ABSTRACT In the title compound, [Au(2)Ba(NCS)(4)(C(20)H(24)O(6))](n), the dithio--cyanato-aurate(I) anion adopts a dimeric structure with an Au⋯Au distance of 3.1109 (10) Å; both Au(I) atoms are also bonded to two S atoms. The Ba(II) ion adopts an irregular BaN(3)O(6) geometry, arising from the crown ether and three adjacent thio-cyanate N atoms; the extended structure of the complex can be described as a one-dimensional coordination polymer generated by the Ba⋯N inter-actions (two on the endo side and one on the exo side of the crown ether) running parallel to the b axis, with an anti-parallel arrangement of ribbons in the unit cell.
Tonia L. Stroud,aNathan L. Cokera* and Jeanette A.
aDepartment of Physical Sciences, Morehead State University, Morehead, KY 40351,
USA, andbDepartment of Chemistry, University of Cincinnati, Cincinnati, OH
Correspondence e-mail: email@example.com
Received 14 September 2009; accepted 28 October 2009
Key indicators: single-crystal X-ray study; T = 150 K; mean ?(C–C) = 0.022 A ˚;
R factor = 0.053; wR factor = 0.128; data-to-parameter ratio = 11.5.
In the title compound, [Au2Ba(NCS)4(C20H24O6)]n, the dithio-
cyanatoaurate(I) anion adopts a dimeric structure with an
Au???Au distance of 3.1109 (10) A˚; both AuIatoms are also
bonded to two S atoms. The BaIIion adopts an irregular
BaN3O6geometry, arising from the crown ether and three
adjacent thiocyanate N atoms; the extended structure of the
complex can be described as a one-dimensional coordination
polymer generated by the Ba???N interactions (two on the
endo side and one on the exo side of the crown ether) running
parallel to the b axis, with an antiparallel arrangement of
ribbons in the unit cell.
For further information on gold chemistry, see: Arvapally et al.
(2007); Beavers et al. (2009); Chen et al. (2005); Coker (2003);
Coker et al. (2004a,b, 2006); Mohamed et al. (2003); Olmstead
et al. (2005); Pathaneni & Desiraju (1993); Schwerdtferger et
al. (1990). For further information on barium macrocycles, see:
Bordunov et al. (1996); Bradshaw & Izatt (1997); Felton et al.
(2008); Henke & Atwood (1998); Masci & Thuery (2006);
Metz et al. (1973). For a description of the Cambridge Struc-
tural Database, see: Allen (2002).
a = 17.5491 (8) A˚
b = 12.6183 (4) A˚
c = 15.6584 (6) A˚
? = 110.598 (2)?
V = 3245.7 (2) A˚3
Z = 4
Cu K? radiation
? = 28.76 mm?1
T = 150 K
0.14 ? 0.08 ? 0.01 mm
Bruker SMART6000 CCD
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
Tmin= 0.118, Tmax= 0.752
14223 measured reflections
4110 independent reflections
2905 reflections with I > 2?(I)
R[F2> 2?(F2)] = 0.053
wR(F2) = 0.128
S = 0.98
H-atom parameters constrained
??max= 1.66 e A˚?3
??min= ?0.85 e A˚?3
Selected bond lengths (A˚).
Symmetry code: (i) x;y þ 1;z.
Data collection: SMART (Bruker, 2003); cell refinement: SAINT
(Bruker, 2003); data reduction: SAINT; program(s) used to solve
structure: SHELXTL (Sheldrick, 2008); program(s) used to refine
structure: SHELXTL; molecular graphics: SHELXTL; software used
to prepare material for publication: SHELXTL.
Funding for the SMART6000 diffractometer through NSF–
MRI grant CHE-0215950 is gratefully acknowledged.
Supplementary data and figures for this paper are available from the
IUCr electronic archives (Reference: HB5102).
Acta Cryst. (2009). E65, m1509–m1510doi:10.1107/S1600536809045218 Stroud et al.
Acta Crystallographica Section E
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Stroud et al.
Acta Cryst. (2009). E65, m1509–m1510
Acta Cryst. (2009). E65, m1509-m1510 [ doi:10.1107/S1600536809045218 ]
T. L. Stroud, N. L. Coker and J. A. Krause
The present work stems from our interest in developing gold(I)-thiocyanate complexes with interesting gold bonding mo-
tifs and luminescent properties (Coker et al., 2004a, Arvapally et al.,2007). We have shown that alkali (K+, Rb+ and
Cs+) salts of bis(thiocyanato)aurate(I) (Coker et al., 2004a) crystallize as linear one-dimensional polymeric chains with
Au—Au distances in the 3.0065 (5)–3.2654 (2) Å range. Bis(thiocyanato)aurate(I) complexes with NH4+ (Coker et al.,
2006) and Me4N+ (Coker et al., 2004a) adopt a similar linear or nearly linear motif, respectively, with alternating sets of
Au—Au distances (NH4+: 3.1794 (2), 3.2654 (2) Å; Me4N+: 3.1409 (3), 3.1723 (3) Å). In sharp contrast, the anion in
[(n-Bu)4N]bis(thiocyanato)aurate(I) (Coker et al., 2004a) crystallizes as a dimer (Au—Au = 3.0700 (8) Å) while the anion
in [Ph4As]bis(thiocyanato)aurate(I) (Schwerdtferger et al., 1990) and [Ph4P]bis(thiocyanato)aurate(I) (Coker, 2003) exist
To further explore the influence of the cation on the motif adopted by the bis(thiocyanato)aurate(I) anion, we synthesized
and characterized the (1,4,7,10,13,16-hexaoxacyclooctadecane)-potassium dithiocyanatoaurate(I) [1,4,7,10,13,16-hexaox-
acyclooctadecane = 18-crown-6] (Coker et al., 2004b) and (18-crown-6)-caesium dithiocyanatoaurate(I) (Coker, 2003)
complexes. The geometry of the [Au(SCN)2]- anion in these complexes is monomeric and analogous to the Ph4P+ and
Ph4As+ salts. The extended structure can be described as a zigzag polymeric chain formed by the coordination of the
N atoms of the thiocyanate via a single intermolecular interaction to the vacant coordination site on the K or Cs atoms.
To extend our bonding motif investigation, complexes utilizing 6,7,9,10,17,18,20,21-octahydro-5,8,11,16,19,22-hexaoxa-
dibenzo[a,j]cyclooctadecene (dbz-18-crown-6) with alkali or alkaline earth cations were studied. In the present work, the
structure of the title complex, (I), is reported.
The geometry of the anion in (I) (Fig. 1) is a dimer with a Au—Au bond distance of 3.1109 (10) Å and Au—S distances
falling in the 2.299 (4)–2.305 (4) Å range. The Au—Au bond distance observed in (I) is less than the sum of the van der Waals
radii of 3.32 Å for a gold-gold interaction (Bondi, 1964). A Cambridge Structural Database (CSD) analysis of gold-gold
interactions reported by Pathaneni & Desiraju (1993) found that distances in the range 2.6–3.4 Å can be considered to have
Au—Au bonding character. Furthermore, the Au—Au and Au—S bond distances in (I) are comparable to those in the related
crown complex [CH3CN-(dbz-18-crown-6-Na)]2[Au(SCN)2]2.dbz-18-crown-6.CH3CN (Au—Au = 3.0661 (4) Å, Au—S
= 2.291 (2)–2.303 (2) Å (Coker, 2003). The metallomacrocyclic gold(I) thiolate cluster, [Au9(µ-dppm)4(µ-p-tc)6](PF6)3
(dppm = bis(diphenylphosphine)methane and p-tc = p-thiocresolate), is reported to have four distinct gold environments.
These environments consist of (a) Au—Au phosphine bridged single bonds (3.0084 (6)–3.1439 (6) Å, (b) Au—Au sulfiur
bridged single bonds (2.9950 (7)–3.1632 (6) Å, (c) Au—Au non-bridged single bonds (3.0135 (7)–3.1825 (7) Å and (d) sul-
fur bridged Au···Au nonbonded interactions (3.7155 (8)–3.9571 (7) Å (Chen et al., 2005). In the same vein, the PMe3 analog
of the antiarthritic gold drug Auranofin, [(Me3PAu)2(µ-TATG)]NO3 (TATG = 2,3,4,6-tetraacetyl-1-thio-D-glucopyranosato)
(Mohamed et al., 2003) forms a tetranuclear gold cluster with Au—Au and Au—S distances in the 3.106 (7)–3.144 (12)
Å and 2.334 (3)–2.355 (3) Å range, respectively. A CSD survey (Cambridge Structural Database v5.30) (Allen, 2002) of
metal-thiocyanate complexes reveals an average M—S distance of 2.39 Å (M = Pt, Pd, Ag or Au), the Au—S distances in
(I) are consistent with this observation.
Alkali and alkaline earth cations have a preferred tendency to bind in a way that high coordination numbers are achieved.
This characteristic makes them useful in applications where coordination- flexible ligating agents are a necessity (e.g. se-
questration) (Bradshaw & Izatt, 1997). The nine-coordinate Ba atom in (I) is bound to the six oxygen atoms of the dbz-18-
crown-6 (Ba—O distances range: 2.940 (9)–2.988 (10) Å) and sits 0.769 (5) Å out of the plane generated by these atoms.
The remainder of the coordination sites consists of two endo side and one exo side Ba···N interaction (2.774 (14)–2.877 (13)
Å). The fourth thiocyanate moiety (N4) remains uncoordinated, the nearest nonbonded distance to Ba is 4.728 (15) Å. Thus
the extended structure of (I) (Fig. 2) can be described as a one-dimensional coordination polymer generated by Ba···N in-
termolecular interactions running parallel to the b axis, with an overall antiparallel arrangement of ribbons in the unit cell.
In contrast, [poly[triaquatetra-µ-cyanido-tetracyanidobis(1,4,10,13- tetraoxa-7,16-diazacyclo-
octadecane)dibarium(II)tetragold(I) crystallizes as a coordination polymer with the [Au(CN)2]- anion in monomer, dimer
and trimer environments while the barium atoms are bound to the diaza-18-crown-6 and solvent water molecules in nine and
ten-coordinate geometries (Beavers et al., 2009). Reported Ba···O and Ba···N distances for this gold-cyanato complex are
2.761 (2)–2.929 (2) Å and 2.867 (3)–2.959 (3) Å, respectively. In the case of catena-poly[[diaqua(1,4,7,10,13,16-hexaoxa-
cyclooctadecane)- barium(II)]-µ-cyano-[dicyano-platinum(II)]-µ-cyano], the extended structure is an alternating chain of
[18-crown-6-Ba]2+ and [Pt(CN)4]2- ions bound through the N-atom of the cyano group to the Ba2+ ion (ten-coordinate geo-
metry about Ba, Ba···N = 2.901 (2) Å and the average Ba—Ocrown and Ba—Owater distances are reported as 2.858 (17) Å and
2.883 (13) Å) (Olmstead et al., 2005). The Ba···O and Ba···N bonds in (I) are also consistent with those observed in structures
such as M(TMTH2)2.nH2O (M = Ca, Sr, Ba and TMT=2,4,6-trimercaptotriazine) (Henke & Atwood, 1998) and Ba-contain-
ing macroethers, cryptands or lariat ethers, e.g. aqua-(7,16-bis((5-chloro-8-hydroxy-2-quinolinyl)methyl)-1,4,10,13- tetra-
oxa-7,16-diazacyclo-octadecane)-barium dibromide (Bordunov et al., 1996), aqua-thiocyanato-crypt(222)-barium thiocy-
anate (Metz et al., 1973), bis(triethylammonium)diaqua- [2.2.2-crypt]-barium bis((p-tert-butyl-[3.1.3]tetrahomodioxa-
calix[4[arene)-dioxo-uranium) pentahydrate (Masci & Thuery, 2006) and (8-propyl-18,21,26,29-tetraoxa-1,7,9,15,32,35-
hexaazapenta-cyclo (220.127.116.11,13.06,34.010,33)pentatriaconta-3,5,10,12,32,34- hexaene)-bis(perchlorato)-barium (Felton et
Reaction of barium hydroxide (1 equiv) with ammonium thiocyanate (2 eqiv) in water results in the formation of barium
thiocyanate with the release of ammonia gas.
Barium bis(thiocyanato)aurate(I) was prepared following the method described by Coker et al., (2004a). (I) was prepared
by the analogous method described for (18-crown-6-K)dithiocyanatoaurate(I) (Coker et al., 2004b). Diffraction quality
crystals were obtained from slow diffusion of acetonitrile-diethyl ether solution at -4 °C.