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New Products from PCl3 P(NMe2)3 and AlCl3.

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COMMUNICATIONS
New Products from Pel3, P(NMe2)3, ant AlCl,**
By Alfred Schmidpeter* and Siegfried Lochschmidt
Dedicated to Professor RolfAppel on the occasion of his
65th birthday
PCI, reacts with P(NMe2)3, resulting in substituent exchange [reaction (l)]."' When AICI, is present as a third
component, the phosphenium tetrachloroaluminate 1 and
phosphonium tetrachloroaluminates 2 and 3 are formed
according to reactions (2) to (4).12'
[(Me2N),P-PCl(NMe2)][AICl4]
[(Me2N),P-P(NMe2),][AICl4]
3
2
Because PCI3, Ph3P, and AICI, undergo a redox reaction
to give the triphosphenium salt 4:31
[Ph3P=P-PPh3][AICI,]
4
it was of interest to find out whether the system PCI,/
P( NMe,),/AICI, could undergo the corresponding reaction ( 5 ) to form 5 . The theoretically required molar ratio of
the reactants PCI, :P(NMe2), :AICI, (1 :3 :2) for the formation of 5 lies just between that for the formation of 3
(1 :2 : 1.5) and that for the formation of 2 (1 : 5 :3). Compound 5 had been synthesized earlier from 4 by means of
Ph3P/P(NMe2), exchange and proved to be stable,I3] so
that we undertook a new investigation of the system PC13/
P(NMe2),/AIC13.
PCI,
+
3 P(NMe2)3
+ 2 AICI, >-
[(Me2N)3PCI][AIC14]
+
We found that the sequence in which the reactants are
added determines the products of the reaction: If a I :3
mixture of PC1, and P(NMe2), in CH2C12is initially prepared, so that the substituent-exchange reaction (1) can occur, then the subsequently added AICI, reacts according to
reactions (2) to (4).The reactions are reversible and, as expected from the stoichiometry, reaction (2) becomes predominant with increasing amounts of AICI,; when
AlC13 :PCI, is 4 : 1 , it is virtually the only reaction. On the
other hand, if P(NMe,), and AICI, in a molar ratio of 3 :2
are dissolved in CH,CI2 at 0°C (cf. ref. [2]) and subsequently treated with PCI,, then reductive formation of 5
takes place according to reaction (5).
Products 1 and 5 , formed via these two pathways, cannot be interconverted. Although different ratios of the
reactants (1 :2 :3 and 1 :3 :2, respectively) are involved in
their formation, subsequent compensation (i.e., addition of
P(NMe2), or P(NMe,)3/PC13 mixtures to 1 or of AICI3 to
5/[(Me,N)3PCl][AlCI,]
does not effect the desired
change.
With an equimolar amount of AICI,, 5, in a fast reaction, gives the adduct 6 [reaction (6)].["'A small amount of
the product 7IS1is also formed by addition of HCI (presumably from the solvent) (cf. ref. [3, 61). Over approximately a week at room temperature, compound 6 reacts
completely with CH,C12 to give the diphosphoniodiphosphirane tetrachloroaluminate 8.['] Although no intermediates can be observed, comparable reactions suggest that
initial chloromethylation occurs [reaction (7)]"."] followed
by cleavage of the resulting intermediate [reaction (S)] and
formation of the three-membered-ring compound 8 by
[2 I] addition of a phosphoniophosphanediyl (formed by
dissociation of 5; cf. ref. [S]) to the P=C system [reaction
(9)]. Like di-tert-b~tyldiphosphirane,'~~
8 is formed as the
trans isomer and is characterized by a ,'P-NMR spectrum[" of the [AB], type.
+
[(Me2N),P-P=CH2][AlCl4]
(5)
[(Me,N),P=P-P(NMe,),]
[AICl4]
5
['I
[**I
Prof. Dr. A. Schmidpeter, Dr. S. Lochschmidt
lnstitut fur Anorganische Chemie der Universitat
Meiserstrasse I , D-8000 Munchen 2 (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
Angew. Chem. Inr. Ed. Engl. 25 (1986) No. 3
If PCI, is added, as described above, at 0°C to a
P(NMe2)JAICl3 mixture, which, however, contains less
AICI, (molar ratio 1 :3 :I), then AIC1, is consumed only
0 VCfl Verlugsgesellschaji mbfl. 0.6940 Weinheim. 1986
0570-0833/86/0303-0253 $ 02.50/0
253
according to reaction (5). The remaining half of the
P(NMeJ3 and PCI, undergoes substituent' exchange (1)
and reacts with subsequently added AICI3 to give 3 according to reaction (4). If more AICI3 is added, reaction
(10) occurs, resulting in an equal decrease in the amounts
of 3 and 5 and in the formation of a new product. On the
basis of the 3'P-NMR spectrum ([AB],C, spin system),["]
this product was identified as the 1,3-diphosphoniocyclotetraphosphane 9 (all-trans isomer, cf. ref. [9]).
r
NMe2
1
NMe2
i
Depending o n the sequence of addition, therefore, the
three-component system PC13/P(NMe,)3/A1C13 may be
used to prepare either the salt 1, 5 , or 9, whereby the oxidation state n/3 of phosphorus steadily decreases: n = 9, I ,
5 . Consequently, the amount of [(Me2N)3PCI][AICI,]
formed also steadily increases. The reaction to give the
product with n = 3 (reduction of Me,NPCI2 to (Me2NP),)
has not yet been possible.["]
Owing to the competing and subsequent reactions, reaction ( 5 ) is not well suited for the preparative formation of
5 . On the other hand, the tetraphenylborate[81of the same
cation
[(Me2N),P=P-P(NMe,),][BPh,J
10
may be synthesized analogously and in a facile manner by
addition of PC1, to P(NMe,),/NaBPh,."*l
Synthesis and Structure of the Co3Ti2Complex
CO Reduction by Two Different Metal Centers
By Sandro Gambarotta, Sergio Stella, Carlo Floriani, *
Angiola Chiesi- Villa, and Carlo Guastini
Metal-oxygen bond formation is the driving force for
the reduction of carbon monoxide by early transition metals. For example, CO is reduced by ZrH complexes to methanol, formaldehyde, and C, compounds.['] The reductive
coupling of C O is achieved by reaction of [(CSHS),Fe2(pCO)2(CO)2] with [(CSHs)2ZrN2]zN2.[21
Other metal carbonyls react with oxophilic metal complexes in low oxidation
states, electron transfer occurring from the oxophilic metal
center to the metal atom of the carbonyl complex; this provides a strong acidic site for the carbonyl's oxygen.[31
In
this
way,
[(C,M~,),Y~-OC-CO(CO)~J~~~
and
[(CsH5),(thf)Ti-OC-Mo(CO)2(CsHs)]~sJ
were obtained.
These reactions are not real reductions of CO, because the
fragment >C-0-M
(M =early transition metal) is not
formed. A few examples of such reductions are provided
by the reactions of [(C,Me,),~["] and [C,HS)Ti(CO)2]['1
with CO,(CO)~to form the complex [(C0)9C03CO-M]. Indeed, this type of complex is very well documented when
M =Ti, Zr, and Hf in the form of cyclopentadienyl derivatives."] These compounds were synthesized, however, by
the metathesis reaction between [(CO)9C03COLiS,] and
[(CsH5),MCI2] derivatives or by the reaction between
[(C5H&MCI2] and C O ~ ( C O ) , . [ ~ ~
We report here the reduction of C O to a >C-0ligand promoted by a Ti" complex acting as a one-electron
reducing agent. This result was achieved by reaction of the
titanium complex 1 with an equimolar amount of the cobalt complex 2 in toluene.191The solution was gently
heated to 50°C for a few minutes, then allowed to stand at
room temperature for one day. Crystals of the air-sensitive
Co,Ti, complex 3 formed (yield: ca. 55%).
Received: August 14, 1985;
revised: October 21, 1985 [Z 1429 IEJ
Publication delayed at the authors' request
German version: Angew. Chem. 98 (1986) 27 I
[I] J. R. Van Wazer, L. Maier, J. Am. Chem. Soc. 86 (1964) 811.
[2] C. W. Schultz, R. W. Parry, Inorg. Chern. 15 (1976) 3046.
[3] A. Schmidpeter, S. Lochschmidt, W. S. Sheldrick, Angew. Chem. 97
(1985) 214; Angew. Chem. Int. Ed. Engl. 24 (1985) 226.
[4] 3'P-NMR of 6 (ABz): 6 A = -142, Sg= +70; JA,=290 Hz.
[S] "P-NMR of 7 (ABz): 6,=-131,
6 8 = + 6 3 ; JA,=270
Hz,
'JpH=241 Hz.
[6] A. Schmidpeter, S. Lochschmidt, K. Karaghiosoff, W. S. Sheldrick, J .
Chem. SOC. Chem. Commun. 1985, 1447.
[7] "P-NMR of 8 (AA'BB'): SA= - 198 (ring phosphorus), &= +67 (phosphonio group); JA,,.=+120
Hz, J A B = T 3 1 2 Hz, J A B . = f 4 7 Hz,
JRB.
= T 48 Hz.An X-ray structure investigation has been carried out on
a differently substituted diphosphoniodiphosphirane.S. Lochschmidt,
G. Miiller, B. Huber, A. Schmidpeter, 2. Naturforsch. 8 4 1 (1986), in
press.
[8] A. Schmidpeter, S. Lochschmidt, A. Willhalm, Angew. Chem. 95 (1983)
561; Angew. Chem. Int. Ed. Engl. 22 (1983) 545; Angew. Chem. Suppl.
1983, 710.
[9] M. Baudler, F. Saykowski, 2. Naturforsch. 8 3 3 (1978) 1208; M . Baudler,
G . Reuschenbach, 2. Anorg. Allg. Chem. 464 (1980) 9.
[lo] "P-NMR of 9 (AA'BB'C2): 6,,= -24 (phosphonio-substituted ring
phosphorus), bc= + 18 (amino-substituted ring phosphorus, cf. [ I I]),
& = + 6 9 (phosphonio groups).
[ I l l R. B. King, N. D. Sadanani, P. M. Sundararn, Phosphoms Sulfur 18
(1983) 125.
[I21 Experimenral procedure: 10: PCI, (0.78 mL, 8.4 mmol) was added with
vigorous stirring to P(NMe2), (4.74 mL, 26.1 mmol) and NaBPh, (6.00 g,
17.4 mmol) in 120 m L o f dimethoxyethane. After 2 h, the colorless precipitate was separated and extracted with 100 mL of CH2C12.After concentration of the extracts by a factor of ten, crystallization occurred to
give 3.92g (69%) of 10: m.p.= 161°C; 'H-NMR: 6=2.76, JPNCr,=
10.7
Hz.--"P-NMR (AB2): 6 ~ -494,
=
&= + 8 5 ; J ~ ~ = 5 Hz
1 3 (cf. [3]).
254
Q VCH Verlagsgesellschaft mbH. D-6940 Weinheim. 1986
?
The Ti atoms in 3 have an oxidation number of + 3
1.85 BM at 293 K per titanium]. The I R spectrum
shows a broad, strong C O band centered at S= 1300 cm-I.
consists of an equilateral
The structure of 3 (Fig. 1)1101
triangle of C o atoms, each of which is bonded to an qs[*I
['I
Prof. Dr. C. Floriani ['I, Dr. S . Gambarotta, S. Stella
Dipartirnento di Chimica e Chirnica Industriale,
Universita di Pisa
1-56100 Pisa (Italy)
Dr. A. Chiesi-Villa, Dr. C. Guastini
lstituto di Strutturistica Chimica,
Centro di Studio per la Strutturistica Diffrattometrica del CNR,
Universita di Parma
1-43 100 Parma (Italy)
Present address:
Chemistry Department, Columbia University
Havemeyer Hall, Box 307, New York, NY 10027 (USA)
0570-0833/86/0303-0254 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 25 (1986) No. 3
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