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Hydrogallinations.

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Isosteres of Hexamethyldisiloxane and
Tris(trimethylsily1)amine
(3) ( C H ~ ) ~ S ~ N P ( C Z H ~ ) ~ . A I m.
( Cp.
H ~169
) ~ ,"C, subl. a t
135 "Cjl mm; (4) ( C H ~ ) ~ S ~ N P ( C Z H ~ ) ~ . G ~m.( C
p. H ~ ) ~ ,
114 ' C .
Received: December 22nd, 1965
[ Z 129/961 I € ]
German version: Angew. Chem. 78, 306 (1966)
By Priv.-Doz. Dr. H. Schmidbaur and
cand. chem. W. Wolfsberger
Institut fur Anorganische Chemie der Universitat
Wurzburg (Germany)
For the preparation of a n isostere (3) of tris(trimethylsily1)amine (2) we required P-trimethyl-N-trimethylsilyliminophosphorane ( I ) . The latter is readily accessible from trimethylsilyl azide and trimethylphosphine [ 1 , 2 1 :
(CH&Si-N3
+ (CH3)3P
-f
N2
[ I ] H. Staudinger and J . Meyer, Helv. chim. Acta 2, 635 (1919);
H. Staudinger and E. Hauser, ibid. 4, 861 (1921); E. Bergmann
and H . A . Wolff,Ber. dtsch. chem. Ges. 63, 1176 (1930).
[2] L. Birlrofer, A . Ritter, and S . M. Kim, Chem. Ber. 97, 2100
( I 964).
131 F. Schindler, H . Schmidbaur, and G . Jonas, Angew. Chern. 77,
170 (1965); Angew. Chern. internat. Edit. 4, 152 (1965); Chem.
Ber. 98, 3345 (1965).
[4] 60 Mc/s, CC14 solution, 30 "C, tetramethylsilane as internal
standard.
+ (CH&Si-N=P(CH3)3
(1)
Hydrogallinations
By Priv.-Doz. Dr. H. Schmidbaur and cand. chem. H. F. Klein
(CHMXOSi(CH3)3
(CHhSiNP(CH,), (1)
(CH3)3AIOP(CHs)3
1 1
-56
3-4
+89
1
100.5/760
169/760
117/1
[a] Not measurable in CC14. [b] J('H-C-31P)
=
E . 4 [cl
I
Institut fur Anorganische Chemie der Universitlt
Wurzburg (Germany)
-3.5
-80.8 [b]
[a1
12.4. [c] J(lH-C-29Si)
=
6.4.
Compound ( I ) is a third [31 isostere of hexamethyldisiloxane.
When warmed for a short time with trimethylaluminum
etherate it affords (3), in which, for the first time, the three
neighbours Al, Si, and P in the Periodic Table are bound to
the same nitrogen atom. Compound (3) is remarkably stable
and does not dissociate even on vacuum distillation. The crystals are sensitive to oxidation and hydrolysis, are readily
soluble in organic solvents that do not contain active protons,
and give the simple molecular weight in benzene. Three
signals of equal area appear in the IH-NMR spectrum, one
being a doublet due to 1H-C-31P coupling.
Addition of boron and aluminum hydrides to olefins is of
great practical importance. Analogous addition of gallium
hydrides has not previously been observed.
We have found that dichlorogallane HGaC12 [I] reach with
olefins even under mild conditions, forming organogallium dihalides RGaC12 [21. A solution of HGaC12 (obtained from gallium trichloride and trimethylsilane) in chlorotrimethylsilane
absorbs ethylene rapidly at 0 "C, with evolution of much heat.
Ethylgallium dichloride [21 (75-78 %) can be obtained from
the reaction mixture by distillation in a vacuum:
2 CH2=CHp+ ( H G ~ C I Z )+
~ (C2HsGaClz)z
Cyclohexene and a suspension of dichlorogallane in cyclohexane rapidly afford cyclohexylgallium dichloride (73
m.p. 67-69"C, b.p. 142"C/1 mm:
x),
T o determine the position of the entering component we have
studied the addition of propene and 1-heptene t o HGaC12. In
both cases homogeneous products were formed, namely, n-propyl- and n-heptyl-gallium dichloride, respectively
m.p. 39-4OoC, b.p. 120-122°C/1 mm;
(C3H7GaC12: 88
CTH15GaC12: 7 2 %, m.p. -3O"C, b.p. 155-16OoC/l mm).
N M R spectroscopy gave no indication of the formation of
isopropylgallium dichloride; the structure of heptylgallium
dichloride was established by degradation to heptyl iodide by
means of iodine. This result proves the anti-Markovnikoff
orientation in addition of :Ga-H to the > C = C < group,
this being analogous to the results of hydroboration and
hydroalanations.
Hydrolysis with HC1 and oxidation with H202 convert compounds RGaC12 into hydrocarbons R H and alcohols ROH,
respectively, but the yields are generally unsatisfactory.
Carbonyl compounds are reduced by HGaC12 to alkoxygallium dihalides. In this way isopropoxygallium dichloride
(b.p. 95-97 "C!l mm) is formed from acetone:
x,
Onreaction with trimethyl-gallium or -indium etherate in
place of the aluminum compound, ( I ) affords (4) and (5),
respectively, in quantitative yield. The continuous decrease
in chemical shifts and coupling constants along the series
( I ) , (3), ( 4 ) , (5) shows that the bond order of P-N i s higher
than that of Si-N and that the acceptor strength of organometallic compounds decreases in the order (CH&AI >,
(CH3)3Ga > (CH3)3In.
(5)
___
79-80
120/ 1
32-34
56/0.1 (decomp.)
43-44
- 13.2
9.0
- 104.0
-98.2
-95.6
+36.5
+32.5
12.7
12.6
6.5
+
61.0
12.8
6.6
6.55
- 6.6
P-triethyl-N-trimethylsilyliminophosphorane
[21 yields, analogously, the P-triethyl homologues of (3) and ( 4 ) :
312
2 CH3-CO-CH3
+ (HGaCI&
+ [(CH~)~CH-O-G~C~~]Z
-
Hydrolysis of these compounds leads to the alcohols without
difficulty.
Received: December 22nd. 1965 [Z 128/960 IE]
German version: Angew. Chem. 78, 306 (1966)
[ I ] H . Schmidbaur and W. Findeiss, Angew. Chem. 77, 170
(1965); Angew. Chern. internat. Edt. 4 , 152 (1965).
121 H . Schmidbaur and W. Findeiss, Angew. Chem. 76, 152, 153
(1964); Angew. Chem. internat. Edit. 3, 696, 696 (1964).
Angew. Chem. internat. Edit.
1 Vol. 5 (1966) / No. 3
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