Molecular structure of 4,4′-sulfandiyl-bis-thiophenol from electron diffraction

Journal

of Molecular

Elsevier

Science

Structure,

Publishers

B.V.,

160 (1987) Amsterdam

267-274 -

Printed

in The Netherlands

MOLECULAR STRUCTURE OF 4,4’-SULFANDIYL-BIS-THIOPHENOL FROM ELECTRON DIFFRACTION

GYGRGY

SCHULTZ,

ISTVAN

HARGITTAI

and MARIA

KOLONITS

Structural Chemistry Research Group of the Hungarian Academy of Sciences, VIII. Puskin utca 1 l-l 3 P.O. Box: Budapest, Pf. 117, H-1431 (Hungary) JOZEF

Budapest,

GARBARCZYK

Instytut

Technologii

60-965

Poznan

(Received

Chemicznej,

Politechnika

Poznanska

PI. Sktodowskiej-Curie

2,

(Poland)

11 February

1987)

ABSTRACT The molecular structure of 4,4’-sulfandiyl-bis-thiophenol (C,,H,,S,) has been determined by gas electron diffraction. Assuming identical geometry and D,, local symmetry for -SC,H,Smoieties, the following bond lengths (rg) and bond angles were obtained: C-H = 1.101 r 0.005, S-H = 1.388 + 0.019, (C-C),,, = 1.400 * 0.003, (S--C),,= 1.778 2 0.004 A, C,S-C, = 103.5 * 1.3, C-C(S)-C = 120.4 f 0.3, C(H)--C(H)-H = 119.1 + 0.9 and C-S-H = 94.6 f 3.1”. Two rotational forms were found to reproduce the experimental data, characterized by dihedral angles of the benzene rings with respect to 2.0”,qp, =4.5+- 7.2”,andp, =69.4+ 2.O”,q,=-26.6? 7.1”. the &SC, plane: ‘pl = 67.8* Identical signs of opt and (p2 indicate that the two benzene rings are rotated in the same direction about the respective S,,td-C axes.

INTRODUCTION

The structure of the diphenyl sulfide molecule was studied by gas electron diffraction some time ago in our laboratory [l, 21. Reliable information on the bond lengths and bond angles were obtained, although the conformational behavior of this molecule could not be determined unambiguously, due to the relatively small contribution of rotation-dependent interactions to electron scattering. On the other hand, a considerable amount of information has accumulated on the conformational properties of diphenyl sulfide derivatives from X-ray crystallography (see ref. 3 and references therein). The present study is an extension of our earlier work on diphenyl sulfide. There has also been an X-ray crystallographic study of the molecule [4]. EXPERIMENTAL

The sample of 4,4’-sulfandiyl-bis-thiophenol Rudi (M. Sktodovska-Curie University, Lublin, 0022-2860/87/$03.50

o 1987

Elsevier

Science

was obtained from Dr. W. Poland). The purity of the

Publishers

B.V.

268

sample was checked by mass spectrometry both at room temperature and at the temperature of the electron diffraction experiment, and no decomposition was observed. The electron diffraction patterns were taken with a modified EG-100A apparatus, using a radiation nozzle system [5, 61. The nozzle temperature was 173°C and the wave length of the electron beam was 0.04905 8. Nozzle-to-plate distances of about 50 and 19 cm were used, and 6 and 5 plates, respectively, were selected for analysis. The treatment of the experimental data was described in ref. 7. The ranges of intensity data used in the analysis were 2.125 < s < 14.0 8-l and 9.0 < s < 35.75 8-l with data intervals As = 0.125 and 0.25 8-l, respectively. The total experimental intensities are available as supplementary material [from BLLD as Supplementary Publication No SUP 26335 (4 pages)]. The final molecular intensities are shown in Fig. 1. The experimental and theoretical radial distributions are presented in Fig. 2. They were calculated with an artificial damping factor exp(-O.002 a*~*). Theoretical values were used in the 0 S s < 2 8-l region. STRUCTURE

ANALYSIS

The least-squares method was used, based on the molecular intensities, as in our earlier studies (e.g. ref. 7). Identical geometries and local DZh symmetries were assumed for the -SC6H4S- moieties throughout the analysis. The following independent parameters were chosen to describe the molecular

vv I

0

5

10

15

20

25

30 s, A-’ 35

Fig. 1. Molecular intensity curves for the two camera ranges (E, experimental; cal). Also shown are the difference curves (experimental - theoretical).

T, theoreti-

269

, 0

1

2

3

4

5

6

I

6

9

10 cA

'1

Fig. 2. Radial distribution curves (E, experimental; T, theoretical). The positions of the most important distances, independent of internal rotation are marked with vertical bars whose height is proportional to the relative weight of the distance. The difference curve (experimental - theoretical) and the numbering of atoms are also shown.

geometry: bond lengths C-H, S-H, Cl-C2, and S-C; the difference between r(Cl-C2) and r(C2-C3), A( C-C); bond angles Cl’-S-Cl, C6-Cl-C2, C3-C2-H2, and C4-Sl-H; and angles p1 and cpz characterizing internal rotation of the two benzene rings with respect to the ClSCl’ plane. Coplanarity of each benzene ring with the corresponding S-H bond was assumed. The 0” values for (pl and (p2 characterize a planar molecule with the Sl-H and Sl’-H bonds located on the same side of the S* - - Sl and S **Sl’ axes, respectively. Equal signs of cp, and p2 correspond to the rotation of the two rings in the same direction about the respective Scentrai-Car axes. All independent geometrical parameters, except A(C-C), were refined simultaneously. The inclusion of A(C-C) into the refinement led to divergency. Its stepwise variation indicated that its change by 0.005 a in either direction would lead to a slight increase of the R-factor. It was concluded that A(C-C) does not exceed 0.005 .&in absolute value, but the present data do not allow its accurate determination; thus only the mean value of r(C-C) was refined. In addition to the geometrical parameters, 14 independent amplitudes of vibration were refined, and 10 other amplitudes were coupled with constraints of constant differences. The coupling scheme of amplitudes is given in Table 1. The amplitudes of all bonds and important rotation-independent non-bonded distances were refined. The remaining amplitudes were assumed as were the amplitudes of rotation-dependent S*- SC, C-*-C, S-.-H, C-*-H and H---H distances (at 0.24-0.26 a).

270 TABLE

1

Molecular

parameters*

Parameter

(a) Independent r( C--C hean r(S--C) r( C-H) r( S-H)

of 4,4’-sulfandiyl-bis-thiophenol

Multiplicity

geometricalparameters 12 1.3984(5) 4 1.7766(7)

B

Key to the coupling scheme of amplitudes

0.0481(5) 0.0509(8)

i ii . ..

1.095( 3)

0.081(4)

2

1.384(13)

0.0713

111

i

104.1(6) 120.5(2) 94.1(22) 119.4(6) 69.4( 14) -26.6(50)

Ipz (b) S.. .S, S. *. C, C.**C,

of internal rotationb,C 2 S**.Sl

S..*H3 S ..*H2

for model

1

8

LCl’-S-Cl f_C6-Cl-C2 LC~-Sl--H LC~-C~--H~ 91

Sl***Sl’ s***c2 s***c3 s***c4 Sl..*Cl’ Sl . ..C4’ Cl***C3 C2*.*C6 Cl***C4 C2**.C5 Cl***c!l’ Cl*.*C4’ c4. * *C4’ Cl...H2 Cl*..H3 C2*..H3 C2..*H5 C2***H6

ra (L)

as obtained

1 8 8 4 2 2 8 4 2 4 1 2 1 8 8 8 8 8 8 8

S-s *H, and C.**Hdistances

independent

6.339(2)

0.084(3)

10.00(4) 2.7524(5) 4.0546(6) 4.562(2) 6.99(2) 8.67(3) 2.4188(7) 2.429( 2) 2.785(2) 2.803(2) 2.80(l) 5.27(l) 7.20(3) 2.174(6) 3.408(5) 2.158(7) 3.898(4) 3.426(5) 4.910(7) 2.905(9)

0.62(31) 0.0788(g) 0.076(l) 0.075(3) 0.20(3) 0.52(18) 0.0604(g) 0.0604 0.0568 0.0568 0.0798 0.14 0.19 0.104(6) 0.082(7) 0.104 0.084 0.082 0.15(l) 0.1068

iv V

vi vii .. . Vlll

ix X

xi xi vi vi &xed ix xii t..

value)

Xl11

xii vii . Xlll xiv vi

aDistances and mean amplitude of vibration are given in .k, angles in degrees. Leastsquares standard deviations are parenthesized as units in the last digit. bOf C!***H and Se * *H distances only those with four or higher multiplicity are listed. CThe rotationdependent S. * *C distances are located at 6.48, 7.08, 7.43, 7.79, 7.95,8.29,8.59, 9.05 .& and the rotation-dependent C* *. C distances are located at 3.02, 3.07, 3.38, 3.79, 4.05, 4.08, 4.12, 4.33, 4.38, 4.63, 4.77, 4.89, 4.90, 4.93, 4.94, 5.17, 5.23, 5.31, 5.49, 5.67, 5.96, 6.02, 6.02, 6.06, 6.12, 6.14, 6.49, 6.59, 6.82, 7.05, 7.08, 7.45 a.

271

Concerning the determination of the angles of internal rotation, the contribution of rotation-dependent distances to electron scattering is relatively small. Ignoring all rotation-dependent distances, for example, resulted in only a relatively small increase of the R-factor, from 4.44% to 5.28%, in the final refinements. The least-squares refinements yielded two different minima depending on the initial values of cpl and q2 corresponding to two different conformations. The independent geometrical parameters and the R-factors characterizing these two models (A and B) are presented in Table 2. The theoretical curves presented in Figs. 1 and 2 correspond to model B. All independent parameters, with the exception of one of the angles of rotation, differ less than twice the standard deviation obtained in the refinements. One benzene ring is nearly perpendicular to the Cl’SCl plane and the other is nearly coplanar with it in both models. It is not possible to decide between the two conformers from electron diffraction data alone. A mixture of the two conformers is also possible. Furthermore, the R-factor has proved to be insensitive to the sense of the C4-Sl-H angle, as was demonstrated by changing the angles of rotation by 180”. The results for conformer B are given in more detail in Table 1. The results for conformer A are deposited at BLLD. The elements of the correlation matrix exceeding 0.4 in absolute value for conformer B are given in Table 3. The mean bond angles and bond distances referring to models A and B are shown in Fig. 3. The total errors presented in Fig. 3 were estimated according to the equations ut =

[(O.O02r)’

TABLE

+

2u2 + (A/2)‘] “’

2

Independent geometrical parameter?, and R-factors molecule as obtained from least-squares refinements Parameter

Model A

r( C-H) r( S-H)

1.095( 3) 1.386(14) 1.3982(6) 1.7769(7) 102.9(9) 120.3(a) 118.9(9) 95.2(25) 67.8(14) 4.6(51) 4.50

r(C-C),, r( S-C) Lc1-s-c1’ ~c2--Cl-C6 LC~-C~--H~ LC~--S~--H b 'PI b 'PI R(s)

(a)

for the 4,4’-sulfandiyl-bis-thiophenol for two models Model B 1.095(3) 1.384(13) 1.3984(5) 1.7766(7) 104.1(6) 120.5(2) 119.4(6) 94.1(22) 69.4(14) -26.6(50) 4.44

aBond distances (ra) are given in iti, bond angles in degrees. Least-squares standard deviations are parenthesized as units in the last digit. bq, and (p2 angles characterize the internal rotations of the benzene rings (see text).

212 TABLE

3

Correlation model B

matrix

elements

(p)

having

absolute

i

i

r( C-C) r( C-H) r( C-H) Lc+c1-c2 LC2-C3-H3 iC2-C3-H3 LC~--S~--H Z(S1. **S2) sc1a sc1a

r( S-H) r( S-H) sc2a

aSCl

and SC2

value

greater

than

0.4

as obtained

pil -0.7 37 0.426 -0.402 -0.800 -0.430 0.417 - 0.401 0.418 0.681 0.479

‘Pz 92

1(S.*.C2) I(Cl...H2) 1(Sl..*C4’) l(C-C) l(S--C) are the scale factors

for short

for

and long camera

distance

Fig. 3. Bond lengths (rg, A) and bond angles (L, “) with estimated sulfandiyl-bis-thiophenol as determined by electron diffraction.

data, respectively.

total

errors

of 4,4’-

for distances, and ut = [2aZ + (A/2)‘]“’ for angles, where u is the standard deviation of the least-squares refinement and A is the difference between the values of a given parameter corresponding to the two conformers. DISCUSSION

The benzene rings in 4,4’-sulfandiyl-bis-thiophenol depart only slightly from Dbh symmetry. The C-C and S-C bond lengths and the C--Cipso-C and C&-S-C, bond angles are identical with the corresponding parameters of diphenyl sulfide and pdithiol-hydroxy benzene, within experimental error (Table 4). Coplanar conformation of 4,4’-sulfandiyl-bis-thiophenol is prevented by proximity of the H6 and H2’ atoms (this distance would be -0.4 a).

273 TABLE

4

Bond lengths (a) and bond angles (“) of 4,4’-sulfandiyl-bis-thiophenol, and p-dithiohydroxybenzene determined by electron diffraction

rg(C-C)mm r&S-C) LC-tip,--c LC=-S-Car aPresent

study.

bRefs.

4,4’-Sulfandiylbis-thiophenoP’

Diphenyl sulfideb

1.400 * 0.003 1.778 f 0.004 120.4 r 0.3 103.5 f 1.3

1.401 1.772 120.2 + 103.7 *

1, 2. ‘Ref.

diphenyl

sulfide

p-DithiohydroxybenzeneC + 0.003 f 0.005 0.6 1.3

1.397 f 0.003 1.774 + 0.003 120.3 f 0.3

8.

Information from the Cambridge Crystallographic Database [9] indicate that one ring usually remains nearly coplanar with the C&SC,, plane while the other becomes nearly perpendicular to it in diphenyl sulfide derivatives [ 31. The X-ray results on the title molecule are in agreement with this observation [ 41. Both possible models described in the present study are consistent with these findings. There is also good agreement between the conformational properties of conformer B of the molecule and crystalline 4,4’-diaminodiphenylsulphide [lo] can be observed. The anglesq, and cp2for the latter are 68.3” and -25.7” (according to the notations of the present paper), and the C&--S-C,, angle is 103.7( 3)“. The amplitudes of vibration determined for the molecule indicate a relative stiffness for the SC,H,S moieties, similar to that observed for simple parudisubstituted benzene derivatives (e.g., p-C12C6H4 [ll], p-F2C6H4 [12] ). On the other hand, the amplitudes of Sl. - - Cl’, Sl. * sC4’ and Sl. - *Sl’ interactions which are independent of internal rotation, are rather large, indicating flexibility of the two HSC6H4 groups relative to each other. This large-amplitude motion is demonstrated by the absence of marked features on the experimental radial distribution at distances greater than 7.1 A. REFERENCES 1 B. Rozsondai, J. H. Moore, D. C. Gregory and I. Hargittai, Acta Chim. (Budapest), 94 (1977) 321. 2 B. Rozsondai, Gy. Schultz and I. Hargittai, J. Mol. Struct. 70 (1981) 309. 3 A. Kucsman, I. Kapovits, L. Parkanyi and A. Kalmln, J. Mol. Struct., 140 (1986) 141. 4 J. Garbarczyk, Makromol. Chem., 187 (1986) 2489. 5 I. Hargittai, J. Tremmei and M. Kolonits, Hung. Sci. Instrum., 50 (1980) 31. 6 J. Tremmel and I. Hargittai, J. Phys. E: Sci. Instrum., 18 (1985) 148. 7 A. Domenicano, Gy. Schultz, M. Kolonits and I. Hargittai, J. Mol. Struct., 53 (1979) 197. 8 A. Domenicano, I. Hargittai, G. Portalone and Gy. Schultz, 7th European Crystallogr. Meeting, Jerusalem, August, 1982 p. 155. 9 F. H. Allen, 0. Kennard and R. Taylor, Ann. Chem. Res., 16 (1983) 146.

274 10 B. K. Vijayakshimi and R. S. Srinivasan, J. Cryst. Mol. Struct., 13 (1973) 147 11 Gy. Schultz, I. Hargittai and A. Domenicano, J. Mol. Struct., 68 (1980) 281. 12 A. Domenicano, Gy. Schultz and I. Hargittai, J. Mol. Struct., 78 (1982) 97.