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The First CarbonЦPhosphorusЦAluminum Cage Compounds Cyclooligomerization of Phosphaalkynes with Trialkylaluminum Compounds.

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nr
220
420
320
hinm
Fig. 3. UV VIS spectra of l a - l c
in
520
620
hexane at room temperature: l a
(.-I:
lb.
( - - - ); Ic. ( .-.).
tion is apparently temperature independent. The extraordinary
color change for this most crowded disilene from yellow in the
solid state to dark red in solution suggests that in solution l c
assumes ;I twisted form as the most stable conformation to
relieve steric strain.
density map for l a showed a few of meaningful residual peaks near the Si=Si
bond. These peaks are explainable by assuming a similar phenomenon to that
observed in (E)-1,2-di(l-adamantyl)dirnesityldisilene [9]. By including only
three Si atoms of the minor component with the occupancy of 15 %, the R value
dropped by 0.04. Further details of the crystal structure investlaation are available on request from the Director of the Cambridge Crystallographic Data
Centre, 12 Union Road, GB-Cambridge CB2lEZ (UK), on quoting the full
journal citation.
191 B. D. Shepherd. D. R. Powell, R. West, Urgunomeru1lir.s1989. X , 2664.
[lo] Very recently, Okazaki et al. reported a n exceptionally long Si Si double bond
[2.228(2) A] in (E)-Tb(Mes)Si=Si(Mes)Tb (Tb = 2,4,6-tris[bis(tr1methylsilyl)methyl]phenyl, Mes = 2,4,6-trimethylphenyI): N. Tokitoh, H. Suzuki. R.
Okazaki. K. Ogawa. J Am. Ckem. Soc., 1993, 115, 10428.
[I I] a) H. Sakurai, H. Tobita. Y. Nakadaira, Chrm. Lett. 1982, 1251 ; b) the comparison between 29Si and I 3 C N M R chemical shifts may not be completely
reliable, since the hybridization at the unsaturated silicon atoms deviates substantially from sp2 as pointed out by a referee. cf. W. Kurzelnigg. A n g c w . Chmi.
1984, 96, 262; Angen,. Ckc,m. Inl. Ed. Engl. 1984, 23. 272.
[12] The solid-state UV/VIS spectra of l a - l c in KBr pellets are similar to one
another and both have an absorption maximum at around 420 nm.
[13] a) M. J. Fink, M. J. Michalczyk. K. J. Haller. R. West, J. Michl. Urgunomerullics 1984, 3, 793; b) B. D. Shepher, C. F. Campana, R. West. Hrrrour. Chwi.
1990, 1, 1.
[14] a) H. Meyer, Monutsh. Chem. 1909. 3U, 165; b) Ber. Drwh. Ckmi. Ges. 1909,
42, 143; c) Y. Tapuhi, 0.Kahsky. 1. Agranat. J Org. Chum. 1979,44,1949,and
references therein.
Received: February 24, 1994 [Z6711IE]
German version: At7gew. Ckem. 1994, 106. 1575
R. West. M. J. Fink J. Michl. Science / Wushinglon) 1981, 214. 1343.
For reviews on stable disilens, see: a) R. West, Angew. Chem. 1987, 99, 1231 ;
A n g m . Ck<wi.hit. Ed. Engl. 1987, 26, 1201; b) G. Raabe, J. Michl in The
Chwiii!ir),of'Orjyzosr/ic.onCompounds, Purl 2 (Eds.: S . Patai, Z. Rappoport).
Wile). Chichester, 1989, Chap. 17; c) T. Tsumuraya. S. A. Batcheller, S . Masamune. .4ngm Chem. 1991, 103.916: Angevr. Ckem. I n l . Ed. Engl. 1991.30,902.
a) M . Karni. Y Apeloig, J. Am. Chem. Soc. 1990. 112. 8589: h) C. Liang, L. C.
Allen. ibirl. 1990. 112. 1039.
Althoiiph tetrakis~bis(trimethylsilyl)methyl]disilene wws isolated as the first
stable te~raalkyldisilene,no X-ray analysis was reported [5a]. Tetrakis(triethy1zilyl)disilcne w'as first detected by UV spectroscopy during photolysis of
liexakis(~riethylsily1)cyclotrisilanebut was not isolated [%I. In 1992 West et al.
isalatcd ( E ) . and (Z)-1.2-bis(2.4.h-triisopropylpheiiyl)disilenes; in these compounds [he trimethylsilyl groups exert no remarkable effects on the structure
[Sc]
a ) S . M a w n u n e . Y. Eriyama. T. Kawase, Aiigcir. Ch<vii.1987. 99, 601; Angew.
Chmi. /n/. Ed. Engl. 1987. 26, 584; b) H. Matsumoto. A. Saknmoto. Y. Nagai,
J Chwi. Soc. Ch<wi. Cummiin. 1986. 1768; c) R. S. Archibald, Y. van den
Winkel. A. J. Millevolte, J. M. Desper, R . West. Orqmomerullics 1992, 11,
3276
a ) S. Mahdmune, Y Hanzawa. S. Murakami. T. Bally. J. F. Blount. J. A m .
C h e w Soc. 1982. 104. 1150; h ) S Masamune. H. Tobita, S. Murakami. ihid.
1983. 10.7. 6524.
Disilene I a was obtained also by the photolysis of the correspondingcyclotrisilanc. wphicli was prepared by the reductive coupling of the corresponding dibroniosilane with lithium naphthalene in THF at -78 C in 3 5 % yield.
The Ibllowing holds for all the structure determinations. The reflection intensities were collected on a Rigaku AFC-SPR diffractometer with a rotating anode
(45 kV. 200 mA) using graphite-monochromated Mo,, radiation (i =
0.71069 A ) . Since the peak profiles for 1b were broad at low temperatures, l b
was measured a t room temperature; 1 a and 1 c were measured at low temper11 data for I a (1 50 K ) : Inclinic, space group Pi. u = 11.225(10),
h=11.651(7). ~'=8.571(8).&. a =103.20(7), /(=111.03(8), 7 =105.22(6),
V = 9 ~ 7 6 ( 1 7 ) ~ ~ . z = l . p ~ ~ ~g~c ,m=~l' ..~0t t1o t a l o f 5 1 5 7 r e f l e c t i o n s w e r e
measured. of which 2655 [F, > 3u(F,)]were used in refinement. R = 0.105,
R , = 0.105. Crystal data for l b (286K): monoclinic. space group C2:r..
N = 21.585(4),
h =7.988(1),
r. = 20.778(4) A,
fl =108.84(1)-. V =
3548.0(1 1) A'. Z = 4. pLlllrd
= 0.968 gcm-'. A total of 5243 reflections were
measured. o l which 2866 [I;, > 3n(FO)]were used in refinement. R = 0.060.
R, = 0.057. Crystal data for l c (170K): monoclinic, space group C2:c,
~ = 1 9 2 2 0 ( 3 ) . h=14.384(1),
~=17.089(2).&, /(=110.88(1).
V=
4413.5(11) A'. Z = 4. {icalCd
= 1.03 gem-'. A total of 4973 reflections were
niensurcd. OT which 3593 [Fo > 3u(F0)]were used in refinement. R = 0.055,
R , = 0.076. The molecules of l a and l c have a crystallographic center of
symmetry. while 1 b has a twofold symmetry axis. All calculations were performed uith an ACOS-2000 computer at Tohoku University with the UNICS
I l l sq'teni and thc RANTANXl program. Whereas the R values for 1 b a n d l c
were r,ither reasonable, 1a gave a relatively high R value. The final electron
The First Carbon - Phosphorus-Aluminum Cage
Compounds : Cyclooligomerization of
Phosphaalkynes with Tkialkylaluminum
Compounds**
Bernhard Breit, Andreas Hoffmann, Uwe Bergstrasser,
Louis Ricard, Franqois Mathey, and Manfred Regitz*
Dedicated to Professor Reinhard Schmutzler
on the occasion of'his 60th birthday
Recently we found that the phosphaalkyne 1 can be spirocyclotrimerized with aluminum trichloride in the molar ratio 3 : 1
with the incorporation of the Lewis acid to give the stable complex 2. Removal of the inetal halide by addition of dimethyl
2
1
tBu
sulfoxide in the presence of a further equivalent of 1 leads to the
desired formation of a cagelike phosphaalkyne cyclotetramer.["
In the present communication we report on completely different cyclooligomerization reactions of 1 with triethylaluminum :
surprisingly, polycycles are obtained highly selectively with the
~
Ai7,qw
Chvm
liir
E d Eng/. 1994. 33, N o . 14
[*] Prof. Dr. M. Regitz, Dr. B. Breit. DipLChem. A. Hoffmann.
Dr. U. Bergstrlsser
Fachbereich Chemie der UniversitHt
Erwin-Schrodiuger-Strasse, D-67663 Kaiserslautern (FRG)
Telefax: Int. code (631)205-2187
Dr. L. Ricard. Prof. Dr. F. Mathey
Ecole Polytechnique, Departement de Chimie. D. C. F. G . (France)
F-91128 Palaiseau (France)
+
[**I
Phosphorus Compounds, Part 77. This work was supported by the Volkswagen-Stiftung and the Fonds der Chemischen Industrie. Part 76: W. Eisfeld, U.
Bergstrisser. M. S h y , M. Regitr, Terruhrdrun Lerr. 1994, 35. 1527-1530.
si,
' VCH Verlu~sgr~seNsrhuft
mbH, 0-69451 Weinkeim, 1994
057n-OX33/Y4:1414-1491 U. lO.OO+ .25!0
1491
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incorporation of the Lewis acid, the composition of which depends on the solvent chosen.
If the reaction mixture containing the phosphaalkyne 1 and
triethylaluminum (molar ratio 3: 2) in n-hexane is allowed to
warm up from - 50 ' C to room temperature. the carbon-phosphorus-aluminum compound 3 can be isolated in 91 % yield;
tBu
Et Et
3
polycycles comprising this combination of elements were hitherto unknown.[']
The composition of 3 is apparent from the 'HNMR spectrum: it is made up from three trrt-butyl groups and six ethyl
groups, which are magnetically inequivalent (Table 1). Also in
Fig. l . Crystal structure of 3 (ORTEP). Selected bond lengths [A] and angles [ l:
P I P7 2.3672(6). PIGC2 1.905(2). P l - C l 6 1.9@3(2),P 7 C 2 1.770(2), P7-CB
1.757(2). Pl5-~A1282.4538(7), P15-CI6 1.816(2). A125-C2 2.115(2). A125-CX
2.105(2). A1 25-C 16 2.075(?), A1 28 -C 8 2.035(2):P7-P 1-C 2 51.04(6). P 7-P I-C 16
102.26(6). C2-P 1-C 16 97.71(8). P I-P 7-C2 56.79(6). P I-P 7-C 8 111.05(6). C2-P 7C 8 108.95(8). A128-Pl5-Cl6 107.60(6). C2-A125-C8 85.76(7). C2-AI25-Cl6
86.37(7). P I-C 2-P 7 72.17(7). P 1 -C2-A125 84.83(7). P 7-C 2-A125 80.65(7). P7-C 8A125 81.22(7). P7-C X-AI28 103.1X(X), Al25-C 8-A128 114.29(8), P I-C 16-P 15
107.66(9). CX-Al25-Cl6 10@.91(7). P15-Al28-CX 94.67(5). P1-C 16-A125
85.98(7). P 15-C 16-A125 108.59(8).
Table 1 Selected spectroscopic data of the cage compounds 3 and 4 [a].
3 : ' H N M R (400.1 MHz): 6 = 0.47-0.66 (m, 6 H , AICH,CH,), 1.02-2.30 (m,
24H. AICH,CH,,'PCH,CH,). 1.41. 1.54 (each s, each 5H. C(CH,),). 1.66 (d,
4J(P.H) = 0.6 Hz. 9 H . C(CH,),); "C N M R : 6 = 4.2 (m, broad, 2 x AICH,CH,),
8.2 (s. broad. AICH,CH,). 8.8 (dd. 2J(P.C) =13.2, 'J(P.C) =7.6 Hz, PCH,CH,).
100. 10.2 (each S. AICH,CH,). 10.9 (d. 'J(P,C) = 5.1 Hz. PCH,CH,). 11.1 (d,
2J(P.C) = 4.9 Hz. PCH,CH,). 11.3 (s, AICH2CH,). 20.3 (d. 'J(P.C) =17.6 Hz.
PC'H,CH,).
20.8 (d. 'J(P.C) = 8.3 Hz, PCH,CH,),
24.2 (pseudo-t,
'4P.C) = 12.3 Hz, PC'H,CH,), 32.8 (dd. 'J(P,C) = 51.8 and 23.4 Hz, C4), 34.6 (dd.
'J(P.C) = 8.3. 4J(P.C) = 3.8 Hz. C(CH,),). 34.8 (dd. 'J(P,C) = 8.4 and 5.0 Hz,
C(CH.31,). 35.2 (d. 'J(P.C) = 6.1 HL, C(CH,),). 36.6 (d. 'J(P,C)=13.7 Hz.
C(CH.,),). 37.0 (dd. 'J(P,C) = 9.7 and 3.3 Hz, C(CH,),). 40.3 (d, *J(P,C) =7.9 Hz,
C(CH,),).45.8(m,C1).68.3(m.C6);31PNMR.6
= -147.3(dd, 'J(P,P) =162.9.
'J(P.P) = 21.7Hr. P3). -61.6
(d. 'J(P,P) =162.5Hz. P7), -1.2
(d.
2JP.P) = 21.7 Hz, P7).
most all the structural data including the P 15-Al28 distance
(2.4538 A) lie in the expected range.[61The only exceptions are
the bond lengths P7-C8 (1.757A) and P7-C2 (1.770,&),
which are comparatively short.i71
If 1 is allowed to react with AlEt, in the molar ratio 4 : l in
diethyl ether instead of in n-hexane, the carbon-phosphorusaluminum polycycle 4 is obtained in 74% yield; there is no
1 PEC-tBu
AlEtl, Et20
- 78-+25OC
P
1
4: ' H NMR (400.1 MHz): 6
= 0.55 (9, 'J(H,H) = 8.1 Hz. 2H. AICH,CH,), 0.971.06 (m. 6 H . 2 x PCH,CH,), 1.22 (s. 18 H, 2 x C(CH,),). 1.40 (s. Y H, C(CH,),).
1.43 ( t , 'J(H.H) = 8.1 Hz, 3H. AICH,CH,), 1.47 (d. 'J(P.H) = 0.9 Hr. 9 H .
C(CH,),), 1.69 1.78 (m, 4H. 2xPCN,CH,): l3C N M R : 6 = 0.8 (m, broad,
AIC'H,CH,). 10.3 (d. 'J(P,C) = 2.6 Hz. AICH,CH,). 12.8 (d. *J(P,C) = 4.1 Hz,
2 x PCH,CH,). 26.6 (dd. 'J(P,C) = 22.0, 'J(P.C) = 2.2 Hz. 2 x PCH,CH,). 32.4
(dd. 'AP.C) = 11.4 and 7.2 Hz. C(CH,),). 33.4 (d. *J(P.C) = 4.8 Hz, C(CH,),).
35.2 - 35.4 (m. 3 x C ( C H 3 ) 3 ) .35.6 (d, 'J(P,C) = 12.1 Hz. C(CH,),). 36.4 (dd.
'J(P.C) = 8.8 and 3.8 HL. 2 x C(CH,),). 44.0-44.6 (m, broad, C 5 0 ) . 59.3 (d.
broad. 'J(P,C) = 39.8 Hr. C 2 ) . 108.0 (d. broad. 'J(P,C) = 40.9 Hz, C7). "P
N M R : 6 = - 32.X (m. P6). - 1.0 (d, broad. 'J(P.P) = 122.0 Hz, P3). + 87.1 (ddd.
IJ(P.P) = 320.6, '8P.P) =122.0 and 14.4 Hz, P l ) , 208.0 (dd, 'J(P.P) = 320.6.
2J(P.P) =10.8 Hz. PX).
+
(100.6 MHz, TMS) and ,'P NMR spectra (80.X MHz, X5% of
[a] ' H (TMS),
H,PO,) in C,D,. Numbering of the atoms as in the formula.
agreement with the structure of 3 is the 31P NMR spectrum
which exhibits three high field absorptions,[31which show h303
and h404 phosphorus with the mutual couplings (Table 1). In
the 13CNMR spectrum of the same compound, absorptions are
found for the framework carbon atoms between 6 = 32.8 and
68.3. and the high-field signal with its two 'J(P,C) couplings
(51 .8 and 23.4 Hz) is assigned unequivocally to C4. The migration of three Al-ethyl groups to phosphorus atoms is indicated
by significant low field shifts and the occurrence of 'J(P,C)
couplings for the corresponding methylene carbon atoms.
Confirmation of the structure of the cage compound 3 was
achieved by an X-ray crystal structure analysis (Fig. l).[",51 Al-
tau
t Bu
evidence in the 31PN M R spectrum for the formation of 3 as a
by-product.
The same ratio of the reaction partners is also apparent from
in the 'H NMR spectrum of 4 (Table 1). In contrast to 3 at least
one phosphorus atom has a h302 configuration (6 = 208.O);[*I
it is split into a double doublet by both 'J(P,P) and 'J(P,P)
coupling (320.6 and 10.8 Hz, respectively). This is in correspondence with the resonance of C 7 at 6 =108.0 with a typical P
coupling of 40.9 Hz. The second P-C double bond of 4 has
methylenephosphorane character; the fact that the resonance
for the ylidic carbon appears at 6 = 59.3 is acceptable.['1 The
relatively high field position of P 3 (6 = - 1.O) results from the
shielding effect of the neighboring aluminate group. The onium
phosphorus PI (6 = 87.1) shows the expected couplings to P8
and P3[Io1(Tablel). The h303phosphorus P 6 absorbs at high
field (6 = - 32.8) as expected. For the tetracycle 4,as in the case
of 3, a low-field shift and 'J(P,C) couplings for the methylene
carbon atoms originally bound to Al indicate ethyl migration to
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the phosphorus. The latter and also the constitution of the reaction product were confirmed by an X-ray crystal structure analysis (Fig. 2).['~' ' ] This analysis shows that the aluminum and all
Fig. 2. Crystal structure of 4 (SCHAKAL-Plot). Selected bond lengths [A] and
angles [ 1: P 4 Al 2.441(3), C3-AI 2.038(6), P I - C l 1.713(6). P2-C2 1.853(6),
P l - C 3 1.813(6). P 3 - C 4 1.651(6), P 3 P I 2.235(2), C2-AI 2.039(6), P 4 C1
1.743(6).PI C21.834(6). P 2 - C 3 1.868(6).P2-C41.917(6);CI-PI-P3 122.2(2),
C3-P2-C? 78.2(3), C4-P2-C3 98.8(3). CI-P4-AI 95.5(2), C3-AI-P4 95.5(2), P2C2-PI 86 1(3).AI-C2-P289.5(3).Al-C3-P289.1(3),P3-C4-P2
116.9(3). C 2 - P l P 3 103.5(?).CZ-PI-CI 120.1(3), C 3 - P I - P 3 103.1(2).C3-PI-C1 119.3(3),C4-P2C 2 100.2(3).C4-P3-P1 88.6(2), C2-AI-P4 96.7(2). C3-AI-C2 70.2(2), P 4 - C I - P I
105.0(3). AI-C?-PI 81.8(2). AILC3-P 1 82.3(2).
the phosphorus atoms as well as the carbon atoms C 1 and C 4
lie in one plane.['21 The P 3 - C 4 distance (1.651 A) lies in the
range expected for P-C double bonds.['31 However, the very
similar bond lengths P 4 - C l and P I - C 1 (1.743 and 1.713 A.
respectively) are indicative of an extensive delocalization of the
positive charge over the PCP unit according to 4 A t t 4 B ; they lie
in the range between those of P-C singleL6]and P-C double
bonds .[ 41
The question of the formation mechanism of the two completely different products 3 and 4 cannot be answered conclusively. However, it i s assumed that the Lewis acid initially attacks at the phosphaalkyne carbon of 1.I'' Then
Et-P=C(rBu)(AlEt,) is formed by a [1,2]-ethyl shift. Not later
than after the analogous 1,2 addition of Et-P=C(tBu)(AIEt,)
to a further equivalent of 1, the reaction must branch out. That
compound 4 contains one equivalent, whereas 3 contains two
equivalents of Lewis acid, must be due to the blocking effect of
the Lewis base diethyl ether.
'
Experimental Procedure
3: A solution of the phosphaalkyne 1 [I 51 (0.35 g. 3.5 mmol) in n-hexane (3 mL) was
added dropwise to a solution of triethylaluminum (0.23 g. 2.0 mmol) in n-hexane
(3 m L ) and stirred at - 50 "C (exclusion of oxygen and moisture). After the reaction
mixture had been allowed to warm to 25 ' C over the course of 12 h, the solvent was
removed at 25 C:l0-' mbar and the residue was left to crystallize at -78 - C in a
little n-hexane. Yield: 0.48 g (91 '4)colorless crystals: m.p. 175'C.
4 ' A solution of the phosphaalkyne 1 [IS] (0.40 g. 4.0 mmol) in diethyl ether (3 mL)
was added dropwise to a solution of triethylaluminum (0.11 g, 1.0 mmol) in diethyl
ether (3 mL) and stirred -78°C (exclusion of air and moisture). After the reaction
mixture had been allowed to warm to 25 'C over the course of 12h, the solvent was
removed at 25'C,10-'mbar to yield a red-brown oil after a further 36h. Yield:
0.38 g (74'!/0): red-brown crystals obtained from little n-hexane or diethyl ether;
m.p. 168 C
Received: February 12, 1994 [Z668XIE]
German version: Angew. Chem. 1994. 106. 1541
[ l ] B. Breit. U. Bergstrisser. G. Maas. M. Regitz. Angew. Chmi. 1992. 1114, 10431046: An,&yw. Chrrn. Int. Ed. Engl. 1992. 31, 1055-1058.
[2] 2-(1-Adamantyl)-l-phosphaacetylene (1, I-Ad instead of tBu) reacts
analogously with triethylaluminum: this is also true for reactions of 1 with
Angru. Chern. h i t . Ed. Engl. 1994. 33, No.14
trimethyl- and tri-n-propylaluminum: "P NMR(C,D,): 6 = -151.0 to
-136.8 (dd, 'J(P.P) =152.4-162.8. 'J(P,P) = 21.9-33.4H~. P3). -75.0 to
-59.9 (d, 'J(P.P) =152.4-162.X Hz. P I ) . -27.9 to + 0.6(d. *J(P,P) = 21.Y
33.4 Hz, P7).
[3] J. G. Verkade. L. D. Quin. P h o s p h u r r r s - 3 1 - N M R - . ~ p ~ ~ t r f i sin~ S/rrcochrmio~~~.
cul Anulvbis, VCH, Deerfield Beach, 1987.
[4] Enraf Nonius CAD4 diffractometer. Cu,. radiation, graphite monochromator: 3: C,,H,,AI,P,; M = 528.6 (recrystallized from n-hexane): monoclinic.
space group P2,:c (no. 14), a =11.433(1). h =17.290(2). c =15.830(2)8,,
fl=Y6.48(1)'. Y=3109(1)8\'. Z = 4 , pC,,,,=1.129gcm-'. p = ? 3 . 8 c m - ' ;
F(000) = 1088; measurement temperature 7'= - 150 C . 461 5 independent reflections were measured. 4152 of wahich were observed with F 2 > 3 . 0 u ( F 2 )and
were used for structure refinement. Number of parameters 289. The linal structural model converges at R = 0.033 and R, = 0.061 and showed a maximum
of 0.31(5) e k 3 and a minimum of O.OO(5) e k ' in the difference Fourier
synthesis. The positions of the H atoms were calculated geometrically and
taken into consideration in the final cycle of the least rquare, refinement.
[ 5 ] Further details of the crystal structure investigations may be obtained from the
Fachinformationszentrum Karlsruhe, D-76344 Eggenstein-Leopoldshafen
(FRG) on quoting the depository number CSD-58074.
[6] A. H . Cowley. R. A. Jonas. M. A. Mardones. .I.
L. Atwood. S. C. Bott, A n g m .
Chem. 1990. 102. 1504-1505; Angew. Cliem. lnt. Ed. Eng/.1990.29.1409-1410;
J. F. Janik. E. N. Duebler, W. F. McNamura. M. Westerhausen. R. T. Paine,
OrgunometuNics 1989, 8. 506-514.
[7] F. H. Allen, 0. Kennard. D. G. Watsen. L. Brammer. A. G. Orpen. R. Taylor,
J Chrm. Soc. Perkin Truns. 2 1987. 1-19,
[S] For more information concerning the NMR spectroscopy of phosphaalkenes
see K. Karaghiosoff in Multiple Bonds und Low Coordmurion in Phosphorus
Chemisrrv (Eds.: M. Regitz. 0. J. Scherer), 1st ed.. Thieme. Stuttgart. 1990, p.
mfr.
[Y] E. Breitmeier. W. Voelter, Curbon-13 N M R Sprr/ro.wip?. VCH. Weinheim.
1987, p. 247ff.
[lo] R. Appel. U. Baumeister, F. Knoch, Chrm. Ber. 1983. 116. 2275-2284; H.
Schmidbaur. T. Costa, B. Milewski-Mahrla. ihid. 1981, 114. 1428-1441
[I I] Enraf-Nonius-CAD4-diffractometer,
Mo,, radiation. full-matrix refinement;
M = 514.8: monoclinic. space group P2Jc (no. 14).
4: C,,H,,AIP,;
a =10.10(1). b = 16.58(1). c =18.31(3) A: fl = 92.32(7)'. V = 3063(6) A'.
p = 2 . 9 c m - ' ; F(000) =1216; pcmlrd
= 1 . 2 2 0 g ~ m - ~5371
;
reflections were
measured, 3210 of which were observed with 1>2u(1)and were used for structure refinement. Number of parameters 343. The final structural model converges a t R = 0.0852 and R, = 0.0662 and showed a maximum o f 0.41 e k '
and a minimum of -0.37 e k ' in the difference Fourier synthesis. The positions of the H atoms were calculated with a fixed C - H distance of 1.08 8, and
with groupwise identical temperature factors. The largest effective standard
deviation was found at 0.206.
1121 Deviations from a least squares plane defined by the atoms mentioned earlier
are smaller than 0.011 A.
[13] R. Hoffmann. D. B. Boyd, S. 2. Goldberg, J An7. Chem. So[,. 1970. Y2. 39293936.
[I41 R. Appel in ref. [XI, p. 160, and references therein.
1151 Syntheses of 1 in ref. [XI, pp. 59-63; optimal yields are obtained by using the
method of W. Rosch. U. Hees. M. Regitz. Cheni. Brr.. 1987. 120. 1645-1652.
Synthesis and Molecular Structure of Calcium
Bis(trimethy1stannanide) 4 THF **
-
Matthias Westerhausen*
I n the cocondensation of calcium with trimethylsilyltrimethylstannane and the subsequent reaction with bromobenzene and water, Mochida and Yamanishi"] isolated hydrolysis products of Me,Si-Ca-SnMe,,
in particular hexamethyldisiloxane, trimethylstannane, hexamethyldistannane,
and hydroxy(trimethy1)stannane. However, the authors also ob-
[*I
Dr. M. Westerhausen
Institut fur Anorganische Chemie der Universitit
Pfaffenwaldring 55, D-70569 Stuttgart (FRG)
Telefax. Int. code (711)685-4241
[**I This work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie. We thank Prof. Dr. J. Weidlein for helpful
discussions and Dr. W. Schwarz for the collection of the data set.
'Q VCH Verlugsgrsrllschufi mbH, 0-69451 Wrinhcirn, 152524
+
0570-0833:94/1414-1493 h" IO.OO+ . 3 / 0
1493
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cyclooligomerization, carbonцphosphorusцaluminum, compounds, first, cage, trialkylaluminum, phosphaalkyne
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