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Coordination Compounds with Stationary and Oscillating Acceptors.

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glow discharge 121 analogously from silicon tetrachloride
failed; even under mild conditions, only (7) was obtained.
Received: March 6th, 1967
[ Z 464 IE]
German version: Angew. Chem. 79, 409 (1967)
[*I Prof. Dr. U. Wannagat, Dip1.-Chem. P. Schmidt, and
DipL-Chem. M. Schulze
Institut fur Anorganische Chemie der
Technischen Hochschule
Pockelstr. 4
33 Braunschweig (Germany)
[l] Chemistry of SIN Compounds, Part 72. - Part 71 : U. Wannagat, P. Schmidt, and M . SchuItze, Angew. Chem. 79,409 (1967);
Angew. Chem. internat. Edit. 6, 446 (1967).
[2] A . Pflagmacher and H. Dahmen, Z . anorg. allg. Chem. 290,
184 (1957); A. Pflugmacher and H . Ernst, unpublished; H. Ernst,
Dissertation, Technische Hochschule Aachen, 1958.
Coordination Compounds with Stationary and
Oscillating Acceptors
whether it can occur through a transition state containing
pentacoordinated metal.
In contrast to (3) and (4), the complex with trimethylindium
( 5 ) at temperatures down to --7OoC gives a temperatureindependent N M R spectrum with one (CH&P doublet only.
Thus for this compound a fixed structure with a pentacoordinated metal atom or an extremely rapid exchange of
positions can be considered. In the latter case the activation
energy for the “jump” must be less than 8 to 9 kcal/mole.
“Stationary” 1:1 complexes with tetracoordinated metal
atoms are obtained from ( I ) and dimethylzinc or dimethylcadmium.
Preparation of ( I ) :
(CH&P (16.5 g) is added slowly from a cooled dropping
funnel to (CH3)2Si(N3)2 (26.5 g) at room temperature.
Reaction ensues immediately with evolution of nitrogen.
Fractional distillation of the reaction mixture gives (2)
(yield 33.3 g; 94 %). 33.2 g of this intermediate reacts with a
further 16.5 g of (CH3)3P in a n autoclave at 11O-13O0C to
give ( I ) , which is purified by distillation (yield 40.1 g; 96 %).
I
By H . Schmidbaur and W . Wo[fberger[*l
If an acceptor molecule A with one free coordination position
is confronted with a donor molecule containing two spatially
proximate donor centers B [I], then the acceptor A may not
form a bond to only one of the two donor positions B but
may interact with both the basic centers alternately 121. Bis(trimethylphosphorany1ideneamino)dimethylsilane ( I ) has
now been found to be a bidentate ligand for which this
phenomenon can be observed. The silane ( I ) is obtained
from dimethyIsilylene diazide and trimethylphosphine via
the
intermediate
dimethyl(trimethylphosphoranylideneamino)silyl azide (2). It forms stable 1:1 complexes (3) and
(4) with trimethylaluminum and trimethylgallium, respectively.
(1)
(2)
24-25
77-78/0.3
90.3
-
93-95
40/0.3
93.6
96.9
1 1
M.P. ( “C)
B.p. (“Clmm)
Yield (%)
NMR [a] 6 CH3Si
30°C
SCH3M
6 CHjP
J(lH-C-31P)
+3.7
-4.4 [b]
-
-
-86.4
12.75
NMR [a1 6 CH3P [cl
-60 “ C J(lH-C-31P) [c]
6 CH3P Id]
J(lH--C-31P)[d]
-
-
-87.7 [hl
12.9 [bl
-
1 1
80-82
74-
97.9
98.3
-10.2
+58.5
-97.0
13.0
-5.0
+37.5
-93.0
12.9
-5.1
1-31
-93
12.8’
-88
13.3
-108
12.8
-86
13.0
-102
12.75
-93
12.7
-93
12.7
The 1H-NMR spectra of solutions of (3) and (4) in methylene dichloride or benzene at room temperature show only
one signal each for the protons of the methy1 groups attached
to the silicon and to the metal atoms, and one doublet for
the H3C-P groups. When the temperature is lowered the
(CH&P doublet becomes broader and eventually splits to
two doublets (see Table) [31.
Since the singlet nature of the (CH3)zSi and (CH&M signals
is retained at all temperatures, this pheonomenon can be explained only by assuming a temperature-dependent exchange
process in the sense (3afb) and (4alb). The phenomenon
is fully reversible and can be repeated ad infiniturn. The
activation energy of the interchange of positions can be
estimated from the alteration in line widths and from the
splitting temperatures as being 13.4 and 12.8 kcal/mole
for (3) and (4), respectively, in CH2C12. The values are
solvent-dependent and are somewhat higher for benzene
solutions 141.
H3C, F H 3
S i,
(CH3)3P=N: N=P(CH3),
M( C H3 )3
(3a), M = A1
(4a), M = G a
*
H3C\ /CH3
Si
/ \
(CH3)3P=N N=P(CH,)3
(H3C )3 M’
(3b), M = A1
(4b), M
=
Ga
It remains to decide whether the interchange of position of
the metal atoms requires intermediate complete dissociation
of the donor from the acceptor (within the solvent cage) or
448
Trimethyl(methy1ene)phosphorane
By H . Schmidbaur and W. Tronich [*I
Trialkyl(a1kylene)phosphoranes cannot be obtained by any
of the synthetic procedures available for phosphorylides.
Their properties are thus substantially unknown [I].
Angew. Chem. internat. Edit. Vol. 6 (1967) No. 5
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compounds, coordination, oscillation, acceptor, stationary
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