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Cations of Boron with Coordination Number Three 1 3 2 4-Diazadiboretidinium Salts.

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rings[']. Semiempirical calculations gave larger, and ab initio methods (for the unsubstituted tetrahedrane 3) smaller
values for the CR-CR bond (Table 1). Compared with
the CR-CQ bonds
single boads (1.54
(1.490, corrected['' 1.502 A) are short, but they have the
[I] a) G. Maier, 9. Wriem, U. Schafer, K.-D. Malsch, R. Matusch, Chem.
Ber. 114 (1981) 3965: b) G. Maier, S. Pfriem, Angew. Chem. 90 (1978)
551; Angew. Chem. Int. Ed. Engl. 17 (1978) 519; c) G. Maier, S. ffriem,
U. SchBfer, R. Matusch, ibid. 90 (1978) 552 and 17 (1978) 520.
[2] G. Maier, S. ffriem, K.-D. Malsch, H.-0. Kalinowski, K. Dehnicke,
Chem. Ber. 114 (1981) 3988.
trigonal131 Room temperature modification: a = 37.95(3), c= 8.786(5)
rhombohedra1 space group RJ or R 3 (from pentane, acetone or ethyl acetate or by sublimation); 2=21,pC.,,=O.88 Mg/m3,p.,,=0.88 Mg/m3.Low temperature modification: colorless needles from ethyl acetate at
-6O"C, size of the crystal studied: 0.60x0.25 xO.15 mm'; temperature
of data collection -60°C; MoKa radiation, Enraf-Nonius CAD4 dif2034 indefractometer, graphite monochromator, sin O/h< 0.664
pendent reflections (including 759 observed reflections [Fo> ?u(F,)D;
R=0.049. Crystallographic data: a = 15.795(4), c = 14.056(6) A; hexagonal space group P6,/m. Assignment of the centrosymmetric space
group was based on the results of statistical tests. Measurements at
lower temperatures possibly could reveal noncentrosymmetric structures. Z = 6 ; p,l,=0.91 Mg/m3. Structure solution: MULTAN [lo]; refinement: C anisotropic, H isotropic (three H atoms fixed at calculated
positions, and the temperature factors of these atoms and of a further H
atom also fixed during the refinement) [Ill.
[4] a) W. D. Hounshell, K. Mislow, Tetrahedron Left. 1979, 1205; b) A.
Schweig, W. Thiel, J. Am. Chem. SOC.I01 (1979) 4742; c) 0. Ermer: Aspekte uon Kruf?eldrechnungen, W. Bauer Verlag, Miinchen 1981, p.
442 f.
[5] V. Schomaker, K. N. Trueblood, Acta Crysfallogr.Sect. B24 (1968) 63.
[6] a) H. Irngartinger, K. L. Lukas, Angew. Chem. 91 (1979) 750; Angew.
Chem. I n f . Ed. Engl. 18 (197')) 694; b) M. N. Paddon-Row, K. N. Houk,
P. Dowd, P. Garner, R. Schappert, Tetrahedron L e f t 22 (1981) 4799; c )
M. Eisenstein, F. L. Hirshfeld, Act4 Crysfallogr.Sect. B39 (1983) 61; d)
P. G. Gassman, M. L. Greenlee, D. A. Dixon, S. Richtsmeier, J. 2. Gougoutas, J . Am. Chem. SOC.105 (1983) 5865.
[7] The correction for thermal motion was carried out separately for each
terf-butyl group, including the associated tetrahedron C atom, using the
RIGID program of K . N. Trueblood and P. Gantzel[5].Since the thermal
parameters of one methyl C atom in the mirror plane were exceptionally
anisotropic, we fitted its thermal parameters to the corresponding values
of the neighboring methyl C atoms of the same rert-butyl group to perform the correction.
[8] J. Haase, W. Zeil, Z. Nururfor.wh. A24 (1969) 1844.
[9] T. Loerzer, R. Machinek, W. Liittke, L. H. Franz, K.-D. Malsch, G.
Maier, Angew. Chem. 95 (19x3) 914; Angew. Chem. Int. Ed. Engl. 22
(1983) 878.
[lo] J. P. Declercq, G. Germain, P. Main, M. M. Woolfson, Acfa Crysfullogr.
Sect. A 2 9 (1973) 231.
Ill] Further details of the crystal structure investigation can be obtained
from the Facbinformationszentrum Energie Physik Mathematik, D-7514
Eggenstein-Leopoldshafen 2, on quoting the depository number CSD
50989, the names of the authors, and the journal citation.
Fig. 3. Structures of I with averaged bond lengths
(in round brackets:
values of scatter; in square brackets: corrected values 171). Individual values
(in round brackets: standard deviations: in square brackets: corrected
values [7]); CR-Cn: 1.487(5), 1.487(3), 1.480(3), 1.487(5); C,-C,:
[1.5121, 1.480(7) [1.499], 1.486(4) 11.4951; CQ-CM: 1.477(5) [1.531]-1.539(4)
[1.561]. The C-C-C bond angles at the tetrahedron are consistent with the
60.0" and 144.7" angles of a regular tetrahedron, as is the interplanar angle
of 70.5" between the planes of the three-membered rings.
Table 1. acornparison of the experimental (1) and calculated (1-3) bond
lengths [A].
Exp. [a]
[Corr.] [a] Force field [b] MNDO [c] MNDO [dj
IMOA[e] 4-31G
STO-3G [g]
CEPA [h]
Cations of Boron with Coordination Number Three:
1,3,2,4-Diazadiboretidinium Salts
[a] This work. [b] [4a]. [c] [4b]. [dl H. Bock, B. Roth, G. Maier, Angew. Chem.
92 (1980) 213; Angew. Chem. I n f . Ed. Engl. 19 (1980) 209. [el K. KovaEeviC,
Z. B. MaksiC, J. Org. Chem. 39 (1974) 539. J. M. Schulman, T. J. Venanzi,
J. Am. Chem. SOC.96 (1974) 4739. [g] W. J. Hehre, J. A. Pople, ibid. 97 (1975)
6941. [h] H. Kollmar, ibid. 102 (1980) 2617.
same order of magnitude as the C(sp)-C(sp') single bonds
in tert-butylacetylene (1.498 A from electron diffraction
measurements[*]). According to 13C-NMR measurements,
the orbitals of the tetrahedrane atoms in these bonds are,
in fact, sp-hybridized[']. Because of torsional vibration or
disorder the CQ-CM bonds (average length 1.513 A) appear shortened; howeve! after correction for thermal motion the value of 1.545 A[71is within the normal order of
Received: July 30, 1984;
revised: September 28, 1984 [Z 943 IE]
German version: Angew. Chem. 96 (1984) 967
CAS Registry number:
1, 66809-06-1
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
By Heinrich Noth* and Siegjiried Weber
The readily accessible tert-butylimino-(2,2,6,6-tetramethy1piperidino)borane 1 is haloborated by boron halides;
for example BBr3 yields the four-membered heterocycle
2"). Addition of dibromo(methy1)borane to 1 leads, via
methyloboration['], to the heterocycle 3, whose structure
can be unequivocally derived from the NMR data. In contrast, 1 undergoes a phenyloboration with dichloro(pheny1)borane to give 4 and a chloroboration to afford 5. We
have not yet succeeded in separating these isomers.
Unexpectedly, addition of bromodimethylborane to 1
affords a 1 : 1 adduct, whose "B-NMR spectrum exhibits
only one signal at 6 = 48.9 ; furthermore, only one 'H- and
"C-NMR signal is observed for the B-methyl and the methyl groups on the piperidine ring. These data indicate a
higher symmetry for the adduct than, e.g., in 2. A considerable electrical conductivity in CH2C12solution and the
[*] Prof. Dr. H. Noth, Dr. S. Weber
Institut fur Anorganische Chemie der Universitat
Meiserstrasse 1, D-8000 Miinchen 2 (FRG)
0570-0833/84/1212-0994 $ 02.50/0
Angew. Chern. Int. Ed. Engl. 23 (1984) No. 12
spectroscopic data suggest the spirocyclic 1,3,2,4-diazadiboretidinium bromide 6.This assignment is corroborated
by the addition of AIBr3: The 'H-, I3C-, and "B-NMR parameters of 6 hardly change, since the Lewis acid AIBr,
only converts the bromide 6 into the tetrabromoaluminate
dergoes methyl- and not bromohoration with CH,BBr,[*':
The product of bromoboration, 9, is formed first, and then
rapidly rearranges to the more stable 3 via bromide migration.
The high mobility of the halides in 2, 3, 4, and 5 at the
tetracoordinated boron atom is also underlined by the fact
that aluminum halides abstract a halide ion from the heterocycles, forming the tetrahalogenoaluminates 10, 11, and
12; as expected, the isomeric mixture 4, 5 leads to the
same cation. Characteristic data are shown in Table 1.
The novel cations 6, 7, 10, 11, and 12, in which boron
has the coordination number 3, contain a diborylamine
structural element (>B-N-B<);
this is isoelectronic
with ally1 cations, and we regard this as the reason for their
high tendency of formation.
3: R' = CH3, X = Br
4: R' = Ph, X = C1
Received: August 3, 1984 [Z 946 IE]
German version: Angew. Chem. 96 (1984) 998
11: R' = CH,, X = Br
12: R ' = Ph, X = C1
[I] H. Nbth, S . Weber, Z. Naturforsch. 838 (1983) 1460.
121 Organoboronations of iminoboranes: P. Paetzold, T. von BennigsenMackiewicz, Chem. Ber. 114 (1981) 298; P. Paetzold, A. Richter, T. Thijssen, S. Wiirtenberg, ibid. 112 (1979) 3811.
131 For preparative details see S. Weber, Dissertation, Universitat Miinchen
By Adalbert Maercker* and Manfred Theis
Ph' \C1
c N =
These results indicate that the expected adduct 8 is unstable because of the insufficient acidity of the CH3BN2
moiety, and at the same time explains the fact that 1 unTable 1. Some characteristic NMR data for compounds 3-7 and 10-12.
The compounds 2 -6 were obtained from equimolar amounts of 1 and halogen(organo)boron in pentane, and the tetrahalogenoaluminates, from these
compounds and the equivalent amount of AlX3 in CH2C12 solution 131.
3: M.p.=99--100"C; 6"B 38.1,O.O; S'H 1.38-0.95 (y2-4), 1.71 (H7), 1.65
(H6), 1.47 (H9), 0.52 (BCHp)
4 : 6"B 36.8,9.6; 6I3C 62 4 (C1,5), 53.3 (CS), 40.6 (C2,d), 34.2, 32.0,27.6,27.4
(C6,7), 30.7 (C9), 16.5 (C3) as well as signals in the phenyl group region
5 : 6"B 29.0, 21.9;6"C 59.9 (C1,5), 53.8 (C8), 39.9 (C2,4), 32.5, 27.8 (C6,7),
31.2 (CS), 16.3 (C3) as well as signals in the phenyl group region
1.53 (H6,7),
1.49 (H9), 1.37 (BCH3); 6I3C 5.7 (BCHa) and further signals
7:M.p.=151--152"C (decomp.); 6"B47.8;S2'AI 79.9, hCllZ)
15 Hz;GIH 1.83
(H2-4), 1.48 (H6,7), 1.41 (H9), 1.30 (BCHs)
10: Decomp. 74-76°C; 6I1B 36.8; 627Al79.7, hf1/2)I5 Hz; S'H 2.02 (H2-4),
1.70 (H6,7), 1.58 (H9)
11: Decomp. 117-118°C; 6I'B 47.8, 36.5; 6"Al 79.9, hCllz)15 Hz; 6'H 1.92
(H2-4), 1.66, 1.52 (H6,7), 1.51 (H9), 1.44 (BCH,)
12: 6"B 46.4, 37.6; fi2'Al 103.7, h[wq 25 Hz;6'H 1.97 (H2-4), 1.72, 1.56
(H6,7), 1.34 (H9), 7.52-7.70 (BCaHs)
Tetralithiomethane 5 was first described by Lagow et
al.['I who were able to generate it in a maximum yield of
40.5% (detected as CD4 in addition to other deuterated
products) by reaction of tetrachloromethane and lithium
vapor. The major side product in this reaction is lithium
carbide in addition to traces of perlithioethene and perlithioethane. An increase of the reaction temperature from
750 to 800°C reduces the yield of CLi, to 14% in favor of
Lagow et a1.['] have also investigated the pyrolysis behavior of tetralithiomethane, reporting that the compound
is thermolabile referred to decomposition into lithium carbide via perlithioethene and perlithiopropyne.
By analogy to previously published procedures for the
synthesis of polylithiated hydrocarbon^[^.'^ bearing several
Li atoms on one C atom ("isocentric"), we have now found
two further methods of generating 5 . Reaction of octamethy1 methanetetraboronate lL5)
with mercury(I1) acetate affords tetrakis(acetoxymercurio)methane 2, which in turn
can be converted by sodium chloride into tetrakis(ch10romercurio)methane 4[6371.If instead of mercury(I1) acetate, ethylmercury acetate is employed, tetrakis(ethy1mercurio)methane 3 is obtained, an approach based on the
synthesis of the corresponding methyl compound developed by Breitinger and Kresd'l.
6 : M.p.=108-I1OoC (decomp.); S"B 48.9; 6lH 1.86 (H2-4),
Angew. Chem. Int. Ed. Engl. 23 (1984) No. 12
[*I Prof. Dr. A. Maercker, M. Theis
Institut fur Organische Chemie der Universitat
Adolf-Reichwein-Strasse, D-5900 Siegen (FRG)
Polylithiumorganic Compounds. Part 3. This work was supported by the
Fonds der Chemischen Industrie. We thank Prof.Dr. D. Breitinger and
Prof. Dr. P. u. R. Schleyer, Erlangen, for discussions.-Part 2: 141.
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
0570-0833/84/1212-0995 $ 02.50/0
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salt, coordination, three, number, diazadiboretidinium, cation, boron
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