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Li12Si7 Theoretical Interest Aroused.

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tion was established between the molecular structure of the
impurity, the crystal structure of the substrate, and the effected growth directions, leading to a proposal of a twostep mechanism for the binding of the impurity at the
growing crystal faces and retardation of growth. We have
found that slightly modified substrate molecules yield impurities which are particularly effective in inducing such
morphological changes.
By application of these principles it becomes possible to
grow crystals with desired morphologies by “tailoring” impurities which bind at a preselected face and thus inhibit
growth in a predictable manner. An advantage of this
method is that the effect of factors such as temperature,
solvent, and supersaturation may be kept constant by performing all crystallization experiments under identical
conditions, except for the nature and concentration of the
impurity. This approach is illustrated here for benzamide.
ysis indicates that only 0.2-0.5% impurities are found in
the bulk of the crystal, even when the amount in solution
was as high as 10%.
Received: March 24, 1982 [Z 163 IE]
German version: Angew. Chem. 94 (1982) 640
The complete version of this communication appears in:
Angew. Chem. Suppl. 1982. 1336-1345
CAS Registry number:
Benzamide, 55-21-0.
[2] P. Hartman in D. Fox, M. M. Labes, A. Weisberger: Physics and Chemistry of the Organic Solid State, by Interscience, New York 1963, Vol. 1, p.
369 and Vol. 2, p. 873; P. Hartman: Crystal Growth. North-Holland, Amsterdam 1973, p. 367.
141 L. Addadi, 2. Berkovitch-Yellin, E. Gati, N. Domb, M. Lahav, L. Leiserowitz, Nature 296 (1982) 21.
[S] Z. Berkovitch-Yellin, L. Addadi, M. Idelson, L. Leiserowitz, M. Lahav,
Nature 296 ( 1982) 27.
161 L. Addadi, 2. Berkovitch-Yellin, 1. Weissbuch, M. Lahav, L. Leiserowitz,
S. Weinstein, J. Am. Chem. SOC.104 (1982) 2075.
[7] L. Addadi, S. Weinstein, E. Gati, I. Weissbuch, M. Lahav, J. Am. Chem.
Sor. 104 (1982), in press.
LiI2Si,: Theoretical Interest Aroused
By Joel F. Liebman* and James S . Vincent*
Von Schnering et a[. recently reported”’ the remarkable
crystal structure of LilzSi7,a compound containing planar
Si, star clusters and planar Si5 rings. For our description of
these two inherent structures we present here alternatives
and precedents based on qualitative and quantitative MO
considerations or on comparisons with isoelectronic species.
We start with the Si, stars, which contain singly coordinated terminal silicon atoms, as found in HNSi and
H,CSiL3];they can be formulated as Si,* (A).
This anion is “n-isoelectronic” with the Y-aromatic(61
carbonate ion Coif, i. e. both ions have the same number
of n-electrons and atoms. Because of the smaller charge,
Siz- should be more stable than the Si:- species postulated by von Schnering et al.‘]’.
Fig. 1. Crystals of benzamide grown in absence and in presence of increasing
amounts of impurities: a) pure benzamide, b) with benzoic acid (3%, 5%.
loo%),c) with o-toluamide (I%, 5%, to%), d ) with p-toluamide (3%, 5%,
Benzamide crystallizes from ethanol in plate-like crystals elongated along the b-direction (Fig. la). The general
features of this morphology may be rationalized in terms
of the packing characteristics.
In the light of the correlation between the crystal structure and morphology of benzamide, it was possible to
choose impurities to specifically modify the relative rates
of growth along the three principal directions: Retardation
of growth primarily along the b-axis was achieved by adding benzoic acid. This induces the crystals to grow in rodform extending along the a-direction (Fig. 1b). Retardation
of growth along the a axis was achieved by adding 1- 10%
of o-toluamide to the mother solution. This induces the
crystals to grow in the form of rods extending along the bdirection (Fig. lc). Finally, as expected, thinner and thinner platelets (Fig. Id) were obtained by adding increasing
amounts of p-toluamide.
In all cases the habit was modified gradually with the
concentration of impurity in solution (Fig. 1). HPLC anal632
0 Verlag Chemie GrnbH, 6940 Weinheim. 1982
Also, because of the high charge, the existence of the
postulated Si:- and S i y - anionsI’l is not very likely.
In our opinion the Sig rings should be formulated as
Si:- ions; such species are n-isoelectronic with the wellknown cyclopentadienide ion. The possible presence of the
2 n Si;’ species has also been considered. From symmetry
considerations and mathematical operations, as well as
consideration of the crystal structure, we deduced that lithium is present as Li+ and Li: in Li12Si71’01.
We therefore
suggest that Li12Si7 be formulated as Li24Si14 =
(Li + ) g ( ~ i : ) 5 ( ~ i ~ - > ( ~ i ~ - ) 2 .
Received: June 12, 1981,
revised: June 8, 1982 [Z 165 IE]
German version: Angew. Chem. 94 (1982) 649
The complete manuscript of this communication appears in:
Angew. Chern. Suppl. 1982, 1424-1428
[“I Prof. Dr. J. F. Liebman, Prof. Dr. J.
S. Vincent
Department o f Chemistry, University of Maryland
Baltimore County, Catonsville, M D 21 228 (USA)
0570-0833/82/0808-0632 $! 02.50/0
Angew. Chem. h i . Ed. Engl. 21 (1982) No. 8
CAS Registry number:
[l] H. G. von Schnering, R. Nesper, J. Curda, K. F. Tebbe, Angew. Chem. 92
(1980) 1070: Angew. Chem. Int. Ed. Engl. 19 (1980) 1033.
[3] J. N. Murrell, H. W. Kroto, M. F. Quest, J. Chem. SOC.Chem. Commun.
1977. 619.
[6] P. Gund, J. Chem. Educ. 49 (1972) 100.
[lo] G. V. Pfeiffer, F. 0. Ellison, J. Chem. Phys. 43 (1965) 3405; J. L. Gole, R.
H. Childs, D. A. Dixon, R. A. Eades, ibid. 72 (1980) 6368.
We assume, on the basis of its very simple IR spectrum
with only three absorptions (cf. Table I), that 6 is best represented as the salt of the anion SN;' (point group &)
which is isoelectronic with SO2.
Reaction of K2SN2 ( 6 ) with chloro(trimethy1)-silane or
-stannane affords the sulfur diimides S(NSiMe& ( l a ) and
S(NSnMe3)2 in 75 and 87% yield, respectively. The reaction of 6 with hexacarbonyltungsten leads to formation of
the isocyanato complex K[W(CO),(NCO)] 8.
Dipotassium Sulfur Diimide, K2SN2**
By Max Herberhold* and Wolfgang Ehrenreich
Organosulfur diimides, S(NR')2 1, are attacked at the
sulfur by nucleophiles such as carbanions, alkoxide ions,
or amide ions''-31. Reaction of S(NR'), [R' = SiMe3 ( l a ) or
tBu (lb)] with potassium amide in liquid ammonia leads
to displacement of one of the two R' groups with formation of salts of the type K[NSNR'] 5141.More drastic reaction conditions lead to the loss of both R' substituents.
l a , R'
l b , R'
p k y
Sa, R' = SiMe3
Sb, R' = tBu
We have found that the reaction of l a with potassium
tert-butoxide in boiling dimethoxyethane (DME) opens up
a route for preparing the pale yellow salt K2SN26 in high
yield (85-96%), thus making it a useful reagent for further syntheses. Potassium sulfinylamide, KNSO 7, can be
prepared in an analogous way"].
N/ \N
2 KOtBu
2 tBuOSiMe,
Table I. Comparison of the fundamental vibrations [cm-'1 of the three isoelectronic 18e-systems SOz, NSOe, and SN:e.
OSO [a]
7 [bl
6 [cl
1360 vs
1151 m
518 m
1270 vs
990 vs
515 vs
1 I98 vs
1001 m
528 m
[I] J. Kuyper, K. Vrieze, J. Chem. SOC.Chem. Commun. 1976. 64.
[2] H. W. Roesky, W. Schmieder, W. Isenberg, D. Bohler, G. M. Sheldrick,
Angew. Chem. 94 (1982) 143; Angew. Chem. Int. Ed. Engl. 21 (1982)
131 H. W. Roesky, W. Schmieder, J. Chem. SOC. Chem. Commun. 1981.
[4] D. Hanssgen, B. Ross, 2.Anorg. ANg. Chem. 473 (1981) 80.
[5] D. A. Armitage, J. C. Brand, J. Chem. SOC.Chem. Commun. 1979, 1078.
KdNi2(N2S2)2(CN)21-A Dinuclear Complex
with the S 2 g Q Chelate Ligand**
The salt 6 is stable up to 180 "C and above. It reacts explosively with water, methanol, or halomethanes (CH2C12,
CHC13, CC14) thereby bursting into flames. It is insoluble
in hydrocarbons, ethers, and liquid ammonia.
CAS Registry numbers:
l a , 18156-25-7; 6,82495-69-0; 7, 73400-02-9; 8,8251 1-75-9; SO2,7446-09-5;
W(CO)f,, 14040-11-0
OQS*No+ tBuOSiMes
Received: March 19, 1982 [Z 173 IE]
German version: Angew. Chem. 94 (1982) 637
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982, 1346-1352
All operations were carried out in oven-dried apparatus
under an atmosphere of dry argon; the solvents were anhydrous and saturated with argon. To 100 mL of a clear
0.79 M solution of KOtBu in DME (content determined by
titration with 0.1 N HCI), heated under reflux (oil bath ca.
95 "C), was added a solution of l a (8.0 g, 38.8 mmol) in
DME (30 mL), dropwise within 3 h. About 15 min after
starting the addition a yellow precipitate formed, the
amount of which steadily increased. After completion of
the addition the reaction mixture was kept at the boiling
point for an additional hour. The solution was then decanted, the precipitate 6 washed with THF and ether, and
dried for 3 h in a high vacuum: yield 4.6 g (85%).
[a] Gas phase; [b]cf. IS]; [c] Nujol/Kel-F-3.
[*I Prof. Dr. M. Herberhold, W. Ehrenreich
Laboratorium fur Anorganische Chemie der Universitat
Universitatsstrasse 30, D-8580 Bayreuth (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
Angew. Chem. h i . Ed. Engl. 21 (1982) No. 8
By Karlheinz Hornemann and Johannes Weiss*
Dedicated to Professor Georg Wittig on the occasion of
his 85th birthday
Mononuclear complexes of Co", Nil', Pd", and Pt" with
the chelate ligand [S=N-S-NH]e
have been known for
some time. These planar complexes 1 are stable, intensely
colored, and have a cis-configuration. They are formed as
the major products in the reaction of S,N, with CoC12,
N U 2 , PdC12, and H2PtC1:".
We have now prepared the first dinuclear complex with
the dianionic chelate ligand. It is formed from 1, M = Ni,
and KCN in methanolic solution in presence of KHC0,I2l;
in contrast, in more alkaline media, i. e. in the absence of
KHC03, the previously known mononuclear complex 2 is
[*] Prof. Dr. J. Weiss, K. Hornemann
Anorganisch-chemisches Institut der Universitgt
Im Neuenheimer Feld 270, D-6900 Heidelberg I (Germany)
[**I Metal Sulfur-Nitrogen Compounds, Part ll.-Part 10: U. Thewalt, J.
Weiss, Z. Naturforsch. B 23 (1968) 1265.
Q Verlag Chemie GmbH, 6940 Weinheim, 1982
0570-0833/82/0808-0633 $ 02.50/0
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