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Diphenylborane Derivatives Containing Boron-Tin Bonds.

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An oily adduct obtained from triethyl phosphite and diethyl
azodicarboxylate was regarded by Morrison [41 as (22),
whereas Ginsburg et al. ill suggested an alternative structure.
Interception of the precursor (21) by a cycloaddition process
provides evidence in favor of (22). O n slow addition of dimethyl azodicarboxylate to trimethyl phosphite and phenyl
isocyanate in benzene, we were able to isolate (17) in 84%
yield; the reaction probably proceeds via a n intermediate
analogous to (16) having OCH3 instead of CsH5 attached to
the phosphorus.
Received: May 23, 1969
[Z 1 IEI
German version: Angew. Chem. 81, 534 (1969)
Fig. 1. Crystal structure of pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium(O).
[*] Prof. Dr. R. Huisgen and Dr. E. Brunn
Institut fur Organische Chemie der Universitat
8 Miinchen 2, Karlstrasse 23 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[l] V . A . Ginsburg, M . N . Vasil’eva, S. S. Dubov, and A . Y.
Yakubovich, J. gen. Chem. USSR (English translation of 2. obSE.
Chim.) 30, 2834 (1960).
[2] R. C. Cookson and J . M . Locke, J. chem. SOC.(London) 1963,
[3] 0.Mitsunobu, M . Yamada, and T . Mukaiyama, Bull. chem.
SOC.Japan 40, 935 (1967).
[4] D. C. Morrison, J. org. Chemistry 23, 1072 (1958).
[ 5 ] For a review, see R. Hursgen, dsterr. Chemiker-Ztg. 55, 237
[6] H . J . Bestmann, G . Joachim, I . Lengyel, J. F. M . Oth, R.
Merenyi, and H. Weitkamp, Tetrahedron Letters 1966, 3355.
[7] E. Grigat and R. Piitrer, Chem. Ber. 97, 3012 (1964).
The Crystal Structure of Pentacarbonyl(2,3-diphenylcycIopropenylidene)chromium(0) 1* *I
By G . Huttner, S. Schelle, and 0. S. Millsc*1
We have determined the crystal structure of pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium(0), recently prepared by ofele[ll, in a n attempt to understand the unusual
bonding in this remarkably stable complex.
The compound crystallizes in the triclinic system, spacegroup Pi (Cf, No. 2) with a = 13.31, b = 9.25, c = 9.93 A,
cc=91.3,P=104.2,andy=129.2°, d , = 1 . 4 2 7 , d c = 1 . 4 2 3
gcm-3, Z = 2. The intensities of 1976 reflexions were measured, with molybdenum radiation (A = 0.71069 A), o n a S t o i
automatic Weissenberg diffractometer. The structure was
solved by conventional Patterson and Fourier methods. At
present, the agreement index, after partial refinement of
anisotropic temperature factors, is R = 0.086.
Pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium (0)
is the first mononuclear carbene complex in which the carbene
ligand is not stabilized by heteroatom substitution. The
chromium atom is coordinated octahedrally (Fig. 1). Five
of the positions are occupied by CO groups (Cr-Cco
1.88-1.92 A, C - 0 1.10-1.15 A) and the sixth by the 2,3diphenylcyclopropenylidene fragment. The Cr-C distance,
2.05 i 0.01 A, is appreciably shorter than that expected for
a single bond between Cro and a sp2-hybridized carbon
(2.21 A) 121 and indicates appreciable double-bonding.
Angew. Chem. internat. Edit. ] Vol. 8 (1969)
1 No. 7
The distances C2-C21 and C3-C31 (Fig. 1) are somewhat
shorter than the single-bond separation between two sp2hybridized carbon atoms (1.48 A) 131. One of the phenyl rings
lies in the plane of the three-membered ring whilst the other
is twisted out of this plane by 7.5 ’, presumably by repulsions
of the phenyl ortho-hydrogens.
The mean C-C distance in the three-membered ring is not
significantly different from that found for the aromatic triphenylcyclopropenylium cation (1.37 A) [41. However, whereas all the distances in the aromatic three-membered ring are
equal within experimental error, in the complex the C1-U
and C1-C3 separations are somewhat different from C2-C3.
This difference is probably significant and points to a small
distortion of the ring towards a cyclopropene system. This
observation is also in accord with the suggestion of doublebond character in the Cr-C1 bond.
Received: April 15, 1969
German version: Angew.
[Z 5 IE]
Chem. 81, 536 (1969)
[*I Dr. G. Huttner and Dip1.-Chem. S. Schelle
Anorganisch-Chemisches Laboratorium
der Technischen Hochschule
8 Miinchen 2, Arcisstrasse 21 (Germany)
Prof. 0. S. Mills
Department o f Chemistry
The University
Manchester 13 (England)
[**I We wish to thank the Bayerische Akademie der Wissenschaften for permission to use the computer installations at the
Leibniz Rechenzentrum, Miinchen.
111 K. ofele, Angew. Chem. 80, 1032 (1968); Angew. Chem.
internat. Edit. 7, 950 (1968).
[2] J . A. Connor and 0. S. Mills, J. chem. SOC.(London), A 1969,
[3] M . J. S. Dewar and H. N . Schmeising, Tetrahedron 11, 96
[41 M . Sundaralingam and L . H . Jensen, J. Amer. chem. SOC.88,
198 (1966).
Diphenylborane Derivatives Containing
Boron-Tin Bonds
By H . Noth, H. Schafer, and G. Schmid[*]
Whereas bis(dimethy1amino)trialkylstannylboranes are accessible from R3SnLi (R = alkyl) and CIB[N(CH3)2]2[1], the
synthesis of dialkyl- and diphenyl-trialkylstannylboranes
could not be accomplished by this method. No boron-tin
) &i,
compounds could be detected on reaction of c(&~&
with BCI3, RBC12, and RzBCl; instead, hexaphenyldistannane
was identified as the main reaction product.
Bis(diphenylboro)bis(tetraphenyldiphosphinoethane)cobalt(I1)[2,31 has proved a suitable reagent for the introduction of diphenylboryl groups into inorganic and organic
compounds. It reacts with methyltin chlorides or bromides
according to equation (1) to give the methylstannyldiphenylboranes (l)-f3) (see Table) in 6 0 4 0 % yield and thus permits the formation of several Sn-B bonds in one molecule.
Reaction with SnBr4 affords tetrakis(diphenylbory1)stannane
Existence of the Oxalyl Dication [C202]2+111
By M . Adelhelm [*I
Reaction of acyl halides RCOX with Lewis acids MX, can
lead to two different products (2-41 :
+ MX.
+ (CH3)4-,,SnXn
[R-C=OI+ [MX,,Ie.g. ( l a ) : R = CH3
M = Sb
X = F , n = 5
The colorless crystalline compounds are of low thermal
stability and are extremely sensitive to oxygen. They react
rapidly even with traces of oxygen to give tetraphenyldiboron oxide and the corresponding stannoxanes via intermediates containing Sn-0-B bonds. Degradation with bromine
yields diphenylboron bromide and (CH3)4_,SnBrn.
The magnetic equivalence of all the B atoms in the molecules
( l ) - ( 4 ) can be deduced from the single broad IlB resonance
signal, whose almost constant position shows that the boron
atoms are exposed to a similar shielding in all four compounds, which is determined mainly by the phenyl groups.
The area ratio of the proton resonance signals are in good
agreement with the calculated intensities. The signals of the
CH3 groups in (1)-(3) are shifted upfield compared to the
corresponding signals of the methyltin chlorides.
Table: Characteristic data for dipbenylborylstannanes.
[a1 In benzene, BF3.0R2 as external standard.
!bl In cyclohexane. Si(CH3)d as external standard.
(20): R = CsH,
M = A1
X-ray analysis has established the structures of the representatives ( l a ) and (2a) 151 of both types of compounds, i.e. of
the oxocarbonium (or acylium) salt ( I ) and the adduct (2).
Compounds ( I ) and ( 2 ) can also be distinguished by means
of their CO bands in the vibrational spectra, which show a
characteristic shift compared to the free acyl halide [394,61.
Thus the CO stretching vibration of ( l a ) is observed at 2294
cm-l[71 and that of (2a) at 1548 cm-l[41, corresponding to an
increase and a decrease of the CO bond order, respectively.
We have attempted to prepare the oxalyl dication, an interestingspecies owingtoits bonding,and toexamineit by vibrational
spectroscopy. It is the simplest representative of the "acyl
dications", which were first descibed by Olah and Comisarow 181.
It proved expedient to carry out the reaction between oxalyl
chloride and antimony pentafluoride directly in an IR lowtemperature cell of the usual typeW Thin films of CzOzC12
and an excess of SbF5 were condensed onto the inner cell
plate (AgCl)[lol, which was cooled with liquid air. The
dotted curve in Figure 1 reproduces the infrared spectrum
measured at this stage[llJ: it arises by superposition of the
individual spectra of the unchanged starting materials.
Gradual increase of the temperature to -35 "C initiates the
reaction, as is evidenced by the appearance of small gas
bubbles on the plate. After cooling to about -50 OC (to avoid
decomposition), the spectrum represented by the continuous
line in Figure 1was recorded. By turning the AgCl plate out of
the beam path the gaseous product could be identified spectroscopically as COFCl with traces of CO (and COFz?) (see
dashed curve in Figure 1). After the gases had been pumped
off, the spectrum of the solid, colorless reaction product was
recorded at -78 "C (Figure 2).
Tetrakis(diphenylbory1)stannane ( 4 ) :
[ ( C ~ H ~ ) ~ P C H ~ C H ~ P ( C[~BH
( C~ ~) ~
~ ]OZ g) is treated with SnBr4 (1.18 g) in 100 ml of anhydrous benzene under
highly pure nitrogen or argon for four hours with stirring;
[ ( C ~ H ~ ) Z P C H ~ C H ~ P ( C ~ H ~ (5.3
) ~ ] Zg)C O
is Bthen
~ ~ filtered off and the solvent removed under vacuum. Compound ( 4 ) is extracted from the residue by stirring for eight
hours with cyclohexane (50 ml). The product is recrystallized
from the same solvent.
[Z 4 IEI
Received: April 15, 1969
German version: Angew. Chem. 81, 5 3 0 (1969)
[*I Prof. Dr. H. Noth, Dip1.-Chem. H. Schafer, and
Priv.-Doz. Dr. G. Schmid
Institut fur Anorganische Chemie der Universitat
355 MarburgiLahn, Gutenbergstr. 18
[I] H. Noth and K. H . Hermannsdorfer, Angew. Chem. 76, 311
(1964); Angew. Chem. internat. Edit. 3, 377 (1964).
[2] G. Schmid and H. Noth, Chem. Ber. 100, 2899 (1967).
[3] H . Noth and G. Schmid, Allg. prakt. Chem. (Wien) 17, 610
500 crn-I
Fig. I.
The absorptions in the CO-triple bond region at 2235 and
2182 cm-1 indicate an oxocarbonium structure ( I ) . On warming, both bands decreased irreversibly in intensity - that at
2235 cm-1 particularly rapidly - owing to formation of
COFCl. The varying intensity ratio of these two bands
indicated two species of different stability in the solid. Since
Angew. Chem. internat. Edit.
/ Vol. 8 (1969) 1 No. 7
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bond, tin, containing, diphenylborane, boron, derivatives
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