METHOD FOR PRODUCING DIALKYLAMIDO ELEMENT COMPOUNDS

Abstract

The invention relates to a method for producing dialkylamido element compounds. In particular, the invention relates to a method for producing dialkylamido element compounds of the type E(NRR′).sub.x, wherein first WAIN is reacted with HNRR′ in order to form M[Al(NRR′).sub.4] and hydrogen, and then the formed M[Al(NRR′).sub.4] is reacted with EX.sub.x in order to form E(NRR′).sub.x and M[AlX.sub.4], wherein M=Li, Na, or K, R=C.sub.nH.sub.2n+1, where n=1 to 20, and independently thereof R′=C.sub.nH.sub.2n+1, where n=1 to 20, E is an element of the groups 3 to 15 of the periodic table of elements, X=F, Cl, Br, or I, and x=2, 3, 4 or 5.

Claims

1. Method for producing compounds of type E(NRR′).sub.x comprising the following steps: a) reacting M[AlH.sub.4] with HNRR′ to form M[Al(NRR′).sub.4] and hydrogen; b) reacting M[Al(NRR′).sub.4] with EX.sub.x to form E(NRR′).sub.x and M[AlX.sub.4], wherein M=Li, Na or K, R=C.sub.nH.sub.2n+1, where n=1 to 20, and independently thereof R′=C.sub.nH.sub.2n+1, where n=1 to 20, E is an element of the groups 3 to 15 of the periodic table of the elements, preferably Zr, Ta, Nb, Bi, As, P, B, Si or Ge, X=F, Cl, Br or I and x=2, 3, 4 or 5.

2. Method according to claim 1, characterized in that R==CH.sub.3 or C.sub.2H.sub.5.

3. Method according to claim 1 or 2, characterized in that M=Li or Na.

4. Method according to claim 1, characterized in that X=Cl.

5. Method according to claim 1, characterized in that step b) is carried out in an organic solvent.

6. Method according to claim 1, characterized in that step b) is carried out in an amine as solvent.

7. Method according to claim 1, wherein step b) is carried out in a temperature range of from −80° C. to 160° C., in particular from −40° C. to 120° C. or from 0° C. to 120° C.

8. Method according to claim 1, characterized in that in step b) a stoichiometric amount of M[Al(NRR′).sub.4] is used and a heteroleptic compounds E(NRR′).sub.xX.sub.y, in which the halide ligands are replaced only partially by amide ligands, is obtained.

9. Method according to claim 18, characterized in that, in step b), after the reaction has taken place, the amine is removed at temperatures of between −80° C. and 0° C.

10. Method according to claim 1, characterized in that, in step b) after the reaction has taken place, it is isolated by sublimation.

11. Method according to claim 1, characterized in that, after step a) and before step b), excess amine HNRR′ is removed.

12. Method according to claim 1, characterized in that step a) is carried out in the presence of an excess of amine HNRR′.

Description

EXAMPLES

Example 1: Preparation of Li[Al(NMe.SUB.2.).SUB.4.] Starting from Recrystallized LiAlH.SUB.4

[0037] ##STR00001##

[0038] LiAlH.sub.4 (1.00 g, 26.4 mmol, 1.0 eq) was recrystallized from ET.sub.2O and the solvent was then removed at 100° C. and 10.sup.−2 mbar. The colorless solid was weighed into a Schlenk flask with Teflon valve. HNMe.sub.2 (17.3 g, 383 mmol, 14.5 eq) was condensed under cooling with liquid nitrogen. The Schlenk flask was first heated to −60° C. under vacuum in a dry ice bath. At this temperature, no reaction took place and LiAlH.sub.4 is undissolved. The reaction mixture was further heated slowly and gas evolution was observed at a temperature of about −50° C. Moreover, LiAlH.sub.4 dissolved slowly in the liquid HNMe.sub.2. In the dry ice bath, the reaction mixture was kept at a temperature of −50° C. for 1 h until gas evolution slowly subsided. The reaction mixture was heated and stirred for 1 h at RT while excess HNMe.sub.2 evaporated. After applying a vacuum (approx. 10.sup.−3 mbar) for approximately 2 min, a colorless solid was obtained which was dried under vacuum (approx. 10.sup.−3 mbar) for 1 h at 55° C. The overall yield was determined by weighing the flask at 98%. The isolated yield was 89% (4.91 g, 23.4 mmol).

[0039] .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=2.49 (s, 24H, NMe.sub.2).

[0040] .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=42.7 (NMe.sub.2).

[0041] .sup.7Li-NMR (THF-d.sub.8, 155 MHz, 300 K): δ/ppm=−0.07 (Li[Al(NMe.sub.2).sub.4]).

[0042] .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=110.1 (Li[A/(NMe.sub.2).sub.4]).

[0043] Elemental analysis: for C.sub.8H.sub.24Al.sub.1Li.sub.1Na.

[0044] calculated: C: 45.71%, H: 11.51%, N: 26.65%.

[0045] found: C: 43.22%, H: 10.60%, N: 25.53%.

[0046] HR-EI-MS: calculated for C.sub.8H.sub.24Al.sub.1Li.sub.1N.sub.4: 210.1976 m/z, found: 210.1966 m/z.

[0047] IR: {tilde over (ν)}/cm.sup.−1=2935 (s), 2817 (m), 2770 (m), 1447 (s), 1242 (m), 1134 (st), 1058 (m), 932 (vst), 840 (m), 624 (st), 602 (vst), 412 (vst).

Example 2: Preparation of Li[Al(NMe.SUB.2.).SUB.4.] Starting from Pestled LiAlH.SUB.4 .Pellets

[0048] ##STR00002##

[0049] LiAlH.sub.4 (1.51 g, 39.7 mmol, 1.00 eq; commercially available pellets, pestled inertly before use) was introduced into a Schlenk flask with Teflon valve. HNMe.sub.2 (39.1 g, 870 mmol, 21.9 eq) was condensed under cooling with liquid nitrogen. The reaction mixture was first heated to −60° C. in a dry ice bath. At this temperature, a reaction did not yet take place. In the dry ice bath, the reaction mixture was further heated gradually, wherein slight gas evolution began from −50° C. The slightly turbid solution was stirred for 2 h at this temperature and was then heated to RT. A colorless, slightly gray solid was obtained by briefly applying a vacuum. This was dried under vacuum (approx. 10.sup.−3 mbar) for 30 min. The overall yield was determined as 99% (8.25 g, 39.3 mmol) by weighing the Schlenk flask. The product could be isolated with a 94% yield (7.83 g, 37.3 mmol), pestled inertly and obtained as a non-pyrophoric solid.

[0050] .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=2.49 (s, 24H, NMe.sub.2).

[0051] .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=42.7 (NMe.sub.2).

[0052] .sup.7Li-NMR (THF-d.sub.8, 155 MHz, 300 K): δ/ppm=−0.09 (Li[Al(NMe.sub.2).sub.4]).

[0053] .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=110.1 (Li[A/(NMe.sub.2).sub.4]).

[0054] Elemental analysis: for C.sub.8H.sub.24Al.sub.1Li.sub.1N.sub.4.

[0055] calculated: C: 45.71%, H: 11.51%, N: 26.65%.

[0056] found: C: 44.78%, H: 11.20%, N: 26.74%.

[0057] IR: {tilde over (ν)}/cm.sup.−1=2934 (s), 2817 (m), 2769 (m), 1447 (s), 1412 (s), 1241 (m), 1133 (st), 1057 (m), 930 (vst), 624 (st), 599 (vst).

Example 3: Preparation of Na[Al(NMe.SUB.2.).SUB.4.] Starting from NaAlH.SUB.4

[0058] ##STR00003##

[0059] NaAlH.sub.4 (2.24 g, 41.4 mmol, 1.00 eq; Acros, 93%) was introduced into a Schlenk flask and cooled with liquid nitrogen. HNMe.sub.2 (29.5 g, 650 mmol, 15.8 eq) was condensed. The reaction mixture was first heated to −60° C. in a dry ice bath, with no reaction being observed. The temperature was slowly increased gradually until a gas evolution occurred at a temperature of −45° C., while NaAlH.sub.4 slowly dissolved. The mixture was stirred for 2 h at this temperature until no more gas evolution was observed. The solution was then carefully heated to RT, wherein excess HNMe.sub.2 evaporated. The resulting colorless solid was obtained by applying a vacuum. This was dried under vacuum (approx. 10.sup.−3 mbar) for 1 h at RT and then pestled inertly. The desired product was obtained with a total yield of 98% (9.18 g, 40.6 mmol) and an isolated yield of 88% (8.25 g, 36.4 mmol). The product is a slightly gray, non-pyrophoric solid.

[0060] .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=2.49 (s, 24H, NMe.sub.2).

[0061] .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=42.9 (NMe.sub.2).

[0062] .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=109.9 (Na[A/(NMe.sub.2).sub.4]).

[0063] Elemental analysis: for C.sub.8H.sub.24Al.sub.1Na.sub.1N.sub.4.

[0064] calculated: C: 42.46%, H: 10.69%, N: 24.76%.

[0065] found: C: 39.03%, H: 9.65%, N: 23.11%.

[0066] IR: {tilde over (ν)}/cm.sup.−1=2933 (s), 2859 (s), 2805 (m), 2757 (m), 1461 (s), 1447 (s), 1409 (s), 1244 (m), 1138 (st), 1059 (m), 936 (vst), 695 (s), 652 (s), 600 (vst) 410 (st).

Example 4: Synthesis of Li[AlH(NEt.SUB.2.).SUB.3.]

[0067] ##STR00004##

[0068] LiAlH.sub.4 (600 mg, 15.8 mmol, 1.00 eq) was introduced and cooled to −60° C. Liquid HNEt.sub.2 (15 mL, 146 mmol, 9.24 eq) was precooled to −30 C and slowly added. HNEt.sub.2 (Smp=−50° C.) initially froze. The reaction mixture was warmed to −50° C., wherein HNEt.sub.2 liquefied and LiAlH.sub.4 slowly dissolved. At a temperature of −40° C., gas evolution could be observed, which was readily controllable. The reaction mixture was stirred for 1 h at −30° C. and then heated to RT. This produced a colorless, slightly turbid solution. Excess HNEt.sub.2 was removed under vacuum (approx. 10.sup.−3 mbar), wherein a colorless solid could be isolated. This was dried for 1 h at a temperature of 60° C. The isolated yield was 89% (3.55 g, 14.1 mmol).

[0069] .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=0.96 (t, .sup.3J.sub.HH=7.0 Hz, 18H, CH.sub.2CH.sub.3), 2.90 (.sup.3J.sub.HH=7.1 Hz, 12H, CH.sub.2CH.sub.3).

[0070] .sup.13C-NMR (THF-d.sub.8, 75 MHz, 300 K): δ/ppm=16.2 (CH.sub.2CH.sub.3), 42.3 (CH.sub.2CH.sub.3).

[0071] .sup.7Li-NMR (THF-d.sub.8, 155 MHz, 300 K): δ/ppm=−0.22 (Li[AlH(NEt.sub.2).sub.3]).

[0072] .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=117.6 (Li[AlH(NEt.sub.2).sub.3]).

[0073] Elemental analysis: for C.sub.12H.sub.31Al.sub.1Li.sub.1N.sub.3.

[0074] calculated: C: 57.35%, H: 12.43%, N: 16.72%.

[0075] found: C: 56.49%, H: 11.89%, N: 16.67%.

[0076] IR: {tilde over (ν)}/cm.sup.−1=2958 (m), 2928 (s), 2883 (s), 2840 (s), 1647 (brs), 1445 (s), 1366 (m), 1343 (s), 1181 (m), 1148 (vst), 1105 (s), 1045 (s), 1005 (st), 896 (m), 872 (st), 789 (st), 698 (vst), 634 (m), 584 (s), 499 (m), 467 (m).

Example 5: Preparation of Li[Al(NEt.SUB.2.).SUB.4.]

[0077] ##STR00005##

[0078] Li[AlH(NEt.sub.2).sub.3] (500 mg, 1.99 mmol, 1.00 eq) was introduced and HNEt.sub.2 (5.0 mL, 48.3 mmol, 24.3 eq) was added at RT. The reaction mixture was heated to 56° C. for 5 h, whereupon gas evolution could be observed. By means of IR spectroscopic reaction control, the completeness of the reaction was checked based on the missing Al—H band at −1650 cm.sup.−1. Excess HNEt.sub.2 was removed under vacuum (approx. 10.sup.−3 mbar) at RT. The colorless oily residue was then dried under vacuum (approx. 10.sup.−3 mbar) at 100° C., after which the crude product was dried at 3.4.Math.10.sup.−7 mbar and 80° C. As a result, the proportion of free HNEt.sub.2 could be reduced to 6% relative to the Li[Al(NEt.sub.2).sub.4]. The product was obtained as a colorless solid with a total yield of 97% (622 mg, 1.93 mmol).

[0079] .sup.1H-NMR (THF-d.sub.8, 300 MHz, 300 K): δ/ppm=0.96 (t, .sup.3J.sub.HH=6.9 Hz, 24H, CH.sub.2CH.sub.3), 2.89 (q, .sup.3J.sub.HH=6.9 Hz, 16H, CH.sub.2CH.sub.3).

[0080] .sup.7Li-NMR (THF-d.sub.8, 194 MHz, 300 K): δ/ppm=−0.33 (s).

[0081] .sup.27Al-NMR (THF-d.sub.8, 130 MHz, 300 K): δ/ppm=107.5 (s).

[0082] IR: {tilde over (ν)}/cm.sup.−1=2954 (st), 2923 (m), 2860 (m), 2835 (m), 2789 (m), 2684 (w), 1451 (w), 1366 (st), 1339 (w), 1285 (w), 1260 (w), 1173 (vst), 1143 (vst), 1096 (m), 1067 (m), 1042 (m), 1011 (vst), 936 (m), 890 (st), 866 (st), 829 (m), 781 (vst), 688 (w), 644 (m), 622 (m), 573 (st), 517 (m), 470 (m), 408 (w).

Example 6: Production of Na[Al(NEt.SUB.2.).SUB.4.]

[0083] ##STR00006##

[0084] NaAlH.sub.4 (50 mg, 0.926 mmol, 1.00 eq) was introduced, cooled to −50° C. and HNEt.sub.2 (1.5 mL, 14.6 mmol, 15.7 eq) was slowly added. The reaction mixture was initially stirred at −50° C. for 1 h, at RT for 1 h and finally at 56° C. for 4 hours. The completeness of the reaction was checked by means of IR reaction control. The solvent was removed under vacuum (approx. 10.sup.−3 mbar) and the residue was digested in npentane. All volatile constituents were removed under vacuum (approx. 10.sup.−3 mbar) and the colorless solid dried at 5:10.sup.−5 mbar. The product was obtained with a yield of 96% (301 mg, 0.889 mmol).

[0085] .sup.1H-NMR (THF-da, 300 MHz, 300 K): δ/ppm=0.94 (t, .sup.3J.sub.HH=6.9 Hz, 24H, CH.sub.2CH.sub.3), 2.90 (q, .sup.3J.sub.HH=6.9 Hz, 16H, CH.sub.2CH.sub.3).

[0086] .sup.13C-NMR (THF-da, 75 MHz, 300 K): δ/ppm=16.7 (CH.sub.2CH.sub.3), 42.7 (CH.sub.2CH.sub.3).

[0087] .sup.27Al-NMR (THF-da, 130 MHz, 300 K): δ/ppm=107.8 (s).

[0088] IR: {tilde over (ν)}/cm.sup.−1=2953 (m), 2922 (m), 2859 (m), 2792 (m), 2683 (w), 1452 (w), 1364 (m), 1339 (w), 1285 (w), 1261 (w), 1174 (st), 1097 (st), 1068 (m), 1039 (m), 1004 (vst), 928 (w), 886 (m), 870 (st), 837 (w), 789 (st), 614 (st), 470 (m), 427 (m).

[0089] Elemental analysis: for C.sub.16H.sub.40AlNaN.sub.4

[0090] calculated: C: 56.77%, H: 11.91%, N: 16.55%.

[0091] found: C: 54.18%, H: 11.60%, N: 15.39%.

[0092] HR-EI-MS: calculated for C.sub.16H.sub.40AlN.sub.4: 315.3068 m/z, found: 315.3057 m/z.

[0093] Melting point: 162° C. (visually 5° C./min).

Example 7: Synthesis of P(NMe.SUB.2.).SUB.3

[0094] ##STR00007##

[0095] Li[Al(NMe.sub.2).sub.4] (200 mg, 0.95 mmol, 0.75 eq) was suspended in 8 mL squalane and cooled to 0° C. PCl.sub.3 (174 mg, 1.27 mmol, 1.00 eq) was added dropwise. The reaction mixture was stirred at 0° C. for 1 h, and then heated to RT and stirred for 16 h. The precipitated grayish precipitate was separated off and the product was condensed out of the filtrate under reduced pressure (10.sup.−2 mbar) at 50° C. P(NMe.sub.2).sub.3 was obtained with a yield of 73% (151 mg, 0.93 mmol).

[0096] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=2.45 (d, .sup.3J.sub.HP=9.0 Hz, NMe.sub.2).

[0097] .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=42.9 (.sup.2J.sub.CP=18.9 Hz, NMe.sub.2).

[0098] .sup.31P-NMR (C.sub.6D.sub.6, 101 MHz, 300 K): δ/ppm=123.1.

Example 8: Synthesis of [Ti(NMe.SUB.2.).SUB.4.]

[0099] ##STR00008##

[0100] Li[Al(NMe.sub.2).sub.4] (111 mg, 0.53 mmol, 1.00 eq) was added to 5 mL squalane. At 0° C., TiCl.sub.4 (100 mg, 0.53 mmol, 1.00 eq) was added dropwise. A color change of the reaction mixture from colorless to dark yellow was immediately observed. The reaction mixture was warmed to RT and stirred for a further 16 h.

[0101] The desired product was condensed out of the reaction mixture under reduced pressure at 60° C. as a light yellow liquid with a yield of 69% (82 mg, 0.366 mmol).

[0102] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=3.11 (s, 24H, NMe.sub.2).

[0103] .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=43.9 (NMe.sub.2).

Example 9: Synthesis of [Zr(NMe.SUB.2.).SUB.4.]

[0104] ##STR00009##

[0105] Li[Al(NMe.sub.2).sub.4 (204 mg, 0.970 mmol, 1.00 eq) was added to liquid HNMe.sub.2 and slowly heated to −40° C. ZrCl.sub.4 (226 mg, 0.970 mmol, 1.00 eq) was added in portions, whereupon a color change from colorless to slightly yellow was observed. The reaction mixture was stirred for 1 h at −40° C. and then freed of excess amine under vacuum (approx. 10.sup.−3 mbar) at −40° C. The slightly yellow residue was heated to RT and the product was sublimated out of the residue under vacuum (approx. 10.sup.−3 mbar) at 45° C. [Zr(NMe.sub.2).sub.4] was obtained with a yield of 81% (210 mg, 0.786 mmol) in the form of colorless crystals.

[0106] The reaction may also be carried out starting from LiAlH.sub.4 and NaAlH.sub.4, which is reacted in HNMe.sub.2 in situ, or starting from previously isolated Na[Al(NMe.sub.2).sub.4].

[0107] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=2.97 (s).

[0108] .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=41.6 (s).

[0109] HR-EI-MS: calculated for C.sub.8H.sub.24N.sub.4Zr: 266.1048 m/z, found: 266.1050 m/z.

Example 10: Synthesis of [Ta(NMe.SUB.2.).SUB.5.]

[0110] ##STR00010##

[0111] Li[Al(NMe.sub.2).sub.4 (222 mg, 1.06 mmol, 5.00 eq) was added to liquid HNMe.sub.2 and slowly heated to −40° C. TaCl.sub.5 (303 mg, 0.845 mmol, 4.00 eq) was added in portions, wherein a color change from colorless to orange was observed.

[0112] The reaction mixture was stirred for 1 h at −40° C. and then freed of excess amine under vacuum (approx. 10.sup.−3 mbar) at −40° C. The residue was brought to RT and the product was sublimated out under vacuum (approx. 10.sup.−3 mbar) at 40° C. [Ta(NMe.sub.2).sub.5] was obtained in the form of orange crystals with a yield of 77% (261 mg, 0.651 mmol).

[0113] The reaction may also be carried out starting from LiAlH.sub.4 and NaAlH.sub.4, which is reacted in HNMe.sub.2 in situ, or starting from Na[Al(NMe.sub.2).sub.4].

[0114] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=3.26 (s).

[0115] .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=43.1 (s).

[0116] HR-EI-MS: Calculated for C.sub.8H.sub.24N.sub.4Ta: 357.1481 m/z, found: 357.1497 m/z.

Example 11: Synthesis of [Al(NEt.SUB.2.).SUB.3.]

[0117] ##STR00011##

[0118] LiAlH.sub.4 (50 mg, 1.32 mmol, 3.00 eq) was introduced and HNEt.sub.2 (1.09 g, 14.9 mmol, 33.9 eq) was added. The suspension-like reaction mixture was heated to boiling point for 2 h, cooled to 0° C. and AlCl.sub.3 (59 mg, 0.440 mmol, 1.00 eq) was added. The reaction mixture was stirred for 1 h at 0° C. and for 16 h at RT before 10 mL nhexane was added. The suspension was filtered and the colorless filtrate was evaporated to dryness to yield the product as a colorless oil. The yield was 90% (386 mg, 1.58 mmol).

[0119] .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=1.24 (t, .sup.3J.sub.HH=6.7 Hz, 18H,

[0120] CH.sub.2CH.sub.3), 3.12 (q, .sup.3J.sub.HH=6.7 Hz, 12H, CH.sub.2CH.sub.3).

[0121] .sup.13C-NMR (C.sub.6D.sub.6, 75 MHz, 300 K): δ/ppm=12.7 (CH.sub.2CH.sub.3), 39.9 (CH.sub.2CH.sub.3).

[0122] .sup.27Al-NMR (C.sub.6D.sub.6, 130 MHz, 300 K): δ/ppm=117.8 (s).

Example 12: Synthesis of [Al(NEt.SUB.2.).SUB.3.]

[0123] ##STR00012##

[0124] Na[Al(NEt.sub.2).sub.4] (337 mg, 1.00 mmol, 3.00 eq) and AlCl.sub.3 (44 mg, 0.33 mmol, 1.00 eq) were introduced together and melted without the addition of solvent. On account of the reaction and accompanying lowering of the melting point, a colorless melt, in which some insoluble NaCl was suspended, formed from 130° C. onwards. After 1 h at 160° C., the volatile product [Al(NEt.sub.2).sub.3] was condensed out of the melt under vacuum (10.sup.−3 mbar). The yield was >90%. .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=1.24 (t, .sup.3J.sub.HH=6.7 Hz, 18H, CH.sub.2CH.sub.3), 3.12 (q, .sup.3J.sub.HH=6.7 Hz, 12H, CH.sub.2CH.sub.3).

Examples 13

[0125] The following syntheses of Si(NMe.sub.2).sub.4 (Example 13a) and E(NMe.sub.2).sub.3 (where E=As (Example 13b), Sb (Example 13c), Bi (Example 13d)) were carried out in an NMR tube starting from one mmol Li[Al(NMe.sub.2).sub.4] without isolation of the products:

##STR00013##

[0126] The chemical shift of each of the products present in solution was compared to literature data and reference samples, thereby identifying the products. The isolation of Si(NMe.sub.2).sub.4 and As(NMe.sub.2).sub.3 from toluene was unsuccessful due to the high volatility, as well as the small batch sizes. Sb(NMe.sub.2).sub.3 and Bi(NMe.sub.2).sub.3 could also be detected, but both compounds are very unstable, especially photosensitive substances, which is why isolation did not take place in this case either. Generally, the dimethylamido-substituted species of the main group elements show no tendency to undergo a reverse reaction to form mixed-substituted compounds. The reactions were not optimized but, with careful reaction control and exact stoichiometry similar to that of P(NMe.sub.2).sub.3, they proceed very selectively and almost quantitatively. Yield losses are expected, particularly in the isolation of the products detected.

[0127] Si(NMe.sub.2).sub.4: .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=3.26 (s)..sup.[1]

[0128] As(NMe.sub.2).sub.3: .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=2.61 (s)..sup.[2]

[0129] Sb(NMe.sub.2).sub.3: .sup.1H-NMR (C.sub.6D.sub.6, 300 MHz, 300 K): δ/ppm=2.76 (s)..sup.[2]

[0130] Bi(NMe.sub.2).sub.3: .sup.1H-NMR (C.sub.6D.sub.6/THF-d.sub.8, 300 MHz, 300 K): δ/ppm=3.14 (s)..sup.[3][1] Banerjee et al., Inorg. Chem. Commun. 2006, 9, 761-763. [2] Schumann, J. Organomet. Chem. 1986, 299, 169-178. [3] Ando et al., J. Inorg. Nucl. Chem. 1975, 37, 2011.