Gold(I) complexes derived from C6Me3(C≡CH) 3-1,3,5, C6Me4(C≡CH)2-1,4, and MeC6H4C≡CH-4

Article abstract of DOI:10.1021/om050665f

C₆Me₃(C≡CH)₃-1,3,5 (Ar(C≡CH)₃) reacts with [AuCl(SMe₂)] and NEt ₃ (1:3:3) to give [Au₃{μ-(C≡C) ₃Ar}]_n (1). Complexes of the general formula [{AuL} ₃

Full text of DOI:10.1021/om050665f

5956
Organometallics 2005, 24, 5956-5963
Gold(I) Complexes Derived from C6Me3(CtCH)3-1,3,5,
C6Me4(CtCH)2-1,4, and MeC6H4CtCH-4§
Jose´ Vicente,† Mar´ıa-Teresa Chicote,*,† and Miguel M. Alvarez-Falco´n
Grupo de Quı´mica Organometa´lica, Departamento de Quı´mica Inorga´nica,
Universidad de Murcia, Aptdo. 4021, Murcia, 30071 Spain
Peter G. Jones*,‡
Institut fu¨r Anorganische und Analytische Chemie der Technischen Universita¨t,
Postfach 3329, 38023 Braunschweig, Germany
Received August 2, 2005
C6Me3(CtCH)3-1,3,5 (Ar(CtCH)3) reacts with [AuCl(SMe2)] and NEt3 (1:3:3) to give [Au3{µ-
(CtC)3Ar}]n (1). Complexes of the general formula [{AuL}3{µ-(CtC)3Ar}] can be obtained
t
from 1 and excess isocyanide (L ) BuNC (2), XyNC (3)), by treating 2 with an excess of
NHEt2 (L ) C(NHtBu)NEt2 (4)), or by reacting [Ar(CtCH)3] with [Au(acac)PPh3] (1:3, L )
PPh3 (5)) or with PPN[AuCl2] (1:3, PPN ) Ph3PdNdPPh3) and an excess of NHEt2 (L )
NHEt2 (6)). The reaction of C6Me4(CtCH)2-1,4 (Ar′(CtCH)2) with PPN[AuCl2] (1:2) and an
excess of NHEt2 gives [{AuNHEt2}2{µ-(CtC)2Ar′}] (7), which reacts with 1,6-bis(diphen-
ylphosphino)hexane (dpph) to give [Au2{µ-(CtC)2Ar′}(µ-dpph)]n (8). The reactions of the
alkynes [Ar(CtCH)3], [Ar′(CtCH)2], and ToCtCH (To ) 4-MeC6H4) with the appropriate
amounts of PPN[Au(acac)2] (acac ) acetylacetonato) allow the syntheses of the anionic
complexes PPN[Au{CtCAr(CtCH)2}2] (9), PPN[Au{CtCAr′CtCH}2] (10), PPN[Au{Ct
CTo}2] (11), (PPN)3n[Au{CtCAr(CtC)2}2Au2]n (12), and (PPN)n[Au{µ-(CtC)2Ar′}]n (13). The
X-ray crystal structures of 5, 9, and 11 have been determined.
Introduction
Q[Au(CtCR)Cl],8 Q[Au(CtCR)2],7,11,14-16 and Q[Au{Ct
C(Py)CtCH}2] (py ) pyridine-3,5-diyl)12 are also known.
The number of ethynyl(arene)gold complexes de-
creases notably as the number of AuCtC fragments in
the complex increases. In fact, many (arenemonoethy-
nyl)gold complexes have been described, most being of
the type [Au(CtCR)L]n (R ) aryl group, L ) monoden-
tate (n ) 1) or bidentate (n ) 2) neutral ligand),1-8
although a few of the general formulas [Au(CtCR)]n,9-13
(Arenediethynyl)gold derivatives are less common, but
some neutral or anionic complexes, including polymers,
have been prepared from the dialkynes Ar(CtCH)2 (Ar
) C6H4-1,3,10 C6H4-1,4,3 (C6H3Me-5)-1,3, (C6H2Me2-2,5)-
1,4,4 (C6HMe3-2,4,6)-1,3,17 C6Me4-2,3,5,6,10 py-3,5,12 C6H2-
3,6-(15-crown-5)-4,5,5 C4Me4-3,4,5,613). Apart from show-
ing interesting ribbon or infinite chain structures,4,18
many of them are luminescent, a property attributable
in part2,6,14,19 to their short intermolecular Au‚‚‚Au
contacts, which are also present in most structurally
characterized luminescent gold(I) complexes.4,6,18,20 Their
conjugated structures might lead to materials applica-
tions.21
§ Dedicated to Dr. Jose´ Antonio Abad, with best wishes, on the
occasion of his retirement.
† E-mail: mch@um.es (M.-T.C.); jvs1@um.es (J.V.). Web: http://
www.um.es/gqo.
‡ E-mail: p.jones@tu-bs.de.
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(Arenetriethynyl)gold complexes are very scarce. As
far as we are aware, only the explosive polymeric
(11) Vicente, J.; Chicote, M. T.; AÄ lvarez-Falco´n, M. M.; Fox, M. A.;
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1996, 3699.
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Chim. Acta 1986, L29. Vicente, J.; Chicote, M. T.; Abrisqueta, M. D.;
Jones, P. G. Organometallics 2000, 19, 2629.
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Humphrey, M. G.; Cifuentes, M. P.; Samoc, M.; Luther-Davies, B.
Organometallics 2000, 19, 2968.
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Bard´ıa, M.; Solans, X. J. Organomet. Chem. 2003, 82, 678.
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M. M. J. Organomet. Chem. 2002, 663, 40.
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10.1021/om050665f CCC: $30.25 © 2005 American Chemical Society
Publication on Web 10/20/2005

Gold(I) Arylethynyl Complexes
Organometallics, Vol. 24, No. 24, 2005 5957
complex [Au3µ-{C6H3(CtC)3-1,3,5}]n22 and a few deriva-
tives of the type [(AuL)3µ-{C6H3(CtC)3-1,3,5}], obtained
by reacting the former with mono- or bidentate phos-
phine, phosphite, or isocyanide ligands, have been
reported, including three of their crystal structures.22,23
Molecules with 3-fold rotation symmetry, which can
exhibit nonzero â values despite being nonpolar, are
promising candidates for second-order nonlinear optical
materials design.23 In addition, there is currently much
interest22 in extending the chemistry of gold beyond the
most common one-directional linear complexes by using
trifunctional core molecules, and 1,3,5-triethynylben-
zene appears particularly well suited for this purpose.24
In this paper we report the synthesis of some new
gold(I) arenemonoethynyl, -diethynyl, and -triethynyl
complexes derived from the alkynes MeC6H4CtCH-4,
C6Me4(CtCH)2-1,4, and C6Me3(CtCH)3-1,3,5, some of
which are unprecedented with respect to their composi-
tion or structural features. The crystal structures of
PPN[Au{CtCC6Me3(CtCH)2-3,5}2], PPN[Au(CtCC6H4-
Me-4)2], and [{AuPPh3}3{µ-(CtC)3-1,3,5-C6Me3}] have
been determined.
Chart 1
mmol), and the mixture was stirred for 40 min. The resulting
solution was filtered through Celite, concentrated under
vacuum (to ca. 3 mL), and slowly added dropwise to n-hexane
(2, 50 mL) or Et2O (3, 25 mL). The suspension was stirred for
15 min and filtered, and the solid collected was air-dried to
give 2 as a white powder or recrystallized from CHCl3 and
Et2O to give 3 as a pale yellow solid.
2: yield 83 mg, 0.08 mmol, 62%; mp 136 °C. Anal. Calcd
for C30H36Au3N3: C, 35.00; H, 3.52; N, 4.08. Found: C, 35.35;
Experimental Section
IR spectroscopy, mass spectrometry (FAB+/-), elemental
analyses, conductance measurements in acetone, and melting
point determinations were carried out as described else-
where.25 The molar conductivity of the neutral complexes gave
very low values (0-5 Ω-1 cm2 mol-1). The NMR spectra were
measured on Bruker Avance 200, 300, or 400 MHz spectrom-
eters. Chemical shifts are referred to TMS (1H, 13C) or H3PO4
(31P). Unless otherwise stated, the reactions were carried out
at room temperature without any precautions to avoid oxygen
or moisture. The syntheses of [AuCl(SMe2)],26 [Au(acac)PPh3]
(acacH ) acetylacetone), PPN[AuCl2], and PPN[Au(acac)2]27
were previously reported. All other chemicals were obtained
from commercial sources and used as received. The solvents
were distilled before use.
1
H, 3.73; N, 4.15. IR (cm-1): ν(CtN), 2224 (s). H NMR (300
MHz, CDCl3): δ 2.72 (s, 9 H, Me), 1.55 (s, 27 H, tBu). 13C{1H}
NMR (50 MHz, CDCl3): δ 142.1, 129.6, 122.2, 101.5 (CtC),
58.8 (CMe3), 30.2 (CMe3), 21.4 (Me).
3: yield 107 mg, 0.09 mmol, 76%; mp 146 °C. Anal. Calcd
for C42H36Au3N3: C, 42.98; H, 3.09; N, 3.58. Found: C, 42.66;
1
H, 3.08; N, 3.52. IR (cm-1): ν(CtN), 2192 (s). H NMR (200
MHz, CDCl3): δ 7.33-7.28 (m, 3 H, Xy), 7.17-7.13 (m, 6 H,
Xy), 2.79 (s, 9 H, Me, Ar), 2.44 (s, 18 H, Me, Xy). 13C{1H} NMR
(50 MHz, CDCl3): δ 129.1, 124.4, 120.1, 118.2, 112.8, 96.9 (Ct
C), 32.4 (Me), 30.5 (Me).
Synthesis of [{AuC(NHtBu)NEt2}3{µ-(CtC)3Ar}] (4).
Complex 2 (73 mg, 0.071 mmol) was stirred in a mixture of
CH2Cl2 (10 mL) and NHEt2 (1 mL, 9.62 mmol) for 2 h. The
suspension was filtered through Celite, and the resulting
solution was concentrated under reduced pressure (to ca. 1
mL). By addition of Et2O (40 mL) a solid was obtained, which
was filtered off, recrystallized from CH2Cl2 and Et2O, and air-
dried to give 4 as a white powder. 4: yield 52 mg, 0.041 mmol,
59%; mp 120 °C. Anal. Calcd for C42H69Au3N6: C, 40.39; H,
5.57; N, 6.73. Found: C, 40.70; H, 5.60; N, 6.48. IR (cm-1):
ν(NH), 3386 (w); ν(CtC), 2101 (w). 1H NMR (300 MHz,
CDCl3): δ 5.82 (s, 3 H, NH), 4.07 (q, 6 H, CH2, 3JHH ) 7.5 Hz),
Synthesis of [Au3{µ-(CtC)3Ar}]n (1). A suspension of
[AuCl(SMe2)] (1.54 g, 5.2 mmol) and Ar(CtCH)3 (Ar ) C6Me3-
2,4,6 (see Chart 1); 335 mg, 1.7 mmol) in a mixture of CH2Cl2
(20 mL) and NEt3 (0.850 mL, 6 mmol) was stirred for 10 min.
The suspension was filtered, and the solid was washed with
CH2Cl2 (2 × 20 mL) and Et2O (20 mL) and dried under reduced
pressure (ca. 1 mbar) for 0.5 h to give 1‚NEt3‚0.25SMe2 as a
bright yellow powder. Its insolubility in all common solvents
prevented the recording of its NMR spectra. Yield: 1.35 g, 1.5
mmol, 89%. Mp: 198 °C dec. Anal. Calcd for C21.5H25.5Au3-
NS0.25: C, 28.79; H, 2.87; N, 1.56; S, 0.89. Found: C, 28.64; H,
2.74; N, 1.31; S, 0.95. IR (cm-1): ν(CtC), 2104 (w).
3
3.22 (q, 6 H, CH2, JHH ) 7.5 Hz), 2.68 (s, 9 H, Me, Ar), 1.65
t
3
(s, 27 H, Bu), 1.28 (t, 9 H, Me, JHH ) 7.5 Hz), 1.16 (t, 9 H,
Me, JHH ) 7.5 Hz). 13C{1H} NMR (50 MHz, CDCl3): δ 206.0
3
Synthesis of [(AuL)3{µ-(CtC)3Ar}] (L ) tBuNC (2),
XyNC (3)). To a suspension of 1 (2, 101 mg, 0.13 mmol; 3, 94
mg, 0.12 mmol) in CH2Cl2 (10 mL) was added the appropriate
(AuCN2), 143.1, 140.6, 123.0, 102.9 (CtC), 54.2 (CH2), 54.0
(CMe3), 43.2 (CH2), 32.0 (CMe3), 20.6 (Me), 14.9 (Me), 11.8 (Me).
Synthesis of [(AuPPh3)3{µ-(CtC)3Ar}] (5). To a solution
of [Au(acac)PPh3] (998 mg, 1.79 mmol) in CH2Cl2 (15 mL) was
added [Ar(CtCH)3] (69 mg, 0.36 mmol), the mixture was
stirred for 9 h and filtered through Celite, and the resulting
solution was concentrated to dryness. The residue was stirred
with Et2O (45 mL), and the suspension was filtered off.
Recrystallization of the solid from CH2Cl2 and Et2O gave 5 as
a bright yellow powder. 5: yield 487 mg, 0.3 mmol, 87%; mp
155 °C. Anal. Calcd for C69H54Au3P3: C, 52.89; H, 3.47.
Found: C, 52.50; H, 3.55. IR (cm-1): no ν(CtC) is observed.
1H NMR (300 MHz, CDCl3): δ 7.60-7.41 (m, 45 H, PPh3), 2.84
(s, 9 H, Me). 13C{1H} NMR (50 MHz, CDCl3): δ 141.5, 134.4
(d, o-PPh3, 2JCP ) 14 Hz), 131.3 (m, p-PPh3), 130.1 (d, i-PPh3,
t
ligand (2, BuNC, 73 µL, 0.65 mmol; 3, XyNC, 79 mg, 0.60
(20) Che, C. M.; Chao, H. Y.; Miskowski, V. M.; Li, Y. Q.; Cheung,
K. K. J. Am. Chem. Soc. 2001, 123, 4985.
(21) Hirsch, A.; Hanack, M. Conjugated Polymeric Materials: Op-
portunities in Electronics, Optoelectronics and Molecular Electronics;
Kluwer Academic: New York, 1990.
(22) Irwin, M. J.; Manojlovic-Muir, L.; Muir, K. W.; Puddephatt, R.
J.; Yufit, D. S. J. Chem. Soc., Chem. Commun. 1997, 219.
(23) Whittall, I. R.; Humphrey, M. G.; Houbrechts, S.; Maes, J.;
Persoons, A.; Schmid, S.; Hockless, D. C. R. J. Organomet. Chem. 1997,
544, 277.
(24) Gardner, G. B.; Kiang, Y. H.; Lee, S.; Asgaonkar, A,; Venkat-
aram, D. J. Am. Chem. Soc. 1996, 118, 6946.
(25) Vicente, J.; Chicote, M. T.; Guerrero, R.; Saura-Llamas, I. M.;
Jones, P. G.; Ram´ırez de Arellano, M. C. Chem. Eur. J. 2001, 7, 638.
(26) Tamaki, A.; Kochi, J. K. J. Organomet. Chem. 1974, 64, 411.
(27) Vicente, J.; Chicote, M. T. Inorg. Synth. 1998, 32, 172.
3
1JCP ) 55 Hz), 129.0 (d, m-PPh3, JCP ) 11 Hz), 121.9, 21.4
(Me). 31P{1H} NMR (121.4 MHz, CDCl3): δ 42.99 (s, PPh3).
Crystals of 5 suitable for an X-ray diffraction study were

5958 Organometallics, Vol. 24, No. 24, 2005
Vicente et al.
obtained by liquid diffusion of Et2O into a solution of the
complex in CH2Cl2.
Calcd for C64H60AuNO2P2: C, 67.78; H, 5.33; N, 1.24. Found:
C, 67.68; H, 5.28; N, 1.16. ΛM (Ω-1 cm2 mol-1): 97. IR (cm-1):
ν(CH), 3286 (s); ν(CtC), 2086 (s). 1H NMR (300 MHz, d6-
DMSO): δ 7.69-7.52 (m, 30 H, PPN), 4.44 (s, 2 H, CH), 3.42
(s, 4 H, H2O), 2.33 (s, 12 H, Me), 2.29 (s, 12 H, Me). 13C{1H}-
HMBC NMR (100 MHz, d6-DMSO): δ 148.0, 135.7, 135.3,
134.5 (m, p-PPN), 134.4, 132.8 (m, o-PPN), 130.4 (m, m-PPN),
128.8, 127.6 (dd, i-PPN, JCP ) 106 Hz, JCP ) 2 Hz), 119.2,
101.6 (CtC), 90.2 (CtCH), 88.3 (tCH), 19.3 (Me), 19.0 (Me).
MS-FAB- (m/z, %): 559 [M-, 100].
Synthesis of [(AuNHEt2)3{µ-(CtC)3Ar}] (6). To a mixture
of [Ar(CtCH)3] (40 mg, 0.21 mmol) and PPN[AuCl2] (499 mg,
0.62 mmol) in degassed CH2Cl2 (11 mL) was added NHEt2 (1.5
mL). After it was stirred for 4.5 h, the suspension was filtered
off and the white solid collected was washed with CH2Cl2 (2
× 4 mL) and dried under reduced pressure (ca. 1 mbar).
Yield: 200 mg, 0.2 mmol, 95%. Mp: 88 °C dec. Anal. Calcd for
C27H42Au3N3: C, 32.44; H, 4.24; N, 4.20. Found: C, 32.32; H,
4.18; N, 4.18. IR (cm-1): ν(NH), 3156 (s); ν(CtC), 2108 (w).
1H NMR (200 MHz, d6-DMSO): δ 5.48 (m, 3 H, NH), 2.95 (m,
12 H, CH2), 2.46 (s, 9 H, Me), 1.30 (t, 18 H, Me, 3JHH ) 7 Hz).
13C{1H} NMR (75 MHz, d6-DMSO): δ 138.57, 123.54, 117.08,
98.00 (CtC), 48.09 (CH2), 21.03 (Me), 14.97 (Me).
1
3
Synthesis of PPN[Au(CtCTo)2] (11). A mixture of PPN-
[Au(acac)2] (0.755 g, 0.81 mmol) and ToCtCH (0.307 mL, 2.42
mmol) in degassed acetone (15 mL) was stirred for 8.25 h. On
addition of Et2O (30 mL) a solid precipitated, which was
filtered, washed with Et2O (2 × 5 mL), and air-dried to give
11‚H2O as a microcrystalline white solid. 11: yield 756 mg,
0.78 mmol, 97%; mp 196 °C dec. Anal. Calcd for C54H46-
AuNOP2: C, 65.92; H, 4.71; N, 1.42. Found: C, 66.20; H, 4.63;
N, 1.71. ΛM (Ω-1 cm2 mol-1): 93. IR (cm-1): ν(CtC), 2104 (s).
1H NMR (200 MHz, CDCl3): δ 7.70-7.39 (m, 30 H, PPN),
7.29-7.25 (m, 4 H, Ar), 6.92-6.88 (m, 4 H, Ar), 2.24 (s, 6 H,
Me), 1.59 (s, 2 H, H2O). 13C{1H}-HMBC NMR (50 MHz,
CDCl3): δ 134.6 (Ar), 134.3 (m, p-PPN), 133.7 (CAu), 133.4
(Ar), 132.5 (m, m-PPN), 130.1 (m, o-PPN), 128.5 (Ar), 127.3
Synthesis of [(AuNHEt2)2{µ-(CtC)2Ar′}] (7). To a solu-
tion of PPN[AuCl2] (1.04 g, 1.29 mmol) in a mixture of CH2Cl2
(10 mL) and NHEt2 (7 mL) was added a solution of Ar′(Ct
CH)2 (Ar′ ) C6Me4-2,3,5,6, 118 mg, 0.64 mmol) in CH2Cl2 (5
mL), and the mixture was stirred under a nitrogen atmosphere
for 1.5 h. The resulting suspension was concentrated under
vacuum (to ca. 10 mL) and filtered. The solid was dried under
reduced pressure (ca. 1 mbar) for 0.5 h to give 7 as a white
powder. 7: yield 433 mg, 0.6 mmol, 94%; mp 99 °C dec. Anal.
Calcd for C22H34Au2N2: C, 36.68; H, 4.76; N, 3.89. Found: C,
36.93; H, 4.86; N, 3.88. IR (cm-1): ν(NH), 3190 (s); ν(CtC),
2102 (w). 1H NMR (400 MHz, d6-DMSO): δ 5.21 (m, 2 H, NH),
2.63 (m, 8 H, NCH2Me), 1.83 (s, 12 H, Me), 1.03 (t, 12 H,
1
3
(dd, JCP ) 107 Hz, JCP ) 1.8 Hz, i-PPN), 125.2 (Ar), 102.9
(CtCAu), 21.7 (Me). MS-FAB- (m/z, %): 427 [M-, 100].
Crystals of 11 suitable for an X-ray diffraction study were
obtained by slow diffusion of Et2O into a solution of the
compound in CH2Cl2.
3
NCH2Me, JHH ) 7 Hz). 13C{1H} NMR (100 MHz, d6-DMSO):
δ 134.9, 124.8, 118.5, 99.3 (CtC), 48.5 (NCH2Me), 19.4 (Me),
15.4 (NCH2Me).
Synthesis of (PPN)3n[Au{µ-CtCAr(CtC)2}2Au2]n (12).
A mixture of PPN[Au(acac)2] (0.246 g, 0.26 mmol) and Ar(Ct
CH)3 (0.034 g, 0.18 mmol) in degassed CH2Cl2 (15 mL) was
stirred under a nitrogen atmosphere for 4 h. The resulting
suspension was filtered and the solid dried under reduced
pressure (ca. 1 mbar) for 0.5 h to give 12‚3CH2Cl2 as a purple
powder. The insolubility of 12 in all common solvents pre-
vented measurement of its NMR spectra. 12: yield 190 mg,
0.067 mmol, 74%; mp 207 °C dec. Anal. Calcd for C141H114Au3-
Cl6N3P6: C, 59.63; H, 4.05; N, 1.48. Found: C, 59.39; H, 4.05;
N, 1.40. IR (cm-1): ν(CtC), 2088 (w).
Synthesis of (PPN)n[Au{µ-Ar′(CtC)2}]n (13). To a solu-
tion of PPN[Au(acac)2] (0.210 g, 0.23 mmol) in degassed CH2-
Cl2 (10 mL) was added a solution of [Ar′(CtCH)2] (0.037 g,
0.20 mmol) in the same solvent (5 mL), and the mixture was
stirred under a nitrogen atmosphere for 12 h. The resulting
suspension was filtered, and the solid was washed with CH2-
Cl2 (20 mL) and dried under vacuum (ca. 1 mbar) for 1 h to
give 13‚0.9CH2Cl2 as a pale yellow powder. Its insolubility in
all common solvents prevented measurement of its NMR
spectra. 13: yield 179 mg, 0.18 mmol, 90%; mp 153 °C dec.
Anal. Calcd for C50.9H43.8AuCl1.8NP2: C, 61.61; H, 4.45; N, 1.41.
Found: C, 61.95; H, 4.47; N, 1.46. IR (cm-1): ν(CtC), 2082
(w).
X-ray Structure Determinations. Data were registered
using Mo KR radiation on a Bruker SMART 1000 CCD
diffractometer. Absorption corrections were based on multiple
scans (program SADABS). Structures were refined anisotro-
pically on F2 (program SHELXL-97, G. M. Sheldrick, Univer-
sity of Go¨ttingen, Go¨ttingen, Germany). Methyl hydrogens
were identified in difference syntheses and refined as rigid
groups allowed to rotate but not tip; other hydrogens were
included using a riding model. To improve the stability of the
refinement, restraints to light-atom displacement parameters
and local phenyl ring symmetry were employed (DELU, SIMU,
FLAT, SAME). Crystal data are presented in Table 1. Special
features/exceptions: compound 5 has high residual electron
density that might be attributed to absorption errors; for
compound 9, acetylenic hydrogens were refined freely but with
C-H distance restraints (SADI).
Synthesis of [Au2{µ-Ar′(CtC)2}(µ-dpph)]n (8). To a solu-
tion of 1,6-bis(diphenylphosphino)hexane (0.090 g, 0.20 mmol)
in degassed CH2Cl2 (10 mL) was added complex 7 (0.143 g,
0.20 mmol), and the mixture was stirred for 1 h. The resulting
suspension was then filtered and the solid washed with CH2-
Cl2 (2 × 5 mL) and dried under reduced pressure (ca. 1 mbar)
to give 8 as a white powder. The insolubility of 8 in all common
solvents prevented measurement of its NMR spectra. 8: yield
197 mg, 0.19 mmol, 96%; mp 272 °C dec. Anal. Calcd for C44H44-
Au2P2: C, 51.37; H, 4.31. Found: C, 51.20; H, 4.35. IR (cm-1):
no ν(CtC) is observed. MS-FAB+ (m/z, %): 1030 [M+, 3].
Synthesis of PPN[Au{CtCAr(CtCH)2}2] (9). A solution
of PPN[Au(acac)2] (280 mg, 0.30 mmol) in acetone (15 mL) was
slowly added dropwise to a solution of Ar(CtCH)3 (230 mg,
1.20 mmol) in the same solvent (5 mL). The mixture was
stirred for 6 h, filtered through Celite, and concentrated under
vacuum to dryness. The residue was stirred with Et2O (4 ×
20 mL), the suspension was filtered, and the solid was air-
dried to give 9 as a pale purple powder. 9: yield: 283 mg, 0.25
mmol, 85%; mp 196 °C. Anal. Calcd for C66H52AuNP2: C, 70.90;
H, 4.69; N, 1.25. Found: C, 70.61; H, 4.68; N, 1.23. ΛM (Ω-1
cm2 mol-1): 75. IR (cm-1): ν(CH), 3320 (s), 3280 (s); ν(CtC),
1
2096 (s). H NMR (200 MHz, CDCl3): δ 7.67-7.37 (m, 30 H,
PPN), 3.37 (s, 4 H, CH), 2.62 (s, 12 H, Me), 2.53 (s, 6 H, Me).
13C{1H} NMR (50 MHz, CDCl3): δ 143.4, 139.4, 133.9 (m,
p-PPN), 131.9 (m, m-PPN), 129.6 (m, o-PPN), 126.8 (dd, i-PPN,
3
1JCP ) 108 Hz, JCP ) 2 Hz), 118.9, 98.8 (CtC), 83.6 (CCH),
82.0 (CH), 20.6 (Me), 19.8 (Me). MS-FAB- (m/z, %): 579 [M-,
100]. Crystals suitable for an X-ray diffraction study were
obtained by slow diffusion of n-pentane into a solution of 9 in
CH2Cl2.
Synthesis of PPN[Au(CtCAr′CtCH)2] (10). To a solu-
tion of [Ar′(CtCH)2] (0.226 g, 1.24 mmol) in degassed CH2Cl2
(5 mL) was added a solution of PPN[Au(acac)2] (0.290 g, 0.31
mmol) in the same solvent (20 mL), and the mixture was
stirred under a nitrogen atmosphere for 2 h, filtered through
Celite, and concentrated under vacuum (to ca. 10 mL). By
addition of Et2O (30 mL) a white solid precipitated, which was
filtered, washed with Et2O (5 mL), and air-dried to give 10‚
2H2O. 10: yield 278 mg, 0.25 mmol, 82%; mp 229 °C dec. Anal.

Gold(I) Arylethynyl Complexes
Organometallics, Vol. 24, No. 24, 2005 5959
Scheme 1a
Table 1. Crystallographic Data for Complexes
5‚CH2Cl2, 9, and 11
5‚CH2Cl2
9
11
formula
Mr
C
70H56Au3Cl2P3
C
66H56AuNP2
C
54H44AuNP2
1651.86
0.28 × 0.10 ×
0.05
1122.02
965.81
cryst size (mm)
0.18 × 0.16 × 0.30 × 0.08 ×
0.05
monoclinic
C2/c
0.08
monoclinic
C2/c
cryst syst
space group
cell constants
a (Å)
monoclinic
P21/c
24.554(2)
16.6859(12)
15.0022(12)
90
100.265(3)
90
27.829(2)
12.7529(11)
19.8249(14)
90
133.930(4)
90
17.5277(12)
17.6004(12)
15.3303(11)
90
115.354(4)
90
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3), Z
λ (Å)
6048.1(8)
0.710 73
1.814
5067.2(7)
0.710 73
1.471
4273.8(5)
0.710 73
1.501
F(calcd) (Mg m-3
µ, mm-1
F(000)
)
7.468
3.010
3.555
3168
2272
1936
T (K)
2θmax (deg)
133(2)
133(2)
133(2)
56.56
60.06
60.06
no. of rflns measd
no. of indep rflns
transmissns
85 546
14 980
0.802 and
0.455
39 441
7397
40 559
6259
0.894 and
0.802 and
0.650
0.0392
0.466
0.0369
Rint
0.0667
no. of data/restraints/ 14980/216/706 7397/97/328 6259/0/264
params
Rw(F2, all rflns)
R(F, > 4σ(F)
0.0806
0.0343
5.205 and
-2.647
0.0645
0.0264
1.451 and
-0.423
0.0446
0.0194
0.988 and
-0.489
max ∆F (e Å-3
)
Results and Discussion
Synthesis. The complex [Au3{µ-(CtC)3Ar})]n (1) (Ar
) C6Me3-2,4,6; see Chart 1) was obtained by reacting
Ar(CtCH)3 with [AuCl(SMe2)] and NEt3 (1:3:3.5)
(Scheme 1); the Cl and SMe2 ligands are both displaced
a Legend: (a) +3[AuCl(SMe2)], +3NEt3, -3SMe2, -3(NHEt3)-
Cl; (b) +3L; (c) +3[Au(acac)PPh3], -3Hacac; (d): +3 PP-
N[AuCl2], +6NHEt2, -3PPNCl, -3[NH2Et2]Cl; (e) +3HNEt2.
3-
from the coordination sphere of gold by the Ar(CtC)3
ligand generated in situ by deprotonation of the tri-
alkyne with the amine. The insolubility of complex 1 in
all common solvents suggests that it is a polymer in
which gold would complete its usual linear dicoordina-
tion by side-on coordination to a CtC bond, as assumed
for related complexes.10 This is why we could not
measure its NMR spectra. The sulfur and nitrogen
contents shown in its elemental analyses, which we
could not remove even after drying under reduced
pressure for several hours, indicate the presence of SMe2
and NEt3 ligands that would coordinate to the terminal
gold atoms in the polymer. The analytical data agree
with the formulation 1‚NEt3‚0.25SMe2.
NHEt2, following a synthetic method that is well
documented in the chemistry of gold (Scheme 1).28 The
complex [(AuPPh3)3{µ-(CtC)3Ar}] (5) was obtained by
reacting [Au(acac)PPh3] with Ar(CtCH)3 (3:1), provid-
ing one more example of the utility of the “acac
method”29 for the synthesis of gold(I) complexes from
the appropriate [Au(acac)L] complex and a variety of
mildly acidic species.29 An excess of [Au(acac)PPh3] was
used over the stoichiometric 1:3 molar ratio, in order to
avoid the formation of mixtures containing species
resulting from the partial replacement of the acetylenic
protons by AuPPh3 fragments. The synthesis of 5 could
offer an alternative route to [{Au(tht)}3{µ-(CtC)3Ar}]
by its reaction with [AuCl(tht)] (1:3), associated with
the formation of the highly stable [AuCl(PPh3)]. Al-
though the latter indeed formed and was isolated
quantitatively from the mother liquor, the expected tht
complex decomposed to give 1, probably as a conse-
quence not only of the lability of the tht ligand but also
of the insolubility of 1. The complex [(AuNHEt2)3{µ-(Ct
C)3Ar}] (6), with a labile NHEt2 ligand, was obtained
by reacting PPN[AuCl2] with Ar(CtCH)3 (3:1) and an
excess of NHEt2 in CH2Cl2 (Scheme 1). Complexes 4 and
6 are the only (arenetriethynyl)gold(I) complexes with
The addition of an excess of isocyanide to suspensions
of 1 in CH2Cl2 produced clear solutions from which
t
[(AuL)3{µ-(CtC)3Ar}] (L ) BuNC (2), XyNC (3)) were
isolated in good yield, resulting from the splitting of the
weak σ(CtC)fAu interactions and the substitution of
the residual labile ligands SMe2 and NEt3 in 1. More
labile ligands such as tetrahydrothiophene (tht) or
NHEt2 did not react at all with 1, which was recovered
quantitatively even if a large excess of the ligands was
used. We attempted these reactions with the aim of
preparing complexes that could serve as starting ma-
terials more suitable than the insoluble polymer 1.
However, complexes of the general formula [(AuL)3{µ-
(CtC)3Ar}] can be prepared through a variety of
alternative syntheses. Thus, the carbene complex [{AuC-
(NHtBu)NEt2}3{µ-(CtC)3Ar}] (4) was obtained by react-
ing the isocyanide derivative 2 with a large excess of
(28) Minghetti, G.; Bonati, F.; Banditelli, G. Inorg. Chem. 1976, 15,
1718. Bandini, A. L.; Banditelli, G.; Minghetti, G.; Peli, B.; Traldi, B.
Organometallics 1989, 8, 590.
(29) Vicente, J.; Chicote, M. T. Coord. Chem. Rev. 1999, 193-195,
1143.

5960 Organometallics, Vol. 24, No. 24, 2005
Vicente et al.
Scheme 2a
Scheme 3a
a Legend: (a) +2PPN[AuCl2], +4NHEt2, -2PPNCl, -2[NH2-
Et2]Cl; (b) +dpph, -2NHEt2.
ligands other than phosphine or isocyanide. Similarly,
the complex [{AuNHEt2}2{µ-(CtC)2Ar′}] (7) was ob-
tained from PPN[AuCl2], Ar′(CtCH)2 (2:1; Ar′ ) C6Me4-
2,3,5,6, see Chart 1), and an excess of NHEt2 (Scheme
2). The replacement of each of the CtCH protons in the
appropriate alkyne by an AuNHEt2 fragment could
occur through a multistep process involving the depro-
tonation of the alkyne by the base to give a monoalkynyl
ligand; this would replace of one of the chloro ligands
in PPN[AuCl2] to give [NH2Et2]Cl and the corresponding
PPN[Au(alkynyl)Cl] complex, in which the Cl ligand
would be replaced by the excess amine to give (PPN)Cl
and the corresponding [Au(alkynyl)NHEt2] derivative.
The final result could be favored by the slight (7) or
almost zero (6) solubility of these complexes in CH2Cl2,
which might be attributed to the formation of intermo-
lecular hydrogen bonds. In contrast to 6, which dissolves
only in dmso, 7 dissolves slightly in CH2Cl2 or CHCl3,
but the solutions decompose within a few minutes to
give the more insoluble polymer [Au2{(CtC)2Ar′}]n,
which we had prepared previously.10 This process can
be avoided by adding HNEt2 to the solution, but once
the polymer forms, it does not react with NHEt2 to give
7 as previously mentioned. The addition of solid complex
7 into a solution of dpph in CH2Cl2 produced the
replacement of the amino ligands in 7 by the diphos-
phine to give [Au2{µ-(CtC)2Ar′}(µ-dpph)]n (8; Scheme
2). The order of addition of the reagents cannot be
reversed, because otherwise, the insoluble complex 1
forms as a result of the instability of 7 in solution (see
above).
The reactions of PPN[Au(acac)2] with the various
alkynes gave the anionic alkynylgold(I) complexes 9-13,
the nature of which depends on the alkyne and on the
stoichiometric ratio of the reagents (Scheme 3). Thus,
the synthesis of the bis(alkynyl)gold(I) complexes PPN-
[Au{CtCAr(CtCH)2}2] (9), PPN[Au(CtCAr′CtCH)2]
(10), and PPN[Au(CtCTo)2] (11) was achieved when a
g4:1 (9, 10) or g3:1 (11) alkyne to Au molar ratio was
used instead of the stoichiometric 2:1 required. The
excess of alkyne was necessary in the syntheses of 9
and 10 to avoid the formation of insoluble polymeric
species (see below) and helped to improve the yield in
the case of 11. As far as we are aware, complexes 9 and
10 are, along with PPN[Au{CtC(1,12-dicarba-closo-
dodecaborane-10)CtCH}2]11 and [Au(CtCCtCH)(P-
a Legend: (a) +2Ar(CtCH)3, -2Hacac; (b) +2Ar′(CtCH)2,
-2Hacac; (c) +2ToCtCH, -2Hacac; (d) +2/3Ar(CtCH)2,
-2Hacac; (e) +Ar′(CtCH)2, -2Hacac.
Ph3)],30 the only gold complexes bearing a partially
aurated polyalkyne. This is interesting, since these
species bear CtCH fragments and thus could behave
as terminal alkynes in which the replacement of each
of the acidic acetylenic hydrogen atoms by another metal
center, for example following the “acac method” or
dehydrohalogenation reactions such as that of Hagi-
hara,31 coud give rise to homo- or heteronuclear σ-alky-
nyl complexes with extended electron delocalization. We
have recently reported a family of such mixed Pt(II)/
Au(I) complexes that we obtained by the opposite
approach: i.e., by reacting various [PtL2{CtCAr(Ct
CH)n}2] complexes with (acetylacetonato)gold(I) deriva-
tives.32
When PPN[Au(acac)2] was reacted with the alkynes
Ar(CtCH)3 and Ar′(CtCH)2 in an Au to alkyne molar
ratio of g3:2 or g1:1, respectively, the polymeric com-
plexes (PPN)3n[Au{CtCAr(CtC)2}2Au2]n (12) and (PP-
N)n[Au{µ-(CtC)2Ar′}]n (13) formed, as a consequence
(30) Bruce, M. I.; Hall, B. C.; Skelton, B. W.; Smith, M. E.; White,
A. H. Dalton Trans. 2002, 995.
(31) Sonogashira, K.; Kataoka, S.; Takahashi, S.; Hagihara, N. J.
Organomet. Chem. 1978, 160, 319.
(32) Vicente, J.; Chicote, M. T.; AÄ lvarez-Falco´n, M. M.; Jones, P. G.
Organometallics 2005, 24, 2764.

Gold(I) Arylethynyl Complexes
Organometallics, Vol. 24, No. 24, 2005 5961
Figure 1. Thermal ellipsoid plot (50% probability) of 5‚
CH2Cl2. H atoms and solvent are omitted for clarity.
Selected bond lengths (Å) and angles (deg): Au(1)-C(7) )
1.985(4), Au(2)-C(10) ) 1.987(5), Au(3)-C(13) ) 1.993(5),
Au(1)-P(1) ) 2.2692(12), Au(2)-P(2) ) 2.2673(12), Au(3)-
P(3) ) 2.2747(14), C(7)-C(8) ) 1.210(6), C(10)-C(11) )
1.206(6), C(13)-C(14) ) 1.196(7); C(7)-Au(1)-P(1) )
176.14(13), C(10)-Au(2)-P(2) ) 174.07(14), C(13)-Au(3)-
P(3) ) 175.4(2).
Figure 2. Thermal ellipsoid plot (50% probability) of the
anion of 9 with the labeling scheme of the asymmetric unit.
Some methyl H atoms are obscured. Selected bond lengths
(Å) and angles (deg): Au-C(1) ) 1.978(3), C(1)-C(2) )
1.208(4), C(10)-C(11) ) 1.187(4), C(13)-C(14) ) 1.165(4);
C(1)-Au-C(1)#1 ) 173.56(15), C(2)-C(1)-Au ) 170.0(2),
C(1)-C(2)-C(3) ) 175.1(3).
of the total replacement of the CtCH protons by gold
and its marked preference for a linear dicoordination.
These complexes are, along with (PPN)n[Au(CtCC6H-
5-R3-2,4,6-CtC)]n (R ) H, Me),17 the first homoleptic
(σ-alkynyl)gold(I) polymers.
An attempt to prepare the pentanuclear complex
PPN[Au{CtCAr(CtCAuPTo3)2}2] by reacting 9 with
[Au(acac)PTo3] (1:4) failed, and a mixture formed in-
stead, from which 12 and [{AuPTo3}3{µ-(CtC)3Ar}]
were isolated in 84 and 82% yields, respectively. Both
components were identified by IR: 12 by its elemental
analyses and [(AuPTo3)3{µ-(CtC)3Ar}] by its NMR
spectra (1H, δ 7.49-7.20 (m, 36 H, PTo3), 2.39 (s, 27 H,
Me, PTo3), 2.83 (s, 9 H, Me); 31P{1H}, δ 40.92 (s, PTo3)].
X-ray Crystal Structures. The crystal structures of
5‚CH2Cl2 (Figure 1), 9 (Figure 2), and 11 (Figure 3) were
determined. In all these complexes the gold atoms are
in essentially linear dicoordinate environments (angles
at gold in the range 173.56(15)-179.12(9)°). The Ct
C(Au) and Au-Calkynyl bond distances (in the ranges
1.196(7)-1.213(3) and 1.978(3)-1.987(5) Å, respectively)
and also the Au-P distances in 5 (2.2673(12)-2.2747-
(14) Å) lie within the ranges found in other alkynylgold-
(I) complexes.33
Figure 3. Thermal ellipsoid plot (50% probability) of the
anion of 11 with the labeling scheme of the asymmetric
unit. Selected bond lengths (Å) and angles (deg): Au-C(1)
) 1.9860(19), C(1)-C(2) ) 1.213(3); C(1)-Au-C(1)#2 )
179.12(9), C(2)-C(1)-Au ) 178.87(16), C(1)-C(2)-C(3) )
178.68(19), P#1-N-P ) 158.04(14).
(2#)C(3#) fragment is slightly bent (C(1)-Au-C(1#) )
173.56(15)° and C(6)‚‚‚Au‚‚‚C(6#) ) 155.7°), and the two
aromatic rings that support the alkynyl groups subtend
an interplanar angle of 59.6°. Although the crystal
structures of some anionic bis(alkynyl)gold(I) derivatives
have been previously reported,7,16,33,35,36 those of 9,
PPN[Au{CtC(1,12-dicarba-closo-dodecaborane(12))Ct
CH}2],11 and [Au(CtCCtCH)(PPh3)]30 are the only ones
to show partially aurated polyalkynes. The CtCAu bond
distances in the latter (1.188(10), 1.166(9), and 1.226(9)
Å, respectively) are longer than CtCH (1.097(11),
The crystal structure of 1,3,5-triethynylbenzene is
known, as well as those of three of its gold(I) derivatives,
analogous to 5, bearing PPh3,34 tBuNC, and P(OMe)3
22
ligands. Whereas the former displays short Au‚‚‚Au
contacts (3.311 Å), these are rather long in the BuNC
t
derivative (3.724 Å) and absent in that with P(OMe)3.
This is also the case in 5‚CH2Cl2, in which the shortest
Au‚‚‚Au contacts are 6.73 Å.
The crystal structure of 9 consists of PPN cations and
[Au{CtCAr(CtCH)2}2] anions (Figure 2), each lying on
a 2-fold symmetry axis. The C(3)C(2)C(1)AuC(1#)C-
(35) Vicente, J.; Chicote, M. T.; Abrisqueta, M. D.; Jones, P. G.
Organometallics 1997, 16, 5628.
(36) Smith, D. E.; Welch, A. J.; Treurnicht, I.; Puddephatt, R. J.
Inorg. Chem. 1986, 25, 4616. Yam, V. W. W.; Cheung, K. L.; Yip, S.
K.; Cheung, K. K. J. Organomet. Chem. 2003, 681, 196.
(33) CCDC CSD version 5.25, December 2004.
(34) Whittall, I. R.; Humphrey, M. G.; Houbrechts, S.; Maes, J.;
Persoons, A.; Schmid, S.; Hockless, D. C. R. J. Organomet. Chem. 1997,
544, 277.

5962 Organometallics, Vol. 24, No. 24, 2005
Vicente et al.
hydrogen bonds with two neighboring anions (H(7)‚‚‚
Au ) 2.85 Å, C(7)-H(7)-Au ) 147°) and two Cpara
-
H‚‚‚Au hydrogen bonds with two cations (H(34)‚‚‚Au )
2.76 Å, C(34)-H(34)-Au ) 136°). The H‚‚‚Au distances
(much shorter than in compound 9 and also shorter than
the sum of the van der Waals radii (2.86 Å))40 and the
C-H‚‚‚Au angles are indicative of the presence of C-
H‚‚‚Au hydrogen bonds in complex 11.37-39 The anion-
cation contacts, from cations above and below the anion
chain, complete layers parallel to the xz plane. A further
contact (not shown in Figure 5) is established between
a methyl H and the ring centroid of a tolyl group
(H‚‚‚Centroid ) 2.76 Å, C-H‚‚‚Centroid ) 145°).
X-H‚‚‚M hydrogen bonds (M being metal and X
being, in most cases, O, N, or C) have received little
attention until quite recently.39,41 These interactions are
favored for electron-rich metals, such as late transition
metals in low oxidation states, because the metal center
acts as a Lewis base with respect to the hydrogen atom.
These bonds are different from the X-H‚‚‚M agostic
interactions, in which the metal center acts as a Lewis
acid with respect to the X-H bond density. The main
structural differences between both types of interactions
are the X-H-M angle, which is narrower for agostic
(<100-130°) than for hydrogen bonds (>130°),37-39 and
the X-M bond distance, which is shorter for agostic
than for hydrogen bond interactions.
Figure 4. Packing diagram of 9 viewed perpendicular to
the yz plane. C-H‚‚‚Au interactions are shown by dashed
lines. The anion chain is seen in the center of the figure
and is drawn with thicker bonds. See text for further
explanation.
Although many structures of gold(I) complexes show
contacts interpretable as C-H‚‚‚Au hydrogen bonds,33
only a few have been discussed explicitly.8,13,42 This
could be attributed to the presence of other, classical
hydrogen bonds or AuI‚‚‚AuI aurophilic interactions or
to the fact that the search for C-H‚‚‚M interactions is
not well integrated into common program systems;
correspondingly, it may be assumed that many such
interactions fail to be reported.43 Our results, which are
the first reporting C-H‚‚‚Au hydrogen bonds shorter
than the sum of the van der Waals radii in a structure
without other classical hydrogen bonds or AuI‚‚‚AuI
aurophilic interactions, should spur ourselves and oth-
ers to look for such interactions in all future crystal
structures of gold complexes or, in general, for any X-
H‚‚‚metal contacts. However, we sound a note of caution.
Hydrogen atom positions are imprecisely determined in
the presence of heavy atoms. It is of course possible, and
normal practice, to calculate the H atom positions, but
some cases remain that cannot be calculated reliably
(notably, methyl groups, especially those lacking sig-
nificant rotational barriers).
Figure 5. Packing diagram showing the C-H‚‚‚Au hy-
drogen bonds (dashed lines) in 11.
1.110(11), and 1.188(9) Å, respectively), which is also
the case in 9 (1.208(4) vs 1.187(4) and 1.165(4) Å).
The anions of 9 form corrugated ribbons (Figure 4)
parallel to the z axis. Each gold is involved in a short
contact to three independent H atoms (and thus six in
all); to H(11) of the neighboring anion at 3.07 Å, to H(25)
at 3.10 Å, and to H(46) at 3.07 Å (for calculations, C-H
bond lengths were normalized to 1.08 Å). The last two
contacts represent the coordination of the anion chain
by the cations. Although the contacts are far from linear
(angles 120-135°) and one could argue that assemblies
of linearly coordinated atoms are the most easily ap-
proached on steric grounds, we feel nevertheless that
there is a case for considering the interactions as
C-H‚‚‚Au hydrogen bonds.37-39 The lengthening of the
H‚‚‚Au distance by less than 0.3 Å with respect to the
sum of the van der Waals radii (H‚‚‚Au ) 2.86 Å)40 has
not been considered critical.37
The crystal structure of 11 shows [Au(CtCTo)2]
anions (Figure 3) and PPN cations; again, both of these
lie on a 2-fold symmetry axis and the aromatic rings
are slightly rotated with respect to each other (inter-
planar angle 18.6°). In contrast to the anions of com-
pound 9, there is no significant deviation from linearity,
with C(6)‚‚‚Au‚‚‚C(6#) ) 179°.
The packing of compound 11 (Figure 5) is similar to
that of 9. The anions form a double chain parallel to
the z axis. Each gold atom forms two Cmeta-H‚‚‚Au
NMR Spectra. The NMR spectra of the polymeric
compounds 1, 8, 12, and 13 could not be measured
because of their insolubility. The spectrum of 9 shows
the Me protons as two resonances at 2.62 and 2.53 ppm
(41) Canty, A. J.; van Koten, G. Acc. Chem. Res. 1995, 28, 406. Yao,
W.; Eisenstein, O.; Crabtree, R. H. Inorg. Chim. Acta 1997, 254, 106.
Crabtree, R. H.; Eisenstein, O.; Sini, G.; Peris, E. J. Organomet. Chem.
1998, 567, 7. Calhorda, M. J. Chem. Commun. 2000, 801. Berenguer,
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Gold(I) Arylethynyl Complexes
Organometallics, Vol. 24, No. 24, 2005 5963
with relative intensities 2:1, which, along with the data
collected from (arenealkynyl)gold complexes derived
from C6H4(CtC)2-1,3, C6H(CtC)2-1,3-Me3-2,4,6,10,17 and
C6H3N(CtC)2-3,5,12 allows us to conclude that the Ct
CAu fragments cause the protons and methyl groups
in ortho positions to be deshielded with respect to those
in meta positions. In the carbene complex 4, the partial
multiple bond character of the C-N bond in the CNHt-
Bu moiety can give rise to two possible isomers, E and
and 13, while this band is absent in the spectra of 2, 3,
5, and 8. For the same alkyne, the ν(CtC) wavenumber
decreases in the series neutral > anionic mononuclear
> anionic polymeric (7 > 10 > 13 and 4, 6 > 9 > 12),
probably because of the contribution of resonance forms
of the type AudCdCd favored by the negative charge
at the gold atom and by the extended dπ-pπ electronic
conjugation in the polymers.
Mass Spectra. The FAB--MS spectra of the anionic
complexes 9-11 show the M- peak with 10% relative
intensity. In the FAB+-MS spectrum of 8 the peak of
higher m/z value, at 1030 (3%), corresponds to the
monomer. However, taking into account the insolubility
of many complexes of the type [Au2(CtCRCtC)(LL)]n,
(LL ) diisocyanide or diphosphine ligand)51 while the
t
Z, depending on the mutual disposition of the Bu and
gold fragments. As only one resonance is observed in
the 1H and 13C NMR spectra for each type of nucleus in
the NHtBu fragment, only one of the isomers can exist
in solution unless the C-NHtBu bond is weak enough
to allow free rotation. In all the alkynylgold complexes
with the same carbene ligand structurally characterized
by us,7,44 the crystal structure corresponds to the less
crowded Z isomer, and we assume this to be also the
case for 4.
30
tetranuclear analogue [Au2(CtCCtC)(dppm)]2 is
soluble, we tentatively assign to 8 a polymeric structure.
Molar Conductivity in Solution. The molar con-
ductivities of the anionic derivatives 9-11, soluble in
acetone, gave values in the range of 75-99 Ω-1 cm2
mol-1, slightly below those reported by Geary52 for 1:1
electrolytes, which we attribute to the much larger size
of the ions in these complexes with respect to those used
in the reference study.
In the 13C{1H} NMR spectra the resonances from the
Au-CRtCâ fragments are difficult to assign on the basis
of the literature. Although most authors assign the
resonance at lower field to the R-C,20,35,45 opposite
assignments can also be found,46 along with others who
do not describe these resonances47,48 or attribute them
to the CtCAu fragment without distinction.47,49 An
HMBC experiment carried out for 11 allowed us to
unequivocally assign the resonances at 133.7 and 102.9
ppm to the R- and â-C nuclei, respectively.
IR Spectra. Only the IR spectrum of 9 shows two
medium-intensity bands at 3320 and 3280 cm-1 assign-
able to ν(CC-H) stretching modes.50 In the 2108-2082
cm-1 region the IR spectra of complexes 9-11 show one
band of medium intensity assignable to ν(CtC)50 (see
the Experimental Section). A weak absorption is ob-
served in the same region for complexes 1, 4, 6, 7, 12,
Conclusions
We report the synthesis of a family of (arenemono-
ethynyl)-, (arenediethynyl)-, and some of the few exist-
ing (arenetriethynyl)gold(I) complexes. In addition, 4
and 6 are the only (arenetriethynyl)gold(I) complexes
with ligands other than phosphine or isocyanide. Com-
plexes 9 and 10 are some of the few gold complexes
bearing a partially aurated polyalkyne, and 12 and 13
are, along with (PPN)n[Au(CtCC6H-5-R3-2,4,6-CtC)]n
(R ) H, Me), the first homoleptic (σ-alkynyl)gold(I)
polymers. The crystal structures of 9 and 11 show
interesting features. Thus, in 9 we propose C-H‚‚‚Au
hydrogen bonds involving a hydrogen of the neighboring
anion and two hydrogens of the cation, and in 11 we
report the first C-H‚‚‚Au hydrogen bonds shorter than
the sum of the van der Waals radii in a structure
without other classical hydrogen bonds or AuI‚‚‚AuI
aurophilic interactions.
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Acknowledgment. We are grateful for the financial
support of the Ministerio de Ciencia y Tecnolog´ıa,
FEDER (CTQ2004-05396), and the Fundacio´n Se´neca
(Comunidad Auto´noma de la Regio´n de Murcia, Spain)
for a grant to M.A.A.-F.
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Supporting Information Available: CIF files giving
crystal data for 5, 9, and 11. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM050665F
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