(Fluoren-9-ylidene)methanedithiolato complexes of gold: Synthesis, luminescence, and charge-transfer adducts

Article abstract of DOI:10.1021/ic049132+

Piperidinium 9H-fluorene-9-carbodithioate and its 2,7-di-tert-butyl- substituted analogue [(pipH){S₂CCH(C₁₂H₆R ₂-2,7)}, R = H (1a), t-Bu (1b)] and 2,7-bis(octyloxy)-9H-fluorene-9- carbodithioic acid [HS₂CCH(C₁₂H₆(OC ₈H₁₇)₂-2,7), 2] and its tautomer [2,7-bis(octyloxy)fluoren-9-ylidene]methanedithiol [(HS)₂C=C(C ₁₂H₆(OC₈H₁₇)₂-2,7), 3] were employed for the preparation of gold complexes with the (fluoren-9-ylidene)methanedithiolato ligand and its substituted analogues. The gold(I) compounds Q₂[Au₂{μ-K²-S,S-S ₂C=C₁₂H₆R₂-2,7)}₂], where Q⁺ = PPN⁺ or Pr₄N⁺ for R = H (Q₂4a) or Q⁺ = Pr₄N⁺ for R = OC ₈H₁₇ [(Pr₄N)₂4c], were synthesized by reacting Q[AuCl₂] with 1a or 2 (1:1) and excess piperidine or diethylamine. Complexes of the type [{Au(PR′₃)} ₂{,u-κ²-S,S-S₂C=C(C₁₂H ₆R₂-2,7)}₂] with R = H and R′ = Me (5a), Et (5b), Ph (5c), and Cy (5d) or R = t-Bu and R′ = Me (5e), Et (5f), Ph (5g), and Cy (5h) were obtained by reacting [AuCl(PR'3)] with 1a,b (1:2) and piperidine. The reactions of 1a,b or 2 with Q[AuCl₄] (2:1) and piperidine or diethylamine gave Q[Au{κ²-S,S-S ₂C=C(C₁₂H₆R₂-2,7)}₂] with Q⁺ = PPN⁺ for R = H [(PPN)-6a], Q⁺ = PPN ⁺ or Bu₄N⁺ for R = t-Bu (Q6b), and Q ⁺ = Bu₄N⁺ for R = OC₈H₁₇ [(Bu₄N)6c]. Complexes Q6a-c reacted with excess triflic acid to give [Au{κ²-S,S-S₂C=C(C₁₂H₆R ₂-2,7)}{κ²-S,S-S₂CCH(C₁₂H ₆R₂-2,7)}] [R = H (7a), t-Bu (7b), OC₈H ₁₇ (7c)]. By reaction of (Bu₄N)6b with PhlCl₂ (1:1) the complex Bu₄N[AuCl₂{κ²-S,S- S₂C= C(C₁₂H₆(t-Bu)₂-2,7)}] [(Bu ₄N)8b] was obtained. The dithioato complexes [Au{SC(S)CH(C ₁₂H₈)}{PCy₃)] (9) and [Au_n(S ₂-CCH(C₁₂H₈)}_n] (10) were obtained from the reactions of 1a with [AuCl(PCy₃)] or [AuCl(SMe ₂)], respectively (1:1), in the absence of a base. Charge-transfer adducts of general composition Q[Au{κ²-S,S-S ₂C=C(C₁₂H₆R₂-2,7)}2]· 1.5TCNQ·xCH₂Cl₂ [Q⁺ = PPN⁺, R = H, x = 0 (11a); Q⁺ = PPN⁺, R = t-Bu, x = 2 (11b); Q⁺ = Bu₄N⁺, R = OC₈H₁₇, x = 0 (11c)] were obtained from Q6a-c and TCNQ (1:2). The crystal structures of 5c·THF, 5e·2/3CH₂Cl₂, 5g·CH ₂Cl₂, (PPN)6a·2Me₂CO, and 11b were solved by X-ray diffraction studies. All the gold(I) complexes here described are photoluminescent at 77 K, and their emissions can be generally ascribed to LMMCT (Q₂4a,c, 5a-h, 10) or LMCT (9) excited states.

Full text of DOI:10.1021/ic049132+

Inorg. Chem. 2004, 43, 7516−7531
(Fluoren-9-ylidene)methanedithiolato Complexes of Gold: Synthesis,
Luminescence, and Charge-Transfer Adducts1
Jose´ Vicente,* Pablo Gonza´lez-Herrero,* and Yolanda Garc´ıa-Sa´nchez
Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de Qu´ımica,
UniVersidad de Murcia, Apdo. 4021, 30071 Murcia, Spain
Peter G. Jones†
Institut fu¨r Anorganische und Analytische Chemie, Technische UniVersita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Manuel Bardaj´ı
AÄ rea de Qu´ımica Inorga´nica, Facultad de Ciencias, UniVersidad de Valladolid, Paseo del Prado
de la Magdalena s/n, 47005 Valladolid, Spain
Received July 2, 2004
Piperidinium 9H-fluorene-9-carbodithioate and its 2,7-di-tert-butyl-substituted analogue [(pipH)
2,7) , R H (1a), t-Bu (1b)] and 2,7-bis(octyloxy)-9H-fluorene-9-carbodithioic acid [HS2CCH(C12H6(OC8H17)2-2,7),
2] and its tautomer [2,7-bis(octyloxy)fluoren-9-ylidene]methanedithiol [(HS)2C C(C12H6(OC8H17)2-2,7), 3] were
employed for the preparation of gold complexes with the (fluoren-9-ylidene)methanedithiolato ligand and its substituted
analogues. The gold(I) compounds Q2[Au2{µ C(C12H6R2-2,7)
2-S,S-S2C 2], where Q+ PPN+ or Pr4N+ for R
H (Q24a) or Q+ Pr4N+ for R
OC8H17 [(Pr4N)24c], were synthesized by reacting Q[AuCl2] with 1a or 2 (1:1) and
excess piperidine or diethylamine. Complexes of the type [ Au(PR C(C12H6R2-2,7) 2] with R
2-S,S-S2C
t-Bu and R′ ) Me (5e), Et (5f), Ph (5g), and Cy
3)] with 1a,b (1:2) and piperidine. The reactions of 1a,b or 2 with Q[AuCl4]
C(C12H6R2-2,7) H [(PPN)-
2] with Q+ PPN+ for R
Bu4N+ for R
OC8H17 [(Bu4N)6c]. Complexes Q6a
C(C12H6R2-2,7)}{κ2-S,S-S2CCH(C12H6R2-2,7)
] [R
(7a), t-Bu (7b), OC8H17 (7c)]. By reaction of (Bu4N)6b with PhICl2 (1:1) the complex Bu4N[AuCl2{κ2-S,S-S2C
C(C12H6(t-Bu)2-2,7) ] [(Bu4N)8b] was obtained. The dithioato complexes [Au SC(S)CH(C12H8) (PCy3)] (9) and [Aun
CCH(C12H8) n] (10) were obtained from the reactions of 1a with [AuCl(PCy3)] or [AuCl(SMe2)], respectively (1:1),
in the absence of a base. Charge-transfer adducts of general composition Q[Au{κ2-S,S-S2C
C(C12H6R2-2,7)
1.5TCNQ H, x t-Bu, x
xCH2Cl2 [Q+ PPN+, R 0 (11a); Q+ PPN+, R 2 (11b); Q+
OC8H17, x 0 (11c)] were obtained from Q6a c and TCNQ (1:2). The crystal structures of 5c
5g CH2Cl2, (PPN)6a
{S2CCH(C12H6R2-
}
)
d
-
κ
d
}
)
)
)
)
{
′
3)}2{µ
-κ
d
}
)
H and R′ ) Me (5a), Et (5b), Ph (5c), and Cy (5d) or R )
(5h) were obtained by reacting [AuCl(PR
′
(2:1) and piperidine or diethylamine gave Q[Au{κ2-S,S-S2C
d
}
)
)
6a], Q+
)
PPN+ or Bu4N+ for R
)
t-Bu (Q6b), and Q+
)
d
)
−c
reacted with excess triflic acid to give [Au{κ2-S,S-S2C
}
)
H
d
}
{
}
{S2-
}
d
} ]‚
2
‚
)
)
)
)
)
)
)
Bu4N+, R
)
‚
)
−
‚THF, 5e
2/3CH2Cl2,
‚
‚2Me2CO, and 11b were solved by X-ray diffraction studies. All the gold(I) complexes here
described are photoluminescent at 77 K, and their emissions can be generally ascribed to LMMCT (Q24a,c, 5a
−h,
10) or LMCT (9) excited states.
Introduction
conducting and magnetic materials,2 metalloenzyme model-
ing and function,3 nonlinear optics,4 sensor5 and photore-
sponsive6 materials, and selective olefin coordination/
separation.7 The recent interest in metal complexes of 1,1-
ethylenedithiolates (XYCdCS22-) is mainly due to their
photophysical properties. Platinum complexes with certain
The chemistry of transition metal complexes containing
dithiolates and related ligands continues to attract consider-
able interest in such active research fields as molecular
* Authors to whom correspondence should be addressed. E-mail:
jvs1@um.es (J.V.), pgh@um.es (P.G.-H.). Web: http://www.um.es/gqo.
† E-mail: p.jones@tu-bs.de.
(1) (Fluoren-9-ylidene)methanedithiolato Complexes. 1.
7516 Inorganic Chemistry, Vol. 43, No. 23, 2004
10.1021/ic049132+ CCC: $27.50
© 2004 American Chemical Society
Published on Web 10/22/2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
ligands of this kind display solvatochromic behavior and
room-temperature luminescence in solution8,9 and have been
the subject of intensive research to explore their suitability
for applications as photocatalysts in light-to-chemical energy
conversion processes.10 Additionally, 1,1-ethylenedithiolates
are versatile ligands which may facilitate the formation of
clusters11,12 and heteropolynuclear complexes,13 stabilize high
oxidation states,14,15 or make use of multiple donor atoms to
form coordination polymers.16 Certain polynuclear complexes
containing 1,1-ethylenedithiolates display semiconducting
behavior.17
1,1-Ethylenedithiolates are usually obtained by reacting
methylene-active compounds XYCH2 (X and/or Y ) CN,
COOR, COR, CONH2, NO2, etc.) with CS2 and a base,18-20
the presence of strongly electron-withdrawing functional
groups being therefore a common feature of many of them.
The majority of 1,1-ethylenedithiolato metal complexes
described to date contain i-mnt (X ) Y ) CN),19,21,22 which
is also the case for the gold complexes,23-28 while other
frequently used ligands are those with X ) CO2R and Y )
CN8,29 or CO2R12,14,15,30 (R ) Et, t-Bu). Part of our recent
research work has been devoted to the synthesis and study
of the reactivity and properties of gold, palladium, and
platinum complexes containing the 2,2-diacetyl-1,1-ethyl-
enedithiolato ligand [X ) Y ) C(O)Me], including het-
eropolynuclear complexes.31-33 In this paper, we describe
the synthesis, structural characterization, emission properties,
(2) Suzuki, W.; Fujiwara, E.; Kobayashi, A.; Fujishiro, Y.; Nishibori, E.;
Takata, M.; Sakata, M.; Fujiwara, H.; Kobayashi, H. J. Am. Chem.
Soc. 2003, 125, 1486-1487. Kubo, K.; Nakano, M.; Tamura, H.;
Matsubayashi, G. E. Eur. J. Inorg. Chem. 2003, 4093-4098. Rob-
ertson, N.; Cronin, L. Coord. Chem. ReV. 2002, 227, 93-127. Tanaka,
H.; Kobayashi, H.; Kobayashi, A. J. Am. Chem. Soc. 2002, 124,
10002-10003. Kobayashi, A.; Tanaka, H.; Kumasaki, M.; Torii, H.;
Narymbetov, B.; Adachi, T. J. Am. Chem. Soc. 1999, 121, 10763-
10771.
(3) Sung, K. M.; Holm, R. H. J. Am. Chem. Soc. 2002, 124, 4312-4320.
Sung, K. M.; Holm, R. H. J. Am. Chem. Soc. 2001, 123, 1931-1943.
Lim, B. S.; Willer, M. W.; Miao, M. M.; Holm, R. H. J. Am. Chem.
Soc. 2001, 123, 8343-8349.
(4) Dai, J.; Bian, C. Q.; Wang, X.; Xu, Q. F.; Zhou, M. Y.; Munakata,
M.; Maekawa, M.; Tong, M. H.; Sun, Z. R.; Zeng, H. P. J. Am. Chem.
Soc. 2000, 122, 11007-11008. Chen, C. T.; Liao, S. Y.; Lin, K. J.;
Lai, L. L. AdV. Mater. 1998, 10, 334-338. Cummings, S. D.; Cheng,
L. T.; Eisenberg, R. Chem. Mater. 1997, 9, 440-450.
(5) Mansour, M. A.; Connick, W. B.; Lachicotte, R. J.; Gysling, H. J.;
Eisenberg, R. J. Am. Chem. Soc. 1998, 120, 1329-1330.
(6) Nihei, M.; Kurihara, M.; Mizutani, J.; Nishihara, H. J. Am. Chem.
Soc. 2003, 125, 2964-2973.
(7) Kanney, J. A.; Noll, B. C.; Dubois, M. R. J. Am. Chem. Soc. 2002,
124, 9878-9886.
(8) Zuleta, J. A.; Chesta, C. A.; Eisenberg, R. J. Am. Chem. Soc. 1989,
111, 8916-8917. Zuleta, J. A.; Burberry, M. S.; Eisenberg, R. Coord.
Chem. ReV. 1990, 97, 47-64. Zuleta, J. A.; Bevilacqua, J. M.; Rehm,
J. M.; Eisenberg, R. Inorg. Chem. 1992, 31, 1332-1337. Bevilacqua,
J. M.; Eisenberg, R. Inorg. Chem. 1994, 33, 2913-2923.
(9) Huertas, S.; Hissler, M.; McGarrah, J. E.; Lachicotte, R. J.; Eisenberg,
R. Inorg. Chem. 2001, 40, 1183-1188.
(10) Cummings, S. D.; Eisenberg, R. J. Am. Chem. Soc. 1996, 118, 1949-
1960. Paw, W.; Cummings, S. D.; Mansour, M. A.; Connick, W. B.;
Geiger, D. K.; Eisenberg, R. Coord. Chem. ReV. 1998, 171, 125-
150. Hissler, M.; McGarrah, J. E.; Connick, W. B.; Geiger, D. K.;
Cummings, S. D.; Eisenberg, R. Coord. Chem. ReV. 2000, 208, 115-
137.
(11) Liu, C. W.; Liaw, B. J.; Wang, J. C.; Liou, L. S.; Keng, T. C. J.
Chem. Soc., Dalton Trans. 2002, 1058-1065. Su, W. P.; Hong, M.
C.; Weng, J. B.; Liang, Y. C.; Zhao, Y. J.; Cao, R.; Zhou, Z. Y.;
Chan, A. S. C. Inorg. Chim. Acta 2002, 331, 8-15. Liu, C. W.; Liaw,
B. J.; Wang, J. C.; Keng, T. C. Inorg. Chem. 2000, 39, 1329-1332.
Liu, C. W.; Staples, R. J.; Fackler, J. P. Coord. Chem. ReV. 1998,
174, 147-177. Su, W. P.; Hong, M. C.; Cao, R.; Chen, J. T.; Wu, D.
X.; Liu, H. Q.; Lu, J. X. Inorg. Chim. Acta 1998, 267, 313-317. Hong,
M. C.; Su, W. P.; Cao, R.; Jiang, F. L.; Liu, H. Q.; Lu, J. X. Inorg.
Chim. Acta 1998, 274, 229-231. Fackler, J. P.; Staples, R. J.; Liu, C.
W.; Stubbs, R. T.; Lopez, C.; Pitts, J. T. Pure Appl. Chem. 1998, 70,
839-844. Dietrich, H.; Storck, W.; Manecke, G. J. Chem. Soc., Chem.
Commun. 1982, 1036-1037. Birker, P. J. M. W. L.; Verschoor, G.
C. J. Chem. Soc., Chem. Commun. 1981, 322-324. McCandlish, L.
E.; Bissell, E. C.; Coucouvanis, D.; Fackler, J. P.; Knox, K. J. Am.
Chem. Soc. 1968, 90, 7357-7359.
(12) Coucouvanis, D.; Swenson, D.; Baenziger, N. C.; Pedelty, R.; Caffery,
M. L.; Kanodia, S. Inorg. Chem. 1989, 28, 2829-2836. Hollander,
F. J.; Coucouvanis, D. J. Am. Chem. Soc. 1977, 99, 6268-6280.
(13) Caffery, M. L.; Coucouvanis, D. J. Inorg. Nucl. Chem. 1975, 37,
2081-2086. Coucouvanis, D.; Baenziger, N. C.; Johnson, S. M. Inorg.
Chem. 1974, 13, 1191-1199.
(14) Hollander, F. J.; Caffery, M. L.; Coucouvanis, D. J. Am. Chem. Soc.
1974, 96, 4682-4684. Hollander, F. J.; Pedelty, R.; Coucouvanis, D.
J. Am. Chem. Soc. 1974, 96, 4032-4034. Coucouvanis, D.; Hollander,
F. J.; Pedelty, R. Inorg. Chem. 1977, 16, 2691-2696.
(15) Coucouvanis, D.; Hollander, F. J.; Caffery, M. L. Inorg. Chem. 1976,
15, 1853-1860.
(16) Zhu, Y. B.; Lu, S. F.; Huang, X. Y.; Wu, Q. J.; Yu, R. M.; Huang, J.
Q. Acta Crystallogr. C: Cryst. Struct. Commun. 1995, 51, 1515-1517.
Long, D. L.; Chen, J. T.; Cui, Y.; Huang, J. S. Chem. Lett. 1998,
171-172.
(17) Singh, N.; Gupta, S.; Sinha, R. K. Inorg. Chem. Commun. 2003, 6,
416-422. Singh, N.; Gupta, S. Synth. Met. 2000, 110, 207-212. Singh,
N.; Gupta, S. Polyhedron 1999, 18, 1265-1271.
(18) Gompper, R.; To¨pfl, W. Chem. Ber. 1962, 95, 2861-2870. Huang,
Z. T.; Zhang, P. C. Chem. Ber. 1989, 122, 2011-2016. El-Shafei, A.
K.; El-Shagier, A. A. M.; Ahmed, E. A. Synthesis 1994, 152.
(19) Fackler, J. P., Jr.; Coucouvanis, D. J. Am. Chem. Soc. 1966, 88, 3913-
3920.
(20) Jensen, K. A.; Henriksen, L. Acta Chem. Scand. 1968, 22, 1107-
1128.
(21) Coucouvanis, D. Prog. Inorg. Chem. 1970, 11, 233-371. McCleverty,
J. A.; Orchard, D. G.; Smith, K. J. Chem. Soc. A 1971, 707-711.
Alkam, H. H.; Hatzidimitriou, A.; Hadjikostas, C. C.; Tsiamis, C.
Inorg. Chim. Acta 1997, 256, 41-50. Hadjikostas, C. C.; Alkam, H.;
Akrivos, P. D.; Raper, E. S.; Creighton, J. R. Inorg. Chim. Acta 1998,
271, 195-198. Kang, B. S.; Chen, Z. N.; Su, C. Y.; Lin, Z.; Wen, T.
B. Polyhedron 1998, 17, 2497-2502. Hong, M. C.; Cao, R.;
Kawaguchi, H.; Tatsumi, K. Inorg. Chem. 2002, 41, 4824-4833.
(22) Werden, B. G.; Billig, E.; Gray, H. B. Inorg. Chem. 1966, 5, 78-81.
(23) Da´vila, R. M.; Elduque, A.; Staples, R. J.; Harlass, M.; Fackler, J. P.,
Jr. Inorg. Chim. Acta 1994, 217, 45-49.
(24) Hanna, S. D.; Khan, S. I.; Zink, J. I. Inorg. Chem. 1996, 35, 5813-
5819.
(25) Hanna, S. D.; Zink, J. I. Inorg. Chem. 1996, 35, 297-302.
(26) Fackler, J. P., Jr.; Staples, R. J.; Assefa, Z. J. Chem. Soc., Chem.
Commun. 1994, 431-432. Khan, M. N. I.; Fackler, J. P., Jr.; King,
C.; Wang, J. C.; Wang, S. Inorg. Chem. 1988, 27, 1672-1673.
(27) Khan, M. N. I.; Wang, S.; Fackler, J. P., Jr. Inorg. Chem. 1989, 28,
3579-3588.
(28) Tang, S. S.; Chang, C. P.; Lin, I. J. B.; Liou, L. S.; Wang, J. C. Inorg.
Chem. 1997, 36, 2294-2300.
(29) Zuleta, J. A.; Bevilacqua, J. M.; Eisenberg, R. Coord. Chem. ReV.
1991, 111, 237-248. Zuleta, J. A.; Bevilacqua, J. M.; Proserpio, D.
M.; Harvey, P. D.; Eisenberg, R. J. Am. Chem. Soc. 1992, 31, 2396-
2404. Bevilacqua, J. M.; Zuleta, J. A.; Eisenberg, R. Inorg. Chem.
1993, 32, 3689-3693. Bevilacqua, J. M.; Eisenberg, R. Inorg. Chem.
1994, 33, 1886-1890. Bevilacqua, J. M.; Zuleta, J. A.; Eisenberg, R.
Inorg. Chem. 1994, 33, 258-266. Cummings, S. D.; Eisenberg, R.
Inorg. Chim. Acta 1996, 242, 225-231.
(30) Coucouvanis, D. Prog. Inorg. Chem. 1979, 26, 301. Coucouvanis, D.;
Swenson, D.; Baenziger, N. C.; Pedelty, R.; Caffery, M. L. J. Am.
Chem. Soc. 1977, 99, 8097-8099. Coucouvanis, D.; Kanodia, S.;
Swenson, D.; Chen, S. J.; Studemann, T.; Baenziger, N. C.; Pedelty,
R.; Chu, M. J. Am. Chem. Soc. 1993, 115, 11271-11278.
(31) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G. Chem.
Commun. 1997, 2047-2048.
(32) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G.;
Humphrey, M. G.; Cifuentes, M. P.; Samoc, M.; Luther-Davies, B.
Inorg. Chem. 1999, 38, 5018-5026.
(33) Vicente, J.; Chicote, M. T.; Huertas, S.; Bautista, D.; Jones, P. G.;
Fischer, A. K. Inorg. Chem. 2001, 40, 2051-2057. Vicente, J.;
Chicote, M. T.; Huertas, S.; Jones, P. G.; Fischer, A. K. Inorg. Chem.
2001, 40, 6193-6200. Vicente, J.; Chicote, M. T.; Huertas, S.; Jones,
P. G. Inorg. Chem. 2003, 42, 4268-4274.
Inorganic Chemistry, Vol. 43, No. 23, 2004 7517

Vicente et al.
Chart 1
Chart 2
and reactivity of the first complexes of gold with (fluoren-
9-ylidene)methanedithiolate and its 2,7-di-tert-butyl- and 2,7-
bis(octyloxy)-substituted derivatives (Chart 1). These new
ligands can be classified as 1,1-ethylenedithiolates but show
remarkable differences with respect to the previously de-
scribed ligands of this kind, which are expected to markedly
affect the photophysical properties and redox behavior of
their metal complexes. Thus, although some degree of
negative charge is delocalized over the fluoren-9-ylidene
moiety (Chart 1, resonance form B), the absence of strong
electron-withdrawing substituents makes them stronger S-
donors. In addition, they feature a planar core which provides
extensive conjugation, can be functionalized to modify their
electronic and steric properties, and constitutes a π-stackable
fragment suitable for the formation of charge-transfer
complexes. The only previously described 1,1-ethylenedithi-
olato ligand with similar properties is (cyclopentadienylidene)-
methanedithiolate, but relatively few metal complexes with
this ligand have been reported and only one of them was
structurally characterized.34
spectrometers usually at 298 K, unless otherwise indicated. Chemi-
cal shifts are referred to internal TMS (1H and 13C{H}) or external
85% H3PO4 (31P{H}). The assignments of the 1H and 13C{H} NMR
spectra were made with the help of HMBC and HSQC experiments.
Chart 1 shows the atom numbering of the dithiolato ligands.
Solution conductivities were measured in acetone with a Crison
microCM 2200 conductimeter. Melting points were determined on
a Reichert apparatus and are uncorrected. Elemental analyses were
carried out with a Carlo Erba 1106 microanalyzer. Infrared spectra
were recorded in the range 4000-200 cm-1 on a Perkin-Elmer 16F
PC FT-IR spectrophotometer using Nujol mulls between polyeth-
ylene sheets or KBr pellets. UV-visible absorption spectra were
recorded on Unicam UV500 (range 190-900 nm) or Hitachi
U-2000 (range 190-1100 nm) spectrophotometers. Excitation and
emission spectra were recorded on a Perkin-Elmer LS-55 spectro-
fluorometer by using finely pulverized dispersions of the samples
in KBr or degassed dichloromethane solutions.
X-ray Structure Determinations. Crystals of 5c‚THF, 5e‚2/3-
CH2Cl2, 5g‚CH2Cl2, (PPN)6a‚2Me2CO, and 11b suitable for X-ray
diffraction studies were obtained by slow diffusion of diethyl ether
into solutions of the compounds in THF (5c), CH2Cl2 (5e,g, 11b),
or acetone [(PPN)6a]. Numerical details are presented in Table 1.
Data were recorded at low temperature on a Bruker SMART 1000
CCD diffractometer using Mo KR radiation (λ ) 0.710 73 Å).
Absorption corrections were based on indexed faces (5c,g, 11b) or
multiple scans (program SADABS). Structures were refined aniso-
tropically on F2 using the program SHELXL-97 (Prof. G. M.
Sheldrick, University of Go¨ttingen). Hydrogen atoms were included
using a riding model or rigid methyl groups.
Experimental Section
General Considerations, Materials, and Instrumentation. All
preparations were carried out under an atmosphere of nitrogen using
Schlenk techniques except in the cases of the gold(III) complexes.
Solvents were dried by standard methods and distilled under
nitrogen before use. [AuCl(SMe2)] was prepared as described for
[AuCl(tht)]35 (tht ) tetrahydrothiophene). The compounds [AuCl-
(PR3)] (R ) Me, Et, Ph, Cy) were prepared by reacting [AuCl-
(SMe2)] with the corresponding phosphine in 1:1 molar ratio in
dichloromethane. Q[AuCl4] [Q+ ) PPN+ ) (Ph3P)2N+, Bu4N+]
were prepared by reacting Na[AuCl4]‚xH2O with QCl in acetone.
Q[AuCl2] (Q+ ) PPN+, Pr4N+),36 PhICl2,37 and the ligand precur-
sors piperidinium 9H-fluorene-9-carbodithioate (1a) and its 2,7-
di-tert-butyl-substituted analogue (1b) and 2,7-bis(octyloxy)-9H-
fluorene-9-carbodithioic acid (2) and its tautomer [2,7-bis(octyl-
oxy)fluoren-9-yliden]methanedithiol (3) were prepared following
literature methods (Chart 2).38 All other reagents were obtained
from commercial sources and used without further purification.
NMR spectra were recorded on Bruker Avance 200, 300, or 400
Special Features of Refinement. 5e, 11b: One dichloromethane
molecule is disordered over two positions. 5g: Apart from the well-
resolved dichloromethane molecule, there is an extensive region
of badly resolved electron density, associated with a 2-fold axis,
that could not be interpreted. The program SQUEEZE (part of the
PLATON system: Prof. A. L. Spek, University of Utrecht) was
therefore used to “remove” this electron density mathematically.
Values for the formula mass and other derived parameters do not
take account of this solvent region.
(PPN)2[Au2{µ-κ2-S,S-S2CdC(C12H8)}2] [(PPN)24a]. To a solu-
tion of 1a (90 mg, 0.27 mmol) in THF (20 mL) were added
piperidine (0.1 mL, 1.01 mmol) and PPN[AuCl2] (202 mg, 0.25
mmol). An orange precipitate formed immediately. The suspension
was stirred for 25 min, and the solid was filtered off, washed with
ethanol (2 × 3 mL) and diethyl ether (3 mL), and vacuum-dried to
give (PPN)24a. Yield: 220 mg, 90%. Anal. Calcd for C100H76-
Au2N2P4S4: C, 61.54; H, 3.92; N, 1.43; S, 6.57. Found: C, 61.16;
H, 3.97; N, 1.48; S, 6.40. Mp: 211 °C (dec). ΛM (acetone, 2.5 ×
10-4 M): 199 Ω-1 cm2 mol-1. IR (KBr, cm-1): ν(CdCS2), 1480,
(34) Bereman, R. D.; Nalewajek, D. Inorg. Chem. 1976, 15, 2981-2984.
Bereman, R. D.; Good, M. L.; Kalbacher, B. J.; Buttone, J. Inorg.
Chem. 1976, 15, 618-621. Kalbacher, B. J.; Bereman, R. D. J. Inorg.
Nucl. Chem. 1976, 38, 471-473. Kalbacher, B. J.; Bereman, R. D.
Inorg. Chem. 1975, 14, 1417-1419. Kalbacher, B. J.; Bereman, R.
D. Inorg. Chem. 1973, 12, 2997-3000. Savino, P. C.; Bereman, R.
D. Inorg. Chem. 1973, 12, 173-176.
(35) Uso´n, R.; Laguna, A.; Vicente, J. J. Organomet. Chem. 1977, 131,
471-475.
1
3
(36) Vicente, J.; Chicote, M. T. Inorg. Synth. 1998, 32, 172-177.
(37) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G. Inorg.
Chem. 1997, 36, 5735-5739.
1470. H NMR (400.9 MHz, CD2Cl2): δ 9.32 (d, JHH ) 8.1 Hz,
3
4 H, H1, H8), 7.75 (d, JHH ) 7.4 Hz, 4 H, H4, H5), 7.62-7.59
(m, 12 H, PPN+), 7.47-7.42 (m, 48 H, PPN+), 7.15 (t, 3JHH ) 7.6
(38) Vicente, J.; Gonza´lez-Herrero, P.; Garc´ıa-Sa´nchez, Y.; Pe´rez-Cadenas,
M. Tetrahedron Lett., in press.
Hz, 4 H, H2, H7), 7.04 (t, JHH ) 7.2 Hz, 4 H, H3, H6). 13C{1H}
3
7518 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
Table 1. Crystallographic Data for 5c‚THF, 5e‚2/3CH2Cl2, 5g‚CH2Cl2, (PPN)6a‚2Me2CO, and 11b
5c‚THF
5e‚2/3CH2Cl2
5g‚CH2Cl2
(PPN)6a‚2Me2CO
11b
formula
fw
C54H46Au2OP2S2
1230.90
133(2)
0.710 73
monoclinic
P21/n
17.0606(12)
14.5181(11)
19.1280(12)
90
106.300(5)
90
4547.3(5)
4
1.798
6.647
0.0182
0.0439
C28.67H43.33Au2Cl1.33P2S2
955.23
C59H56Au2Cl2P2S2
1355.53
133(2)
0.710 73
monoclinic
C2/c
23.380(2)
19.4509(14)
25.424(2)
90
100.004(4)
90
11386.0(16)
8
1.582
5.407
0.0273
0.0558
C70H58AuNO2P2S4
1332.32
133(2)
0.710 73
monoclinic
P21/n
9.4807(4)
22.3323(12)
13.7936(8)
90
93.834(5)
90
2913.9(3)
2
1.518
2.771
0.0173
0.0457
C200H176Au2Cl8N14P4S8
3833.44
133(2)
0.710 73
triclinic
T (K)
133(2)
λ (Å)
0.710 73
monoclinic
P21/c
29.0247(16)
17.3765(11)
21.5570(12)
90
109.674(4)
90
10237.5(10)
12
cryst syst
space group
(Å)
P1h
16.0361(6)
17.1629(6)
18.7000(6)
72.593(4)
85.251(4)
66.974(4)
4516.3(3)
1
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å)
Z
F
calcd (Mg m-3
)
1.476
4.647
0.0267
0.0550
1.409
1.926
0.0271
0.0754
µ (mm-1
R1a
)
wR2b
a R1 ) Σ||Fo| - |Fc||/Σ|Fo| for reflections with I > 2σ(I). b wR2 ) [Σ[w(Fo2 - Fc )2]/Σ[w(Fo )2]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2 + bP, where
2
2
2
2
P ) (2Fc + Fo )/3 and a and b are constants set by the program.
NMR (100.8 MHz, CD2Cl2): δ 177.3 (CS2), 140.8 (C8a, C9a),
136.4 (C4a, C4b), 129.6 (C9), 127.2 (C1, C8), 125.4 (C2, C7),
121.9 (C3, C6), 117.9 (C4, C5).
[{Au(PMe3)}2{µ-κ2-S,S-S2CdC(C12H8)}] (5a). To a suspension
of [AuCl(PMe3)] (213 mg, 0.69 mmol) in THF (20 mL) were added
successively piperidine (0.1 mL) and compound 1a (115 mg, 0.35
mmol). The resulting yellow suspension was stirred for 30 min,
and the solvent was evaporated to dryness. The residue was treated
with diethyl ether, and the solid was collected by filtration, washed
with ethanol (2 × 5 mL) and diethyl ether (2 × 3 mL), and
recrystallized from dichloromethane/diethyl ether to give 5a as a
yellow powder. Yield: 253 mg, 93%. Anal. Calcd for C20H26-
Au2P2S2: C, 30.55; H, 3.33; S, 8.15. Found: C, 30.33; H, 3.32; S,
(Pr4N)2[Au2{µ-κ2-S,S-S2CdC(C12H8)}2] [(Pr4N)24a]. This or-
ange compound was prepared as described for (PPN)24a, starting
from 1a (116 mg, 0.35 mmol) and Pr4N[AuCl2] (151 mg, 0.33
mmol). Yield: 199 mg, 96%. Anal. Calcd for C52H72Au2N2S4: C,
50.07; H, 5.81; N, 2.24; S, 10.28. Found: C, 49.70; H, 5.86; N,
2.28; S, 9.91. Mp: 209 °C (dec). ΛM (acetone, 2.3 × 10-4 M):
137 Ω-1 cm2 mol-1. IR (KBr, cm-1): ν(CdCS2), 1474. 1H NMR
[400.9 MHz, (CD3)2SO]: δ 9.18 (d, 3JHH ) 8.3 Hz, 4 H, H1, H8),
7.80 (d, 3JHH ) 7.6 Hz, 4 H, H4, H5), 7.18 (t, 3JHH ) 7.6 Hz, 4 H,
1
7.90. Mp: 270 °C (dec). IR (Nujol, cm-1): ν(CdCS2), 1484. H
3
NMR (200 MHz, CD2Cl2): δ 9.02 (d, JHH ) 8.1 Hz, 2 H, H1,
3
H8), 7.81-7.73 (m, 2 H, H4, H5), 7.31-7.12 (m, 4 H, H2, H3,
H6, H7), 1.63 (d, 2JHP ) 9.7 Hz, 18 H, PMe3). 31P{1H} NMR (81
MHz, CD2Cl2): δ -3.64 (br). The 13C{1H} NMR spectrum of 5a
could not be measured; see Results and Discussion.
H2, H7), 7.08 (t, JHH ) 7.3 Hz, 4 H, H3, H6), 3.07-3.03 (m, 16
3
H, NCH2), 1.55-1.53 (m, 16 H, CH2), 0.84 (t, JHH ) 7.3 Hz, 24
H, Me). 13C{1H} NMR [100.8 MHz, (CD3)2SO]: δ 175.5 (CS2),
139.7 (C8a, C9a), 135.6 (C4a, C4b), 128.7 (C9), 126.3 (C1, C8),
125.2 (C2, C7), 122.1 (C3, C6), 118.0 (C4, C5), 59.3 (NCH2), 14.8
(CH2), 10.6 (Me).
[{Au(PEt3)}2{µ-κ2-S,S-S2CdC(C12H8)}] (5b). A solution of
[AuCl(PEt3)] (138.9 mg, 0.40 mmol) in THF (15 mL) at 0 °C was
treated successively with piperidine (0.1 mL, 1.01 mmol) and 1a
(69 mg, 0.21 mmol). The resulting yellow suspension was stirred
for 20 min, and the solvent was removed under vacuum. Treatment
of the oily residue with diethyl ether (40 mL) gave a yellow solid
which was filtered off, washed with methanol (3 × 3 mL) and
diethyl ether (2 × 3 mL), and vacuum-dried to give 5b. Yield:
113 mg, 65%. Anal. Calcd for C26H38Au2P2S2: C, 35.87; H, 4.40;
S, 7.37. Found: C, 36.23; H, 4.46; S, 7.31. Mp: 163 °C (dec). IR
(Nujol, cm-1): ν(CdCS2), 1486. 1H NMR (400.9 MHz, CD2Cl2):
δ 9.05 (d, 3JHH ) 8.0 Hz, 2 H, H1, H8), 7.75 (d, 3JHH ) 7.4 Hz, 2
H, H4, H5), 7.24 (m, 2 H, H2, H7), 7.15 (m, 2 H, H3, H6), 1.85
(Pr4N)2[Au2{µ-κ2-S,S-S2CdC(C12H6(OC8H17)2-2,7)}2][(Pr4N)24c].
To a solution of 2 (279 mg, 0.56 mmol) in THF (15 mL) were
added successively diethylamine (0.1 mL) and Pr4N[AuCl2] (242
mg, 0.53 mmol). Reaction took place immediately to give an orange
solution and a white precipitate of Et2NH2Cl. The mixture was
stirred for 15 min, and the precipitate was removed by filtration.
The clear orange filtrate was evaporated to dryness and the residue
dissolved in dichloromethane (5 mL). Addition of diethyl ether (25
mL) led to the slow formation of a bulky precipitate which was
purified by recrystallization from dichloromethane/diethyl ether and
vacuum-dried to give (Pr4N)24c as an orange solid. Yield: 440 mg,
94%. Anal. Calcd for C84H136Au2N2O4S4: C, 57.32; H, 7.79; N,
1.59; S, 7.29. Found: C, 57.23; H, 8.08; N, 1.70; S, 7.16. Mp:
103 °C. ΛM (acetone, 4.8 × 10-4 M): 98 Ω-1 cm2 mol-1. IR (KBr,
3
3
(m, 12 H, CH2), 1.24 (dt, JHP ) 18.3 Hz, JHH ) 7.6 Hz, 18 H,
Me). 13C{1H} NMR (100.8 MHz, CD2Cl2, -10 °C): δ 162.7 (CS2),
139.6 (C8a, C9a), 137.4 (C4a, C4b), 132.4 (C9), 126.7 (C1, C8),
1
cm-1): ν(CdCS2), 1480, 1466. H NMR (200 MHz, CDCl3): δ
125.7 (C2, C7), 124.2 (C3, C6), 118.2 (C4, C5), 18.0 (d, JCP
)
32.9 Hz, CH2), 8.8 (Me). 31P{1H} NMR (162.3 MHz, CDCl3): δ
8.79 (d, 4JHH ) 2.0 Hz, 4 H, H8, H1), 7.32 (d, 3JHH ) 8.2 Hz, 4 H,
H4, H5), 6.55 (dd, 4 H, H3, H6), 3.86 (br t, OCH2, 8 H), 2.48 (br,
16 H, NCH2), 1.70 (br m, 8 H, OCH2CH2), 1.29 (br, 40 H, CH2,
C8H17), 1.11 (br, 8 H, CH2, Pr4N+), 0.89 (app t, 12 H, Me, C8H17),
0.65 (app t, 24 H, Me, Pr4N+). 13C{1H} NMR (50.3 MHz,
CDCl3): δ 175.7 (CS2), 157.2 (C2, C7), 141.1 (C8a, C9a), 129.8
(C9), 129.6 (C4a, C4b), 117.2 (C4, C5), 112.7 (C1, C8), 110.4
(C3, C6), 68.1 (OCH2), 58.7 (NCH2), 31.9, 29.6, 29.5, 29.3, 26.2,
22.7 (all CH2, C8H17), 15.2 (CH2, Pr4N+), 14.1 (Me, C8H17), 10.9
(Me, Pr4N+).
34.1 (s).
[{Au(PPh3)}2{µ-κ2-S,S-S2CdC(C12H8)}]‚THF (5c). A solution
of [AuCl(PPh3)] (314 mg, 0.64 mmol) in THF (20 mL) was treated
successively with piperidine (0.1 mL, 1.01 mmol) and 1a (104.0
mg, 0.317 mmol). The resulting yellow suspension was stirred for
1 h and filtered to remove the precipitate of piperidinium chloride.
Partial evaporation of the clear yellow filtrate (to ca. 5 mL) led to
the precipitation of a yellow solid. Diethyl ether (20 mL) was added,
and the solid was filtered off, washed with ethanol (2 × 3 mL)
Inorganic Chemistry, Vol. 43, No. 23, 2004 7519

Vicente et al.
and diethyl ether (2 × 3 mL), and recrystallized from THF/diethyl
ether to give 5c‚THF as a yellow microcrystalline solid. Yield: 333
mg, 85%. Anal. Calcd for C54H46Au2OP2S2: C, 52.70; H, 3.77; S,
5.21. Found: C, 52.27; H, 3.75; S, 5.08. Mp: 122 °C (dec). IR
(KBr, cm-1): ν(CdCS2), 1488, 1480. 1H NMR (400.9 MHz, CD2-
Cl2): δ 9.13 (d, 3JHH ) 8.0 Hz, 2 H, H1, H8), 7.78 (d, 3JHH ) 7.4
Hz, 2 H, H4, H5), 7.51-7.41 (m, 18 H, PPh3), 7.32-7.26 (m, 14
H, PPh3 + H2, H7), 7.18 (t, 3JHH ) 7.2 Hz, 2 H, H3, H6), 3.70 (m,
4 H, CH2, THF), 1.83 (m, 4 H, CH2, THF). 13C{1H} (100.8 MHz,
CD2Cl2, -10 °C): δ 160.5 (CS2), 139.6 (C8a, C9a), 137.7 (C4a,
C4b), 134.1 (d, 2JCP ) 13.7 Hz, o-C, PPh3), 132.7 (C9), 131.5 (p-
(s, 18 H, t-Bu). 13C{1H} NMR (100.8 MHz, CDCl3, -10 °C): δ
156.0 (CS2), 148.0 (C2, C7), 140.0 (C8a, C9a), 135.7 (C4a, C4b),
134.0 (d, 2JCP ) 13.7 Hz, o-C, PPh3), 131.4 (C9), 131.2 (p-C, PPh3),
129.6 (d, JCP ) 55.9 Hz, i-C PPh3), 128.9 (d, JCP ) 11.4 Hz,
m-C, PPh3), 124.0 (C1, C8), 120.7 (C3, C6), 116.9 (C4, C5), 68.0
(CH2, THF), 35.0 [C(CH3)3], 31.8 [C(CH3)3], 25.5 (CH2, THF).
31P{1H} NMR (162.3 MHz, CDCl3): δ 35.7 (br).
1
3
[{Au(PCy3)}2{µ-κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}] (5h). This
yellow complex was prepared as described for 5b, starting from
[AuCl(PCy3)] (235 mg, 0.46 mmol) and 1b (117 mg, 0.25 mmol).
Yield: 244 mg, 82%. Anal. Calcd for C58H90Au2P2S2: C, 53.29;
H, 6.94; S, 4.91. Found: C, 53.16; H, 7.13; S, 4.97. Mp: 202 °C
1
3
C, PPh3), 129.5 (d, JCP ) 57.1 Hz, i-C, PPh3), 129.1 (d, JCP
)
1
(dec). IR (KBr, cm-1): ν(CdCS2), 1491. H NMR (400.9 MHz,
11.4 Hz, m-C, PPh3), 126.8 (C1, C8), 125.9 (C2, C7), 124.5 (C3,
C6), 118.3 (C4, C5), 67.9, 25.6 (both CH2, THF). 31P{1H} NMR
(162.3 MHz, CD2Cl2): δ 35.4 (br).
CDCl3): δ 9.33 (d, 4JHH ) 1.6 Hz, 2 H, H1, H8), 7.56 (d, 3JHH
)
7.9 Hz, 2 H, H4, H5), 7.13 (dd, 2 H, H3, H6), 7.95-7.66 (m, 36
H, PCy3), 1.39 (m, 30 H, t-Bu + PCy3), 1.26-1.15 (m, 18 H, PCy3).
13C{1H} NMR (100.8 MHz, CDCl3, -15 °C): δ 158.9 (CS2), 147.3
(C2, C7), 140.5 (C8a, C9a), 135.1 (C4a, C4b), 133.6 (C9), 123.9
(C1, C8), 120.7 (C3, C6), 116.9 (C4, C5), 34.9 [C(CH3)3], 32.8 (d,
2JCP ) 27.4 Hz, C1, PCy3), 31.9 [C(CH3)3], 30.1 (C2, PCy3), 27.0
[{Au(PCy3)}2{µ-κ2-S,S-S2CdC(C12H8)}] (5d). This yellow
complex was prepared as described for 5b, starting from [AuCl-
(PCy3)] (230 mg, 0.45 mmol) and compound 1a (79 mg, 0.24
mmol). Yield: 174.3 mg, 65%. Anal. Calcd for C50H74Au2P2S2:
C, 50.25; H, 6.24; S, 5.37. Found: C, 50.15; H, 6.33; S, 5.29. Mp:
200 °C (dec). IR (KBr, cm-1): ν(CdCS2), 1489. 1H NMR (400.9
3
(d, JCP ) 11.8 Hz, C3, PCy3), 25.7 (C4, PCy3). 31P{1H} NMR
3
MHz, CDCl3): δ 9.26 (d, JHH ) 8.0 Hz, 2 H, H1, H8), 7.71 (d,
(162.3 MHz, CDCl3): δ 54.7 (s).
3JHH ) 7.2 Hz, 2 H, H4, H5), 7.23 (m, 2 H, H2, H7), 7.11 (m, 2
H, H3, H6), 1.94-1.15 (m, 66 H, PCy3). 13C{1H} NMR (100.8
MHz, CDCl3, -15 °C): δ 162.1 (CS2), 140.0 (C8a, C9a), 137.2
(C4a, C4b), 132.5 (C9), 126.6 (C1, C8), 125.2 (C2, C7), 123.5
(C3, C6), 117.9 (C4, C5), 32.8 (d, 2JCP ) 27.5 Hz, C1, PCy3), 30.1
PPN[Au{κ2-S,S-S2CdC(C12H8)}2] [(PPN)6a]. A suspension of
PPN[AuCl4] (878 mg, 1.00 mmol) in THF (50 mL) was treated
successively with piperidine (0.1 mL, 1.01 mmol) and compound
1a (678 mg, 2.07 mmol). The resulting dark green suspension was
stirred for 6 h. The solvent was removed, and the remaining residue
was treated with diethyl ether to give a green solid which was
filtered off and washed with ethanol (2 × 5 mL) and diethyl ether
(2 × 5 mL). The product was recrystallized from dichloromethane/
diethyl ether to give (PPN)6a. Yield: 1.049 g, 86%. Anal. Calcd
for C64H46AuNP2S4: C, 63.20; H, 3.81; N, 1.15; S, 10.54. Found:
C, 63.53; H, 4.03; N, 1.23; S, 10.40. Mp: 259 °C. ΛM (acetone,
2.5 × 10-4 M): 101 Ω-1 cm2 mol-1. IR (Nujol, cm-1): ν(Cd
CS2), 1538; ν(Au-S), 364. 1H NMR (400.9 MHz, CDCl3): δ 8.44-
8.42 (m, 4 H, H1, H8), 7.78-7.76 (m, 4 H, H4, H5), 7.52-7.47
(m, 6 H, PPN+), 7.39-7.32 (m, 24 H, PPN+), 7.24-7.17 (m, 8 H,
H2, H3, H6, H7). 13C{1H} NMR (50.32 MHz, CDCl3): δ 157.6
(CS2), 138.4 (C8a, C9a), 137.2 (C4a, C4b), 129.5 (C9), 126.2 (C2,
C7), 124.1 (C3, C6), 123.9 (C1, C8), 118.7 (C4, C5).
3
(C2, PCy3), 27.0 (d, JCP ) 11.8 Hz, C3, PCy3), 25.7 (C4, PCy3).
31P{1H} NMR (162.3 MHz, CDCl3): δ 54.9 (s).
[{Au(PMe3)}2{µ-κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}] (5e). This
yellow microcrystalline compound was prepared as described for
5b, starting from [AuCl(PMe3)] (288 mg, 0.93 mmol) and 1b (222
mg, 0.50 mmol). Yield: 346 mg, 82%. Anal. Calcd for C28H42-
Au2P2S2: C, 37.42; H, 4.71; S, 7.14. Found: C, 37.32; H, 4.92; S,
1
6.69. Mp: 181 °C (dec). IR (Nujol, cm-1): ν(CdCS2), 1486. H
NMR (200 MHz, CDCl3): δ 9.22 (br, 2 H, H1, H8), 7.61 (br d,
3JHH ) 7.9 Hz, 2 H, H4, H5), 7.18 (dd, 3JHH ) 7.9, 4JHH ) 1.7 Hz,
2 H, H3, H6), 1.53 (br, 18 H, PMe3), 1.38 (s, 18 H, t-Bu). 31P{1H}
NMR (81 MHz, CDCl3): δ -3.67 (br). The 13C{1H} NMR
spectrum of 5e could not be measured; see Results and Discussion.
[{Au(PEt3)}2{µ-κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}] (5f). This
yellow complex was prepared as described for 5b, starting from
[AuCl(PEt3)] (182 mg, 0.52 mmol) and 1b (126 mg, 0.26 mmol).
Yield: 234 mg, 92%. Anal. Calcd for C34H54Au2P2S2: C, 41.55;
H, 5.54; S, 6.52. Found: C, 41.85; H, 5.48; S, 6.53. Mp: 176 °C
PPN[Au{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}2] [(PPN)6b]. This
green complex was prepared as described for (PPN)6a, starting from
PPN[AuCl4] (1.004 g, 1.14 mmol) and 1b (1.078 g, 2.45 mmol).
Yield: 1.230 g, 74%. Anal. Calcd for C64H46AuNP2S4: C, 66.70;
H, 5.46; N, 0.97; S, 8.90. Found: C, 66.42; H, 5.51; N, 0.92; S,
1
(dec). IR (KBr, cm-1): ν(CdCS2), 1487. H NMR (400.9 MHz,
8.77. Mp: 272 °C. ΛM (acetone, 4.9 × 10-4 M): 70 Ω-1 cm2 mol-1
.
CDCl3): δ 9.25 (d, 4JHH ) 1.5 Hz, 2 H, H1, H8), 7.58 (d, 3JHH
)
IR (cm-1): ν(CdCS2), 1536; ν(Au-S), 372. 1H NMR (400.9 MHz,
7.9 Hz, 2 H, H4, H5), 7.16 (dd, 2 H, H3, H6), 1.78 (m, 12 H, CH2,
CDCl3): δ 8.53 (d, 4JHH ) 1.3 Hz, 4 H, H1, H8), 7.64 (d, 3JHH
)
3
3
PEt3), 1.38 (s, 18 H, t-Bu), 1.18 (dt, JHP ) 18.3 Hz, JHH ) 7.8
Hz, 18 H, Me, PEt3). 13C{1H} NMR (100.8 MHz, CDCl3, -10
°C): δ 157.9 (CS2), 147.8 (C2, C7), 140.1 (C8a, C9b), 135.4 (C4a,
C4b), 133.6 (C9), 124.1 (C1, C8), 121.3 (C3, C6), 117.0 (C4, C5),
35.0 [C(CH3)3], 31.8 [C(CH3)3], 17.8 (d, JCP ) 32.7 Hz, CH2, PEt3),
8.7 (Me, PEt3). 31P{1H} NMR (162.3 MHz, CDCl3): δ 33.8 (s).
[{Au(PPh3)}2{µ-κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}]‚THF (5g).
This yellow complex was prepared as described for 5b, starting
from [AuCl(PPh3)] (249 mg, 0.50 mmol) and 1b (125 mg, 0.26
mmol). Yield: 324 mg, 96%. Anal. Calcd for C62H62Au2OP2S2:
C, 55.44; H, 4.65; S, 4.77. Found: C, 55.65; H, 4.85; S, 4.54. Mp:
140 °C. IR (KBr, cm-1): ν(CdCS2), 1499. 1H NMR (400.9 MHz,
8.0 Hz, 4 H, H4, H5), 7.45-7.29 (m, 30 H, PPN+), 7.23 (dd, 4 H,
H3, H6), 1.36 (s, 36 H, t-Bu). 13C{1H} (50.3 MHz, CDCl3): δ
155.5 (CS2), 148.8 (C2, C7), 138.9 (C8a, C9a), 134.9 (C4a, C4b),
129.9 (C9), 121.3 (C3, C6), 121.0 (C1, C8), 117.9 (C4, C5), 34.9
[C(CH3)3], 31.8 [C(CH3)3].
Bu4N[Au{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}2] [(Bu4N)6b]. This
green complex was prepared as described for (PPN)6a, starting from
Bu4N[AuCl4] (405 mg, 0.70 mmol) and 1b (630 mg, 1.43 mmol).
Yield: 531 g, 67%. Anal. Calcd for C60H84AuNS4: C, 62.96; H,
7.40; N, 1.22; S, 11.21. Found: C, 62.66; H, 7.53; N, 1.29; S, 11.09.
Mp: 311 °C (dec). ΛM (acetone, 2.6 × 10-4 M): 88 Ω-1 cm2
mol-1. IR (cm-1): ν(CdCS2), 1532; ν(Au-S), 374. 1H NMR (200
CDCl3): δ 9.30 (d, 4JHH ) 1.5 Hz, 2 H, H1, H8), 7.63 (d, 3JHH
)
MHz, CD2Cl2): δ 8.47 (d, JHH ) 1.7 Hz, 4 H, H1, H8), 7.65 (d,
4
7.9 Hz, 2 H, H4, H5), 7.46-7.24 (m, 30 H, PPh3), 7.19 (dd, 2 H,
H3, H6), 3.75 (m, 6 H, CH2, THF), 1.85 (m, 6 H, CH2, THF), 1.36
3JHH ) 7.9 Hz, 4 H, H4, H5), 7.29 (dd, 4 H, H3, H6), 2.89 (m, 8
H, NCH2), 1.40 (s, 36 H, t-Bu), 1.30 (m, 8 H, CH2), 1.20 (m, 8 H,
7520 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
4
3
CH2), 0.78 (t, 3JHH ) 7.0 Hz, Me). 13C{1H} NMR (50.3 MHz, CD2-
Cl2): δ 153.9 (CS2), 149.8 (C2, C7), 138.7 (C8a, C9a), 135.2 (C4a,
C4b), 130.5 (C9), 122.5 (C3, C6), 121.2 (C1, C8), 118.6 (C4, C5),
58.9 (NCH2), 35.2 [C(CH3)3], 31.9 [C(CH3)3], 24.1, 20.0 (both
CH2), 13.7 (Me, Bu4N+).
Bu4N[Au{κ2-S,S-S2CdC(C12H6(OC8H17)2-2,7)}2] [(Bu4N)6c].
To a solution of 2 (432 mg, 0.87 mmol) in THF (15 mL) were
added successively diethylamine (0.1 mL) and Bu4N[AuCl4] (228
mg, 0.39 mmol). Reaction took place immediately to give a dark
green suspension, which was stirred for 45 min and filtered to
remove the white precipitate of Et2NH2Cl. The clear dark green
filtrate was evaporated to dryness, and the residue was dissolved
in dichloromethane (5 mL). Addition of ethanol led to the formation
of a green precipitate, which was collected by filtration, recrystal-
lized from dichloromethane/ethanol, and vacuum-dried to give
(s, 2 H, H1, H8, dithioato), 7.02 (dd, JHH ) 1.7, JHH ) 8.4 Hz,
2 H, H3, H6, dithioato), 6.80 (dd, 4JHH ) 1.7, 3JHH ) 8.4 Hz, 2 H,
H3, H6, dithiolato), 5.17 (s, 1 H, H9, dithioato), 4.00 (m, 8 H,
OCH2), 1.80 (m, 8 H, CH2), 1.46 (m, 8 H, CH2), 1.29 (m, 40 H,
CH2), 0.88 (m, 12 H, Me). The 13C{1H} NMR spectrum of 7c could
not be measured because of its very low solubility.
Bu4N[AuCl2{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}] [(Bu4N)8b]. A
solution of PhICl2 (174 mg, 0.63 mmol) in dichloromethane (15
mL) was added dropwise to a stirred solution of (Bu4N)6b (622
mg, 0.54 mmol) in the same solvent (50 mL) over a period of 10
min. The resulting brown solution was stirred for 2 h and
concentrated to ca. 15 mL. Addition of diethyl ether (25 mL) led
to the precipitation of a pale green solid, which was filtered off,
washed with a 1:2 mixture of dichloromethane and diethyl ether
(2 × 5 mL), and vacuum-dried to give (Bu4N)8b. Yield: 348 mg,
74%. Anal. Calcd for C38H60AuCl2NS2: C, 52.89; H, 7.01; N, 1.62;
S, 7.43. Found: C, 52.81; H, 7.26; N, 1.65; S, 7.25. Mp: 200 °C.
ΛM (acetone, 3.8 × 10-4 M): 96 Ω-1 cm2 mol-1. IR (cm-1):
(Bu4N)6c. Yield: 290 mg, 52%. Anal. Calcd for C76H116
-
AuNO4S4: C, 63.70; H, 8.16; N, 0.98; S, 8.95. Found: C, 63.67;
H, 8.32; N, 1.06; S, 8.86. Mp: 164 °C. ΛM (acetone, 4.9 × 10-4
M): 76 Ω-1 cm2 mol-1. IR (cm-1): ν(CdCS2), 1538; ν(Au-S),
368. 1H NMR (200 MHz, CD2Cl2): δ 7.91 (d, 4JHH ) 2.2 Hz, 4 H,
H8, H1), 7.46 (d, 3JHH ) 8.4 Hz, 4 H, H4, H5), 6.72 (dd, 4 H, H6,
H3), 3.96 (t, 3JHH ) 6.6 Hz, 8 H, OCH2), 2.57 (br m, 8 H, NCH2),
1.78 (m, 8H, OCH2CH2), 1.50-1.30 (br m, 40 H, CH2, C8H17),
1.10 (br m, 16 H, CH2, Bu4N+), 0.90 (m, 12 H, Me, C8H17), 0.76
(m, 12 H, Me, Bu4N+). 13C{1H} NMR (50.3 MHz, CDCl3): δ 157.9
(C2, C7), 155.5 (CS2), 139.0 (C8a, C9a), 130.7 (C4a, C4b), 129.6
(C9), 118.7 (C4, C5), 111.8 (C1, C8), 109.9 (C3, C6), 68.3 (OCH2),
57.7 (NCH2), 31.8, 29.5, 29.4, 29.3, 26.2 (all CH2, C8H17), 23.5
(CH2, Bu4N+), 22.7 (CH2, C8H17), 19.45 (CH2, Bu4N+), 14.1 (Me,
C8H17), 13.7 (Me, Bu4N+).
1
ν(CdCS2), 1572, 1564; ν(Au-S), 384; ν(Au-Cl), 318, 302. H
NMR (400.9 MHz, CD2Cl2): δ 8.13 (dd, JHH ) 0.4, JHH ) 1.7
5
4
5
3
Hz, 2 H, H1, H8), 7.64 (dd, JHH ) 0.4, JHH ) 7.9 Hz, 2 H, H4,
H5), 7.33 (dd, 4JHH ) 1.7, 3JHH ) 7.9 Hz, 2 H, H3, H6), 3.07 (m,
8 H, NCH2), 1.53 (m, 8 H, CH2), 1.38 (m, 26 H, t-Bu + CH2),
0.96 (t, 3JHH ) 7.3 Hz, Me, Bu4N+). 13C{1H} NMR (75 MHz, CD2-
Cl2): δ 150.3 (C2, C7), 139.3 (CS2), 138.4 (C8a, C9a), 135.7 (C4a,
C4b), 130.5 (C9), 123.5 (C3, C6), 120.0 (C1, C8), 119.0 (C4, C5),
59.4 (NCH2), 35.2 [C(CH3)3], 31.8 [C(CH3)3], 24.4 (CH2), 20.1
(CH2), 13.8 (Me, Bu4N+).
[Au{SC(S)CH(C12H8)}(PCy3)] (9). To a solution of 1a (100
mg, 0.31 mmol) in dichloromethane (15 mL) was added [AuCl-
(PCy3)] (143 mg, 0.28 mmol), and the resulting orange solution
was stirred for 20 min. Partial evaporation of the solvent (3 mL)
and addition of diethyl ether (15 mL) led to the precipitation of an
orange-pink solid, which was filtered off, washed with ethanol (2
× 2 mL) and diethyl ether (2 mL), and vacuum-dried to give 9.
Yield: 174 mg, 87%. Anal. Calcd for C32H42AuPS2: C, 53.47; H,
5.89; S, 8.92. Found: C, 53.60; H, 5.95; S, 9.14. Mp: 157 °C (dec).
IR (Nujol, cm-1): ν(CS2), 970. 1H NMR (400.9 MHz, CD2Cl2): δ
7.76-7.73 (m, 4 H, H1, H4, H5, H8), 7.42-7.38 (m, 2 H, H2,
H7), 7.35-7.31 (m, 2 H, H3, H6), 5.64 (s, 1 H, H9), 2.07-2.02
(m, 3 H, CH, PCy3), 2.00-1.15 (m, 30 H, CH2, PCy3). 13C{1H}
NMR (100.8 MHz, CD2Cl2): δ 255.2 (CS2), 146.3 (C8a,C9a), 141.5
(C4a, C4b), 128.1 (C3,C6), 127.6 (C2, C7), 125.3 (C1, C8), 120.1
(C4, C5), 74.9 (C9), 33.8 (d, 2JCP ) 27.8 Hz, C1, PCy3), 31.0 (C2,
[Au{κ2-S,S-S2CdC(C12H8)}{κ2-S,S-S2CCH(C12H8)}] (7a). A
solution of (PPN)6a (142 mg, 0.117 mmol) in dichloromethane (20
mL) was treated with trifluoromethanesulfonic acid (21 µL, 0.23
mmol). A red precipitate formed immediately, which was filtered
off, washed with dichloromethane (2 × 5 mL), and vacuum-dried
to give 7a. Yield: 74 mg, 94%. Anal. Calcd for C28H17AuS4: C,
49.55; H, 2.52; S, 18.90. Found: C, 49.13; H, 2.53; S, 18.91. Mp:
202 °C (dec). IR (cm-1): ν(CdCS2), 1548, ν(Au-S), 366. NMR
data for 7a could not be obtained because of its very low solubility.
[Au{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}{κ2-S,S-S2CCH(C12H6-
(t-Bu)2-2,7)}] (7b). This complex was obtained as a dark red solid
by following the procedure described for 7a, starting from (PPN)-
6b (220 mg, 0.15 mmol) and trifluoromethanesulfonic acid (27 µL,
0.30 mmol). Yield: 132 mg, 96%. Anal. Calcd for C44H49AuS4:
C, 58.52; H, 5.47; S, 14.20. Found: C, 58.35; H, 5.47; S, 14.22.
Mp: 276 °C (dec). IR (cm-1): ν(CdCS2), 1570, 1558; ν(Au-S),
380. 1H NMR (200 MHz, CD2Cl2): δ 8.18 (d, 4JHH ) 1.3 Hz, 2 H,
H1, H8, dithiolato), 7.75-7.71 (br m, 4 H, H1, H4, H5, H8,
dithioato), 7.63 (d, 3JHH ) 8.0 Hz, 2 H, H4, H5, dithiolato), 7.59-
7.54 (m, 2 H, H6, H3, dithioato), 7.33 (dd, 3JHH ) 8.0, 4JHH ) 1.7
Hz, 2 H, H3, H6, dithiolato), 1.39 (s, 18 H, t-Bu), 1.37 (s, 18 H,
t-Bu) (H9 not observed). The 13C{1H} NMR spectrum of 7b could
not be measured because of its very low solubility.
PCy3), 27.5 (d, JCP ) 11.9 Hz, C3, PCy3), 26.3 (C4, PCy3). 31P-
3
{1H} NMR (162.3 MHz, CD2Cl2): δ 56.8 (s).
[Aun{S2CCH(C12H8)}n] (10). To a suspension of [AuCl(SMe2)]
(106 mg, 0.36 mmol) in THF (12 mL) was added 1a (123 mg,
0.38 mmol). A red precipitate formed immediately. The suspension
was stirred for 30 min, and the solid was filtered off, washed with
THF (3 × 3 mL) and dichloromethane (3 × 3 mL), and vacuum-
dried to give 10. Yield: 124 mg, 79%. Anal. Calcd for C14H9-
AuS2: C, 38.36; H, 2.07; S, 14.63. Found: C, 38.75; H, 2.05; S,
14.35. Mp: 196 °C (dec). IR (Nujol, cm-1): ν(CS2), 1074, 1032,
1004. The 1H NMR spectrum of this compound in (CD3)2SO shows
very complex signals in the aromatic region; see Results and
Discussion.
PPN[Au{κ2-S,S-S2CdC(C12H8)}2]‚1.5TCNQ (11a). To a solu-
tion of (PPN)6a (122 mg, 0.10 mmol) in dichloromethane (30 mL)
was added tetracyano-7,7,8,8-quinodimethane (TCNQ) (35 mg, 0.17
mmol). The resulting dark brown solution was stirred for 2 h and
concentrated to ca. 8 mL. Addition of diethyl ether (2 mL) led to
the precipitation of a dark blue microcrystalline solid, which was
2
2
[Au{κ -S,S-S2CdC(C12H6(OC8H17)2-2,7)}{κ -S,S-S2CCH(C12H6-
(OC8H17 )2-2,7)}] (7c). This complex was obtained as a dark red
solid by following the procedure described for 7a, starting from
(Bu4N)6c (302 mg, 0.21 mmol) and trifluoromethanesulfonic acid
(40 µL, 0.46 mmol). Yield: 218 mg, 87%. Anal. Calcd for C60H81-
AuO4S4: C, 60.48; H, 6.85; S, 10.76. Found: C, 60.20; H, 7.14;
S, 10.74. Mp: 218 °C (dec). IR (cm-1): ν(CdCS2), 1550, ν(Au-
S), 370. 1H NMR (400.9 MHz, CDCl3): δ 7.66 (d, 4JHH ) 1.7 Hz,
3
2 H, H1, H8 of dithiolato), 7.58 (d, JHH ) 8.4 Hz, 2 H, H4, H5,
3
dithioato), 7.49 (d, JHH ) 8.4 Hz, 2 H, H4, H5, dithiolato), 7.14
Inorganic Chemistry, Vol. 43, No. 23, 2004 7521

Vicente et al.
Scheme 1
filtered off, washed with a 4:1 mixture of dichloromethane/diethyl
ether (2 × 5 mL), and vacuum-dried to give 11a. Yield: 140 mg,
92%. Anal. Calcd for C82H52AuN7P2S4: C, 64.69; H, 3.44; N, 6.44;
S, 8.42. Found: C, 64.29; H, 3.39; N, 6.62; S, 8.32. Mp: 200 °C
(dec). IR (Nujol, cm-1): ν(CtN)TCNQ, 2216; ν(CdCS2), 1530;
1
δ(C-H)TCNQ, 832; ν(Au-S), 368. H NMR (300 MHz, CD2Cl2):
δ 8.36 (m, 4 H, H1, H8), 7.76 (m, 4 H, H4, H5), 7.63-7.40 (m, 30
H, PPN+), 7.26 (m, 8 H, H2, H3, H6, H7).
PPN[Au{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}2]‚1.5TCNQ‚
2CH2Cl2 (11b). A solid mixture of (PPN)6b (138 mg, 0.1 mmol)
and TCNQ (24 mg, 0.12 mmol) was treated with dichloromethane
(25 mL), and the resulting dark brown solution was stirred for 7 h.
Partial evaporation of the solvent (10 mL) and addition of diethyl
ether (20 mL) led to the precipitation of a black microcrystalline
solid, which was filtered off, washed with a 1:2 mixture of
dichloromethane/diethyl ether (2 × 5 mL), and vacuum-dried to
give 11b. Yield: 132 mg, 72%. Anal. Calcd for C100H88-
AuCl4N7P2S4: C, 62.66; H, 4.63; N, 5.12; S, 6.69. Found: C, 62.74;
H, 4.94; N, 5.19; S, 6.33. Mp: 270 °C. IR (Nujol, cm-1): ν(Ct
N)TCNQ, 2216; ν(CdC)TCNQ, 1544; ν(CdCS2), 1526; δ(C-H)TCNQ
,
1
834; ν(Au-S), 370. H NMR (300.1 MHz, CD2Cl2): δ 8.45 (d,
4JHH ) 1.5 Hz, 4 H, H1, H8), 7.64-7.39 (m, 34 H, H4, H5 +
4
3
PPN+), 7.29 (dd, JHH ) 1.5 Hz, JHH ) 8.1 Hz, 4 H, H3, H6),
1.41 (s, 36 H, t-Bu).
Bu4N[Au{κ2-S,S-S2CdC(C12H6(OC8H17)2-2,7)}2]‚1.5TCNQ
(11c). A solid mixture of (Bu4N)6c (145 mg, 0.10 mmol) and TCNQ
(42 mg, 0.21 mmol) was treated with dichloromethane (15 mL),
and the resulting solution was stirred at room temperature for 16
h. A dark green precipitate gradually formed, which was filtered
off, washed with a 4:1 mixture of dichloromethane/diethyl ether
(5 mL), and vacuum-dried to give 11c. Yield: 145 mg, 82%. Anal.
Calcd for C94H122AuN7O4S4: C, 64.91; H, 7.07; N, 5.64; S, 7.37.
Found: C, 64.74; H, 7.12; N, 5.71; S, 7.16. Mp: 215°C. IR (Nujol,
cm-1): ν(CtN)TCNQ, 2216; ν(CdCS2), 1542; δ(C-H)TCNQ, 834;
ν(Au-S), 370. 1H NMR (400.9 MHz, CD2Cl2): δ 7.90 (d, 4JHH
)
1.5 Hz, 4 H, H1, H8), 7.47 (d, 3JHH ) 8.3 Hz, 4 H, H4, H5), 7.78
3
(dd, 4 H, H3, H6), 4.05 (t, JHH ) 6.5 Hz, 8 H, OCH2), 2.88 (m,
8 H, NCH2 of Bu4N+), 1.81 (m, 8 H, OCH2CH2), 1.53-1.26 (m,
56 H, CH2 of C8H17 and Bu4N+), 0.93-0.87 (m, 24 H, Me of C8H17
and Bu4N+).
Results and Discussion
must increase the acidity of the H9 hydrogen atom. These
reactions give piperidinium or diethylammonium chloride
as the only byproduct, which can usually be separated by
washing the crude products with methanol or ethanol.
The gold(I) compounds Q2[Au2{µ-κ2-S,S-S2CdC(C12H6R2-
2,7)}2], where Q+ ) PPN+ or Pr4N+ for R ) H (Q24a) or
Q+ ) Pr4N+ for R ) OC8H17 [(Pr4N)24c], were prepared in
high yields by reacting the corresponding Q[AuCl2] salts with
the dithioate 1a and piperidine or the dithioic acid 2 and
diethylamine in THF (Scheme 1). The dithiol 3 can also be
used as ligand precursor for the preparation of (Pr4N)24c.
Complexes Q24a,c are slowly oxidized under atmospheric
conditions in solution, giving the corresponding gold(III)
complexes Q[Au{κ2-S,S-S2CdC(C12H6R2-2,7)}2] (Q6a,c; see
below) and unidentified species. The reaction of PPN[AuCl2]
with 1b and piperidine or diethylamine in THF gave an
Synthesis and Properties of Gold Complexes with
(Fluoren-9-ylidene)methanedithiolato and Substituted
Derivatives. Gold(I) and gold(III) complexes with the
(fluoren-9-ylidene)methanedithiolato ligand and its 2,7-di-
tert-butyl- and bis(octyloxy)-substituted derivatives were
prepared by reacting the dithioates (pipH){S2CCH(C12H6R2-
2,7)}, where R ) H (1a) or t-Bu (1b), or the dithioic acid
HS2CCH(C12H6(OC8H17)2-2,7) (2) or its stable dithiol tau-
tomer (HS)2CdC(C12H6(OC8H17)2-2,7) (3) (Chart 2) with
chlorogold(I) or -gold(III) precursors in the presence of
piperidine or diethylamine (Scheme 1). The formation of the
complexes takes place through the displacement of the chloro
ligands by the dithioates (when the dithioic acid 2 or the
dithiol 3 are used, the dithioate is generated in situ upon
reaction with the base) and the subsequent deprotonation of
the C9 carbon atom of the 9-fluorenyl moiety by the base.
Given that the piperidinium dithioates 1a,b do not react with
excess piperidine, it is clear that their deprotonation takes
place only after their coordination to the metal center, which
1
orange precipitate which, according to its H NMR data,
contained the desired dianionic complex [Au2{µ-κ2-S,S-S2Cd
C(C12H6(t-Bu)2-2,7)}2]2- (4b) as a mixture of PPN+ and
piperidinium or diethylammonium salts that could not be
7522 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
Scheme 2
separated by washing with methanol or ethanol. The oxida-
tion of this product by atmospheric oxygen in chloroform
or dichloromethane solutions is much faster than in the cases
of Q24a,c, taking place within 1 h with formation of an
unidentified orange-yellow precipitate and salts of the gold-
(III) complex [Au{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}2]- (6b;
1
see below), which were identified by their H NMR data.
Although it was not possible to grow crystals of Q24a,c, we
assume that they possess a dinuclear structure analogous to
those of other gold(I) complexes containing i-mnt,27 trithio-
carbonato,39 or dithiocarbimato40 ligands. This structure is
compatible with their 1H and 13C NMR spectra, which show
only one set of signals for the dithiolato ligand.
The neutral dinuclear phosphino complexes [{Au(PR′3)}2-
{µ-κ2-S,S-S2CdC(C12H6R2-2,7)}2] with R ) H and R′ ) Me
(5a), Et (5b), Ph (5c), and Cy (5d) or R ) t-Bu and R′ )
Me (5e), Et (5f), Ph (5g), and Cy (5h) were obtained in
moderate to high yields by reacting the corresponding [AuCl-
(PR′3)] precursors with the dithioates 1a or 1b and excess
piperidine in THF. This series was prepared to obtain an
insight into the influence of the nature of the dithiolato and
phosphine ligands on their emission properties (see below).
Complexes 5a-h are stable, yellow solids. However, they
slowly decompose in solution at room temperature to give
complex mixtures. Like Q24a,c, in the presence of atmo-
spheric oxygen they are slowly oxidized in solution, giving
mixtures containing the gold(III) anionic complexes 6a or
6b, [Au(PR′3)2]+, and other unidentified species.
The gold(III) complexes Q[Au{κ2-S,S-S2CdC(C12H6R2-
2,7)}2] with Q+ ) PPN+ for R ) H [(PPN)6a], Q+ ) PPN+
or Bu4N+ for R ) t-Bu (Q6b), and Q+ ) Bu4N+ for R )
OC8H17 [(Bu4N)6c] were obtained from the reactions of the
corresponding Q[AuCl4] salts with the dithioates 1a,b or the
dithioic acid 2 in the presence of piperidine or diethylamine
in THF. These compounds are remarkably stable, green
solids.
yield as a pale green solid.41 Attempts to prepare the salts
PPN[AuCl2{κ2-S,S-S2CdC(C12H8)}] [(PPN)8a] and (PPN)-
8b by following the same procedure gave oily materials
which, according to their 1H NMR data, contained the desired
products but could not be purified. We have previously
reported the halogen oxidations of [Au{κ2-S,S-S2CdC(CO-
Me)2}2]- 32 and [Au{κ2-S,S-S2CdS}2]-,37 which afforded
analogous results.
Gold Complexes with 9H-Fluorene-9-carbodithioato.
Gold(I) complexes containing the 9H-fluorene-9-carbodithio-
ato ligand have been prepared by reacting 1a with chlo-
rogold(I) precursors in absence of base. The reaction of
[AuCl(PCy3)] with 1 equiv of 1a in dichloromethane resulted
in the displacement of the chloro ligand by the dithioate and
the formation of [Au{SC(S)CH(C12H8)}(PCy3)] (9) (Scheme
2), which was isolated in high yield. Attempts to prepare
analogous complexes with PMe3 or PPh3 gave mixtures
containing the desired compounds, along with the deproto-
nated complexes 5a or 5c and unidentified species. Crystals
of 9 suitable for X-ray diffraction studies could not be
obtained, but we assume that the dithioato coordinates to
gold through only one of its sulfur atoms. Previously
described mononuclear gold(I) complexes with dithioato
ligands display a linear coordination around the gold
atom.42,43 The NMR and IR data of 9 (see below) are
consistent with this structure.
The reactions of Q6a-c with excess triflic acid (HO3SCF3,
HOTf) in dichloromethane resulted in the protonation of one
of the dithiolato ligands at the C9 carbon atom of the
9-fluorenylidene moiety and the formation of the neutral
compounds [Au{κ2-S,S-S2CdC(C12H6R2-2,7)}{κ2-S,S-S2-
CCH(C12H6R2-2,7)}] [R ) H (7a), t-Bu (7b), OC8H17 (7c)],
which precipitated as dark red solids and were isolated in
almost quantitative yields. Complexes 7a-c are easily
deprotonated when exposed to weak bases. Thus, they slowly
dissolve in deuterated dimethyl sulfoxide or acetone to give
Compound 1a also reacted with 1 equiv of [AuCl(SMe2)]
in dichloromethane to give a red precipitate, whose elemental
analysis is consistent with the formulation [Aun{S2CCH-
(C12H8)}n] (10). Due to its very low solubility in all common
solvents, crystals of 10 suitable for X-ray diffraction studies
1
could not be obtained. Its H NMR spectrum in (CD3)2SO
shows very complex signals in the aromatic region, suggest-
ing a polymeric structure. Previously described gold(I)
dithioates have been found to possess oligomeric structures,
like [Au6(S2CC6H4Me-2)6]44 and [Au4(S2CMe)4],45 or as-
sumed to be polymeric, like [Aun(S2CC6H4Me-4)n].43
1
green solutions which, according to their H NMR data,
contain the corresponding parent anionic complexes 6a-c.
The deprotonation may be caused by small amounts of water
that are usually present in the solvent or by the solvent itself.
The reaction of (Bu4N)6b with 1 equiv of PhICl2 resulted
in the oxidation of one of the dithiolato ligands and the
formation of the dichloro complex Bu4N[AuCl2{κ2-S,S-S2Cd
C(C12H6(t-Bu)2-2,7)}] [(Bu4N)8b], which was isolated in high
(41) The replaced dithiolato ligand was probably oxidized to several dimeric
or oligomeric species containing S-S bonds. A mixture of compounds
(1H NMR) was obtained from the mother liquor as an oily material.
(42) Otto, H.; Werner, H. Chem. Ber. 1987, 120, 97.
(43) Lanfredi, A. M. M.; Ugozzoli, F.; Asaro, F.; Pellizer, G.; Marsich,
N.; Camus, A. Inorg. Chim. Acta 1992, 192, 271-282.
(44) Schuerman, J. A.; Fronczek, F. R.; Selbin, J. J. Am. Chem. Soc. 1986,
108, 336-337.
(39) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G. J. Chem.
Soc., Chem. Commun. 1995, 745-746.
(40) Assefa, Z.; Staples, R. J.; Fackler, J. P., Jr. Acta Crystallogr. 1995,
C51, 2271-2273.
(45) Chiari, B.; Piovesana, O.; Tarantelli, T.; Zanazzi, P. F. Inorg. Chem.
1985, 24, 366-371.
Inorganic Chemistry, Vol. 43, No. 23, 2004 7523

Vicente et al.
Figure 2. Structure of the anion of complex (PPN)6a.
Table 3. Selected Bond Distances (Å) and Angles (deg) for
(PPN)6a‚2Me2CO
Au-S(1)
2.3224(4)
2.3407(4)
1.7576(14)
1.7596(14)
1.3575(18)
S(1)-Au-S(2)
S(1)-Au-S(2)#1
C(10)-S(1)-Au
C(10)-S(2)-Au
S(1)-C(10)-S(2)
74.728(12)
105.272(12)
89.35(5)
88.72(5)
107.15(7)
Au-S(2)
S(1)-C(10)
S(2)-C(10)
C(9)-C(10)
and 58.0-77.0°, respectively]. This arrangement seems to
help the formation of the Au‚‚‚Au short contact in all cases,
because it allows the approach of the gold atoms while
keeping the phosphine ligands as far as possible from each
other. The trimethylphosphine complex 5e displays a slightly
shorter Au‚‚‚Au contact [2.9994(2), 2.9714(2), 2.9828(3) Å]
than the triphenylphosphine analogues [3.05910(18) Å for
5c, 3.0738(3) Å for 5g]. The complex [{Au(PPh3)}2(µ-κ2-
i-mnt)] has a similar structure,46 but the Au‚‚‚Au contact is
appreciably longer [3.156(1) Å]. The C(9)-C(10) bond
distances in 5c,e,g [range 1.362(4)-1.380(5) Å] are close
to the higher limit of the range found for C(sp2)dC(sp2)
double bonds (1.294-1.392 Å)47 and very similar to or
slightly shorter than the CdC bond distances found for the
i-mnt ligand in its gold(I) complexes [range 1.37(1)-1.401-
(19) Å].23,24,27,28,46
The crystal structure of 5d was solved as a dichlo-
romethane monosolvate and refined, but the high R values
and large residual electron density indicated twinning
problems (optical examination of the crystals with polarized
light generally indicated twinning, although the crystal that
was measured seemed to be untwinned). For this reason we
do not present the full structure. The intramolecular Au‚‚‚
Au distance was 3.167(1) Å.
The structure of complex (PPN)6a was solved as an
acetone disolvate. Figure 2 shows the molecular structure
of the anion. Selected bond distances and angles are listed
in Table 3. The asymmetric unit contains half an [Au{κ2-
S,S-S2CdC(C12H8)}2]- anion, half a PPN+ cation (both with
inversion symmetry; this is quite rare for PPN+, with only
30 of 999 PPN+ cations in the Cambridge Crystallographic
Database displaying P-N-P angles above 170°), and one
acetone molecule. The anion is almost planar (mean deviation
0.066 Å). The gold atom is in a square-planar environment
distorted by the small bite of the (fluoren-9-ylidene)-
methanedithiolato ligand [S(1)-Au-S(2), 74.728(12)°; S(1)-
Figure 1. Structure of complex 5c.
Table 2. Selected Bond Distances (Å) and Angles (deg) for 5c‚THF,
5e‚2/3CH2Cl2, and 5g‚CH2Cl2
5c
5e
5g
Au(1)-P(1)
Au(1)-S(1)
2.2600(5)
2.3330(5)
2.2544(10), 2.2533(10), 2.2611(10) 2.2517(8)
2.3258(9), 2.3143(9), 2.3244(9)
2.3118(8)
3.0738(3)
2.2561(8)
2.3180(8)
1.775(3)
1.775(3)
1.362(4)
Au(1)-Au(2) 3.05910(18) 2.9994(2), 2.9714(2), 2.9828(3)
Au(2)-P(2)
Au(2)-S(2)
S(1)-C(10)
S(2)-C(10)
C(9)-C(10)
2.2713(6)
2.3390(5)
1.762(2)
1.772(2)
1.371(3)
2.2650(9), 2.2533(12), 2.2463(10)
2.3250(9), 2.3277(10), 2.3101(9)
1.775(4), 1.780(4), 1.756(4)
1.763(4), 1.760(4), 1.760(4)
1.367(5), 1.366(5), 1.380(5)
P(1)-Au(1)-S(1)
P(2)-Au(2)-S(2)
C(10)-S(1)-Au(1)
C(10)-S(2)-Au(2)
S(1)-C(10)-S(2)
171.95(2)
175.57(4), 175.26(4),
175.22(4)
167.46(4), 175.23(4),
171.34(3)
172.44(3)
101.69(10)
100.27(10)
116.31(16)
177.23(2)
101.42(7)
100.85(7)
116.37(11)
167.95(4)
100.57(12), 102.71(12),
102.72(12)
107.15(12), 104.07(13),
106.81(12)
116.78(19), 117.7(2),
118.0(2)
Crystal Structures of Complexes. The crystal structures
of 5c‚THF, 5e‚2/3CH2Cl2, and 5g‚CH2Cl2 were solved by
X-ray diffraction studies and show very similar structural
arrangements for the dinuclear complexes. Compound 5e
crystallizes with three independent molecules of the complex
and two dichloromethane molecules in the asymmetric unit,
while in the other cases the asymmetric unit contains one
molecule of the complex and one of the solvent. The
molecular structure of 5c is shown in Figure 1. Selected bond
distances and angles for the three compounds are listed in
Table 2. The fluoren-9-ylidene fragment is practically planar
(mean deviations of C1-C9A: 0.032; 0.071, 0.078, 0.021;
0.015 Å, with C10 lying 0.19; 0.40, 0.55, 0.26; 0.14 Å out
of the plane) and slightly rotated (by 15; 14, 19, 16; 7°) with
respect to the CS2 plane. The coordination around the gold
atoms is essentially linear, but in some cases the deviation
of the P-Au-S angles (range 167.46-177.23°) from the
ideal value of 180° is significant. The P-Au-S axes lie out
of the CS2 plane and are considerably twisted with respect
to each other [the torsion angles S(1)-Au(1)-Au(2)-S(2)
and P(1)-Au(1)-Au(2)-P(2) fall in the ranges 57.8-67.6
(46) Khan, M. N. I.; Wang, S.; Heinrich, D. D.; Fackler, J. P., Jr. Acta
Crystallogr. 1988, C44, 822-825.
(47) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
7524 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
Au-S(2)#1, 105.272(12)°]. The C(9)-C(10) bond distance
of 1.3575(18) Å is slightly shorter than those found in 5c,e,g
and similar to the CdC distances found in PPN[Au{κ2-S,S-
S2CdC(COMe)2}2] [1.353(6) and 1.365(4) Å],31 K[Cu{κ2-
S,S-S2CdC(CO2Et)2}2] [1.32(2) Å], and (BzPh3P)2[Ni{κ2-
S,S-S2CdC(CO2Et)2}2] [1.367(6) Å].15
ligand and its substituted derivatives (Q24a,c, 5a-h) show
one or two bands between 1466 and 1486 cm-1 assignable
to the ν(CdCS2) mode.20 For the gold(III) complexes, the
wavenumbers of the corresponding bands fall in the range
1532-1572 cm-1 and increase in the sequence Q6a-c
(1532-1538) < 7a-c (1548-1570) < (Bu4N)8b (1572
cm-1). The observed variations in the energies of the ν(Cd
CS2) bands can be connected to the strength of the π
component of the CdCS2 bond. Thus, the higher electron-
accepting character of the gold(III) center must favor the
contribution of the resonance form A of the dithiolato ligand
(Chart 1) to a greater extent than do two gold(I) centers,
resulting in higher energies for the ν(CdCS2) band. In the
series of gold(III) complexes, the variations are attributable
to the different electron-donating character of the ligands
coordinated to the metal center, which decreases in the
sequence dithiolato > dithioato > chloro. Bands assignable
to the ν(Au-S) mode can be observed only for the gold(III)
complexes and lie in the range 364-384 cm-1, which is
typical for gold(III) compounds with a AuS4 core.32,37,48 The
spectrum of the dichloro complex (Bu4N)8b shows the
expected ν(Au-Cl) bands at 318 and 302 cm-1.
1
NMR Spectra. The H NMR spectra of the gold com-
plexes with the (fluoren-9-ylidene)methanedithiolato ligand
and its substituted derivatives show the signals corresponding
to the aromatic protons of the ligands between δ 9.33 and
7.04, the most remarkable feature being that the resonances
of the H1 and H8 protons are shifted downfield by 1.72-
1.31 ppm for the gold(I) complexes Q24a,c and 5a-h or
0.86-0.46 ppm for the gold(III) complexes Q6a-c, 7b,c,
and (Bu4N)8b, with respect to the resonances observed for
the corresponding dithioates 1a,b or the dithioic acid 2. This
fact might be attributable to the magnetic anisotropy of the
C(9)dCS2 double bond, which produces a considerable de-
shielding of the H1 and H8 atoms situated at its nodal plane.
The 1H NMR spectrum of 7a could not be measured due to
its very low solubility in most common organic solvents;
the analogous complexes 7b,c are slightly more soluble, and
1
their H NMR spectra show two different sets of signals
The infrared spectra of the dithioato complexes 9 and 10
show bands arising from ν(CS2) modes;43,45 in the case of
the mononuclear complex 9 only one intense band is
observed at 970 cm-1, whereas the polymeric compound 10
gives bands at 1074, 1032, and 1004 cm-1.
corresponding to one dithiolato and one dithioato ligand.
The 13C{1H} NMR spectra of Q24a,c, Q6a-c, and 8b were
measured at room temperature, while those of 5b-d,f-h
had to be measured at -10 or -15 °C because of their very
low stability in solution. All of them show the resonance of
the C9 atom within a very narrow range around δ 130,
whereas the chemical shift of the CS2 carbon atom undergoes
significant variations, decreasing in the sequence Q24a,c (δ
177.3-175.5) > 5b-d,f-h (δ 162.7-156.0) > Q6a-c (δ
157.6-153.9) > (Bu4N)8b (δ 139.3). The CS2 resonance is
therefore markedly affected by the metal center(s), and its
chemical shift decreases as the negative charge on the
complex decreases or as the oxidation state of the metal
center or its electron-accepting character increase.
Electronic Absorption Spectra. The UV-visible absorp-
tion spectra of compounds 1-10 were measured in the range
200-700 nm in dichloromethane at 298 K (see Supporting
Information for details). The spectra of the dithioates 1a,b
show the characteristic bands of the parent fluorenes slightly
shifted and broadened, together with an intense band at 347
nm which most probably arises from n-π* transitions
involving the CS2 group; absorptions of related origin are
observed as shoulders in the spectra of dithioic acid 2 (345
nm) and dithiol 3 (350 nm). Coordination of 1a to gold(I)
centers to give complexes 9 and 10 causes only slight
variations in the absorption spectra, the most noticeable being
the shift of the 347 nm band to 355 nm for 9 or 360 nm for
10. The common features of the spectra of complexes 4-8
can be ascribed to the fluoren-9-ylidene moiety: an intense
absorption at 230 nm is typical of aromatic rings (extinction
coefficients are higher for compounds containing PPh3 or
PPN+),49 while the intense absorption around 250 nm and
the less intense peak at ca. 300 nm (complexes 7a-c show
an absorption at 268 nm instead of the 300 nm peak) are
related to the bands observed at 260-280 and 290-300 nm,
respectively, for the underivatized fluorenes. In addition to
these bands, the spectra of Q24a,c and 5a-h show one band
at ca. 450 or 415 nm, respectively. The lowest energy band
in all gold(I) complexes can be assigned to dithiolate-to-
gold charge-transfer transitions.50,51 The energy of this band
decreases in the sequence 9 ∼ 10 > 5a-h > Q24a,c, as the
The 13C{1H} NMR spectrum of the trimethylphosphine
complex 5a could not be measured because of its very limited
solubility at low temperatures. In the case of 5e, variable-
temperature NMR experiments (1H and 31P{1H}) showed that
this complex undergoes a fluxional process in solution, giving
rise to multiple signals for the t-Bu groups (1H NMR) or
the phosphine (31P{1H} NMR) between -30 and -10 °C.
The existence of this process, whose nature could not be
established, prevented an effective measurement of the 13C-
{1H} NMR spectrum of 5e. The 13C{1H} NMR spectra of
7a-c could not be measured due to their very low solubility.
1
The H NMR spectrum of complex 9 shows that the
resonances arising from the protons of the dithioato ligand
are slightly shifted with respect to those found for the
piperidinium salt 1a, the main variation corresponding to the
H9 resonance (δ 5.64 for 9 vs δ 5.85 for 1a). The variations
observed in the 13C{1H} NMR data for 9 relative to 1a are
also small, the most noticeable corresponding to the CS2
resonance (δ 255.2 for 9 vs δ 263.3 for 1a).
(48) Beurskens, P. T.; Blaauw, H. J. A.; Cras, J. A.; Steggerda, J. J. Inorg.
Chem. 1968, 7, 805-810.
(49) King, C.; Wang, J. C.; Khan, M. N. I.; Fackler, J. P., Jr. Inorg. Chem.
1989, 28, 2145-2149.
IR Spectra. The solid-state infrared spectra of the gold-
(I) complexes with the (fluoren-9-ylidene)methanedithiolato
Inorganic Chemistry, Vol. 43, No. 23, 2004 7525

Vicente et al.
Table 4. Excitation and Emission Data (nm) at 77 K for Compounds 1, 4a,c, 5a-h, 9, and 10
solid
CH2Cl2 glass
a
a
compd
λexc
343, 399, 438, 457
λemis
λexc
λemis
1
485 sh, 520
664
668
666
651
531
508
512
509
530
564, 613
539
425 sh, 447
684
343, 358, 395, 445 sh
357, 391, 402, 417, 469
343, 404, 418, 443, 476
323, 358, 400, 419, 459, 467
353, 417, 455
343, 389, 406, 411, 440
338, 411, 438
526
643
648
643
546, 650 sh
514
502
504
530
505
531
513
436
(PPN)24a
(Pr4N)24a
(Pr4N)24c
340, 400, 412, 456, 469, 479
342, 413, 457, 470, 479
472, 479, 503
5a
5b
5c
5d
5e
5f
5g
5h
9
342, 396, 441
340, 395, 412, 442
344, 391, 411, 434
337, 413, 443
383, 403, 435
341, 397, 414, 440
343, 355, 390, 412
344, 412, 442
337, 404, 438
340, 418, 452
343, 400, 414, 435
411, 441
344, 411, 441
282, 291, 343
284, 293, 306, 336, 342, 358, 363
343, 356, 393, 456, 469, 479, 501, 564
10
342, 388, 470, 569
640, 675 sh
a Excitation spectra are complex and broad: range 300-460 nm for 3; 300-500 nm for 4a,c; 300-450 nm for 5a-h; 280-370 nm for 9; 300-590 nm
for 10. The most intense peak is italicized.
Table 5. Solid-State Excitation and Emission Data (nm) for 1, 5g, 4a,
and 10 at 298 K
negative charge of the ligand or the complex increases. In
the spectra of the gold(III) compounds, bands above 300 nm
a
compd
λexc
λemis
529
575, 619
612
610
642
are observed at ca. 340, 395, and 410 nm for Q6a-c, 360,
410, and 512-534 nm for 7a-c, and 360 and 410 nm for
(Bu4N)8b and most probably arise from charge-transfer
transitions between the dithiolato ligand and the metal center,
although the very broad and low intensity band at 512-534
nm observed for complexes 7a-c could correspond to a d-d
transition.22,52
1
339, 402, 416, 445, 456
334, 389, 433
5g
(PPN)24a
(Pr4N)24a
10
a The most intense peak is italicized. The excitation spectra of 4a and
10 could not be effectively measured because of the very low intensity of
their emissions; the wavelengths of the excitation maxima at 77 K were
used to measure their emission spectra.
Luminescence Studies. Gold(I) complexes with a variety
of S-donor ligands, including thiolates,50,53-56 dithiocarbam-
ates,5,28,56,57 xanthates,58,59 O-alkyldithiophosphonates60,61 and
O,O′-dialkyldithiophosphates,62 have been found to be
luminescent. However, the only (1,1-dithiolato)gold com-
plexes for which luminescence studies have been carried out
are those containing the i-mnt ligand.24,25,28,49 In mononuclear
and dinuclear gold(I) complexes containing both thiolate and
phosphine ligands, the origin of the emission has been
ascribed to a ligand-to-metal charge-transfer triplet state
(LMCT, RS- f Au).50,53,63 Lower emission energies are
observed when the thiolate contains electron-donating sub-
stituents and also when short Au‚‚‚Au contacts are present.
In the latter case, the excited state is better described as a
ligand-to-metal-metal charge transfer (LMMCT).55 Simi-
larly, the luminescence of [(AuPPh3)2(µ-κ2-i-mnt)]25 and [Au-
(PEt3)2][Au(AuPEt3)2(µ-κ2-i-mnt)2]24 has been assigned to a
charge transfer from the dithiolate ligand to the metal centers,
which has been confirmed by ab initio calculations on the
model complex [(AuPH3)2(µ-κ2-i-mnt)].64 For annular di-
nuclear compounds of the type [Au2(diphosphine)(µ-κ2-i-
mnt)] both MC (metal centered) and LMCT transitions have
been proposed as responsible for the emission.28 In the case
of the dianionic complex [Au2(µ-κ2-i-mnt)2]2-, the emission
has been assigned to intraligand and ligand-to-metal charge-
transfer transitions;60,61 a similar assignment has been made
on the basis of ab initio calculations.65
weakly and the rest of gold(I) complexes do not emit. None
of the compounds emits in solution at 298 K. The results of
the measurements at 77 and 298 K are summarized in Tables
4 and 5, respectively, and representative excitation and
emission spectra are shown in Figures 3 and 4.
(50) 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, 2506-2517.
(51) Yam, V. W. W.; Cheng, E. C. C.; Zhu, N. Y. Angew. Chem., Int. Ed.
2001, 40, 1763-1765.
(52) Mason, W. R.; Gray, H. B. J. Am. Chem. Soc. 1968, 90, 5721-5729.
Mason, W. R.; Gray, H. B. Inorg. Chem. 1968, 7, 55-58. Isci, H.;
Mason, W. R. Inorg. Chem. 1983, 22, 2266-2272.
(53) Forward, J. M.; Bohmann, D.; Fackler, J. P.; Staples, R. J. Inorg. Chem.
1995, 34, 6330-6336. Jones, W. B.; Yuan, J.; Narayanaswamy, R.;
Young, M. A.; Elder, R. C.; Bruce, A. E.; Bruce, M. R. M. Inorg.
Chem. 1995, 34, 1996-2001.
(54) Tzeng, B. C.; Che, C. M.; Peng, S. M. Chem. Commun. 1997, 1771-
1772. Watase, S.; Nakamoto, M.; Kitamura, T.; Kanehisa, N.; Kai,
Y.; Yanagida, S. J. Chem. Soc., Dalton Trans. 2000, 3585-3590.
(55) Yam, V. W. W.; Chan, C. L.; Li, C. K.; Wong, K. M. C. Coord.
Chem. ReV. 2001, 216, 173-194.
(56) Bardaj´ı, M.; Laguna, A.; Vicente, J.; Jones, P. G. Inorg. Chem. 2001,
40, 2675-2681.
(57) Bardaj´ı, M.; Laguna, A.; Jones, P. G.; Fischer, A. K. Inorg. Chem.
2000, 39, 3560-3566.
(58) Assefa, Z.; Staples, R. J.; Fackler, J. P., Jr. Inorg. Chem. 1994, 33,
2790-2798. Bardaj´ı, M.; Laguna, A. Inorg. Chim. Acta 2001, 318,
38-44.
(59) Mohamed, A. A.; Kani, I.; Ram´ırez, A. O.; Fackler, J. P., Jr. Inorg.
Chem. 2004, 43, 3833-3839.
(60) van Zyl, W. E.; Lopez-de-Luzuriaga, J. M.; Fackler, J. P., Jr. J. Mol.
Struct. 2000, 516, 99-106.
All the gold(I) complexes described in this paper are
luminescent at 77 K, and their excitation and emission spectra
have been measured both in the solid state and in CH2Cl2
glass. Additionally, room-temperature luminescence in the
solid state can be clearly observed for the CH2Cl2 and THF
solvates of 5g, while (PPN)24a, (Pr4N)24a, and 10 emit very
(61) van Zyl, W. E.; Lopez-de-Luzuriaga, J. M.; Mohamed, A. A.; Staples,
R. J.; Fackler, J. P., Jr. Inorg. Chem. 2002, 41, 4579-4589.
(62) Lee, Y. A.; McGarrah, J. E.; Lachicotte, R. J.; Eisenberg, R. J. Am.
Chem. Soc. 2002, 124, 10662-10663.
(63) Roundhill, D. M.; Fackler, J. P., Jr. Optoelectronic Properties of
Inorganic Compounds; Plenum Press: New York, 1998.
(64) Pan, Q. J.; Zhang, H. X. Eur. J. Inorg. Chem. 2003, 4202-4210.
(65) Pan, Q. J.; Zhang, H. X. Chem. J. Chin. UniV. 2003, 24, 310-314.
7526 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
thermal expansion, suggesting a significant influence of the
Au‚‚‚Au contact on the energy of the emission. A similar
effect has been reported by Fackler and co-workers to occur
in dinuclear gold(I) dithiophosphonate complexes61 and by
Fackler, Schmidbaur, and co-workers in [AuCl(TPA)] and
[AuCl(TPA-HCl)] (TPA ) 1,3,5-triaza-7-phosphaadaman-
tane), which form dimers through Au‚‚‚Au contacts.66 The
considerably lower emission energies of Q24a,c and 5a-h,
when compared with their i-mnt counterparts (Bu4N)2[Au2-
(µ-κ2-i-mnt)2] (495, 527 nm)60,61 and [(AuPPh3)2(µ-κ2-i-mnt)]
(462 nm),24,25 can be ascribed to the expected stronger
electron-donating character of the (fluoren-9-ylidene)-
methanedithiolato ligands relative to i-mnt. Contribution of
intraligand transitions to the emission of complexes Q24a,c
and 5a-h, as is the situation with [Au2(µ-κ2-i-mnt)2]2-,
cannot be completely ruled out. Salts of the (fluoren-9-
ylidene)methanedithiolate ligand or its substituted derivatives
could not be isolated, and therefore, their emission spectra
are not available. The dithioates 1a,b and the dithioic acid 2
do not emit at 77 K, but the dithiol 3 is luminescent at 77 K
both in the solid state and in CH2Cl2 glass, with an emission
maximum at 525 nm, most probably associated with the Cd
CS2 moiety. However, the above-discussed observations and
the fact that the gold(III) complexes here described are not
luminescent indicate that the gold(I) centers have a crucial
participation in the luminescence of Q24a,c and 5a-h.
The variation of the substituents of the fluoren-9-ylidene
moiety does not produce any changes in the emission of
complexes 4a,c, and in the series 5a-h the changes are not
regular, suggesting that these substituents have little or no
influence over the luminescence. The variations due to the
phosphine ligands along the series 5a-h do not follow a
regular trend either. Initially, we expected significant changes
in the Au‚‚‚Au intramolecular distances and, therefore, in
the observed emission, depending on the size of the phos-
phine. However, the variations in the Au‚‚‚Au distances are
small and do not have any effect on the emission. The most
striking differences found in the series 5a-h are the
emissions of 5a (R ) H, R′ ) Me) and 5g (R ) t-Bu, R′ )
Ph) in the solid state. Because these differences disappear
in CH2Cl2 glass, it is clear that they are attributable to effects
of the supramolecular structures. Unfortunately, we have not
been able to grow crystals of 5a suitable for X-ray diffraction
studies, but the low energy of its solid-state emission (651
nm) might be due to the presence of intermolecular Au‚‚‚
Au contacts. Although the structures of 5c,e,g do not display
intermolecular Au‚‚‚Au contacts, in the case of 5a they might
be favored due to the absence of substituents on the (fluoren-
9-ylidene)methanedithiolato ligand. The solid-state excitation
and emission spectra of 5g (Figure 4) are unique in the series
5a-h. In addition, 5g is the only compound of this series
which emits intensely at room temperature. The two maxima
observed in its emission spectrum (564, 613 nm) are
considerably red-shifted relative to the only maximum
observed for 5b-f,h in the solid state (range 508-539 nm),
Figure 3. Excitation and emission spectra of complexes (PPN)4a (s) and
5c (---) in CH2Cl2 glass at 77 K. Intensity in arbitrary units.
Figure 4. Excitation and emission spectra of complex 5g in the solid state
(s) and in CH2Cl2 glass (---) at 77 K. Intensity in arbitrary units.
The dianionic complexes Q24a,c emit around 665 nm in
the solid state and 645 nm in CH2Cl2 glass at 77 K. At room
temperature, the emission of Q24a in the solid state is blue-
shifted to 610 nm. The neutral complexes 5a-h generally
emit at considerably higher energies, and their emission
maxima fall in the range 502-546 nm, with the remarkable
exceptions of the solid-state emissions of 5a (651 nm) and
5g (564, 613 nm) at 77 K, which are discussed below. The
corresponding excitation spectra are broad and complex, but
in most cases they show one absolute maximum which relates
to the charge-transfer bands observed in the UV-visible
absorption spectra (475 nm for Q24a,c and 440-455 nm for
5a-h in CH2Cl2 glass).
A typical LMMCT transition could explain the lumines-
cence of the dinuclear complexes Q24a,c and 5a-h, as is
the case of the related i-mnt complexes and some dinuclear
gold(I) compounds with other dithio ligands.59,61 The dra-
matic red-shift of the emission maximum of the dianionic
compounds Q24a,c with respect to those of the neutral
complexes 5a-h (up to 4488 cm-1 in CH2Cl2 glass) is
attributable to both the anionic character and the considerably
stronger Au‚‚‚Au interaction of the first. In fact, the Au‚‚‚
Au distances found in dianionic dinuclear complexes with
an annular structure fall in the narrow range 2.800-2.811
Å,27,39,40 while the distances found for 5c-e,g (see above)
are appreciably longer. The considerable blue-shift observed
in the emission maximum of Q24a at 298 K with respect to
the 77 K emission in the solid state (1280 cm-1) is probably
due to an increase in the Au‚‚‚Au separation as a result of
(66) Assefa, Z.; McBurnett, B. G.; Staples, R. J.; Fackler, J. P., Jr.;
Assmann, B.; Angermaier, K.; Schmidbaur, H. Inorg. Chem. 1995,
34, 75-83.
Inorganic Chemistry, Vol. 43, No. 23, 2004 7527

Vicente et al.
Scheme 3
while the emission spectrum in CH2Cl2 glass is completely
different and does not contain the peaks observed in the solid
state. This means that the supramolecular order of 5g strongly
affects the LMMCT emitting state, leading to a substantially
different emission spectrum. The crystal structure of 5g (CH2-
Cl2 solvate) is similar to those of 5c,e, but the crystal
packings of the three structures are different: 5g has a layer
structure, with layers at x ) 0.25 and 0.75; in the structure
of 5e the three independent molecules occupy the regions at
x ) 0.5, 0, and 0.25, respectively, while in 5c the packing
has no well-defined layers. The structure of the THF solvate
of 5g could not be refined satisfactorily because of solvent
disorder, but this compound is isostructural with the CH2-
Cl2 solvate, consistent with their identical solid state emission
spectra. Recently, several luminescent gold(I) complexes
have been reported, which crystallize as different polymorphs
with clearly distinct emission properties, thus revealing that
the supramolecular order in the solid state can have a critical
effect on the luminescence.67
synthesis of donor-π-acceptor molecules.70 The (fluoren-
9-ylidene)methanedithiolato ligand and the derivatives de-
scribed in this work are not expected to function as electron
acceptors, because they do not bear any electron-withdrawing
substituents. On the contrary, the facile oxidations of the
gold(I) complexes Q24a,c and 5a-h under atmospheric
conditions reveal the strongly donating character of our
ligands, which could therefore behave as donors in the
formation of charge-transfer π-adducts. To explore this
possibility and to confirm the electron donating character of
the coordinated ligands, we have carried out the reactions
of the gold(III) complexes Q6a-c and (Bu4N)8b and also
the gold(I) complexes Q24a,c and 5c with the widely used
organic acceptor TCNQ (tetracyano-7,7,8,8-quinodimethane).
The addition of TCNQ to dichloromethane solutions of
the gold(III) complexes Q6a-c resulted in the formation of
compounds with the general composition Q[Au{κ2-S,S-S2Cd
C(C12H6R2-2,7)}2]‚1.5TCNQ‚xCH2Cl2 [Q+ ) PPN+, R ) H,
The emission spectrum of the mononuclear dithioato
complex 9 shows one maximum at 447 or 436 nm,
respectively, in the solid state and in CH2Cl2 glass. Certain
complexes of the type [Au(SR)(PR′3)] with no intermolecular
Au‚‚‚Au interactions display similar emission energies.53 We
assign the luminescence of 9 to a LMCT excited state, since
an intraligand transition can be ruled out (the uncoordinated
dithioate 1a does not emit) and intermolecular Au‚‚‚Au
contacts are unlikely because of the presence of the bulky
PCy3 ligand. Also, the higher emission energy of 9 relative
to the dinuclear PCy3 complexes 5d,h (504 and 513 nm,
respectively, in CH2Cl2 glass) can be attributed to the absence
of Au‚‚‚Au contacts in 9 and the lower electron-donating
character of the monoanionic dithioate as compared with the
dianionic dithiolato ligand. In contrast, the polymeric deriva-
tive 10 displays the lowest emission energy of all compounds
described in this work (684 nm in the solid state, 640 nm in
CH2Cl2 glass at 77 K). As is the case with Q24a, the emission
maximum of 10 is significantly blue-shifted at 298 K (956
cm-1) with respect to the 77 K emission in the solid state.
These observations are consistent with an emitting state
strongly influenced by multiple Au‚‚‚Au contacts, which are
likely to exist in the structure of 10. In fact, the structures
of previously reported gold(I) dithioates show multiple Au‚
‚‚Au contacts.44,45 Therefore, the emission of 10 most
probably arises from LMMCT transitions, although MC
transitions are also possible, since they are common in
compounds with extended Au‚‚‚Au interactions.5,28,62
Reactions with TCNQ. Crystal Structure of PPN[Au-
{κ2-S,S-S2CdC(C12H6(t-Bu)2-2,7)}]‚1.5TCNQ‚2CH2Cl2
(11b). Fluorene derivatives containing electron-withdrawing
functional groups behave as acceptors68 and have been used
for the formation of charge-transfer complexes69 and the
x ) 0 (11a); Q+ ) PPN+, R ) t-Bu, x ) 2 (11b); Q+
)
Bu4N+, R ) OC8H17, x ) 0 (11c)] (Scheme 3). These
formulations have been determined by means of elemental
analyses and the crystal structure of 11b (see below). The
new compounds are sparingly soluble solids which precipitate
from dichloromethane either spontaneously (11c) or by
adding small amounts of diethyl ether (11a,b) and can be
isolated in high yields. Their colors are dark blue (11a), black
(11b), and dark green (11c), which are typical of charge-
transfer complexes of TCNQ.
The crystal structure of 11b was solved by X-ray diffrac-
tion studies. The asymmetric unit contains one [Au{κ2-S,S-
S2CdC(C12H6(t-Bu)2-2,7)}2]- (6b) anion, one PPN+ cation,
(70) Perepichka, D. F.; Bryce, M. R.; Perepichka, I. F.; Lyubchik, S. B.;
Christensen, C. A.; Godbert, N.; Batsanov, A. S.; Levillain, E.;
McInnes, E. J. L.; Zhao, J. P. J. Am. Chem. Soc. 2002, 124, 14227-
14238. Perepichka, D. F.; Perepichka, I. F.; Popov, A. F.; Bryce, M.
R.; Batsanov, A. S.; Chesney, A.; Howard, J. A. K.; Sokolov, N. I. J.
Organomet. Chem. 2001, 637, 445-462. Perepichka, I. F.; Perepichka,
D. F.; Bryce, M. R.; Goldenberg, L. M.; Kuzmina, L. G.; Popov, A.
F.; Chesney, A.; Moore, A. J.; Howard, J. A. K.; Sokolov, N. I. Chem.
Commun. 1998, 819-820. Perepichka, D. F.; Bryce, M. R.; McInnes,
E. J. L.; Zhao, J. P. Org. Lett. 2001, 3, 1431-1434.
(67) White-Morris, R. L.; Olmstead, M. M.; Balch, A. L. J. Am. Chem.
Soc. 2003, 125, 1033-1040. Lu, W.; Zhu, N. Y.; Che, C. M. J. Am.
Chem. Soc. 2003, 125, 16081-16088.
(68) Loutfy, R. O.; Hsiao, C. K.; Ong, B. S.; Keoshkerian, B. Can. J. Chem.
1984, 62, 1877-1885.
(69) Olmstead, M. M.; Jiang, F. L.; Attar, S.; Balch, A. L. J. Am. Chem.
Soc. 2001, 123, 3260-3267.
7528 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
Figure 5. Structure of 11b (H atoms, PPN cation, and solvent omitted
for clarity). The half-TCNQ has been completed by inversion symmetry.
Table 6. Selected Bond Distances (Å) and Angles (deg) for 11b
Anion 6b
Figure 6. Anionic stack in the crystal structure of 11b.
Au-S(4)
Au-S(2)
Au-S(1)
Au-S(3)
S(1)-C(10)
S(4)-Au-S(2)
S(4)-Au-S(1)
S(2)-Au-S(1)
S(4)-Au-S(3)
S(2)-Au-S(3)
S(1)-Au-S(3)
2.3291(5)
2.3307(5)
2.3308(5)
2.3358(4)
1.7652(18)
105.331(17)
178.828(17)
74.347(17)
74.155(16)
178.969(18)
106.185(17)
S(2)-C(10)
S(3)-C(30)
S(4)-C(30)
C(9)-C(10)
C(29)-C(30)
C(10)-S(1)-Au
C(10)-S(2)-Au
C(30)-S(3)-Au
C(30)-S(4)-Au
S(2)-C(10)-S(1)
S(4)-C(30)-S(3)
1.7461(19)
1.7540(19)
1.7519(18)
1.361(2)
indicates that a relatively high degree of negative charge is
delocalized over the fluoren-9-ylidene groups. There are no
significant interactions between the metal center and the CN
groups, the shortest Au-N distances being 3.842 and 3.775
Å. The bond distances in the 6b anion are very similar to
those found for the analogous 6a in its PPN salt, and in the
TCNQ molecules they are only slightly different from those
found for pure TCNQ,71 indicating that these molecules are
essentially neutral. Crystals of 11a,c suitable for X-ray
diffraction studies could not be obtained, but it is likely that
they also comprise infinite anionic stacks. This arrangement
could be responsible for the low solubilities observed: 11a,b
dissolve moderately in dichloromethane but 11c only poorly,
and none of them is soluble in chloroform or other common
organic solvents.
Infrared spectra are frequently used for assigning the
oxidation state and coordinative status of TCNQ in its
compounds.72,73 The most important bands of this organic
acceptor correspond to the ν(CtN), ν(CdC) (ν20, b1u), and
δ(C-H) (ν50, b3u) modes, which appear at 2222, 1542, and
862 cm-1, respectively, for neutral TCNQ (in our infrared
spectrophotometer) and shift to lower frequencies as the
degree of charge (F) increases. Linear dependences between
the frequencies of the ν(CtN), ν20, and ν50 modes and F
have been proposed.74,75 However, in some cases deviations
1.360(2)
89.25(6)
89.72(6)
89.44(6)
89.71(6)
106.67(10)
106.69(9)
TCNQ (General)
C(101)-C(107)
C(101)-C(102)
C(101)-C(106)
C(102)-C(103)
C(103)-C(104)
C(104)-C(110)
C(104)-C(105)
C(105)-C(106)
1.369(3) C(107)-C(108)
1.442(3) C(107)-C(109)
1.444(3) C(108)-N(2)
1.342(3) C(109)-N(3)
1.442(3) C(110)-C(112)
1.368(3) C(110)-C(111)
1.448(3) C(111)-N(4)
1.342(3) C(112)-N(5)
1.438(3)
1.439(3)
1.143(3)
1.143(3)
1.441(3)
1.443(3)
1.140(3)
1.138(3)
C(102)-C(101)-C(106) 117.94(19) N(3)-C(109)-C(107)
176.8(3)
C(103)-C(104)-C(105) 117.60(19) C(112)-C(110)-C(111) 115.40(19)
C(108)-C(107)-C(109) 113.4(2)
N(4)-C(111)-C(110)
N(5)-C(112)-C(110)
179.9(3)
177.5(2)
N(2)-C(108)-C(107)
177.1(3)
TCNQ (Centrosymmetric)
C(121)-C(124)
C(121)-C(122)
C(121)-C(123)
C(122)-C(123)#1
C(122)-C(121)-C(123) 117.83(17)
C(126)-C(124)-C(125) 115.49(18)
1.377(3)
1.446(3)
1.448(3)
1.347(3)
C(124)-C(126)
1.430(3)
C(124)-C(125)
C(125)-N(6)
C(126)-N(7)
1.437(3)
1.145(3)
1.146(3)
N(6)-C(125)-C(124) 177.2(2)
N(7)-C(126)-C(124) 178.9(3)
two CH2Cl2 molecules, one TCNQ molecule on a general
position, and a further half TCNQ molecule, the second half
of which is generated by inversion symmetry (Figure 5).
Selected bond distances and angles are listed in Table 6. The
anions and the TCNQ molecules form an infinite stack with
the sequence ‚‚‚TCNQ(centrosymmetric)‚6b‚2TCNQ(general)‚
6b‚‚‚, with the stack direction perpendicular to (110) (Figure
6). The centers of the TCNQ molecules are located ap-
proximately above the chemically equivalent C9 and C29
atoms of the 2,7-di-tert-butylfluoren-9-ylidene groups; dis-
tances to the TCNQ planes are 3.38 and 3.34 Å and to the
TCNQ ring centroids 3.46 and 3.45 Å. This arrangement
(71) Long, R. E.; Sparks, R. A.; Trueblood, K. N. Acta Crystallogr. 1965,
18, 932.
(72) Bozio, R.; Girlando, A.; Pecile, C. J. Chem. Soc., Faraday Trans. 2
1975, 71, 1237-1254. Bozio, R.; Zanon, I.; Girlando, A.; Pecile, C.
J. Chem. Soc., Faraday Trans. 2 1978, 74, 235-248. Schiavo, S. L.;
Tresoldi, G.; Mezzasalma, A. M. Inorg. Chim. Acta 1997, 254, 251-
257. O’Kane, S. A.; Cle´rac, R.; Zhao, H.; Ouyang, X.; Gala´n-Mascaro´s,
J. R.; Heintz, R.; Dunbar, K. R. J. Solid State Chem. 2000, 152, 159-
173. Miyasaka, H.; Campos Ferna´ndez, C. S.; Clerac, R.; Dunbar, K.
R. Angew. Chem., Int. Ed. 2000, 39, 3831-3835.
(73) Ballester, L.; Gutie´rrez, A.; Perpin˜a´n, M. F.; Azcondo, M. T. Coord.
Chem. ReV. 1999, 190-192, 447-470.
(74) Chappell, J. S.; Bloch, A. N.; Bryden, W. A.; Maxfield, M.; Poehler,
T. O.; Cowan, D. O. J. Am. Chem. Soc. 1981, 103, 2442-2443.
Inorganic Chemistry, Vol. 43, No. 23, 2004 7529

Vicente et al.
from linearity have been found for the dependence of the
ν(CtN) frequencies from F,76 and some authors prefer to
use the ν20 or ν50 modes to estimate the value of F.75,77,78
The infrared spectra of 11a-c show only one ν(CtN) band
at 2216 cm-1 in all cases. The ν(CdC) region is dominated
by the intense and relatively broad ν(CdCS2) band, which
is shifted by ca. 10 cm-1 to lower frequencies for 11a,b or
4 cm-1 to a higher frequency for 11c, relative to the
corresponding Q6a-c salts. The ν(CdC) band arising from
TCNQ can be observed only for 11b at 1544 cm-1 as a
shoulder of the ν(CdCS2) band, while for 11a,c it must be
obscured. The δ(C-H) band appears at 832 cm-1 for 11a
and 834 cm-1 for 11b,c. These data reveal that the formation
of the charge-transfer complexes produces only minor
changes in the frequencies of the vibrational modes of both
TCNQ and the gold(III) anion, with the exception of δ(C-
H). The frequency of this band in 11a-c is close to those
found for salts of TCNQ- (820-825 cm-1) and would
correspond to a high F value. However, the frequencies of
ν(CtN) in 11a-c and ν(CdC) in 11b indicate a small
degree of charge transfer, which is also consistent with the
bond distances found for the TCNQ molecules of 11b.
Unlike Q6a-c, the dichloro complex (Bu4N)8b does not
form an adduct with TCNQ under the conditions described
above. It is reasonable that the fluoren-9-ylidene moiety in
the anion 8b has a lesser electron-donating character than
in 6a-c because of the chloro ligands, which make the unit
+
AuCl2 a stronger electron acceptor than Au{κ2-S,S-S2Cd
C(C12H6(t-Bu)2-2,7)}+. This is consistent with the high
energy of the ν(CdCS2) band observed in the infrared
spectrum of (Bu4N)8b (see above), which indicates that the
π component of the CdCS2 bond is relatively strong and
therefore the degree of negative charge delocalized over the
fluoren-9-ylidene group must be low.
Attempts to obtain charge-transfer adducts of the gold(I)
complexes 4a,c and 5c with TCNQ resulted in their oxidation
to the corresponding gold(III) species 6a or 6c and the
formation of salts of 6a,c‚1.5TCNQ. Thus, the reaction of
(PPN)24a with TCNQ (1:4 molar ratio) gave 11a and PPN-
(TCNQ)2, which were identified by their IR spectra and
elemental analyses; an insoluble precipitate, probably con-
taining a gold(I) species, was also obtained, but its nature
could not be established. (Pr4N)24c reacted with TCNQ (1:
2) to give a scarcely soluble precipitate, which, in agreement
with its IR spectrum, contains both (Pr4N)6c‚1.5TCNQ,
neutral TCNQ, and a salt of TCNQ-; its elemental analysis
is consistent with the formulation (Pr4N)26c‚3.5TCNQ‚
0.33CH2Cl2. The neutral phosphino complex 5c also reacted
with excess TCNQ (1:4) to give a mixture, which, according
to its IR spectrum, contained a salt of the charge-transfer
adduct 6a‚1.5TCNQ and both neutral and anionic TCNQ;
the rest of the products of this reaction could not be
identified. Only a few examples of reactions of gold(I)
complexes with organic acceptors have been reported to
produce oxidation of the metal centers. The dinuclear ylide
complex [Au2{µ-κ2-(CH2)2PPh2}2] reacted with TCNQ or
DDQ (2,3-dichloro-5,6-dicyanobenzoquinone) to give com-
pounds in which the gold atoms are in fractional oxidation
states higher than +1.81 Trimers of the type [Au3{µ-κ2-C,N-
RNdCOR′}3] and related complexes form charge-transfer
adducts with TCNQ and other organic acceptors in which
relatively short Au‚‚‚Au distances indicate a partial oxidation
of the metal centers.69,82
Molar Conductivities. The molar conductivities of the
ionic compounds Q24a,c, Q6a-c, and (Bu4N)8b have been
measured in acetone at concentrations of ca. 5 × 10-4 M.
The conductivity of (PPN)24a (199 Ω-1 cm2 mol-1) corre-
sponds to a 2:1 electrolyte according to the range given by
Geary83 (160-200 Ω-1 cm2 mol-1). However, the Pr4N+ salts
of 4a,c give very low conductivity values (137 and 98 Ω-1
cm2 mol-1, respectively), probably because of the formation
of ion pairs. The values obtained for the Q6a-c and (Bu4N)-
8b salts (between 70 and 101 Ω-1 cm2 mol-1) fall in most
cases below the lower limit of the range given for 1:1
electrolytes (100-140 Ω-1 cm2 mol-1).
1
The H NMR spectra of 11a-c in CD2Cl2 show the
resonances of the ligand protons slightly shifted with respect
to those of the corresponding parent compounds Q6a-c,
while the resonances of the TCNQ protons are not observed,
which is indicative of a significant interaction between the
6a-c anions and the TCNQ molecules in solution.78,79 The
electronic absorption spectra of diluted solutions of 11a,b
in dichloromethane (∼10-5 M) show one band at 25 500
cm-1 which corresponds to neutral TCNQ73 and partially
overlaps other bands arising from the anions. One broad band
at 9900 cm-1 is observable in the electronic spectrum of
saturated solutions of 11a in dichloromethane, which can
be assigned to the intermolecular charge-transfer transition
between the anion 6a and the TCNQ molecules;80 for 11b,
the maximum of this band falls below 9090 cm-1, which is
the lower limit of our spectrophotometer, while in the case
of 11c a highly concentrated solution could not be obtained
because of its very low solubility in dichloromethane. The
observation of these bands proves that the adducts 11a,b are
present in solution, probably as fragments of the stack
observed in the structure of 11b.
(75) Bigoli, F.; Deplano, P.; Devillanova, F. A.; Girlando, A.; Lippolis,
V.; Mercuri, M. L.; Pellinghelli, M. A.; Trogu, E. F. J. Mater. Chem.
1998, 8, 1145-1150.
(76) Hutchison, K. A.; Srdanov, G.; Menon, R.; Gabriel, J. C. P.; Knight,
B.; Wudl, F. J. Am. Chem. Soc. 1996, 118, 13081-13082. Obertelli,
S. D.; Friend, R. H.; Moore, A. J.; Bryce, M. R.; Bates, P. Synth.
Met. 1988, 27, 327-332.
(77) Ballester, L.; Gutie´rrez, A.; Perpin˜a´n, M. F.; Rico, S.; Azcondo, M.
T.; Bellitto, C. Inorg. Chem. 1999, 38, 4430-4434.
(78) Ballester, L.; Gil, A. M.; Gutie´rrez, A.; Perpin˜a´n, M. F.; Azcondo,
M. T.; Sa´nchez, A. E.; Marzin, C.; Tarrago, G.; Bellitto, C. Chem.s
Eur. J. 2002, 8, 2539-2548.
(79) Leoni, P.; Pasquali, M.; Fortunelli, A.; Germano, G.; Albinati, A. J.
Am. Chem. Soc. 1998, 120, 9564-9573. Kaim, W.; Moscherosch, M.
Coord. Chem. ReV. 1994, 129, 157-193.
(81) Cerrada, E.; Gimeno, M. C.; Laguna, A.; Laguna, M.; Orera, V.; Jones,
P. G. J. Organomet. Chem. 1996, 506, 203-210.
(82) Rawashdeh-Omary, M. A.; Omary, M. A.; Fackler, J. P., Jr.; Galassi,
R.; Pietroni, B. R.; Burini, A. J. Am. Chem. Soc. 2001, 123, 9689-
9691.
(80) Pace, L. J.; Ulman, A.; Ibers, J. A. Inorg. Chem. 1982, 21, 199-207.
Bergamini, P.; Bertolasi, V.; Ferreti, V.; Sostero, S. Inorg. Chim. Acta
1987, 126, 151-155. Spellane, P. J.; Interrante, L. V.; Kullnig, R. J.;
Tham, F. S. Inorg. Chem. 1989, 28, 1587-1590.
(83) Geary, W. J. Coord. Chem. ReV. 1971, 7, 81-122.
7530 Inorganic Chemistry, Vol. 43, No. 23, 2004

Gold (Fluoren-9-ylidene)methanedithiolato Complexes
Conclusions
The gold(I) complexes here described are photolumines-
cent at 77 K, and their emissions can be assigned to LMMCT
(Q24a,c, 5a-h, 10) or LMCT (9) excited states. The low
energies of the emission maxima relative to those of
analogous i-mnt complexes can be attributed to the strongly
electron-donating character of the new ligands.
The dithioates 1a,b and the dithioic acid 2 (or its dithiol
tautomer 3) have been used as ligand precursors for the high-
yield preparations of the first complexes with (fluoren-9-
ylidene)methanedithiolate and its 2,7-di-tert-butyl- and 2,7-
bis(octyloxy)-substituted analogues. The reactivity and
properties of the gold complexes here described reveal the
stronger electron-donating character of the new ligands as
compared with previously described 1,1-ethylenedithiolates.
A variable degree of negative charge is delocalized over the
fluoren-9-ylidene groups, which depends on the electron-
accepting character of the metal center(s). The gold(I)
complexes 4a-c and 5a-h are readily oxidized under
atmospheric conditions or through their reactions with the
organic acceptor TCNQ to the corresponding gold(III)
complexes 6a-c, which in turn form anionic charge-transfer
adducts with the stoichiometry 6a-c‚1.5TCNQ. The struc-
ture of (PPN)6b‚1.5TCNQ‚2CH2Cl2 (11b) shows infinite
anionic stacks in which the TCNQ molecules are located
above and below the fluoren-9-ylidene groups of the 6b
anions, thus revealing the ability of the coordinated ligands
to act as donors in the formation of charge-transfer adducts.
Acknowledgment. We thank the Ministerio de Ciencia
y Tecnolog´ıa (Spain), FEDER (BQU2001-0133), for finan-
cial support. P.G.-H. thanks the Fundacio´n Se´neca (Comu-
nidad Auto´noma de la Regio´n de Murcia, Spain) for a grant
and the Ministerio de Ciencia y Tecnolog´ıa (Spain) and
Universidad de Murcia for a contract under the Ramo´n y
Cajal Program. Y.G.-C. thanks the Ministerio de Educacio´n,
Cultura y Deporte (Spain) for a grant.
Supporting Information Available: UV-visible absorption
data for complexes 1-10 and crystallographic data in CIF format
for complexes 5c‚THF, 5e‚2/3CH2Cl2, 5g‚CH2Cl2, (PPN)6a‚2Me2-
CO, and 11b. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC049132+
Inorganic Chemistry, Vol. 43, No. 23, 2004 7531