamine Diethylamine Diethylamine Pyrrolidine Pyrrolidine Pyrrolidine Pyrrolidine

Diethylketone Diethylketone Diethylketone Diethylketone Diethylketone Diethylketone Diethylketone Diethylketone Methylethylketone Methylethylketone Methylethylketone Methylethylketone Methylethylketone Methylethylketone Methylethylketone Methylethylketone

VI (45) VI (48) VII (30) VII (52) VII (63) VII (69) VIII (25) VIII (32) VIII (36) IX (26) IX (30) IX (34) IX (40)

(63) (65) (56) (72) (80) (84) (51) (56) (60) (57) (74) (82) (85)

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G . E . M A N O U S S A K I S and J. A. T O S S I D I S

is attributed to the following methyl group proton. This, in the case of methylethyl enamines CHaC(NEh)=CHCHa, (VIII) and CH3C(NC4Hs)=CHCH8 (IX) shows that the double bond, C=C is situated between the second and third carbon atoms. The unresolved multiplet at r = 5.62-5.92, in NMR spectra of enamines, particularly of enamine (IX) is associated to the great tendency of enamines to polymerization. Indeed, the fresh enamines are yellowish liquids which soon turn to dark brown oily liquids. This tendency to polymerization in addition to the sensitivity to moisture and oxygen is associated with low yields of enamines in comparison to metal oxides. The yield of the reactions increases from Si to Sn. This is attributed to the relative strength of M-N bonds (Si-N > Ge-N > Ti-N > Sn-N). This is in agreement with Jones and Lappert's[12] statement about Si-N, G e - N and Sn-N in analogous aminoderivatives. Pyrrolidine enamines were prepared in a higher yield than the corresponding ethyl enamines. This phenomenon is attributed to the stronger Lewis basic character of pyrrolidine and to steric hinderance. 12. K. Jones and M. Lappert, J. chem. Soc. 1944 (1965).