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Novel Redox Reactions of Tri-tert-butylphosphane with Tetrahalides of Germanium and Tin.

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Triorganophosphane-dichloro- and dibromo-germanediyl and -stannanediyl: Phosphane-Stabilized Ge” and
Sn“ Halides
By Wolf-Walther du Mont, Brigitte Neudert, Gero Rudolph,
and Herbert Schumann[*]
Silylene-, germylene-, and stannylene-phosphoranes corresponding to methylenephosphoranes are hitherto unknown.
Only some phosphane-germanediyls and -stannanediyls formally analogous to methylenephosphoranes have been
reported[’*’! We have found that triorganophosphane-dichloro- and -dibromogermanediyls (2) can be obtained by aelimination reactions from trihalogermylphosphanes
:
[(CH3),C],PGeX3
+
R3P
-
[(CH3)3Clz P X
+
R3PGeX2
(Za), R = CsH5, X = C 1
(1)
salts of the type R3PH+EC13.Fast exchange reactions already
occur at room temperature with an excess of phosphane.
Thus mixtures of tri-tert-butylphosphane with (2b), (3 a),
or (3b) give 31P-NMRspectra invariably showing only one
signal whose chemical shift is the average between that for
the phosphane [63’P=62.5ppm] and that of its adducts with
EX2. The ‘H-NMR spectra contain only a doublet with
“coupling constants” 3J(’H31P)between 9.8 Hz [tri-tert-butylphosphane] and the values for (2 b), (3 a), or (3 b) (cf. Table
1).
If the phosphorus in ( 2 n ) or (2b) possesses a further
reactive function then dichlorogermanediyl can insert into
that bond in a subsequent reaction step, e.g.:
( Z b ) , R = (CH3)3C, X = C 1
(Zc), R = C6H5, X = B r
[ G e C 1 2 . C4H8O21 + R 2 P C l
-
,GeC12
R 2 P,
- R 2 PG e C l 3
c1
-C~HF.OZ
The fact that this reaction proceeds under very mild conditions-at 20°C in benzene-and the considerable thermal
stability of the phosphanedihalogermanediyls indicate a surprisingly high formation tendency of the P-Ge bond in ( 2 ) .
Thus organophosphanes readily displace dioxane from
GeCI, .dioxane, leading to compounds (2) in high yield
[(Za): 87%; (2b):95%]:
[GeC12. C4H802] + R 3 P
-
R3P Ge C12
+
C4H802
Tri-tert-butylphosphane even undergoes a corresponding
reaction with tin dichloride and dibromide:
R = C(CH3)3
(4)
(1)
The transformation ( 4 ) + ( 1 ) is the first example of germylene insertion into a phosphorus-halogen bond. It demonstrates that a-eliminations of trichlorogermylphosphanes can
be reversible. Since the insertion reaction ( 4 ) (1 ) is much
slower than formation of ( 4 ) we have been able to identify
di-tert-butylchlorophosphane-dichlorogermanediyl ( 4 ) by
spectroscopy [6’H = 1.29 ppm, 3J(HP)= 13.6 Hz; h3’P= 127.1
ppm; v(PGeC12)=330 and 275 cm-’] and thus confirm the
electrophilic attack of the germylene on the phosphoruschlorine bond.
--f
Pi-tert-butylphosphane-dichlorostannanediyl(3 a )
The adducts (2) and (3) are obtained as colorless crystals
which are moderately soluble in benzene and only sparingly
soluble in pentane. The coordination of the phosphorus is
shown by ‘H- and 31P-NMR spectra (Table 1).
Formulation of the phosphane-dihalogermanediyls and
-stannanediyls as base-stabilized “germylenes” and “stannylenes” ( A ) and not as germylene- and stannylenephosphoranes
( B ) is supported by the following properties of compounds
(2) and (3) : hydrogen chloride immediately cleaves the P-Ge
and P-Sn bonds in ( 2 b ) and (3a), giving phosphonium
Table 1. Properties of the compounds ( 2 ) and ( 3 ) .
Cpd. [a]
(20) [2]
(2b)
(2c)
( 3 a ) [d]
(3b)
M.p. [“C] [b]
145-175
175-1 76 (dec.)
175--178(dec.)
98-100
112-114
v(PE?)
[cm- 1
328, 313, 300
322, 298
242,227, 205
290,250
204, 192
63’P
[PPml
13.
J( HCC3‘P)
[Hzl
- 3.9
-
- 8.2
-
+49.3
+46.8
12.35
12.4
+ 35.6
Prof. Dr. H. Schumann, Dr. W.-W. du Mont, B. Neudert, and Dipl.-Chem.
G. Rudolph
Institut fur Anorganische und Analytische Chemie der Technischen Universitat
Strasse des 17. Juni 135, loo0 Berlin 12 (Germany)
308
Received: January 13, 1976;
revised: February 20, 1976 [Z 414a IE]
German version: Angew. Chem. 88, 303 (1976)
CAS Registry numbers:
( Z a ) , 51812-24-9; ( 2 b ) , 58802-38-3; ( Z c ) , 58802-39-4; ( 3 a ) , 58802-40-7;
( 3 b ) , 58802-41-8; ( 4 ) , 58802-42-9; [(CH3)3C]2PGeC13, 55748-12-4;
[(CH&CI2PGeBr3, 58802-29-2; Ph3P, 603-35-0; [GeCI2 .C4H802], 1565663-0; SnCI,, 7772-99-8; SnBr,, 10031-24-0; [(CH3)3C]2PCI,13716-10-4; 31P,
7723-14-0; ‘19Sn, 14314-35-3
[l] H. Schumann, H . KOpL and M . Schmidt, Z. Naturforsch. 196, 168 (1964);
R . B. King, Inorg. Chem. 2 , 199 (1963).
[2] 0.M . Nefedou, S. P . Kolesnikou, and I. S. Rogozhin, Izv. Akad. Nauk
SSSR, Ser. Khim. 1973.2824.
[3] W-W du Mont and H . Schumann, J. Organomet. Chem. 85, C45 (1975).
12.2
[a] Composition confirmed by elemental analysis.
[b] In sealed capillaries (Cu block).
[c] Varian XL 100 (40.5 MHz); positive values correspond to downfield
shifts relative to 85 % H3P04.
[d] ll9Sn Mossbauer data: I . S. = 3.20 i 0.06, Q. S. = 1.43 k 0.12
mm/s (Ba”’Sn03 standard).
[‘I
[(CH3)3C]3P (2.0g, 10mmol) is added to a suspension of
SnC12 (2.1 g, 11 mmol) in benzene (50ml). After 2 h, unreacted
SnClz is separated off and the solution evaporated to dryness
under reduced pressure. The colorless residue is dried at 1
torr; yield 3.5 g (90 %) of (3a).
Novel Redox Reactions of Tri-reut-butylphosphane with
Tetrahalides of Germanium and Tin
By Wolf-Waltherdu Mont, Brigitte Neudert, and Herbert Schumann[*l
In combination with a tetrahalomethane, tertiary phosphanes are versatile reagents in preparative chemistry. In the
absence of substrates triphenylphosphane and CCl,, for ex-
p]
Prof. Dr. H. Schumann, Dr. W.-W. du Mont, and B. Neudert
lnstitut f i r Anorganische und Analytische Chemie der Technischen Universitat
Strasse des 17. Juni 135, loo0 Berlin 12 (Germany)
Angew. Chem. Int. Ed. Engl. J Vol. 15 (1976) N o . 5
ample, undergo a complicated redox reaction to give dichlorotriphenylphosphorane and (triphenylphosphoranediylchloromethy1)triphenylphosphonium chloride[']. In contrast, the
reaction of phosphanes with the tetrachlorides of silicon, germanium, tin, or titanium has hitherto only been found to
yield 1 : 1 or 2: 1 adducts.
We have disovered that tri-tert-butylphosphane (I), of
which complexes with transition metals in low oxidation states
are known, does not form stable addition compounds with
element(1v)tetrahalides. Instead, (I) is oxidized by the tetrahalides of germanium and tin in benzene solution to give
tri-tert-butylhalophosphoniumsalts (2)['].
[(CH3)3C]3P + EX4
+
[(CH~)SCI~PX+EX<
( 2 a ) . E = G e , X = C1
(2b), E = G e , X = Br
( 2 c ) , E = Sn, X= C1
( 2 d ) , E = Sn, X = B r
(1)
NMR signals appear at very low field, and variation of the
anions expectedly effects slight changes (Table 1).
The relatively low sensitivity of the cations (2) and ( 3 )
to hydrolysis can be rationalized by stereochemical arguments. The fact that the tetrahalides of germanium and tin
behave not only as Lewis acids but also as oxidizing agents
towards bases such as R3P warrants attention.
Tri-tert-butylchlorophosphoniumtrichlorogermanate(r1) ( 2 a ) :
Compound ( 1 ) (2.0g, 10mmol) is added dropwise to a
stirred solution of GeCl, (2.14g, 10mmol) in benzene (20ml).
Two liquid phases appear and the mixture exhibits slight
warming. The lower phase is separated and freed from solvent
at 0.1 torr/5O0C. Compound (2a) (4 g, 95%) is obtained as
colorless crystals. The conductivity of a 0.01 M solution of
(2a) in CHzClz is 0.41 x
R - ' cm-'.
Received: January 13, 1976 [Z 414b IE]
German version: Angew. Chem. 88,304 (1976)
Compounds of type (2) have also been formulated for the
reaction of phosphanes with tetrahalomethanes (E = C) as ionpair intermediate but have so far defied detection. The halophosphonium salts (2a)-(2d)
however, are stable compounds open to identification by analysis and spectroscopy.
Nevertheless, on variation of the stoichiometry formation of
(2) may be followed by secondary reactions. Thus the anions
SnCl; and SnCli- are formed from SnCl, and (2c). In the
presence of an excess of ( I ) the halophosphonium salts are
accompanied by tri-tert-butylphosphane-dichloro-and -dibromogermanediyls and stannanediyls which are poorly
:
soluble in benzeneL3]
CAS Registry numbers:
(I), 998-40-3; (Za), 58832-61-4; (261, 58832-64-7; (Zc), 58832-65-8; (2d).
58832-66-9; ( 3 a ) , 58816-81-2; (3b), 58816-82-3; (4a), 58802-38-3; (4b),
58832-59-0; (4c), 58802-40-7; (4d), 58802-41-8; t-Bu,PI,, 58816-83-4; GeCI,,
10038-98-9; GeBr,, 13450-92-5; SnCI,, 7646-78-8; SnBr,, 7789-67-5; "P,
7723-14-0
[I] R . Appel, Angew. Chem. 87, 863 (1975); Angew. Chem. Int. Ed. Engl.
14, 801 (1975).
[2] ( 2 ) is also oxidized to (3) by Tic],, and to [(CH&CI3PI+ by Sn14.
[3] W - W du Mont, B. Neudert, G. Rudolph, and H . Schumann, Angew.
Chem. 88, 303 (1976); Angew. Chem. Int. Ed. Engl. 25, 308 (1976).
[4] W-W du Mont, H . 4 . Kroth, and H. Schumann, Chem. Ber., in press.
[5] M . Weidenbruch and W Peter, Angew. Chem. 87, 670 (1975); Angew.
Chem. Int. Ed. Engl. 14,642(1975);M . Weidenbruch,personalcommunication.
A Phosphorus(m) Derivative with Sterically Fixed Bis(trimethylsilyl)aminoGroups"]
[ ( C H S ) ~ C ] Q P X + X+- [ ( C H ~ ) ~ C I ~ P E X Z
(3a).X
(3b). X
= C1
=
Br
(4a), E = Ge, X = C1
(4b), E = G e , X = B r
( 4 c ) , E = Sn, X = C1
The ionic character of compounds (2a)-(2d)
and ( 3 )
was established by comparison of vibrational and NMR spectra and of their conductivity with those of tri-terf-butyldihalophosphoranes, which also exist in ionic form, and by independent preparation of the chlorophosphonium salts (e.g. (2c)
from (3a) with SnC1,)I4I. The IR spectra of the tri-tert-butylhalqphophonium ions dis;plqy remarkable analwies with
those of the isoelectronic tri-fert-butylhalosilanes[5! Two to
three stretching vibrations between 500 and 620 cm- ' are to be
assigned to the inner molecular framework C3PX (C3")undergoing coupled vibrations. In keeping with the positive charge
and the electronegative substituents at phosphorus the "P~
By Edgar Niecke, Wilhelm Flick, and Siegfiried Pohl"]
According to present knowledge aminoiminophosphanes,
phosphorus nitrogen ylides with a doubly coordinated P'"
atom, are capable of existence in the monomeric form if there
are sterically bulky substituents on the amine and imine
nitrogens"!
Especially interesting steric relations were to be expected
if a [2 + 21-cycloaddition product is observed besides a relatively stable monomer. We report here on the structural investigation of a compound of this type.
Pure bis(trimethy1silyl)aminotrimethylsilyliminophosphane
. { I )~ y ~ ! ~ ! i z ~ ~ ~ ! o.Ir.ert-2as9t-35PS.~c-~~;le~.
~.~,~;r.~~~r.
1;3. &<t&
methylsilyl)-trans-2,4-bis[bis(trimethylsilyl)amino]-l,3,2h3,4h3diazadiphosphetidine (2)13]. The crystalline product (m. p.
204--206°C) can be obtained in pure form by separation from
P
R-N,
Table I . Properties of tri-tert-butylhalophosphoniumsalts (2) and ( 3 ) .
Cpd.
Cal
M.p. ["C]
Cbl
GPjO
[cm- 1
631P
CPPml [cl
J('HCC"P)
[Hzl
612, 548
605, 571, 520
618, 545
610, 578, 525
618, 548
610, 575, 522
600, 562, 508
121.9
123.7
122.0
124.8
122.7
121.2
92.5
17.45
17.3
17.4
17.8
17.3
17.25
16.55
R
(2a)
111-116
106-109
(2b)
149-153
(2c)
(2d)
134-138
( 3a)
76-77
(36)
86-88
tBusPI2 [2] 145-150
(dec.)
(dec.)
(dec.)
(dec.)
(dec.)
(dec.)
(dec.)
[a] Composition confirmed by elemental analysis.
[b] In sealed capillaries (Cu block).
[c] Varian XL 100 (40.5 MHz); positive values correspond to downfield shifts
relative to 85 % H,PO,, solutions in CH2C12/C6D6.
Angew. Chrm. Int. Ed. Engl. / Vol. 15 (1976) No. 5
R
=
Si(CH3)3
(2)
the liquid monomer and subsequent repeated washing with
small quantities of absolute cyclohexane.
[*I
Dr. E. Niecke and Dipl.-Chem. W. Flick
Anorganisch-Chemisches Institut der Universitat
Tammannstrasse 4, 3400 Gottingen (Germany)
Dr. S . Pohl
Fakultat fur Chemie der Universitat
Universitatsstrasse, 4800 Bielefeld (Germany)
309
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tin, butylphosphan, tetrahalides, reaction, tri, redox, germanium, tert, novem
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