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X-Ray Structure Analysis of a 4 5-Dihydro-3H-14 2 6-thiadiazine.

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other by 4 %, one being axial and the other equatorial, and
the adjacent C O bonds by 2 % in the opposite sense.
Structure ( B ) would indicate the four protons of the dioxaphospholane ring (2) to differ from each other; in solution,
however, they are found to be equivalent by NMR. Hence
( B ) must exist in mobile equilibrium with other structures
[including ( A ' ) ] in solution.
In a very recent publication['], Trippett et a / . describe the
phosphorane ( 3 ) , which, having the same structural alternatives ( A ' ) / ( B ) , adopts the C, structure ( A ' ) , presumably
owing to the greater difference in electronegativity between
the atoms exchanging positions: On going from ( A ' ) to ( B ' )
an 0 , O pair must relinquish its apical position to on 0 , N
pair in the case of (2), but to a C,C pair in the case of
ment, 8/2 8 scan); 183 reflections were unobserved (I I 2 q).
The structure was solved by direct methods. All atoms (except
H) could be located by an E-Fourier synthesis with the 300
largest E-values. Refinement by the method of least squares
(full matrix), first using isotropic and then anisotropic temperature parameters initially gave an R value of 8.2x. At
this stage of the refinement all hydrogen atoms could be
located in a difference Fourier synthesis. On inclusion of the
H-atoms with isotropic thermal parameters the refinement
converged at an R value of 4.1%.
Received: September 6. 1976 [Z 577 IE]
German version: Angew. Chem. X X . 851 (1976)
Four- and Five-Membered Phosphorus Heterocycles, Part 20. This work
was supported by the Fonds der Chemischen 1ndustrie.-Part
19: J .
Luher and A. Schmidpeter. Chem. Ztg.. in press.
W S. Sheldrick, A . Schniidperrr, and J . H. W,iiiimier, Angew. Chem.
X7,519(1975);Angew.Chem. Int. Ed. Engl. /4.490(1975); W S . ShelrlricL,
Acta Crystallogr. 8 3 2 . 925 (1976).
A. Srhinidperer. J . Liher. D. Schoinhiirg. and W S. Sheldrick, Chem.
Ber. 109. 3581 (1976).
M . I . Kahachiiik. !L A . Gi/roror. N. A. Ti!dioiiii~rr, A. E. Koliiiiii, V
G . Adriuiior. Yu. T: S r r d i k o r . . and G . I. Tiino/reru. Phosphorus 5. 65
( I 974).
A . Schniidprto. and J . H. Weiiiimier, Angew. Chem. X7, 517 (1975):
Angew. Chem. Int. Ed. Engl. 14, 489 (1975).
( 2 ) . m.p. 140°C: b 3 ' P = 16.4ppm I% H 3 P 0 4 (in CH2C12):
14.1 Hz: monoclinic crystals. P2,/n
b'H(C2H4)=4.17ppm. d. JPOCH=
with a = 10.173(2), h=8.988(2). r=21,053(4)r\. p= 101.69(2)". Z = 4 .
f/c,l, = 1.38gcm~2.Thestructurewassolved
bydirect methodsand refined
to R=0.053, Rw=0.047 for 2602 independent reflections [/>2.0(1)].
H. A. E. A/!.. J . H. Burlon, D. R. Ru.sse/, D. J . H . Smith, M . Sirind/r.s,
and S. Trippett, J . Chem. SOC.Chem. Commun. 1976.449.
X-Ray Structure Analysis of a 4,5-Dihydro-3H-1L4,2,6thiadiazine
By Alfred Gieren and Franz Pertlik"]
X-ray structure analyses of non-cyclic sulfur diimides"] Itd
to the conclusion that the S"=N bond lengths (ca. 1.53 A)
are independent of the substituents at the SN2 group and
of the configuration at the S=N bonds.
We have now carried out an X-ray structure analysis of
the cyclic sulfur diimide 4-(4-chlorophenyl)-4,5-dihydro-3H1h4,2,6-thiadiazine (I) ['I.
The compound crystallizes from ethanol in the monoclinic
. space gr2up P2,/n; lattice constants: a = 12.58,, b= 10.95,,
c = 7.27, A, 3! = 103.0," ; Dexp= 1.44, g . ~ m - ~DX.ray
, = 1.45, ; Z = 4 . 1876 independent reflections were measured
on an automatic single crystal diffractometer with Cu-K,
radiation up to a maximum 8 value of 70" (5-value measure[*] Dr. habil. A. Gieren
Max-Planck-lnstitut fur Biochemie. Abt. Strukturforschung I
Am Klopferspitz. D-8033 Martinsried (Germany)
Dr. F. Pertlik
lnstitut fur Minerologie und Kristallograph~eder Universitit
Dr. Karl Lueger-Ring I , A-1010 Wien (Austria)
Fig. I . Molecular structure of4-(4-chlorophenyl)-4,5-dihydro-3H-l
i.4,2.6-thiadiazine ( I ). The standard deviations of the given bond lengths vary between
0.003 and 0.005A (except C-H: 0.03 4 0 4 A ) . those of the angles between
0.2 and 0.3".
Figure 1 shows the molecular structure. The ring containing
the SN2 group has a half-boat conformation with the apex
at C-2. The p-chlorophenyl moiety occupies an equatorial
position at C-2 and is orientated almost perpendicularly to
the best plane through the heterocyclic ring. The best planes
through the coplanar atoms of the two six-membered rings
are at an angle of 84" to each other. To a good approximation
the molecule contains a plane of symmetry perpendicular
to the heterocyclic ring in the plane of the p-chlorophenyl
ring. The cause ofthe half-boat conformation is the coplanarity
of the sulfur diimide group with the substituents at the
nitrogen atoms. In the meantime the same conformation has
been found in the S3N304 anion[31and in a cyclotetraphosphazene bridged by a sulfur diimido group[41, in which the SN,
group is likewise part of a six-membered ring.
The length of the S=N double bond is 1.534A and agrees
within limits of error with the S=N bond lengths in the
reference compounds. Since the substituents at the N atoms
in ( I ) do not allow rc-interaction with the SN, system it can
be concluded from the above agreement that the length of
the S'"=N bond in organic sulfur diimides is independent
of the nature of the substituents, even though the reactive
behavior of the SN2 group is subject to a distinct substituent
effect. The configuration at the S'"=N double bond also
has no influence on the bond length.
The angle at the sulfur atom is I 18.5" and obviously varies
only within narrow limits. In the open-chain reference compounds it is I17""] and 1 15°[1b1,in the cyclic compounds
The nitrogen atoms of the SN2 group are sp2 hybridized,
which follows not only from the bond angles at the N atoms
(1 18.3"),but also from the N - C bond lengths (1.455A). These
bond lengths correspond to the value for N - - C single bonds
of the type sp2-sp3. The angles at C-1 and C-2 are about
4.5" wider than an ideal tetrahedral angle.
The structure of ( 1 ) contradicts a "double ylide" structure[']
in sulfur diimides.
Received. October 14. 1976 [Z578a IE]
German version: Angew. Chem. 88. 852 (1976)
CAS Registry numbers:
( I ). 60840-53-1
[I] a) G . Lwridri, K Btwtri. G . K d k . and M . M~iiiinii,Chem. Commun.
IY70.413: b) A . Gierwi and f . Prrtlil. Abstracts of the Second European
Crystdlographic Meeting. Keszthely (Hungary). 1974. p 303.
First results: G . K r e . ~ ein C . J . M. S r d i r i g ; Organic Sulphur Chemlstry.
Butterworths. Londott 1975. p. 65.--We thank Professor K'rcsx~ and
Dr. WIILIim.p/c,riiiiyfor supplying the substance. A'. Schriiihei.yw. Dtplomarbelt. Technische Universitiit Miinchen, Miirz 1970.
[3] I. R L I ~ I I Iand
~ ~ IH.
I ~ M . M. Shrorer, Acta Crystallogr. Sect. A 3/, S 62
(1975): H . M . M. Shrorrr. private communication.
[4] A. Girwri. B. Dedrrrr, H. W Roesky. and E . Jorisseii. Angew. Chem.
XX. 852 (1976): Angew. Chem. Int. Ed. Engl. I S , 783 (1976).
[ S ] A . F Coiiirrort. I. R. Coiiirroii. M. M . Coiiiphell, and G . Johrisori, Acta
Crystallogr. Sect. B 32. 1277 (1976).
which fulfil the higher symmetry of the space group B2/b.
In a subsequent Fourier synthesis with all reflections phased
by the phosphorus atoms it was possible to recognize the
sulfur atoms which breached the symmetry of the more
highly symmetrical space group. The remaining atoms (F
and N) could be located by a further Fourier synthesis with
inclusion of the sulfur atoms in the phase determination.
Refinement by the method of least squares, first using isotropic
and then anisotropic temperature factors converged at an R
value of 5.2% (observed reflections).
The analysis showed that (1 ) does not have the proposed
constitution ( I a ) [ ' ] , but that of a 9h4-thia-2,4,6,8,10,11hexaaza- 1h5,3h5,5h', 7h5- tetraphosphabicyclo [5.3.11undeca1,3,5,7(11),8,9-hexaene ( I b). The bridging of the cyclotetraphosphazene system by the S N 2 group permits planar arrangesystem (Fig. I). The six-memment of the P-N=S=N-P
bered ring arising by virtue of the SN2 bridge proves to
have a half-boat conformation with the apex at N-4. This
conformation is consistent with that of the 4-(4-chlorophenyl)4,5-dihydro-3H-l h4,2,6-thiadiazine[3', in which the SN2 group
is likewise part of a six-membered ring.
The Structure of a Cyclotetraphosphazene Bridged by
a Sulfur Diimido Group
By Alfred Giereri, Bernhurd Dederer, Herbert W Roesky, and
EllllO JtJll.S.Sell[*l
The synthesis of a novel cyclotetraphosphazene bridged
by a sulfur diimido group has recently been reported['! The
constitution ( I n ) was proposed for the compound. Such a
constitution assumes a non-planar arrangement of the
system and would beinconsistent with recent
X-ray structure analyses[2.'I, which indicate a coplanar arrangement of the SN2 system and the substituents at the nitrogen atoms as being characteristic for sulfur diimides. We have
therefore carried out an X-ray structure analysis of ( I ) .
il a )
The crystals of ( I ) obtained by sublimation crystallize in
the monoclinic space group P2Jb with a=9.43,, b= 20.102,
c = 11.62, ; y = 103.5,'. The unit cell contains eight formula
units (2 formula units/asymmetric unit). The crystal structure has an additional pseudosymmetry of the space group
B2/b, since reflections of the type h + 1= 2n + 1 are on average
much weaker than those of the type /I + I= 211. This pseudoextinction comes about since the greater parts of the two molecules of the asymmetric unit can to a good approximation
be interconverted by the translation (2+?)/2.6176 independent
reflections were measured with MoK,-radiation (Nb filter)
on an automatic single crystal diffractometer up to a maximum t) value of 30" (5-value measurement; 8/28 scan). 2109
. structure was solved
reflections were unobserved ( I 1 2 0 ~ )The
by direct methods. An E-Fourier synthesis with 213 phased
reflections showed the positions of the phosphorus atoms
. -
[*] Dr. habil. A. Gieren and Dipl.-Chem. B. Dederer
Max-Planck-lnstitut fur Biochemie, Abt. Strukturforschung I
Am Klopferspitz, D-8033 Martinsried (Germany)
Prof. Dr. H. W. Roesky and Dr. E. Janssen
Anorganisch-chemisches lnstitut I der Universitiit
Niederurseler Hang, D-6000 Frankfurt 50 (Germany)
F 2
N 3
F 5
Fig. I . Structure of the 9~i-thia-2.4, l - h e ~ a a z a - l i ~ , 3 i . ~ . 5 ~ . ~ . 7 ~ ~ - t e t r a phosphabicyclo[5.3.1]undeca-1.3.5,7( I I ).8.9-hexaene ( I h ) . The bond lengths
and angles have been averaged over the two molecules of the asymmetric
unit. The mean standard deviations are 0.003A for the bond lengths and
0.2" for the bond angles.
The eight-membered cyclotetraphosphazene ring has a
crown-saddle conformation, the larger part of which is flattened out. Except at N-4 the eight-membered ring is almost
planar. The greatest deviation from planarity of theobest
plane through its atoms (excluding N-4) is only 0.11A. In
the crystalline state the molecule has, to a first approximation, a plane of symmetry through S-I, N-4, and N-2 perpendicular to the best plane through the eight- and six-membered
The S-N bonds are 1.53 A long and are pure S"=N
double bonds, as has also been found in all other sulfur diimides
investigate by X-ray structure ,analysis. The angle at the
sulfur atom (119.3") is practically the same as that in 4-(4chlorophenyl)-4,5-dihydro-3H-I h4,2,6-thiadiazinec3l: (118.5").
The S-N bond lengths point to the fact that there is no
coupling between the d,-p,eIectron system of the SN, group
and that of the cyclotetraphosphazene ring. This fact is
also supported by the P-N bond lengths. In the cyclotetraphosphazene ring the P-N bond lengths vary between 1.56
and 1.51 A and thus evidence distinct partial double bonding,
whereas the P-No bond lengths to the SN2 system (1.67 A)
are more than 0.1A longer. The variation in the length of the
P-N bonds in the phosphazene ring can be correlated with
the degree of fluorine substitution at the phosphorus atom
and the bond angles at the N atoms: the P-N bond length
is shorter the higher the degree of F-substitution and the
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dihydro, structure, thiadiazine, analysis, ray
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