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Crystal Structure of B2S3 Four-Membered B2S2 Rings and Six-Membered B3S3 Rings.

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[2] a ) R . A p p e l . M. Hulstertberg, J. Organomet. Chem. 99, C 2 5 (1975):
b) R . 4ppel. M. Moiireirodt, Z . Naturforsch. B 3 0 , 847 (1975).
131 Concerning the comparable preparation of bis(trimet1iylsilyl)carbodiimide from cyanogen halide and silyl derivatives of ammonia. bee: I .
Hiriidrck. Angew. Chem. 77. 729 (1965); Angew. Chem. Int. Ed. Engl.
4, 704 (1965).
[4] L. Bir!,ofw. A. Ritter, P. Richter. Tetrahedron Lett. 1962, 195.
[S] U . Wniiriogat, H . Niederpriim, Chem. Ber. 94. 1540 (1961).
[6] For comparison, the carbodiimide carbon atom of analogous representatives of this class of substances exhibits the following chemical shifts:
- 124.5.tBu-NCN-Ph
- 136.1,Ph-NCN-Ph
MeJSi-NCN-SiMeJ
- 135.1 ppm (in CDCI, L'S. internal TMS).
[7] ',C-NMR measurements on authentic samples gave the following shifts
- 112.5, Et2N-CN
- 117.3,
for the cyanamide carbon: PhNH-CN
Ph2N--CN - 1 12.4 ppm.
[XI Review: F. Kiirzer, K . Douru<glii-Zudeh, Chem. Rev. 67. 107 (1967): cf.
also: N. Wibrry. C. Hiibler. Z . Naturforsch. 8 3 1 , 1317 (1976).
[BSN(C2Hs)2]2[61,(BSSH)2, and (BSSC2Hs)2[71could not
previously be characterized structurally or spectroscopically.
The very short transannular B.. .B (2.237 A) and S.. .S distances
(2.878A)in thestrained four-membered ring warrant attention;
the average B-S bond length (1.823A) differs but slightly
from the average value taken over all B-S bonds in the
structure (1.808 A).
' 11021
Crystal Structure of B2S3:
Four-Membered B2S2 Rings and Six-Membered B3S3
Rings [**I
By Harald Diercks and Bernt Krebs"]
Characterization of boron chalcogenides runs into the
obstacle that crystalline phases are difficult to prepare. Crystalline B2S3 has been available since 1962 by a variety of
methods"]; however, the quality of the crystalline material
was in no case sufficient for a structure determination. The
same applies to all other binary boron chalcogenides.
According to a preliminary report by Chen, Conurd, and
G i / / r . ~BzS3
[ ~ ~ forms monoclinic crystals (C2, Cm, or C2/m)
with a=4.048, b=37.09, c=10.73A, fi=9O.O0, 2=14.1;
an attempted complete structure analysis was unsuccessful.
During studies on the synthesis of heavy metal thioborates
we obtained single crystals of B2S3 suitable for X-ray structure
determination by thermal decomposition of ternary phases (cf.
also [ I h ] ) . For example, if the stoichiometric reaction mixture for preparation of Ag3BsSgr3](closed graphite crucible
in an evacuated sealed quartz glass tube) is subjected to a
temperature gradient of 800 to 600°C for ca. IOd, then apart
from silver thioborate the extremely moisture sensitive colorless compound B2S3 is obtained as 0.3 mm long column shaped
single crystals which are microtwinned [B :S = 1 : 1.49(2);
monoclinic (P2,/c) with
a=4.039(1),
b= 10.722(2),
~=18.620(4)A,p=96.23(3)", Z=8, V=801.6A3; dcalc=1.952,
delp= 1.93(3) g/cm3]. The crystal structure was determined
for a twin along (201) from four-circle diffractometer
and refined to R=5.7"/0.
The structure is made up of planar B3S3 six-membered
rings and B2S2 four-membered rings linked by S bridges to
almost planar infinite two-dimensional high-polymer layers.
The projection of two unit cells perpendicular to the plane
of the layer is depicted in Figure 1. Zig-zag chains of six-membered rings run through the layers parallel to b; each six-membered ring is bonded via a four-membered ring (situated at
an inversion center) to a six-membered ring of the adjacent
chain. All the boron atoms exhibit trigonal-planar coordination. While the B3S3 ring corresponds to those of trimeric
metathioboric acid (BSSH)3 and its alkali salts in structure
and bonding13,'I, the 1,3,2,4-dithiadiboretanering is of particular interest because the four-membered ring skeletons of
~
[*] Prof. Dr. B. Krebs, Dr. H. Diercks
Anorganisch-chemisches lnstitut der Universitat
Gievenbecker Weg 9. D-4400 Miinster (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.
[**I
An<gew Cbem. / l i t . Ed. Eiiyl 16 (1977) No. 5
Fig. I . Layer structure of B2S3 with bond lengths
[A] and angles ["I
Only van der Waals forceyoact between the (B2S3)n layers
(S...S distances 2 3.814(2)A); the perpendicular interlayer
spacing is 3.55 A.Overall, the packing of the S atoms can be
regarded formally as a distorted ..ABAB.. closest packing.
The extensive angular distortions in the trigonal-planar BS3
groups (Fig. 1) are mainly due to the influence of S...S repulsive forces within the layers (shortest S... S distances within
the BS3 groups: S1 ... S2 2.898, S1 ... S4 2.926, S4 ... S5
2.945(2)w; between S atoms within the layers not belonging
to the same BS3 polyhedron: S2 ... S3 3.194, S3.. . S6 3.256(2)A),
The structure of B2S3 bears no resemblance to the threedimensionally linked B2O3 crystal structurer8!
Received: February 9, 1977 [Z 672 IE]
German version: Angew. Chem. 89. 317 (1977)
CAS Registry numbers:
B2S3, 12007-33-9
[l] a) P. Hayenmiiller, F. Chopin, C. R . Acad. Sci. 255, 2259 (1962): b?
P. Hagerimiiller, F. Chopiri. R . Custugiiri, ihid. C262. 418 (1966): c) E.
G. Zhirkoc, Yu. Kli. Grinberg, Izv. Akad. Nauk SSSR. Neorg. Mater.
1969, 1646; d ) H.-Y Choi, P. W Cillrs, J. Am. Chem. SOC. 92. 2309
( 1970).
[2] H.-E Cheri, B. R. Cortnrrl, P . W Gilles, Inorg. Chem. 9. 1776 (1970).
131 B. Krebs. H . Dirrcks, X. Int. Congr. Crystallogr., Amsterdam. August
1975; Acta Crystallogr. ,431, S66 (1975); in part unpublished work.
141 The hitherto unrecognized twinning leads to complete coincidence of
the hkl reflections of one individual with hk( - / I - I ) of the other. Relation
of the correct (I) cell to that (11) reported by Cheit et ol.: u(I)=ci(lI).
MI) = c(ll), c(l)= b(l1)/2sin/<(lI).
[ S ] W Scliwari, H . D. Huirsett, H . Hess, J . Moriilr, W Scliinrlx~r,B. Krebs,
Acta Crystallogr. 829.2029 (1973): F . Chopbi. G. 7 i w e l l . J . Mol. Struct
3, 57 (1969).
161 J . A . Forstiter, E. L . Muerterries, Inorg. Chem. 5 . 164 (1966).
[7] E. Wibrrg. W Sturnt, Z . Naturforsch. 8b. 530 (1953); /Oh. I14 (1955):
Angew. Chem. 67,483 (1955).
[8] G. E. G u m , P. W Moiirgoiwr!~.C . D. Knutsori, B . 7: Corres, Acta Crystallogr. 8 2 6 , 906 (1970).
313
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