M_r =140∙19, monoclinic, P2_1/n, a = 10∙612(3), b=6∙820(1), c= 10∙975 (2) Å, β=95∙31(2)°, V=790.9(5) Å^3, Z=4, D_m=1.13(5) (flotation), D_x = 1∙177 g cm^(-3), Mo Kα, λ = 0.71073 Å, μ= 0.848 cm^(-1), F(000) = 304, T= 295 K, R = 0∙077 for 704 observed reflections. This potentially antiaromatic or homoaromatic ring system has a flattened boat conformation with both N-methyls in equatorial positions. Bond angles and distances (excluding H's) predicted to be symmetry equivalent exhibit variations of 0.002-0.014 Å and 0.0-2.0°. Substantial delocalization of the electron lone pairs of N(1) and N(4) is found

Bemis, Guy W.

Mayo, Stephen L.

Olofson, R. A.

Whittle, Robert R.

English

Caltech Authors - Main

2076 ACIDE tert-BUTYL-2 CYCLOHEXENE-3  CARBOXYL IQUE- I - t rans  
R~f~rences 
ALLINGER, N. L. & CHANG, S. H. M. (1977). Tetrahedron, 33, 
1561-1567. 
AYCARD, J. P. & BODOT, H. (1973). Can. J. Chem. 51,741-747. 
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226-236. 
BEAGLEY, B. (1973). Molecular Structure by Diffraction Methods, 
Tome 1, p. 93. London: The Chemical Society. 
BEAGLEY, B. (1975). Molecular Structure by Diffraction Methods, 
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BUCOURT, R. (1974). Top. Stereochem. 8, 159-224. 
BUSING, W. R., MARTIN, K. O. & LEVY, H. A. (1962). ORFLS. 
Rapport ORNL-TM-305. Oak Ridge National Laboratory, 
Tennessee. 
Cossu, M., VIANI, R. & LAPASSET, J. (1981). Acta Cryst. B37, 
481-483. 
DOYLE, P. A. & TURNER, P. S. (1968). Acta Cryst. A24, 390-397. 
HUGHES, E. W. (1941).J. Am. Chem. Soc. 63, 1737-1752. 
LAFRANCE, R., AYCARD, J. P. & BODOT, H. (1977). Org. Magn. 
Resort. 9, 253-259. 
MAIN, P., WOOLFSON, M. M., LESSINGER, L., GERMAIN, G. & 
DECLERCQ, J.-P. (1974). MULTAN. A System of Computer 
Programs for the Automatic Solution of Crystal Structures from 
X-ray Diffraction Data. UniTs. de York, Angleterre t Louvain, 
Belgique. 
MONNIER, M. (1977). Th6se de Sp6cialit~ (Chimie Organique). 
Univ. de Provence, Marseille, France. 
SCHARPEN, L. H., WOLLRAB, J. E. & AMES, D. P. (1968). J Chem. 
Phys. 49, 2368-2372. 
SPEAKMAN, J. C. (1976). Molecular Structure by Diffraction 
Methods, Tome 4, p. 66. London: The Chemical Society. 
STEWART, R. F., DAVIDSON, E. R. & SIMPSON, W. T. (1965). J. 
Chem. Phys. 42, 3175-3187. 
VIAN1, R., Cossu, M. & LAPASSET, J. (1981). Acta Co'st. B37, 
484-486. 
VlANI, R. & LAPASSET, J. (1978). Acta Co'st. B34, 1195-1198. 
VIANI, R. & LAPASSET, J. (1981). Acta Cryst. B37, 477-480. 
V1ANI, R., LAPASSET, J., AYCARD, J. P., LAFRANCE, R. & BODOT. 
H. (1978). Acta Cryst. B34, 1190-1194. 
Acta Cryst. (1984). C40, 2076-2078 
1,3,4,6-Tetramethyl- 1,4-dihydro- 1,2,4,5-tetrazine, C6H12N 4 
BY GuY W. BEMIS, ROBERT R. WHITTLE, STEPHEN L. MAYO AND R. A. OLOFSON 
Department of  Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA 
(Received 16 April 1984; accepted 8 August 1984) 
Abstract. M r = 140.19, monoclinic, P21/n ,
a= 10.612(3), b=6.820(1) ,  c= 10.975 (2) /~, f l=  
95.31(2) °, V=790.9(5),A,3,  Z=4,  Om=l .13(5)  
(flotation), D x = 1. 177 g cm -3, Mo Kct, 2 = 0.71073 ,A,, 
/~ = 0-848 cm -l, F(000) = 304, T= 295 K, R = 0.077 for 
704 observed reflections. This potentially antiaromatic 
or homoaromatic ring system has a flattened boat 
conformation with both N-methyls in equatorial 
positions. Bond angles and distances (excluding H's) 
predicted to be symmetry equivalent exhibit variations 
of 0 .002-0.014/~ and 0 .0-2 .0  °. Substantial delo- 
calization of the electron lone pairs of N(1) and 
N(4) is found. 
Introduction. In the past, planar antiaromatic (1), 
homoaromatic (2) and nonaromatic (3a), (3b) for- 
mulations as well as boat shapes (4) have been 
considered for the 8re-electron-available 1,4-dialkyl- 
1,4-dihydro-l,2,4,5-tetrazines (Kohn & Olofson, 1972; 
Hoskin, Wooden & Olofson, 1982). In a boat confor- 
mation, both N-alkyl groups may be axial, both 
equatorial or one axial and one equatorial (4a)-(4e). 
Previous NMR studies indicate that in solution the 
system is either symmetrical or rapidly inverting (Kohn 
& Olofson, 1972). An earlier attempt to resolve the 
structural ambiguity by solving the structure of 1,4- 
0108-2701/84/122076-03501.50 
dimethyl-l,4-dihydro-l,2,4,5-tetrazine failed because 
the molecule was disordered in the crystal (Hoskin, 
1981). A single-crystal X-ray diffraction study of the 
1,3,4,6-tetramethyl-substituted 1,4-dihydro- 1,2,4,5-te- 
trazine i(1)-(4),  R = R' = Mel is presented here. 
. . . . . . . . .  
(1)  (2)  
3(a) 3(b) 
•:• ~ R R R I I I , 
R--N N--R N--R 
N -, ~'R' N ~R' N ~'R' 
4(a) 4(b) 4(c) 
© 1984 International Union of Crystallography 
G. W. BEMIS, R. R. WHITTLE, S. L. MAYO AND R. A. OLOFSON 2077 
Experimental. Preparation by reaction of ethyl 
acetimidate.HCl with methylhydrazine (adapted from 
Kohn & Olofson, 1972), m.p. 363-365 K, lit. 364- 
365 K (Skorianetz & Kovats, 1972); very volatile solid 
slowly crystallized from dried hexanes; irregularly 
shaped piece (0.30 × 0.30 × 0.64 mm) cut from larger 
crystal and mounted in capillary. Unit-cell parameters 
(least squares) from 20 reflections in 0 range 6-13°; 
Enraf-Nonius CAD-4 diffractometer (graphite mono- 
chromator); data corrected for Lorentz and 
polarization factors but not for absorption; min. 
(s in~/2= 0.040, max. (sin0)/2 = 0.5323,/t-1; h,k,l 
min. 0,0,-11, max. 11,7,11; 3 standard reflections 
every hour (drift correction: empirical 0.996-1.000, 
intensity variation 0.9%, anisotropic 0.990-1.038); 
1168 reflections measured, 1004 unique; Rln t ---0.014; 
300 unobserved [I < 2tr(/)]; structure solved by direct 
methods (MULTAN78) with all non-H atoms refined 
anisotropically;* H's located from difference Fourier 
maps and refined with B~so fixed at 5.0,/~2; 127 
parameters efined; R = 0.077, wR - 0.097, S = 2.69; 
Corfield, Doedens & Ibers (1967) weighting scheme, 
p = 0.06, w = F2/a2(F2); max. A/o = 0.02; max. height 
in final difference Fourier map = 0.166 e ,/~-3; f, f , ,  
from Cromer & Waber (1974)compilation; programs: 
MULTAN78 (Main, Hull, Lessinger, Germain, De- 
clercq & Woolfson, 1978), SDP-Plus version 1.0 
(Frenz, 1983), OR TEPII (Johnson, 1965). 
Discussion. Atomic positional parameters are listed in 
Table 1 and significant bond distances and bond angles 
are given in Fig. 1 along with the crystallographic 
numbering system. From the stereoscopic view in Fig. 
2, it is evident hat the molecule has adopted a flattened 
boat shape with pyramidal N-methyl nitrogens [N(1) 
and N(4)] at the prow and stern. Bond distances and 
angles expected to be symmetry equivalent exhibit 
variations of 0.002-0.014 A and 0.0-2.0 ° (excluding 
H's). Both N-methyls [C(7) and C(9)] are pseudo- 
equatorial and the relationship between the H's on C(7) 
and C(9) and the substituents along with the sp 3 part of 
the lone pairs on the attached N(1) and N(4) is a nicely 
staggered one. The H's on the methyls [C(8) and 
C(10)], while nearly staggered with respect to the 
substituents on C(3) and C(6), are somewhat skewed, 
possibly from an attractive interaction between H and 
the sp 2 lone pairs on N(2) and N(5). N(1) and N(4) are 
only 0.240 (3) and 0.249 (3)/k from the planes made 
by the attached N(2)-C(6)-C(7) and N(5)-C(3)-- 
C(9), respectively. Thus, substantial delocalization of 
* Complete bond distances and angles, least-squares planes, 
anisotropic thermal parameters, structure factors and a stereo 
packing diagram have been deposited with the British Library 
Lending Division as Supplementary Publication No. SUP 39677 
(I 2 pp.). Copies may be obtained through The Executive Secretary, 
International Union of Crystallography, 5 Abbey Square, Chester 
CH 1 2HU, England. 
the N(1) electron pair to N(5) [and of N(4) to N(2)] is 
predicted and is confirmed by the small difference 
between the lengths of the classically double-bonded 
C(6)=N(5) (1.32,/k) vs the single-bonded C(6)-N(1) 
(1.38A) [also C(3)-N(4) 1.39 and C(3)=N(2) 
1.31 ,/~]. These differences are similar to those found 
for C(3)-N(4) (1.35A) and C(3)=N(2) (1.29A) 
in the 1,1,4-trimethyl-l,4-dihydro-l,2,4,5-tetrazinium 
cation (Hoskin, Wooden & Olofson, 1982). There both 
Table 1. Positional coordinates and Beq (A 2) values 
Beq = ~[a2Bll + b2B22 + 81B33 + ac(cosfl)Bj3l. 
x y z Beq 
N(I) 0-0513 (3) 0.1650 (5) 0.7071 (3) 6-68 (8) 
N(2) -0.0606 (2) 0.1874 (4) 0.7562 (2) 4.11 (6) 
N(4) -0-0206 (3) -0-1213 (5) 0.8375 (3) 7.34 (8) 
N(5) 0.0567 (2) -0.1683 (4) 0.7499 (2) 4.47 (6) 
C(3) -0-1043 (3) 0.0325 (5) 0.8098 (3) 5.34 (8) 
C(6) 0.0818 (3) -0.0237 (5) 0.6757 (3) 6.00 (8) 
C(7) 0.0890 (3) 0.3272 (6) 0.6350 (3) 6-13 (9) 
C(8) -0.2144 (3) 0.0551 (6) 0.8763 (3) 5.71 (9) 
C(9) -0.0583 (4) -0.2848 (6) 0.9087 (4) 6.7 (1) 
C(10) 0.1772 (3) -0.0566 (6) 0.5907 (3) 6.16 (9) 
% 
"~ 18.1 
119 .8~ 
O) "" ~j,o)/118.5 115.4~u~  
1198 J '~ 114.7 
~116.0  116.0 ~ 
.... .~  . . . . .  ~ 119.9 
Fig. 1. Crystallographic numbering system with bond distances (N) 
and angles (°) for non-H atoms (e.s.d. ranges are 0.003-0-004 A 
and 0.2°). 
Fig. 2. Stereoscopic view with thermal e lipsoids for non-H atoms at 
35% probability. 
2078 1,3,4,6-TETRAM ETHYL- 1,4-DIHYDRO- 1,2,4,5-TETRAZ I1~; E 
bonds in an unsymmetrically flattened boat are 
somewhat shorter because of the attractive ffect of the 
positive charge. Since C(3) is only 0.162 (3) A from the 
N(2)--N(4)--C(8) plane [and C(6) 0.151 (3) tk from 
N(1)-C(5)-C(10)], near sp 2 hybridization at C(3) 
[and C(6)] is indicated. The symmetry of the system 
is further evident from a comparison of the 
distances of related atoms from the C(7) -N(1) -  
N(4)--C(9) plane (0.002-0.003/k): N(2) 0.283 (2) vs 
N(5) 0.272 (3) ,/~, C(3) 0.443 (3) vs C(6) 0.406 (3) A, 
C(8) 0.584 (4) vs C(10) 0.519 (4)/k; similarly using 
the C(10)-C(6)-C(3)-C(8) plane (0.005-0.011 /k): 
N(I) 1.131 (3) vs N(4) 1.117 (3)A, N(2)1.169 (3) vs 
N(5) 1.177 (3) A, C(7) 2.399 (4)vs C(9) 2.392 (4) A. 
We thank Drs H. Kohn and D. Hoskin for useful 
discussions. We also are grateful to the National 
Institutes of Health and McNeil Pharmaceutical for 
grants that supported this investigation. 
References 
CORFIELD, P. W. R., DOEDENS, R. J. & IBERS, J. A. (1967). Inorg. 
Chem. 6, 197-204. 
CROMER, D. T. & WABER, J. T. (1974). International Tables for 
X-ray Crystallography, Vol. IV, Table 2.2A. Birmingham: 
Kynoch Press. 
FRENZ, B. A. (1983). Enraf-Nonius Structure Determination 
Package; SDP Users Guide, version of 6 January, 1983. 
HOSKIN, D. H. (198 l). PhD Thesis. The Pennsylvania State Univ. 
HOSKIN, D. H., WOODEN, G. P. & OLOFSON, R. A. (1982). J. Org. 
Chem. 47, 2858-2861. 
JOHNSON, C. K. (1965). ORTEPII. Report ORNL-5138. Oak 
Ridge National Laboratory, Tennessee. 
KOHN, H. & OLOESON, R. A. (1972). J. Org. Chem. 37, 
3504-3509. 
MAIN, P., HULL, S. E., LESS1NGER, L., GERMAIN, G., DECLERCQ, 
J.-P. & WOOLFSON, M. M. (1978). MULTAN78. A System of 
Computer Programs for the Automatic Solution of Co'stal 
Structures from X-ray Diffraction Data. Univs. of York, 
England, and Louvain, Belgium. 
SKORIANETZ, W. & KOVATS, E. (1972). Hell'. Chim. Acta, 55, 
1404-1414. 
Acta Cryst. (1984). C40, 2078-2079 
Struktur von 1,8-Di-2-pyridyl-3,6-dithiaoetan, CI6H2oN2S2 
VON ALFONSO CASTINEIRAS UND MARIA V. PAREDES 
Departamento de Qu[mica Inorganica, Facultad de Farmacia, Universidad e Santiago, Santiago de Compostela, 
Spanien 
UND WOLFGANG HILLER 
lnstitut ffir Anorganische Chemie der Universitdt Tdbingen, Auf  der Morgenstelle 18, D-7400 Tiibingen, 
Bundesrepublik Deutschland 
(Eingegangen am 19. Mdrz 1984; angenommen am18. August 1984) 
Abstract. M r= 304.48, monoclinic, P21/c, a = 
15.189(3), b=4.825(9) ,  c=11.833(2)  A, f l= 
107.64 (1) °, V= 826.3/k 3, Z = 2, D x= 1.224 g cm -3, 
Mo Kct, it = 0.71073/k, a = 3.015 cm -l, F(000) = 
324, T= 293 K, final R = 0.057 for 1032 significant 
[ I> 2a(/)] reflections. In the crystal structure the 
molecule xhibits the form of a chain, the pyridine rings 
being trans orientated. There are no unusual bond 
distances or angles. 
Einle|tung. 1,8-Di-2-pyridyl-3,6-dithiaoctan (bpdto) 
kann als vierziihniger N,S,S',N'-  und als zweiz~ihniger 
N,N'-Chelatligand fungieren (Castineiras, Molleda, 
Masaguer & Coto, 1983). Im Rahmen unserer Unter- 
suchungen fiber Komplexe von Kobalt(II) mit bpdto 
(Castineiras, Hiller, Striihle, Paredes & Sordo, 1984) 
als Modellsubstanzen ffir die homogene Katalyse 
berichten wir im folgenden fiber die Kristallstruktur des 
Chelatliganden bpdto. 
0108-2701/84/122078-02501.50 
Experimentelles. Farblose Kristallnadeln von bpdto 
wurden durch Umsetzung von 1,2-Ethandithiol mit 
2-Vinylpyridin erhalten (Goodwin & Lions, 1960). Die 
Substanz kristallisiert in schlechter Qualitiit. Kristall- 
gr6sse 0,9 x 0,15 x 0,1 mm, Buerger-Priizessions- 
aufnahmen" monoklin, P21/c. Vierkreisdiffraktometer 
CAD-4 von Enraf-Nonius, Mo Ka-Strahlung, 
Graphitmonochromator. Ermittlung der Gitter- 
konstanten anhand von 25 genau zentrierten Reflexen 
hoher Beugungswinkel (3 ° < 0 < 27°). Registrierung 
der Intensitiiten mit 20/0-scan, 0max=31 °. Keine 
signifikante A, nderung der Intensit~iten der Kontroll- 
reflexe im Verlauf der Messung. h +22, k +7, l + 17. 
3599 gemessene Reflexe, 2629 unabhiingige Reflexe, 
1032 Reflexe mit einer Intensitiit 1 > 20(/), die f/ir die 
Verfeinerung verwendet wurden. LP-Korrektur, 
Extinktionskorrektur, auf eine Absorptionskorrektur 
wurde verzichtet. Strukturaufkliirung mit MULTAN80 
(Main et al., 1980); H-Atomlagen wurden einer 
© 1984 International Union of Crystallography 


1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4

Enraf-Nonius Structure Determination Package; SDP Users Guide,

Spanien UND WOLFGANG HILLER lnstitut ffir Anorganische Chemie der Universitdt Tdbingen, Auf der Morgenstelle 18, D-7400 Tiibingen, Bundesrepublik Deutschland (Eingegangen am 19. Mdrz 1984; angenommen am 18.

Universidad e Santiago, Santiago de Compostela, Spanien UND WOLFGANG HILLER lnstitut ffir Anorganische Chemie der Universitdt Tdbingen, Auf der Morgenstelle 18, D-7400 Tiibingen, Bundesrepublik Deutschland (Eingegangen am 19. Mdrz 1984; angenommen am18.

https://authors.library.caltech.edu/24118/1/Bemis_1984_Acta_Crystallographica_Section_C_Crystal_Structure_Communications_1_3_4_6-Tetramethyl-1_4-dihydro-1.pdf

1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4

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