A low temperature redetermination of the monoclinic β form of cyclo­octaselenium

organic papers

Acta Cryst.(2004). E60, o2235±o2237 doi: 10.1107/S1600536804024055 Tiina Maaninenet al. Se₈

o2235

Acta Crystallographica Section E

Structure Reports

Online ISSN 1600-5368

A low-temperature redetermination of the

monoclinic

b

-form of cyclooctaselenium

Tiina Maaninen, Jari Konu and Risto S. Laitinen*

Department of Chemistry, PO Box 3000, FIN-90014 University of Oulu, Finland

Correspondence e-mail: [email protected]

Key indicators Single-crystal X-ray study T= 150 K

Mean(Se±Se) = 0.001 AÊ Rfactor = 0.040 wRfactor = 0.095

Data-to-parameter ratio = 24.9

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2004 International Union of Crystallography Printed in Great Britain ± all rights reserved

Monoclinic -cyclooctaselenium, Se8, crystallizes as discrete

eight-membered ring molecules. The low-temperature (150 K) crystal structure is composed of cyclic crown-shaped mol-ecules, similar to those of - and -Se8. The average SeÐSe

bond length is 2.308 (8) AÊ, the average bond angle is 105.7 (8)_{and the average torsion angle is 101 (2). In contrast}

with-Se8, the structure of-Se8does not show elongation of

the ring at low temperatures.

Comment

Selenium exhibits allotropy consisting of both cyclic and open-chain molecular forms. Hexagonal selenium is the stable allotrope of the element at normal temperatures and pres-sures. It consists of long trigonal polymeric chains (Keller et al., 1977). There are three modi®cations of cyclic Se8. While

the crystal structure of monoclinic-Se8has been determined

both at room temperature (Burbank, 1951; Cherin & Unger, 1972) and at low temperatures (Maaninen et al., 2001), the structural information about monoclinic -Se8relies only on

two early reports. Burbank (1952) suggested that monoclinic

-Se consists of chain molecules of eight atoms. Marshet al.

(1953), however, showed this to be in error and proved that the Se8molecule is a puckered crown-shaped ring, similar to

that found in monoclinic-Se8. The third modi®cation,-Se8,

was reported by Foss & Janickis (1977, 1980) and has a similar molecular geometry. The fourth cyclic allotrope of selenium is Se6(Miyamoto, 1979, 1980). In this contribution, we report the

redetermination of the crystal structure of -Se8, (I), at low

temperature. The compound was crystallized as an unexpected side-product of an attempt to prepare cyclic 1,3,5-triadamantyl triselenium triimide.

Monoclinic-selenium is composed of cyclic crown-shaped molecules, similar to those in- and-Se8(Fig. 1). At 150 K,

the average SeÐSe bond length is 2.308 (8) AÊ, the average bond angle is 105.7 (8) _{and the average torsion angle is}

101 (2)_{. As expected, the bond lengths (Table 1) are}

signi®-cantly shorter than the corresponding SeÐSe bond lengths at room temperature (Marshet al., 1953). While a similar trend is also observed for-Se8(Cherin & Unger, 1972; Marshet al.,

1953; Maaninenet al., 2001), it is interesting to note that, in the

case of -Se8, the eight-membered ring molecule becomes

more distorted as the temperature is lowered (Maaninenet al., 2001), resulting in an increase in the bond-length range [2.269 (1)±2.327 (1) AÊ; average 2.301 (18) AÊ; see Table 1]. A similar distortion is not so pronounced in -Se8 [2.301 (1)±

2.324 (1) AÊ].

The shortest intermolecular distances in -Se8 are

Se2 Se5 and Se5 Se8 [3.382 (1) and 3.417 (1) AÊ, respec-tively]. There are also several other close contacts in the range 3.519 (1)±3.656 (1) AÊ, which link the molecules into a three-dimensional network, as shown in Fig. 1.

Experimental

Adamantylamine (4.084 g, 27.0 mmol) was treated with selenium dichloride, which was prepared in situ from elemental selenium (0.911 g, 9.0 mmol) and sulfuryl chloride (1.215 g, 9.0 mmol) (Maaninenet al., 1999). The reaction was carried out at 193 K in 40 ml of tetrahydrofuran (THF). A small number of red crystals were obtained from the reaction solution.

Crystal data

Se8

Mr= 631.68 Monoclinic,P21=c

a= 9.2004 (18) AÊ

b= 8.0000 (16) AÊ

c= 12.735 (3) AÊ

= 92.95 (3)

V= 936.1 (3) AÊ3

Z= 4

Dx= 4.482 Mg mÿ3

MoKradiation Cell parameters from 9298

re¯ections

= 2.2±26.0

= 31.14 mmÿ1

T= 150 (2) K Prism, red

0.150.080.05 mm

Data collection

Nonius KappaCCD diffractometer

'scans, and!scans withoffsets Absorption correction: multi-scan

(SHELXTL; Bruker, 2001)

Tmin= 0.062,Tmax= 0.211

9298 measured re¯ections 1821 independent re¯ections

1463 re¯ections withI> 2(I)

Rint= 0.078 max= 26.0

h=ÿ10!11

k=ÿ9!9

l=ÿ15!15

Refinement

Re®nement onF2

R[F2_{> 2(F}2_{)] = 0.040}

wR(F2_{) = 0.095}

S= 1.09 1821 re¯ections 73 parameters

w= 1/[2_(Fo2_{) + (0.0413P)}2

+ 5.4999P]

whereP= (Fo2_{+ 2Fc}2_)/3

(/)max= 0.001 max= 1.13 e AÊÿ3 min=ÿ1.23 e AÊÿ3

Table 1

Cell parameters (AÊ, AÊ3_{), bond lengths (AÊ) and angles () for Se}

8 at

different temperatures (K).

Polymorph and

temperature at 150 (2) K-Se8 a _{at r.t.}-Se8b _{at 123 (2) K}-Se8 c _{at 299 K}-Se8 d

Cell parameters

a 9.200 (2) 9.31 (1) 8.9247 (2) 9.054 (3)

b 8.000 (2) 8.07 (1) 8.9665 (2) 9.083 (5)

c 12.735 (3) 12.85 (1) 11.3687 (2) 11.601 (6)

92.95 (3) 93.8 (5) 90.583 (1) 90.81 (5)

V 936.1 (3) 964 (1) 909.71 (3) 953.9 (8) Bond

Se1ÐSe2 2.302 (2) 2.30 2.327 (1) 2.346 (5) Se2ÐSe3 2.314 (1) 2.36 2.307 (1) 2.337 (5) Se3ÐSe4 2.310 (1) 2.33 2.310 (1) 2.333 (5) Se4ÐSe5 2.312 (1) 2.33 2.320 (1) 2.331 (5) Se5ÐSe6 2.324 (1) 2.37 2.293 (1) 2.332 (4) Se6ÐSe7 2.301 (2) 2.34 2.291 (1) 2.345 (5) Se7ÐSe8 2.303 (2) 2.36 2.269 (1) 2.326 (4) Se8ÐSe1 2.305 (1) 2.31 2.293 (1) 2.337 (4) Angle

Se1ÐSe2ÐSe3 106.50 (5) 106.7 107.88 (5) 107.68 (4) Se2ÐSe3ÐSe4 104.60 (5) 104.2 107.35 (4) 107.51 (4) Se3ÐSe4ÐSe5 105.09 (5) 105.8 106.78 (4) 106.60 (5) Se4ÐSe5ÐSe6 105.92 (5) 107.1 103.15 (4) 103.97 (4) Se5ÐSe6ÐSe7 105.19 (5) 105.7 103.32 (5) 103.65 (4) Se6ÐSe7ÐSe8 105.87 (5) 104.7 105.30 (5) 105.23(4) Se7ÐSe8ÐSe1 106.97 (5) 106.3 107.41 (5) 107.10 (5) Se8ÐSe1ÐSe2 105.37 (5) 104.8 103.98 (5) 104.08 (4)

(a) This work. (b) Marshet al.(1953) utilized the cell parameters of Burbank (1951); the temperature is unspeci®ed; the atoms have been renumbered to correspond to those in the present structure. (c) Maaninenet al.(2001). (d) Cherin & Unger (1972); the atoms have been renumbered to correspond to those reported by Maaninenet al.(2001).

The maximum residual electron density is 0.89 AÊ from atom Se4 and the minimum residual electron density is 0.72 AÊ from atom Se2. Data collection:KappaCCD Server Software(Nonius, 1997); cell

re®nement: DENZO-SMN (Otwinowski & Minor, 1997); data

reduction: DENZO-SMN; program(s) used to solve structure:

SHELXS97 (Sheldrick, 1997); program(s) used to re®ne structure:

SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND

(Brandenburg & Berndt, 1999); software used to prepare material for publication:WinGX(Farrugia, 1999).

Financial support from the Academy of Finland, the Emil Aaltonen Foundation and the Finnish Cultural Foundation's

organic papers

o2236

Tiina Maaninenet al. Se₈ Acta Cryst.(2004). E60, o2235±o2237

Figure 1

The molecular structure of-Se8, indicating the labelling scheme of the

atoms. Displacement ellipsoids have been drawn at the 50% probability level. The shortest intermolecular Se Se close contacts are indicated by dotted lines. [Symmetry codes (as suf®xes): (1)ÿx,1

2+y,32ÿz; (2)x,

1 +y,z; (3) 1ÿx, 1ÿy, 2ÿz; (4)x,3

2ÿy,12+z; (5)x,12ÿy,12+z; (6)x,

ÿ1 +y,z; (7)x,1

Regional Fund of North Ostrobothnia is gratefully acknowl-edged.

References

Brandenburg, K & Berndt, M (1999).DIAMOND.Release 2.1. Crystal Impact GmbH, Bonn, Germany.

Bruker (2001). SHELXTL (Version 6.12). Bruker AXS Inc., Madison, Wisconsin, USA.

Burbank, R. D. (1951).Acta Cryst.4, 140±148. Burbank, R. D. (1952).Acta Cryst.5, 236±246. Cherin, P. & Unger, P. (1972).Acta Cryst.B28, 313±317. Farrugia, L. J. (1999).J. Appl. Cryst.32, 837±838.

Foss, O. & Janickis, V. (1977).J. Chem. Soc. Chem. Commun.pp. 834±835. Foss, O. & Janickis, V. (1980).J. Chem. Soc. Dalton Trans.pp. 624±627.

Keller, R., Holzapfel, W. B. & Schulz, H. (1977).Phys. Chem. Rev.B16, 4404± 4412.

Maaninen, A., Chivers, T., Parvez, M., PietikaÈinen, J. & Laitinen, R. S. (1999).

Inorg. Chem.38, 4093±4097.

Maaninen, A., Konu, J., Laitinen, R. S., Chivers, T., Schatte, G., PietikaÈinen, J. & Ahlgren, M. (2001).Inorg. Chem.40, 3539±3543.

Marsh, R. E., Pauling, L. & McCullough, J. D. (1953).Acta Cryst.6, 71±75. Miyamoto, Y. (1979).Fukuoka Daigaku Rigaku Shuho,9, 1±13.

Miyamoto, Y. (1980).Jpn. J. Appl. Phys.19, 1813±1819.

Nonius (1997).KappaCCD Server Software. Nonius BV, Delft, The Nether-lands.

Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,

Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307±326. New York: Academic Press.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of GoÈttingen, Germany.

organic papers

supporting information

sup-1 Acta Cryst. (2004). E60, o2235–o2237

supporting information

Acta Cryst. (2004). E60, o2235–o2237 [https://doi.org/10.1107/S1600536804024055]

A low-temperature redetermination of the monoclinic

β

-form of

cyclo-octaselenium

Tiina Maaninen, Jari Konu and Risto S. Laitinen

beta-monoclinic cyclooctaselenium

Crystal data

Se8

Mr = 631.68

Monoclinic, P21/c Hall symbol: -P 2ybc

a = 9.2004 (18) Å

b = 8.0000 (16) Å

c = 12.735 (3) Å

β = 92.95 (3)°

V = 936.1 (3) Å3

Z = 4

F(000) = 1088

Dx = 4.482 Mg m−3

Mo Kα radiation, λ = 0.71073 Å Cell parameters from 9298 reflections

θ = 2.2–26.0°

µ = 31.14 mm−1

T = 150 K Prism, red

0.15 × 0.08 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

φ scans, and ω scans with κ offsets Absorption correction: ψ scan

(SHELXTL; Bruker, 2001)

Tmin = 0.062, Tmax = 0.211

9298 measured reflections 1821 independent reflections 1463 reflections with I > 2σ(I)

Rint = 0.078

θmax = 26.0°, θmin = 2.2°

h = −10→11

k = −9→9

l = −15→15

Refinement

Refinement on F2 Least-squares matrix: full

R[F2 _{> 2σ(F}2_{)] = 0.040}

wR(F2_{) = 0.095}

S = 1.09 1821 reflections 73 parameters 0 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

w = 1/[σ2_(F

o2) + (0.0413P)2 + 5.4999P] where P = (Fo2 + 2Fc2)/3

(Δ/σ)max = 0.001 Δρmax = 1.13 e Å−3 Δρmin = −1.23 e Å−3

Special details

supporting information

sup-2 Acta Cryst. (2004). E60, o2235–o2237

Refinement. Refinement of F2 _{against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F}2_, conventional R-factors R are based on F, with F set to zero for negative F2_{. The threshold expression of F}2 _{> σ(F}2_{) is used} only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2₎

x y z Uiso*/Ueq

Se1 0.06355 (10) 0.68641 (11) 0.91290 (7) 0.0288 (2)

Se2 0.25586 (11) 0.77285 (11) 1.02241 (8) 0.0304 (3)

Se3 0.25827 (11) 0.60084 (11) 1.16858 (7) 0.0279 (2)

Se4 0.44886 (10) 0.41857 (11) 1.14620 (7) 0.0256 (2)

Se5 0.34045 (11) 0.17089 (11) 1.09083 (7) 0.0270 (2)

Se6 0.35943 (10) 0.16250 (11) 0.90960 (7) 0.0240 (2)

Se7 0.13558 (10) 0.24704 (12) 0.84010 (7) 0.0297 (3)

Se8 0.16495 (11) 0.52018 (13) 0.78818 (7) 0.0329 (3)

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

Se1 0.0278 (5) 0.0309 (5) 0.0278 (5) 0.0072 (4) 0.0030 (4) 0.0012 (4)

Se2 0.0354 (6) 0.0211 (5) 0.0350 (6) −0.0020 (4) 0.0058 (4) 0.0020 (4)

Se3 0.0337 (6) 0.0245 (5) 0.0261 (5) 0.0009 (4) 0.0075 (4) −0.0018 (4)

Se4 0.0241 (5) 0.0279 (5) 0.0246 (5) −0.0011 (4) 0.0005 (4) −0.0008 (4)

Se5 0.0358 (6) 0.0223 (5) 0.0236 (5) −0.0006 (4) 0.0068 (4) 0.0026 (3)

Se6 0.0281 (5) 0.0208 (5) 0.0235 (5) 0.0008 (4) 0.0057 (4) 0.0002 (3)

Se7 0.0246 (5) 0.0364 (6) 0.0283 (5) −0.0029 (4) 0.0022 (4) −0.0082 (4)

Se8 0.0342 (6) 0.0398 (6) 0.0251 (5) 0.0104 (4) 0.0040 (4) 0.0043 (4)

Geometric parameters (Å, º)

Se1—Se2 2.3021 (15) Se4—Se5 2.3121 (13)

Se1—Se8 2.3052 (14) Se5—Se6 2.3244 (13)

Se2—Se3 2.3141 (14) Se6—Se7 2.3010 (15)

Se3—Se4 2.3095 (14) Se7—Se8 2.3029 (15)

Se2—Se1—Se8 105.37 (5) Se4—Se5—Se6 105.92 (5)

Se1—Se2—Se3 106.50 (5) Se7—Se6—Se5 105.19 (5)

Se4—Se3—Se2 104.60 (5) Se6—Se7—Se8 105.87 (5)

Se3—Se4—Se5 105.09 (5) Se7—Se8—Se1 106.97 (5)

Se8—Se1—Se2—Se3 −99.24 (6) Se4—Se5—Se6—Se7 −99.75 (6)

Se1—Se2—Se3—Se4 104.27 (6) Se5—Se6—Se7—Se8 102.57 (5)

Se2—Se3—Se4—Se5 −103.15 (6) Se6—Se7—Se8—Se1 −103.24 (6)