(Isocyanide)gold(I) thiosalicylates: Supramolecular assembly based on both auriophilic and hydrogen bonding

Article abstract of DOI:10.1021/om960682s

Reaction of (RNC)AuCl [R = tert-butyl (1a), mesityl (1b)] with sodium thiosalicylate in the two-phase system water / dichloromethane gives high yields of the corresponding (isocyanide)gold(I) thiosalicylates (2a,b). The solid-state structures of 2a,b have been determined by X-ray diffraction studies. The supramolecular structure of both compounds is governed by Au-Au interactions [2a, Au-Au 3.157(2) ?; 2b, Au-Au 3.3186(5) ?] and hydrogen bonding through the carboxylic acid groups.

Full text of DOI:10.1021/om960682s

Organometallics 1996, 15, 5445-5446
5445
(Isocya n id e)gold (I) Th iosa licyla tes: Su p r a m olecu la r
Assem bly Ba sed on both Au r iop h ilic a n d Hyd r ogen
Bon d in g
Wolfgang Schneider, Andreas Bauer, and Hubert Schmidbaur*
Anorganisch-chemisches Institut der Technischen Universita¨t Mu¨nchen,
Lichtenbergstrasse 4, D-85747 Garching, Germany
Received August 12, 1996X
Summary: Reaction of (RNC)AuCl [R ) tert-butyl (1a ),
mesityl (1b)] with sodium thiosalicylate in the two-phase
system water/ dichloromethane gives high yields of the
corresponding (isocyanide)gold(I) thiosalicylates (2a ,b).
The solid-state structures of 2a ,b have been determined
by X-ray diffraction studies. The supramolecular struc-
ture of both compounds is governed by Au--Au interac-
tions [2a , Au--Au 3.157(2) Å; 2b, Au--Au 3.3186(5) Å]
and hydrogen bonding through the carboxylic acid
groups.
(2a , 148 °C; 2b, 226 °C with decomposition). Their
composition is readily confirmed by analytical data,5 but
these do not exclude the presence of isomeric ionic
systems of the general formula [L2Au]+[AuX2]-.6 The
IR absorptions for ν(NC) of the solids (2a , 2234 cm-1
;
2b, 2200 cm-1) indicate standard isocyanide coordina-
tion to gold(I) centers, and broad ν(OH) bands (2a ,
2550-3300 cm-1; 2b, 2520-3200 cm-1) are proof for
strong hydrogen bonding of the carboxylate units in the
crystals. The NMR spectra of solutions of the com-
pounds in dichloromethane or chloroform show all
resonances in the correct molar ratio 1:1 of L and X
components,5 but this result also gives no clue as to the
structures. The solid-state structures were therefore
determined by single-crystal X-ray diffraction studies.
From extensive studies in the structural chemistry
of gold(I) compounds it has been recognized that self-
assembly of species L-Au-X (L ) neutral donor, X )
anionic ligand) through Au--Au contacts (“auriophilic-
ity”) is a general phenomenon determining many solid-
state structures of such compounds.1 The energies of
the individual Au--Au interactions are in the order of
6-11 kcal/mol,2 resembling closely the energetics of
hydrogen bonding.1a This resemblance of auriophilic
and hydrogen bonding suggested that there should be
cases where both phenomena synergistically codeter-
mine the assembly mode of solid-state structures. After
a number of experiments, where the results failed to
corroborate this assumption,3 we are now able to present
two examples with L representing isocyanide and X
thiolate ligands.
Compound 2a crystallizes in the orthorhombic space
group Pbca with Z ) 16 formula units in the unit cell.
There are two crystallographically nonequivalent mol-
ecules in the asymmetric unit, which both have a quasi-
linear C-N-C-Au-S skeleton extending from the
central atom of the tert-butyl group to the sulfur atom
of the thiol (Figure 1).7-9 There is a short intermolecu-
lar auriophilic Au--Au contact [Au1--Au2 3.157(2) Å]
which leads to pairs of molecules with a dihedral angle
S1-Au1-Au2-S2 ) 47.5°. The thiosalicylate ligands
The reactions of (dimethyl sulfide)gold(I) chloride with
tert-butyl or mesityl isocyanide afford high yields of the
corresponding (RNC)AuCl complexes (1a ,b) as air-
stable, colorless, crystalline materials.4 These precur-
sors are readily converted into the thiosalicylates (2a ,b)
by reaction with sodium thiosalicylate in the two-phase
system water/dichloromethane.5
(5) Preparation of 2a ,b: The RNCAuCl complex was dissolved in
dichloromethane (5 mL) and added to an equimolar amount of sodium
thiosalicylate dissolved in water (5 mL). After the mixture was stirred
for 3 h, the water layer was removed, the CH2Cl2 layer was evaporated
to dryness, and the colorless residue was crystallized from a tetrahy-
drofuran/pentane mixture. 2a (0.177 g, 65% yield) was obtained from
tBuNCAuCl (0.198 g, 0.63 mmol) and 2-(NaS)C6H4COOH (0.111 g, 0.63
mmol). 2b (0.123 g, 0.25 mmol) was obtained from MesNCAuCl (0.141
g, 0.37 mmol) and 2-(NaS)-C6H4COOH (0.066 g, 0.38 mmol). Spectro-
scopic and analytical data for 2a : 1H NMR (CDCl3, 399.78 MHz) δ
13.10 (br s, COOH), 8.28 (d, J ) 8.0 Hz, Ph-H3), 7.63 (d, J ) 7.3 Hz,
Ph-H6), 7.18-7.34 (m, Ph-H4, H5), 1.53 (s, tert-butyl); 13C NMR (CDCl3,
100.54 MHz) δ 167.6 (s, COO), 139.5 (br s, NC), 137.8 (s, C4), 137.3 (s,
C2), 133.1 (s, C6), 131.7 (s, C3), 131.3 (s, C1), 126.1 (s, C5), 59.1 (s,
C(CH3)3), 29.6 (s, CH3); IR (KBr) νCOO-H 3300-2550 (s), νNC 2234 (s),
νCdO 1718 (s) and 1682 (s) cm-1. Anal. Calcd for C12H14NAuO2S: C,
33.3; H, 3.3; N, 3.2. Found: C, 33.2; H, 3.1; N, 3.1. Mp: 148 °C.
Spectroscopic and analytical data for 2b: 1H NMR (CDCl3, 399.78
MHz) δ 13.00 (br s, COOH), 8.28 (d, J ) 7.9 Hz, Ph-H3), 7.69 (d, J )
7.6 Hz, Ph-H6), 7.22-7.33 (m, Ph-H4, H5), 2.41 (s, o-CH3), 2.31 (s,
p-CH3); because of the low solubility of 2b, no 13C-NMR spectrum was
recorded; IR (KBr) νCOO-H 3300-2520 (s), νNC 2200 (s), νCdO 1715 (w)
and 1676 (s) cm-1. Anal. Calcd for C12H14NAuO2S: C, 41.2; H, 3.3; N,
2.8. Found: C, 41.9; H, 3.7; N, 2.4. Mp: 226 °C with decomposition.
(6) (a) Ahrland, S.; Dreisch, K.; Noren, B.; Oskarsson, A. Mat. Chem.
Phys. 1993, 35, 281. (b) Ahrland, S.; Noren, B.; Oskarsson, A. Inorg.
Chem. 1985, 24, 1330. (c) Hormann-Arendt, A. L., Shaw, C. F., III.
Inorg. Chem. 1990, 29, 4683. (d) Hormann, A. L., Shaw, C. F., III:
Bennet, D. W.; Reiff, W. M. Inorg. Chem. 1986, 25, 3953. (e) Conzel-
man, W.; Hiller, W.; Stra¨hle, J . Z. Anorg. Allg. Chem. 1984, 512, 169.
(f) Adams, H.-N.; Hiller, W.; Stra¨hle, J . Z. Anorg. Allg. Chem. 1982,
485, 81. (g) Akhtar, M. N.; Gazi, I. H.; Isab, A. A.; Al-Arfaj, A. R.;
Wazeer, M. I. M.; Hussain, M. S. J . Coord. Chem. 1995, 36, 149. (h)
Bauer, A.; Schmidbaur, H. J . Am. Chem. Soc. 1996, 118, 5324. (i)
Schneider, W.; Bauer, A.; Schmidbaur, H. J . Chem. Soc., Dalton Trans.,
in press.
(RNC)AuCl + 2-(NaS)C6H4COOH f
2-[(RNC)AuS]C6H4COOH + NaCl
The products are again colorless, crystalline compounds
stable to air and moisture and with high melting points
X Abstract published in Advance ACS Abstracts, November 15, 1996.
(1) For reviews see: (a) Schmidbaur, H. Gold Bull. 1990, 23, 11. (b)
Schmidbaur, H. Interdisc. Sci. Rev. 1992, 17, 213. (c) Schmidbaur, H.
Chem. Soc. Rev. 1995, 24, 391.
(2) (a) Schmidbaur, H.; Graf, W.; Mu¨ller, G. Angew. Chem., Int. Ed.
Engl. 1988, 27, 417. (b) Schmidbaur, H.; Dziwok, K.; Grohmann, A.;
Mu¨ller, G. Chem. Ber. 1989, 122, 893. (c) Dziwok, K.; Lachmann, J .;
Wilkinson, D. L.; Mu¨ller, G.; Schmidbaur, H. Chem. Ber. 1990, 123,
423. (d) Narayanaswamy, R.; Young, M. A.; Parkhurst, E.; Ouellette,
M.; Kerr, M. E.; Ho, D. M.; Elder, R. C.; Bruce, A. E.; Bruce, M. R. M.
Inorg. Chem. 1993, 32, 2506. (e) Harwell, D. E.; Mortimer, M. D.;
Knobler, C. B.; Anet, F. A. L.; Hawthorne, M. F. J . Am. Chem. Soc.
1996, 118, 2679.
(3) Lange, P. Dissertation, Technische Universita¨t Mu¨nchen, 1995.
(4) (a) Eggleston, D. S.; Chodosh, D. F.; Webb, R. L.; Davis, L. L.
Acta Crystallogr. 1986, C42, 36. (b) Schneider, W.; Angermaier, K.;
Sladek, A.; Schmidbaur, H. Z. Naturforsch. 1996, 51b, 790.
S0276-7333(96)00682-6 CCC: $12.00 © 1996 American Chemical Society

5446 Organometallics, Vol. 15, No. 26, 1996
Communications
F igu r e 1. Tetrameric unit of 2a aggregated via Au--Au
and hydrogen bonding. Phenyl and tert-butyl hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Au1-Au2 3.157(2), Au1-C1 2.01(2), Au1-
S1 2.278(5), Au2-C6 2.00(2), Au2-S2 2.274(9); C1-Au1-
S1 175.5(9), C6-Au2-S2 174.5(7), S1-Au1-Au2 90.3(2),
C1-Au1-Au2 87.1(8), C6-Au2-Au1 90.5(7), S2-Au2-
Au1 84.1(3). Hydrogen-bonding parameters: O12-H12
0.850, H12- O11′ 1.783, O12-O11′ 2.633, O12-H12-O11′
179.5.
F igu r e 2. Four molecules of 2b aggregated via Au--Au
and hydrogen bonding as part of an extended chain. The
ORTEP diagram shows 50% probability ellipsoids; phenyl
and methyl hydrogen atoms are omitted for clarity. Se-
lected bond lengths (Å) and angles (deg): Au-Au′ 3.3186(5),
Au-C 1.962(4), Au-S 2.273(1); C-Au-S 175.2(1), C-Au-
Au′ 99.5(1), S-Au-Au′ 83.41(3). Hydrogen-bonding
parameters: O2-H 0.850, H-O1′ 1.796, O2-O1′ 2.646,
O2-H-O1′ 170.8.
asymmetric unit comprises only one molecule. Two of
these molecules are associated (parallel and head to tail)
to form centrosymmetrical dimers through weak aurio-
philic bonding [Au--Au′ 3.3186(5) Å; dihedral angle
S-Au-Au′-S′ 180°]. These dimers are further ag-
gregated via bifurcated hydrogen bonding between the
carboxylic acid groups to give one-dimensional polymers
(Figure 2). As already pointed out for compound 2a ,
the individual molecules of 2b have a linear C-N-C-
Au-S axis with normal bond distances for gold(I)
isocyanide/thiolate complexes in both cases. The angles
Au-S-C are also similar, with values of 105.4(1)° for
2b and 106.4(7)°/109(1)° for 2a .
of neighboring dimers are linked through bifurcated
hydrogen bonding typical for carboxylic acids. These
double hydrogen bridges connect crystallographically
equivalent monomers related by a center of inversion
coinciding with the center of the resulting eight-
membered ring. Selected distances and angles are given
in the caption to Figure 1. In total the lattice is
composed of tetranuclear aggregates with alternating
auriophilic (Au--Au) and hydrogen bonding (O-H--O)2.
Compound 2b crystallizes in the triclinic space group
P1h with Z ) 2 formula units in the unit cell. The
(7) Crystallographic data for 2a : C12H14AuNO2S, fw 433.27, ortho-
rhombic, space group Pbca (No. 61), a ) 11.617(2) Å, b ) 9.520(1) Å,
c ) 49.548(7) Å, V ) 5485(1) Å3, Z ) 16, dcalcd ) 2.101 g/cm3, Enraf
Nonius CAD4 diffractometer, Mo KR radiation (λ ) 0.710 69 Å), T )
-62 °C, 4384 reflections measured, 4219 unique reflections of which
4206 were used. The refinement of 252 parameters converged at wR2
(used reflections) ) 0.1936 and R1 [3009 observed reflections with Fo
g 4σ(Fo)] ) 0.0907. Poor crystal quality (c-axis!) prevented further
improvements. Crystallographic data for 2b: C17H16AuNO2S, fw
495.33, triclinic, space group P1h (No. 2), a ) 7.575(1) Å, b ) 11.203(1)
Å, c ) 12.702(2) Å, R ) 107.03(1)°, â ) 105.40(1)°, γ ) 100.66(1)°, V )
The present results indicate that a large variety of
supramolecular structures can be anticipated on the
basis of combinations of hydrogen bonding with signifi-
cant contributions from auriophilic interactions.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft and by Fonds der
Chemischen Industrie. The authors are grateful to J .
Riede for establishing the X-ray data sets.
952.43(2) Å3,
Z
) 2, dcalcd ) 1.727 g/cm3, Enraf Nonius CAD4
diffractometer, Mo KR radiation (λ ) 0.710 69 Å), T ) -62 °C, 8264
reflections measured, 4096 unique reflections of which 4045 were used.
The refinement of 199 parameters converged at wR2 (used reflections)
) 0.0624 and R1 [3822 observed reflections with Fo g 4σ(Fo)] ) 0.0226.
The structures were solved by direct methods8 and refined by full-
matrix least-squares calculations against F2.9
Su p p or tin g In for m a tion Ava ila ble: Tables giving the
structure determination summary, atomic coordinates, isotro-
pic and anisotropic displacement parameters, and bond dis-
tances and angles (17 pages). Ordering information is given
on any current masthead page.
(8) Sheldrick, G. M. SHELXTL-PLUS, Release 4.0 for Siemens R3
Crystallographic Research Systems, Siemens Analytical X-ray Instru-
ments, Inc., Madison, WI, 1989.
(9) Sheldrick, G. M. SHELXL-93, Go¨ttingen, 1993.
OM960682S