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Synthesis and Crystal Stucture of a Salt Containing the Anion ; Precursors and Related Compounds.

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*-I
(7): A solution of aniline (1.45 g, 15.6 mmol) in ether (5
ml) is added to a solution of (I) (0.86 g, 7.80 mmol) in ether
(20 ml). A colorless precipitate is formed which is filtered off
and washed with redistilled solvent. The filtrate is evaporated to dryness. Yield 88%; m.p. 57 " C.
NaOCH,
Me2Y-OCH3
16)
The unusual properties of these prototypes deserve comment: it is a little-known fact that the BH3group in phosphaneboranes has, for much discussed but still unclear reasons[41,
lost its hydride activity to such an extent that it is even stable
towards acids and based5]. According to our findings the
monofunctional derivatives behave similarly and thus the
H3B(CH&P group proves to be a relatively inert and readily
exchangeable substituent. It is apparent then that many of
the known reactions of (CH3)3Sicompounds can be accomplished with the corresponding H3B(CH3)*Pcompounds, but
the products have a characteristically higher polarity.
Received: June 1, 1979 [ Z 296a IE]
German version: Angew. Chem. 91, 847 (1979)
[I] Earlier data referring to a product prepared from MeZPCI and B2H6 gas
which was described as decomposable could not be confirmed; most of the
spectroscopic findings, however, correspond to our findings for ( I ) : J. D.
Odom, S. Riethmiller, J. R. Durig, J. Inorg. Nucl. Chem. 36, 1713 (1974).
[2] N . Wiberg, W. Uhlenbrock, Chem. Ber. 104, 2643 (1971).
[3] Cf. the reactivity of LiN(SiMe&: U . Wannagat, H. Niederprirm, 2. Anorg.
Allg. Chem. 308, 337 (1961).
141 A. B. Burg, R. J. Wagner, J. Am. Chem. Soc. 75, 3872 (1953); F. Hewrrr, A. K.
Holliday, J. Chem. SOC.1953, 530 F. G. A. Stone, Q. Rev. Chem. Soc. 9. 174
(19%); E. L. Muetterries: Boron Hydride Chemistry. Academic Press, New
York 1975.
151 Gmelin Handbuch der Anorganischen Chemie, Supplement to the 8th edit.,
Vol. 19, Part 3. Springer-Verlag, Berlin 1975, p. 117ff.
Experimental
(I): A 1 M THF solution of BH3.C4H80(63 ml, 63 mmol)
is added to 6.0 g (62.7 mmol) Me2PCl at 0 "C. The solvent is
removed at 20 mbar/2O0C and the residue distilled at 0.1
mbar/20 "C; colorless liquid"'.
(2): To a solution of (I) (0.46 g, 4.2 mmol) in THF (15 ml)
is added Ag20 (0.48 g, 2.1 mmol) and the mixture stirred in a
sealed vessel for one week at 20 "C. All volatile components
are removed at 0.1 mbar/20 "C, and the residue washed with
pentane (5 ml) and sublimed at 60 "C/10p4 mbar. Yield 66%;
m.p. 74 "C.
(3): (I) (2.96 g, 26.8 mmol) is added to a solution of
NaNH2 (1.10 g, 20.2 mmol) in T H F (10 ml) at -78 "C. The
mixture is warmed up and stirred for 1 h. Workup as in the
case of (2) gives (3) in 68% yield.-The same product is obtained on passage of NH3 into a solution of (I) (5.00 g, 45.3
mmol) in ether (75 ml) at 0 "C. After filtration from precipitated NH4Cl and removal of solvent, (3) is obtained in 98%
yield; m. p. 29 "C.
(4): One equivalent of t-BuLi in pentane is added to a suspension of (3) (2.33 g, 25.6 mmol) in pentane (20 ml) at 0 "C
and the mixture stirred for 12 h at 20°C. (I) (2.80 g, 25.6
mmol) is then added at 0 "C and stirring continued for a further 4 h at 20 "C. Removal of solvent, washing with 2 x 10 ml
water, and crystallization from toluene affords (4) in 47%
yield; m. p. 164 "C.
(6): To a solution of CH30Na.CH30H (0.93 g, 10.8
mmol) in ether (10 ml) is added 1.19 g (10.8 mmol) of (I) at
0 "C and the mixture is stirred for 1 h. Workup as for (I) affords (6) in 73.5% yield; colorless liquid.
Solvent
Compound
'H
GCH,P
'J(PH)
GBH,
'J(BH)
'J(PH)
"P
SP
'J(PB)
"C
6CH1P
'J(PC)
CeD,
(2)
1.35, "d"
9.0
1.30, dq
98
14
127, br
-
17.2, " d
39.1
C6D,
131
CDCli
(4)
1.03, d
10.5
1.05, dq
97.5
16.5
1.19, "d"
9.5
br
[a1
45.5, q
73
-
58.4, br
17.2, d
41
17.0, "d'
42
CDCli
(6)
1.51, d
9.2
0.48
96.5
16 lhl
118.2, q
70.1
14.8, d
41 [b]
By Hubert Schmidbaur, Erwin Weiss, and Beate ZimmerGassed'l
Phosphaneboranes R3PBH3 are relatively inert owing to
the reduction in polarity of their HB and BP structural elements by specific bonding in the H,BP group. CH, groups
(R = Me) in such compounds, however, have distinct acidic
character due to the stability of the corresponding ylide
bases"]. This effect ought to be much more pronounced in
compounds of the type [Rz(H3B)PI2CH2and thus enable
metalation at the central atom.
and the borane adStarting from the bisphosphane
duct H3B.OC4HR,we have now synthesized (2), which crystallizes in the form of stacked hexagonal scales (a crystal
structure analysis could not be carried out because of the extreme thinness of the flakes). Conversion into a metalated
derivative was accomplished by reaction with alkyllithium in
an inert solvent, and a crystalline Li-complex salt (3) could
be isolated by precipitation with tetramethylethylenediamine
(TMEDA).
Hz
ChDn
7)
MezP/"PMez
r
(I)
rr
(3)
H
1"
0.60
10
br
[c]
47.4, q
70.1
-
[a] 6NH=2.86, broad. IR: u(NH)=3180, u(BH)=2380cm-'.
[b] 6CH,O=3.63, d, 'J(PH)=12; 6CH10=52.9, d, 2J(PC)=3.9.
[c] S N H = 3.70, d, 'J(PH) = 13: 6C,H5 = 5.83-6.97, m.
782
Synthesis and Crystal Structure of a Salt Containing
the Anion [H3B(CH3)2P-CH-.P(CH3)2BH3] ; Precursors and Related Compounds[**]
0 Verlag Chemie, GmbH, 6940 Weinheim, 1979
['I
Prof. Dr. H. Schmidbaur, DipLChem. E. Weiss, Dipl.-Chem. B. ZimmerGasser
Anorganisch-chemisches Institut der Technischen Universitat Munchen
Lichtenbergstr. 4, D-8046 Garching (Germany)
r * ] Chemistry of the H3B(CH1)zP Group, Part 2.-Part 1: [4].
0570-0X33/79/1010-0782$ 02.50/0
Angen,. Chem. Inr. Ed. Engl. I 8 (tY79) No. 10
In order to confirm the proposed structure and to gain a
closer insight into the characteristic geometries of
Me2(H3B)Pcompounds in general, an X-ray structure analysis was carried out on (3)13]. As expected, independent ions
are present in the crystal. In the anion (Fig. 1) both P atoms
show a tetrahedral ligand arrangement PC3B. The bond
lengths in the angular (128.6") PCP bridge are almost equal
and distinctly shorter than the terminal PC bonds, thus proving the ylidic nature of the bridge. The lengths of the outer
PC and PB bonds differ only slightly, so that the overall
shape of the H3B(CH3)2Pgroup does in fact closely resemble
that of the isosteric (CH&3 group141.Details can be correlated with the structure of (Me3Si)2NH.
(3a)
iC6H5CH2Br
- LiBr
1. LIR
2. CH31
In contrast to the metalation, the halogenation of (2) takes
place at the B-atom. Thus, reaction with two equivalents of
HBr affords the difunctional haloborane (7), which readily
undergoes further reaction.
+2HBr
i2i
HZ
Me z P/'\PMe z
BI H z B r BHzB
I
r
17)
The phosphino-substituted ylide (8)I6lleads to a molecule
isosteric with the anion in (3) since it reacts with H3B.0C4Hx
at the P-atom to give the phosphaneborane (9). The formal
Fig. 1 . Structure of the anion in the crystal of the complex salt (3). Bond lengths
in A.
replacement of one B-atom in (3) by a C-atom determines
the neutral character of (9), which now has only four alternating charges.
The composition and structure of all the new compounds
have been confirmed by elemental analysis and by IR,
NMR, and mass spectrometry.
Experimental
(3) is attacked by alkyl halides at the central C-atom, e. g.
reaction with benzyl bromide leads to the crystalline product
(4). The already well-known151
phenyl homolog of (2) can be
alkylated in a similar way via the Li-salt [(5)-+(6)].
(2): To a solution of (1) (2.73 g, 20.8 mmol) in THF (50
ml) is added two equivalents of H3B.C4H80(46.5 ml of a
0.9 M THF solution). After 30 minutes' stirring at 20 "C, filtration, removal of solvent and crystallization from THF affords 2.85 g (84%) of (2); m. p. 145 "C.
NMR data of the new phosphaneboranes;coupling constants in Hz.
'H
3'P
"C
2.09, d
SCH,
10.8
"(PH)
SCH,P2
2.54, t
2 ~ ( ~ ~ ) 12.0
SBH3
1.20, dq
'J(BH)
99.8
z ~ ( ~ ~ ) 14.2
SP
'J(PB)
'J(PP)
-
GCH,P
' J(PC)
SCHP2
'J( PC)
13.6, d
39
25.3, I
24.4
1.23, m
1.20, d
10.5
-0.29, t
3.5
br
1.40, d [a]
10.5
0.03, t
5.3
br
-
-
-
7, rn
-
-
- 6.20, q
85.4
-
19.5, d [a]
41 .o
11.0, t
38
[a] Cation: SCH3=2.20, s; SCH2=2.20, s; SCH,=46.0, s; SCHz=5?.4, s.
[b] 'J(HH)=6.0 GCH2=4.03, dt, 'J(PH)=l3.2; GCnHs=8.20, s.
Angew. Chem. Ini. Ed. Engl. 18 (197Y) No. 10
2.14, dd
10.5
3.13, tt
6.0 [bl
br
-
3.87, qt
7.0 [c]
br
1.65, d
11.2
2.43, t
13.1
br
-
-
-
-
-
17.1, m
21.6, br
-
-
-
-
-
3.9, br
-
1 .1 5, d; 1.29, d
12.7; 11.0
0.05, m
-
1 S O , dq
95.4
13.5
4.1, d - 8.5, d
70.1
51.8
18.4 [d]
-
4.4 [d]
-
[c] 3J(HH)=7.0; SCH3C=1.23, dt, 'J(PH)=15.0 SChHS=7.33-8.33, m.
[dl 4 lines, whose assignment is uncertain.
0 Verlag Chemie. GmbH, 6940 Weinherm, 1979
0570-0833/7Y/l010-0783 $ O2.S0/0
783
(3): a) Metalation of (2) (1 g, 5.9 mol) in pentane (10 ml)
with one equivalent of t-BuLi at 0 ° C for 12 h furnishes a
product, which, after removal of solvent, has the composition
corresponding to (3a); dec. pt. 90 "C, soluble in ether, THF,
dioxane.-b) Addition of TMEDA and of pentane to an
ethereal solution of (34 leads on cooling to quantitative precipitation of the crystalline complex (3); m. p. 70 "C.
(4): Reaction of (3a) with excess benzyl bromide in pentane at 20 "C for 12 h and separation of LiBr affords (4) in
74% yield; m.p. 123 "C (from THF).
(6): Metalation of (5)I5]with excess CH3Li in ether at 0 "C,
followed by reaction with excess CHJ and hydrolytic
workup, furnishes (6) in 95% yield; m.p. 197 "C (dec., from
CH2CIZ).
(7): HBr gas is passed into a solution of (2) (2.61 g, 15.9
mmol) in benzene (100 ml) until evolution of H2 ceases.
Yield 75% after removal of benzene and crystallization from
CH2C12at -78°C; m.p. 131 "C.
(9): A solution of (8)[61(0.9 g, 6 mmol) in THF (10 ml) is
allowed to react with one equivalent of H3B.C4Hs0 for 1 h
at 20°C. Removal of solvent, dissolution of the residue in
benzene, filtration, removal of benzene, and crystallization
from pentane affords (9) in 80% yield; m. p. 46 "C.
Received: June 1, 1979 [Z 296b IE]
German version: Angew. Chem. 91, 848 ( 1 979)
[I] H. Schmidbaur, G. Miiller, U. Schubert, 0. Orama, Angew. Chem. 90. 126
(1978); Angew. Chem. Int. Ed. Engl. 17, 126 (1978).
121 H. H. Karsch, H. Sehmidbaur, 2.Naturforsch. B 32. 762 (1977).
[3] Monoclinic, P2,/c; a=9.30(1), b=20.07(3), c=16.31(2)
p=110.3(1)",
V= 2854(8)
pCalL
=0.94 g cm - 7 . MoK, radiation, Syntex four circle diffractometer, R = 0.095.
141 H. Schmidbaur, E. Weiss, Angew. Chem. 91, 847 (1979); Angew. Chem. Int.
Ed. Engl. 18, 781 (1979)
[5] K. C. Nainan, G. E. Ryschkewizsch, Inorg. Chem. 8, 2671 (1969).
[6] H. Schmidbaur, W.Tronich, Chem. Ber. 101. 3545 (1968).
A'.
A,
in tetrahydrofuran solution at - 100 "C from the I3C-labeled
( 0 )dibromides['] (2u)-(4u) and n-butyllithium (solution in
hexane).
R\
R\
,R'
R/2\Li
c/R'
R/"Br
R/R = H , Alkyl,
$ -
, ,C=,
R'd
= Alkyl-metal
R'a
= Alkyl-halogen,
Heteroatoms
>-o, <Si-X
Scheme 1. Acceptor and donor reactivity of brornocdrhenoids (1)
For comparison we also determined the "C-( 0 ) - N M R
shifts of the corresponding Br/Br, Br/H, Li/H, and H/H
compounds ( 2 4 c-e)-(4a,
c-e). All the data are compiled
in Table 1. The signals of the lithium derivatives are on average ca. 8 ppm wide at -100°C and are without structure;
they become sharper at higher temperature. Chemical proof
of the identity of the organometallic species was provided by
protonation (in the sample tube and on a preparative scale['')
to the corresponding CH compounds (212, e)-(4c, e) and
their NMR analysis and isolation. In the case of (3b), the
rearrangementis1 to the 1,2-cyclononadiene (6 C2= 208r9')
which occurs on warming could be monitored: the signal of
(3b) became increasingly sharp at -80 and -7O"C, and
reached normal line width (as for solvent signals) at - 60 "C;
at the same time it loses intensity in favor of the allene-C2
signal.
Direct I3C-NMR Spectroscopic Observation of Cyclopropylidene Bromolithiocarbenoids
By Dieter Seebach, Herbert Siegel, Klaus Miillen, and Kurt
Hiltbrunner[']
The first detection of a halolithiocarbenoid by Kobrich
and Trappila]was followed by initially extensive mechanistic
studies[ib1while the preparative scope of this class of substances, which are stable only at very low temperatures, was
not fully appreciated until the 1 9 7 0 ' ~ ' The
~ ~ . geminal position
of the positive (metal) and negative (halogen) leaving group,
i. e. the joint acceptor and donor properties of the C atom of
compounds such as (I),leads to the versatile and surprisingly
stereosele~tive~~~
reaction behavior shown in Scheme 1. In
spite of, or precisely because of, the plethora of chemical results available the nature of the bond in intermediates like
( I ) is still unclear; they have hitherto escaped direct observation in the temperature rangeI41 in which the reactions mentioned take place.
We have successfully examined by "C-NMR spectroscopy
the carbenoids (2b)-(4b) generated in an NMR sample tube
['I
Prof. Dr. D. Seebach, Dr. H. Siegel. Prof. Dr. K. Mullen [**I,
K. Hiltbrunner
Laboratorium fur Organische Chemie der Eidgenossischen Technischen
Hochschule
ETH-Zentrum, Universitatstrasse 16, CH-8092 Zurich (Switzerland)
[**I Present address: Institut Fur Organische Chemie der Universitat, Greinstrasse 4, D-5000 Koln 4 (Germany)
784
0 Verlag Chemie, GmbH. 6940 Weinherm, 1979
(2)
(3)
(a): R' = R~ = ~ i ( b ) : R' = Li, R Z = B r
( c ) : R' = H , R~ = B r
(4)
( d ) : R'
= H, RZ = L1
( e ) : R' = R2 = H
Table 1. "C-NMR shifts of the 90% "C-labeled ( 0 )compounds (2)-(4) in 6
values relative to TMS. Temperature - 100"C, solvent C4H,0/C4Dx0 (9: 1);
Varian XL-100 spectrometer, 25 MHz measuring frequency; F T recording technique up to 2500 pulses.
i
;
Chemical shift or shift difference
(41 161
40.1
37.9
53.8
87.0
80.7
102.0
24.5
24.9
35.4
62.5
55.8
66.6
10.0
108
11.8
9.6
103
11.8
0.4
0.5
0.0
The pronounced downfield shift Asbc of the Li/Br carbenoid C atoms ( 0 )by values of up to 67 relative to the H/Br
compounds is surprising (cf. Table 1): large shift differences
are not normally found for the saturated (sp') C atom between CH and CLi
as is confirmed by the
cyclopropanes ( 2 4 e)-(4d, e) (Asd, in Table 1). The observed deshielding is also unexpectedly large in cornparison
0570-0833/79/1010-0784 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 18 (1979) No. 1 0
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