Copper-catalyzed huisgen [3 + 2] cycloaddition of gold(I) alkynyls with benzyl azide. Syntheses, structures, and optical properties

Article abstract of DOI:10.1021/om9005774

The copper(I)-catalyzed Huisgen [3 + 2] cycloaddition is a general reaction encompassing wide ranges of organoazide and primarily terminal alkyne reacting partners. Strained internal alkynes can also undergo cycloaddition with azides. We report here that

Full text of DOI:10.1021/om9005774

Organometallics 2009, 28, 6171–6182 6171
DOI: 10.1021/om9005774
Copper-Catalyzed Huisgen [3 þ 2] Cycloaddition of Gold(I) Alkynyls with
Benzyl Azide. Syntheses, Structures, and Optical Properties
David V. Partyka,† Lei Gao,‡ Thomas S. Teets,§ James B. Updegraff III,‡ Nihal Deligonul,‡
and Thomas G. Gray*,‡
‡Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, §Department of
Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
†Creative Chemistry, L.L.C., Cleveland, Ohio 44106
Received July 4, 2009
The copper(I)-catalyzed Huisgen [3 þ 2] cycloaddition is a general reaction encompassing wide ranges
of organoazide and primarily terminal alkyne reacting partners. Strained internal alkynes can also
undergo cycloaddition with azides. We report here that tetrakis(acetonitrile)copper(I) hexafluoropho-
sphate catalyzes the [3 þ 2] cycloaddition of (phosphine)- and (N-heterocyclic carbene)gold(I) alkynyls
with benzyl azide. Isolated yields of up to 96% result. The reaction protocol broadly tolerates
functionalities on the alkynyl reagent. Gold(I) triazolate products form with complete 1,4-regioselec-
tivity. Some 15 new gold(I) triazolates are reported along with crystal structures of nine. Triazolate
complexes bearing polycyclic aromatic substituents show dual singlet- and triplet-state luminescence
from excited states localized on the aromatic fragment. Time-resolved emission experiments find long
lifetimes consistent with triplet emission parentage. Absorption and emission transitions are analyzed
with time-dependent density-functional theory calculations.
Introduction
from relativistic effects.16-18 Formally two-coordinate gold(I)
cations19-25 are powerful catalysts that mediate a host of
organic transformations, chiefly at unsaturated carbon.26-34
The (phosphine)gold(I) thiosugar auranofin is the only orally
Gold commands attention in subfields ranging from nano-
materials1-3 to catalysis,4-9 and from cancer treatment10-12 to
energy recovery.13,14 The (phosphine)- and (N-heterocyclic
carbene)gold(I) fragments are at the center of much current
research. These cations are isolobal with the proton;15 unlike
Hþ, they are soft Lewis acids whose properties derive partly
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*To whom correspondence should be addressed. E-mail: tgray@case.
edu.
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Published on Web 10/14/2009
pubs.acs.org/Organometallics

6172 Organometallics, Vol. 28, No. 21, 2009
Partyka et al.
ingestible gold(I) arthritis prodrug.35,36 Later observations
show auranofin and other (phosphine)- and (carbene)gold(I)
species to be toxic toward cancer cell lines in vitro; gold itself is
the cytoactive component.37-40 Very recent work by Teets and
Nocera41 shows that AuIII and mixed-valence AuI-AuIII com-
plexes reductively eliminate elemental chlorine and bromine on
photoexcitation of ligand-to-metal charge-transfer absorption
bands. When photolysis proceeds without a halogen trap, a net
energy-storing reaction is achieved. Clearly, the synthesis of
gold-bearing molecules and materials is an inviting goal.
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carbon skeletons to exploit the chemical and relativistic
propensities of gold(I).42 Direct attachment of gold to aro-
matic rings occurs on reacting arylboronic acids or pinacol-
boronate esters with gold(I) bromides.43 (Phosphine)- or (N-
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with terminal alkynes.55-58 The resulting compounds are
frequently stable in air; some are water-stable and even
water-soluble.59 Base deprotonations of terminal alkynes
are incompatible with electrophilic and Bronsted acidic
e
functional groups.
A report from this laboratory discloses a facile, room-tem-
perature [3 þ 2] cycloaddition reaction of (phosphine)gold(I)
azides and terminal alkynes that forms carbon-bound (tri-
azolato)gold(I) complexes B.60 This reaction is limited to
terminal alkynes. In a related process, gold(I) alkynyls react
with hydrazoic acid equivalents to yield the same triazolate
complexes, although this reaction does not generate any net
carbon-gold bonds. Organic (nonhydrolyzable) azides are
unreactive toward (alkynyl)gold(I) species at room tempera-
ture or with heating.
This reaction, like alkynylgold(I) syntheses, adds no practic-
able functionality to the organogold product. A sensible objec-
tive is the synthesis of metallotriazolates C that unites alkyne
precursors, gold, and functionalized azides. Triazoles C are the
anticipated products of “gold click chemistry”, the Huisgen
[3 þ 2] cycloaddition of gold(I) alkynyls and organic azides.
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azides and alkynes61-63 is now universally recognized for its
synthetic power and experimental ease.64 This reaction is the
prototype of click chemistry, an exclusive subset of organic
reactions that combine faithful reliability with ready execu-
tion and purification.65 Triazole synthesis is heavily exergo-
nic, releasing more than 20 kcal mol-1 of energy per product
formed. The copper-catalyzed process selectively affords 1,4-
regioisomeric products, whereas the uncatalyzed thermal
reaction produces a mixture of 1,4- and 1,5-isomers, eq 1.
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Article
Organometallics, Vol. 28, No. 21, 2009 6173
the 1,5-triazolate isomers.66-68 The ruthenium-catalyzed
variant produces triazolates from unstrained internal al-
kynes. Applications of these catalytic cycloadditions span
materials synthesis,69-76 bioconjugation,77-82 and drug de-
sign.83,84 The field has been reviewed frequently,85-89 and
activity shows no signs of subsiding. The vast majority of
copper-catalyzed [3 þ 2] cycloadditions involve terminal
acetylenes, despite two observations of copper-catalyzed
click cycloadditions to the symmetric alkyne 3-hexyne.90,91
The advent of click chemistry has produced terminal-
alkyne-bearing materials in profusion. We report here that
gold(I) 1,4-triazolate products form regioselectively in high
yields in the presence of copper(I) salts. This reaction repre-
sents an unusual instance of copper(I)-catalyzed cycloaddi-
tion of internal, unstrained alkynes. Several new gold
triazolates luminesce and show triplet-state phosphores-
cence or dual singlet and triplet emission at room tempera-
ture. The excited states of gold(I) triazolates are discussed
alongside results of density-functional theory calculations.
commercial sources and were used as received. (PCy3)AuCl and
(PPh3)AuCl were synthesized by a slight modification of the
literature procedures (using toluene and Au(THT)Cl).92 (SIPr)-
AuCl was made according to the literature procedure.93 Proce-
dures for alkynylgold(I) complexes were done in air; these were
prepared with methods described previously.94 Microanalyses
(C, H, and N) were performed by Robertson Microlit Labora-
tories, Inc. NMR spectra (1H and 31P{1H}) were recorded on a
Varian AS-400 spectrometer operating at 399.7 and 161.8 MHz,
respectively. For 1H NMR spectra, chemical shifts were deter-
mined from peaks of residual protiated solvent and are stated in
parts-per-million relative to tetramethylsilane. For 31P{1H}
NMR spectra, chemicals shifts were determined relative to
85% aqueous H3PO4.95
[(SIPr)Au(1-benzyl-4-(2-naphthyl)triazolato)] (1). In a nitro-
gen-filled glovebox, [(SIPr)Au(2-ethynylnaphthalene)] (96.1
mg, 0.13 mmol) was suspended in 5 mL of acetonitrile. To this
was added a mixture of benzyl azide (48 mg, 0.36 mmol) and
[Cu(MeCN)4]PF6 (4.6 mg, 10 mol %) under stirring. The mixture
was then stirred under argon at room temperature for 12 h.
Solvent was stripped under rotary evaporation. The remaining
residue was extracted with benzene and filtered through Celite to
yield a slightly yellow solution. Benzene was removed under
rotary evaporation. Pentane was used to triturate the resultant
residue, and an off-white powder was collected by filtration.
Vapor diffusion of pentane into a benzene solution yielded
colorless crystals. Yield: 103 mg (96%). 1H NMR (C6D6): δ
(ppm) 9.12 (s, 1H), 8.16 (dd, 1H, J = 8.4 Hz, 2 Hz,
2-naphthyl), 7.83 (d, 1H, J=7.6 Hz, 2-naphthyl), 7.60 (d, 1H, J=
8 Hz, 2-naphthyl), 7.43 (d, 1H, J = 8.8 Hz, 2-naphthyl), 7.30 (t,
1H, J=6.8 Hz, 2-naphthyl), 7.20-7.23 (m, 3H, 2-naphthyl, CH
aromatic on SIPr), 7.00-7.03 (m, 3H, CH aromatic on benzyl),
6.98 (d, 4H, J=8 Hz, CH aromatic on SIPr), 6.78-6.80 (m, 2H,
CH aromatic on benzyl), 5.02 (s, 2H, CH2-benzyl), 3.12 (s, 4H,
CH2 imidazole), 2.90 (septet, 4H, J = 7.2 Hz, CH(CH3)2), 1.25
(d, 12H, J = 6.8 Hz, CH(CH3)2), 1.11 (d, 12H, J = 6.8 Hz,
CH(CH3)2). UV-vis (THF): λ (ε, M-1 cm-1) 257 (30700), 267
(28 200), 312 (16800) nm. Anal. Calcd for C46H52AuN5: C,
63.37; H, 6.01; N, 8.03. Found: C, 63.58; H, 5.91; N, 8.07.
[(SIPr)Au(1-benzyl-4-tert-butyltriazolato)] (2). In a nitrogen-
filled glovebox, [(SIPr)Au(tert-butylethynyl)] (75.7 mg, 0.11
mmol) was dissolved in 5 mL of acetonitrile. To this was added
the mixture of benzyl azide (44 mg, 0.33 mmol) and [Cu(Me-
CN)4]PF6 (4.1 mg, 10 mol %) under stirring. The mixture was
then stirred under argon at room temperature for 12 h. Aceto-
nitrile was then removed under rotary evaporation. The re-
maining residue was first triturated with pentane to yield a
greenish powder. The powder was then redissolved in benzene
and filtered through Celite. Benzene was removed from the
filtrate by rotary evaporation. Pentane was used to triturate the
residue, and an off-white powder was collected by filtration.
Layering pentane onto a benzene solution yielded colorless
crystals. Yield: 77.2 mg (85%). 1H NMR (C6D6): δ (ppm) 7.11
(d, 2H, J=7.6 Hz, CH aromatic SIPr), 6.98-6.99 (m, 3H, CH
aromatic on benzyl), 6.96 (d, 4H, J=8 Hz CH aromatic SIPr),
6.77-6.79 (m, 2H, CH aromatic on benzyl), 5.06 (s, 2H, CH2-
benzyl), 3.15 (s, 4H, CH imidazole), 2.89 (septet, 4H, J=7.2 Hz,
CH(CH3)2), 1.38 (s, 9H, tert-butyl), 1.33 (d, 12H, J=6.8 Hz,
CH(CH3)2), 1.13 (d, 12H, J = 6.8 Hz, CH(CH3)2). Anal. Calcd
for C40H54AuN5: C, 59.92; H, 6.79; N, 8.73. Found: C, 60.06; H,
6.74; N, 8.48.
Experimental Section
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(95) Abbreviations: Cy, cyclohexyl; NHC, N-heterocyclic carbene;
SIPr, 1,3-bis(2,6-di-isopropylphenyl)-4,5-dihydroimidazol-2-ylidine; tht,
tetrahydrothiophene.
ꢀ
´
(90) Dıez-Gonzalez, S.; Correa, A.; Cavallo, L.; Nolan, S. P. Chem.;
Eur. J. 2006, 12, 7558–7564.
(91) Candelon, N.; Lastecoueres, D.; Diallo, A. K.; Aranzaes, J. R.;
ꢀ
ꢁ
Astruc, D.; Vincent, J.-M. Chem. Commun. 2008, 741–743.

6174 Organometallics, Vol. 28, No. 21, 2009
Partyka et al.
[(PPh3)Au(1-benzyl-4-carboxymethyltriazolato)] (3). In a ni-
trogen-filled glovebox, [(PPh3)Au(carboxymethylethynyl)] (84
mg, 0.15 mmol) was dissolved in 5 mL of acetonitrile. To this
was added the mixture of benzyl azide (60 mg, 0.45 mmol) and
[Cu(MeCN)4]PF6 (5.6 mg, 10 mol %) under stirring. The
mixture was then stirred under argon at room temperature for
12 h, after which solvent was evaporated. The remaining residue
was first triturated with pentane to yield a greenish-brown
powder. The powder was then redissolved in benzene and
filtered through Celite. Benzene was removed by rotary eva-
poration. Pentane was used to triturate the resultant residue,
and an off-white powder was collected by filtration. Layering
pentane onto a benzene solution yielded colorless crystals.
first triturated with pentane to yield a greenish-brown powder.
The powder was then redissolved in benzene and filtered
through Celite. Benzene was removed by rotary evaporation.
Pentane was used to triturate the resultant residue, and an
off-white powder was collected by filtration. The original white
precipitate and the powder were combined as the product.
Layering pentane onto a benzene solution yielded colorless
crystals. Yield: 72 mg (66%). 1H NMR (C6D6): δ (ppm)
8.71 (dd, 2H, J = 8 Hz, 5.6 Hz, CH aromatic), 6.89-7.13
(m, 22H, CH aromatic), 5.49 (s, 2H, CH2-benzyl). 31P{1H}
NMR (C6D6): δ 44.1 (s) ppm. HR-MS (ESþ): calcd m/z =
712.1592 (M þ H)þ; found m/z = 712.1591. Anal. Calcd for
C33H26AuN3PF: C, 55.71; H, 3.68; N, 5.91. Found: C, 55.83; H,
3.44; N, 5.82.
1
Yield: 67 mg (58%). H NMR (C6D6): δ (ppm) 7.33-7.35 (m,
[(PPh3)Au(1-benzyl-4-(4-formylphenyl)triazolato)] (7). In a
glovebox, in 2 mL of degassed 1,2-dichloroethane was sus-
pended (PPh3)Au(4-formylphenylethynyl) (53 mg, 0.091 mmol).
Benzyl azide (3 equiv, 36 mg, 0.27 mmol) in 2 mL of degassed
acetonitrile was added, and to this solution was added [Cu-
(MeCN)4]PF6 (3.4 mg, 0.0091 mmol). The mixture was stirred
for 12 h, and the solvent was removed in vacuo. The residue was
triturated with pentane in the glovebox, causing separation of a
solid, which was collected, dried, and extracted into benzene.
The mixture was filtered through Celite, and the filtrate reduced
to dryness by rotary evaporation. The residue was triturated
with pentane, and the solid was collected and extracted into
toluene and filtered. The filtrate was slowly evaporated in air;
after several hours, a small amount of a light green material
precipitated. After the toluene filtrate had evaporated to ∼1 mL,
the suspension was filtered through Celite to remove the light
green material, and pentane vapor was diffused. After 2-3 days,
a light yellow crystalline solid had separated, which was col-
lected and dried. Yield: 23 mg (35%). 1H NMR (C6D6): δ 9.72 (s,
1H, C6H4(CHO)), 8.88 (d, 2H, C6H4(CHO), J = 8.0 Hz), 7.66
(d, 2H, C6H4(CHO), J = 8.0 Hz), 6.87-7.21 (m, 20H), 5.47 (s,
2H, CH2(C6H5)) ppm. 31P{1H} NMR (C6D6): δ 43.7 (s) ppm. IR
(KBr): 1693 (w, νCdO) cm-1. HR-MS (ESþ): calcd m/z =
722.1636 (M þ H)þ; found m/z = 722.1643. Anal. Calcd for
C34H27AuN3OP: C, 56.60; H, 3.77; N, 5.82. Found: C, 56.39; H,
3.57; N, 5.78.
6H, CH aromatic), 7.07 (d, 3H, J = 7.6 Hz, CH aromatic),
6.84-6.97 (m, 14H, CH aromatic), 5.36 (s, 2H, CH2-benzyl),
3.68 (s, 3H, CO2CH3). 31P{1H} NMR (C6D6): δ 43.3 (s) ppm. IR
(KBr): 1712 (vs, νCdO) cm-1. HR-MS (ESþ): calcd m/z =
676.1428 (M þ H)þ; found m/z = 676.1441. Anal. Calcd for
C29H25AuN3O2P: C, 51.57; H, 3.73; N, 6.22. Found: C, 51.67;
H, 3.75; N, 6.21.
[(PPh3)Au(1-benzyl-4-phenyltriazolato)] (4). In a nitrogen-
filled glovebox, [(PPh3)Au(phenylethynyl)] (71 mg, 0.13 mmol)
was dissolved in 5 mL of acetonitrile. To this was added the
mixture of benzyl azide (51 mg, 0.38 mmol) and [Cu(MeCN)4]-
PF6 (4.7 mg, 10 mol %) under stirring. The mixture was then
stirred under argon at room temperature for 12 h. Solvent was
removed by rotary evaporation. The remaining residue was first
triturated with pentane to yield a greenish-brown powder. The
powder was then redissolved in benzene and filtered through
Celite. Benzene was removed from the filtrate by rotary eva-
poration. Pentane was used to triturate the resultant residue,
and an off-white powder was collected by filtration. Layering
pentane onto a benzene solution yielded colorless crystals.
1
Yield: 60 mg (67%). H NMR (C6D6): δ (ppm) 8.81 (d, 2H,
J=7.2 Hz, CH aromatic), 7.27 (t, 2H, J=7.6 Hz, CH aromatic),
6.90-7.13 (m, 21H, CH aromatic), 5.50 (s, 2H, CH2-benzyl).
31P{1H} NMR (C6D6): δ 43.9 (s) ppm. HR-MS (ESþ): calcd
m/z=694.1686 (M þ H)þ; found m/z=694.1670. Anal. Calcd
for C33H27AuN3P: C, 57.15; H, 3.92; N, 6.06. Found: C, 57.05;
H, 3.94; N, 6.05.
[(PPh3)Au(1-benzyl-4-(3-thienyl)triazolato)] (8). In a nitro-
gen-filled glovebox, [(PPh3)Au(3-thienylethynyl)] (68.7 mg)
was dissolved in 5 mL of acetonitrile. To this was added the
mixture of benzyl azide (49 mg) and [Cu(MeCN)4]PF6 (4.5 mg,
10 mol %) under stirring. The mixture was then stirred under
argon at room temperature for 12 h. Acetonitrile was removed
by rotary evaporation. The remaining residue was first tritu-
rated with pentane to yield a greenish powder. The powder was
then redissolved in benzene and filtered through Celite. Benzene
was removed by rotary evaporation. Pentane was used to
triturate the resultant residue, and an off-white powder was
collected by filtration. Layering pentane onto a benzene solu-
[(PPh3)Au(1-benzyl-4-(4-tolyl)triazolato)] (5). In a nitrogen-
filled glovebox, [(PPh3)Au(4-tolylethynyl)] (66 mg, 0.11 mmol)
was dissolved in 5 mL of acetonitrile. To this was added a
mixture of benzyl azide (44 mg, 0.33 mmol) and [Cu(MeCN)4]-
PF6 (4.0 mg, 10 mol %) under stirring. The mixture was then
stirred under argon at room temperature for 12 h. Acetonitrile
was removed by rotary evaporation. The remaining residue was
first triturated with pentane to yield a greenish-brown powder.
The powder was then redissolved in benzene and filtered
through Celite. Benzene was removed by evaporation. Pentane
was used to triturate the resultant residue, and an off-white
powder was collected by filtration. Layering pentane onto a
benzene solution yielded colorless crystals. Yield: 48 mg (58%).
1H NMR (C6D6): δ (ppm) 8.23 (d, 2H, J = 6.8 Hz, CH
aromatic), 7.16 (s, 2H, CH aromatic), 6.92-7.10 (m, 20H, CH
aromatic), 5.50 (s, 2H, CH2-benzyl), 2.17 (s, 3H, CH3). 31P{1H}
NMR (C6D6): δ 44.0 (s) ppm. HR-MS (ESþ): calcd m/z =
708.1843 (M þ H)þ; found m/z = 708.1860. Anal. Calcd for
C34H29AuN3P: C, 57.72; H, 4.13; N, 5.94. Found: C, 57.57; H,
4.21; N, 5.79.
1
tion yielded colorless crystals. Yield: 56 mg (66%). H NMR
(C6D6): δ (ppm) 8.32 (dd, 1H, J = 1.2 Hz, 4 Hz, 3-thienyl), 8.22
(dd, 1H, J = 1.2 Hz, 2.8 Hz, 3-thienyl), 7.18 (s, 2H, 3-thienyl, CH
aromatic) 7.10-7.11 (m, 3H, CH aromatic), 6.90-7.00 (m, 16H,
CH aromatic, P(C6H5)3), 5.48 (s, 2H, CH2-benzyl). 31P{1H}
NMR (C6D6): δ 44.3 (s) ppm. HR-MS (ESþ): calcd m/z =
700.1251 (M þ H)þ; found m/z = 700.1278. Anal. Calcd for
C31H25AuN3PS: C, 53.22; H, 3.60; N, 6.01. Found: C, 53.37; H,
3.38; N, 5.81.
[(PPh3)Au(1-benzyl-4-(4-fluorophenyl)triazolato)] (6). In a
nitrogen-filled glovebox, [(PPh3)Au(4-fluorophenylethynyl)]
(87.7 mg, 0.15 mmol) was dissolved in 5 mL of acetonitrile. To
this was added the mixture of benzyl azide (60 mg, 0.45 mmol)
and [Cu(MeCN)4]PF6 (5.6 mg, 10 mol %) under stirring. The
mixture was then stirred under argon at room temperature for
12 h. The resultant precipitate was collected by decanting the
upper solution carefully. Solvent was removed from the upper
solution under rotary evaporation. The remaining residue was
[(PPh3)Au(1-benzyl-4-ferrocenyltriazolato)] (9). (PPh3)Au-
(ethynylferrocene) (77 mg, 0.11 mmol) was suspended in 5 mL
of acetonitrile. To this was added the mixture of benzyl azide
(45 mg, 0.33 mmol) and [Cu(MeCN)4]PF6 (4.3 mg, 10 mol %)
under stirring. The mixture was then stirred under argon at
room temperature for 12 h. Acetonitrile was removed by rotary
evaporation. The remaining residue was first triturated with
pentane to yield a dark orange powder. The powder was then
redissolved in benzene and filtered through Celite. Benzene was

Article
Organometallics, Vol. 28, No. 21, 2009 6175
then removed by rotary evaporation. Pentane was used to
triturate the resultant residue, and an orange powder was
collected by filtration. Layering pentane onto a benzene solu-
tion yielded orange crystals. Yield: 68 mg (73%). 1H NMR
(C6D6): δ (ppm) 7.26-7.31 (m, 8H, CH aromatic), 6.90-7.10
(m, 12H, CH aromatic), 5.52 (s, 2H, CH2-benzyl), 5.41 (t, 2H,
J = 1.6 Hz, ferrocenyl), 4.15 (t, 2H, J = 1.6 Hz, ferro-
cenyl), 4.10 (s, 5H, ferrocenyl). 31P{1H} NMR (C6D6): δ 44.6
(s) ppm. Anal. Calcd for C37H31AuN3PFe: C, 55.45; H, 3.90; N,
5.24. Found: C, 55.18; H, 3.63; N, 5.18.
Scheme 1. Copper-Catalyzed Gold(I) Triazolate Synthesis
[(PCy3)Au(1-benzyl-4-trimethylsilyltriazolato)] (10). In 2 mL
of acetonitrile was suspended (PCy3)Au(trimethylsilylethynyl)
(91 mg, 0.16 mmol), and to this was added (in a glovebox) a 1 mL
acetonitrile solution of benzyl azide (62 mg, 0.47 mmol).
[Cu(MeCN)4]PF6 (5.8 mg, 0.016 mmol) was added to this
suspension, and the resultant mixture was stirred for 12 h. The
product, which had precipitated, was collected by filtration and
recrystallized by diffusion of pentane vapor into a saturated
benzene solution to yield analytically pure material. Yield: 26
mg (23%). 1H NMR (C6D6): δ 7.15-7.20 (m, 2H, CH2C6H5),
6.93-7.02 (m, 3H, CH2C6H5), 5.66 (s, 2H, CH2-benzyl),
0.89-1.78 (m, 33H, C6H11), 0.73 (s, 9H, Si(CH3)3) ppm. 31P{1H}
NMR (C6D6): δ 58.1 (s) ppm. Anal. Calcd for C30H49AuN3PSi:
C, 50.91; H, 6.98; N, 5.94. Found: C, 50.68; H, 7.25; N, 5.93.
[(PCy3)Au(1-benzyl-4-(4-biphenyl)triazolato)] (11). In 2 mL of
0.012 mmol) with stirring. The resultant mixture was stirred 12 h
under an inert atmosphere. The solvent was stripped in vacuo,
and the residue soaked in pentane for several hours in the
glovebox. The pentane was decanted, the residue was dried
and then extracted into benzene, and ether was added (∼1:1
v/v). The extract was filtered through Celite, and the solvent
removed by rotary evaporation. Pentane was added and then
removed by rotary evaporation to remove as much benzene as
possible, in which the product is highly soluble. The crude
material was taken back into the glovebox, extracted into a
minimum of toluene, and filtered, and pentane vapor was
diffused to cause separation of a crystalline solid, which was
collected and dried. The solid appeared to be mildly sensitive to
acetonitrile in
a glovebox was suspended [(PCy3)Au(4-
biphenylethynyl)] (75 mg, 0.12 mmol), and to this suspension
was added a 1 mL acetonitrile solution of 3 equiv (46 mg, 0.35
mmol) of benzyl azide. [Cu(MeCN)4]PF6 (4.3 mg, 0.012 mmol)
was added to this suspension, and the resultant mixture was
stirred for 12 h. An off-white solid was collected by filtration
and washed twice with pentane and dried. This precipitate
1
air and/or light. Yield: 39 mg (63%). H NMR (C6D6): δ 9.31
1
was analytically pure. Yield: 68 mg (75%). H NMR (C6D6):
(s, 2-naphthyl, 1H), 9.08 (d, 2-naphthyl, 1H, J = 1.6, 8.4 Hz),
7.84 (t, 2-naphthyl, 2H, J = 8.8 Hz), 7.70 (d, 2-naphthyl, 1H,
J = 8.0 Hz), 6.97-7.32 (m, 7H), 5.67 (s, 2H, CH2-benzyl),
0.94-1.80 (m, 33H, C6H11) ppm. 31P{1H} NMR (C6D6): δ 57.9
(s) ppm. HR-MS (ESþ): calcd m/z = 762.3246 (M þ H)þ; found
m/z = 762.3240. 31P{1H} NMR (CDCl3): δ 37.8 (s) ppm.
UV-vis (2-MeTHF): λ (ε, M-1 cm-1) 285 (16 000), 301
(16 300), 345 (2700) nm. Anal. Calcd for C37H47AuN3P: C,
58.34; H, 6.22; N, 5.52. Found: C, 58.10; H, 6.50; N, 5.51.
[(PCy3)Au(1-benzyl-4-(9-phenanthryl)triazolato)] (14). In 1 mL
of acetonitrile in a glovebox was suspended [(PCy3)Au(9-
ethynylphenanthrene)] (68 mg, 0.10 mmol), and to this suspen-
sion was added a 1 mL acetonitrile solution of 3 equiv (40 mg,
0.10 mmol) of benzyl azide. To enhance solubility, 2 mL of 1,2-
dichloroethane was added. [Cu(MeCN)4]PF6 (3.7 mg, 0.010
mmol) was added to this suspension, and the resultant solution
was stirred for 12 h. The solvent was removed in vacuo, and the
residue soaked with pentane for several hours in a glovebox. The
pentane was decanted and the dry residue was extracted into the
minimum amount of benzene needed to dissolve the residue.
Approximately one volume equivalent of ether was added, and
the suspension was filtered through Celite. The filtrate was
reduced to dryness by rotary evaporation, and the residue
triturated with pentane. The powder was collected, extracted
into a minimum of benzene, and filtered, and the material was
recrystallized by vapor diffusion of pentane. Washing the
recrystallized material thoroughly with cold benzene yielded
analytically pure material. Yield: 31 mg (38%). 1H NMR
(C6D6): δ 9.33-9.40 (m, 1H, 9-phenanthryl), 8.50-8.60 (m,
2H, 9-phenanthryl), 8.47 (s, 1H, 9-phenanthryl), 7.75 (d, 1H,
9-phenanthryl, J = 5.6 Hz), 7.33-7.45 (m, 6H), 7.00-7.14 (m,
3H), 5.72 (s, 2H, CH2-benzyl), 0.80-1.80 (m, 33H, C6H11) ppm.
31P{1H} NMR (C6D6): δ 57.6 (s) ppm. UV-vis (2-MeTHF):
λ (ε, M-1 cm-1) 263 (14400), 311 (9300) nm. Anal. Calcd for
C41H49AuN3P: C, 60.66; H, 6.08; N, 5.17. Found: C, 60.48; H,
5.93; N, 5.17.
δ 8.97 (d, biphenyl, 2H, J = 8.4 Hz), 7.70 (d, biphenyl, 2H, J =
8.4 Hz), 7.60 (d, biphenyl, 2H, J = 7.2 Hz), 7.24 (t, biphenyl, 2H,
J = 7.6 Hz), 7.11-7.21 (m, 5H), 5.61 (s, 2H, CH2-benzyl), 0.91-
1.70 (m, 33H, C6H11) ppm. 31P{1H} NMR (C6D6): δ 58.1 (s)
ppm. UV-vis (2-MeTHF): λ (ε, M-1 cm-1) 305 (18 100) nm.
Anal. Calcd for C39H49AuN3P: C, 59.46; H, 6.27; 5.33. Found:
C, 59.18; H, 6.55; N, 5.61.
[(PCy3)Au(1-benzyl-4-(1-naphthyl)triazolato)] (12). In 1 mL
of acetonitrile in a glovebox was suspended [(PCy3)Au(1-
ethynylnaphthalene)] (54 mg, 0.086 mmol), and to this suspen-
sion was added a 0.5 mL acetonitrile solution of 3 equiv (34 mg.
0.26 mmol) of benzyl azide. [Cu(MeCN)4]PF6 (3.2 mg,
0.0086 mmol) was added to this suspension, and the resultant
mixture was stirred for 12 h. The acetonitrile was removed in
vacuo, and pentane was added in air, allowed to soak for 2 h, and
decanted. Ether was added and then removed by rotary evapora-
tion. Repeating this process solidified the product residue. The
solid was extracted into benzene and filtered through Celite, and
pentane vapor was diffused into the saturated solution. After
approximately 2 days, the mother liquor immersing the crystals
that separated was decanted, and the crystals were washed with
pentane and dried. The dry crystals were washed thoroughly
twice with a small amount of very cold xylenes to remove a small
amount of a red-brown residue, followed by a pentane and ether
wash (small amount of ether). The light brown crystals were dried
1
and collected. Yield: 25 mg (38%). H NMR (C6D6): δ 9.37
(d, 1H, J = 8.4 Hz), 8.32 (d, 1H, J = 7.2 Hz), 7.71 (t, 2H, J =
7.2 Hz), 7.39 (t, 1H, J = 7.6 Hz), 7.20-7.35 (m, 4H), 7.08 (t, 2H,
J = 7.6 Hz), 6.99-7.05 (m, 1H), 5.67 (s, 2H, CH2-benzyl),
0.70-1.60 (m, 33H, C6H11) ppm. 31P{1H} NMR (C6D6): δ 57.7
(s) ppm. Anal. Calcd for C37H47AuN3P: C, 58.34; H, 6.22; N,
5.52. Found: C, 58.09; H, 6.51; N, 5.64.
[(PCy3)Au(1-benzyl-4-(2-naphthyl)triazolato)] (13). In 2 mL
of 1,2-dichloroethane in a glovebox was dissolved recrystallized
(PCy3)Au(2-ethynylnaphthalene) (51 mg, 0.081 mmol). To this
solution was added benzyl azide (3 equiv, 33 mg, 0.25 mmol)
dissolved in 2 mL of acetonitrile, followed by CuI (2.3 mg,
[(PCy3)Au(1-benzyl-4-(3-thienyl)triazolato)] (15). In a nitro-
gen-filled glovebox, a 2 mL acetonitrile solution of benzyl azide

6176 Organometallics, Vol. 28, No. 21, 2009
Table 1. Syntheses of Gold(I) Triazolate Complexes
Partyka et al.
(42 mg, 0.32 mmol) was added to a 2 mL 1,2-dichloroethane
solution of [(PCy3)Au(3-thienylethynyl)] (61 mg, 0.10 mmol).
To this solution was added [Cu(MeCN)4]PF6 (3.9 mg, 0.010
mmol), and the resultant mixture was stirred for 12 h. The
solvent was removed in vacuo, and the residue was triturated
with pentane in a glovebox. The pentane was decanted, and the
dry residue was extracted into benzene/ether (∼1:1 v/v) and
filtered through Celite. The filtrate was stripped of solvent by
rotary evaporation, and the resultant residue soaked in copious
pentane (30 mL). The pentane was removed by rotary evapora-
tion, which dried the residue. The off-white solid was mixed
thoroughly with toluene; the undissolved solid was washed with
pentane and dried to yield 34 mg of pure product. Pentane vapor
was diffused into the Celite-filtered toluene washing, and the
crystalline mass that separated was washed with pentane and
dried. This material was also pure by NMR and microanalysis.
Combined yield: 54 mg (72%). 1H NMR (C6D6): δ 8.35 (dd, 1H,
3-thienyl, J=1.2, 5.2 Hz), 8.28 (dd, 1H, 3-thienyl, J=1.2, 3.2
Hz), 7.07 (dd, 1H, 3-thienyl, J=3.2, 4.8 Hz), 6.97-7.05 (m, 5H),
5.55 (s, 2H, CH2-benzyl), 0.90-1.64 (m, 33H, C6H11) ppm.
31P{1H} NMR (C6D6): δ 58.3 (s) ppm. HR-MS (ESþ): calcd
m/z = 718.2659 (M þ H)þ; found m/z=718.2661. Anal. Calcd
for C31H43AuN3PS: C, 51.88; H, 6.04; N, 5.85. Found: C, 51.61;
H, 6.09; N, 5.76.
[(PPh3)Au(1-adamantyl-4-(carboxymethyl)triazolato)] (17).
In 2 mL of acetonitrile in a glovebox was suspended (PPh3)-
Au(carboxylmethylethynyl) (16)96 (66 mg, 0.12 mmol) and 1-
azidoadamantane (67 mg, 0.38 mmol), and to this suspension
was added 2 mL of 1,2-dichloroethane. [Cu(MeCN)4]PF6
(4.5 mg, 0.012 mmol) was added to this solution, and the
resultant mixture was stirred for 72 h. The solvent was removed
in vacuo, and the residue washed with pentane, dried, extracted
into benzene, and filtered through Celite in a glovebox. The
filtrate was reduced to dryness by rotary evaporation and
triturated with pentane, and the solid that separated was
(96) Bruce, M. I.; Horn, E.; Matisons, J. G.; Snow, M. R. Aust. J.
Chem. 1984, 37, 1163–1170.

Article
Organometallics, Vol. 28, No. 21, 2009 6177
Table 2. Crystallographic Data for Triazolatogold(I) Complexes
1
3
4
5
6
formula
fw
cryst syst
space group
a, A
b, A
c, A
R, deg
β, deg
C
46H52AuN5 C6H6
C29H25AuN3O2P
675.46
monoclinic
P21/c
9.6041(7)
C33H27AuN3P
693.51
monoclinic
P21/n
17.073(2)
9.1697(13)
17.541(2)
C34H29AuN3P C6H6
3
C33H26 AuFN3P
711.50
monoclinic
P21/c
10.6315(13)
16.827(2)
15.2109(18)
3
1900.00
triclinic
P1
746.59
monoclinic
C2/c
11.3686(11)
12.6375(13)
16.3123(16)
103.1030(10)
101.8910(10)
95.3870(10)
2209.2(4)
2
1.428
100(2)
3.371
950
0.49 ꢀ 0.47 ꢀ 0.44
1.32, 26.94
24 345
9301
531
24.504(4)
8.8512(14)
28.802(4)
14.4554(10)
18.4921(13)
91.0140(10)
95.925(2)
100.730(2)
102.9620(10)
γ, deg
cell volume, A3
Z
2566.9(3)
4
1.748
100(2)
5.825
1320
0.22 ꢀ 0.20 ꢀ 0.11
1.79, 27.97
30 741
6109
326
1.027
0.0162
2731.4(7)
4
1.686
100(2)
5.472
1360
0.44 ꢀ 0.43 ꢀ 0.18
1.58, 27.75
31 466
6359
343
0.984
0.0286
6137.7(17)
8
1.616
100(2)
4.877
2952
0.46 ꢀ 0.32 ꢀ 0.10
1.44, 27.49
35 642
7047
380
1.071
0.0167
2651.8(6)
4
1.782
100(2)
5.644
1392
0.36 ꢀ 0.18 ꢀ 0.16
1.83, 27.11
27 379
5721
352
1.086
0.0399
Dcalcd, Mg, m-3
T, K
μ, mm-1
F(000)
cryst size, mm3
θ
min, θmax, deg
no. of reflns collected
no. of indep reflns
no. of refined params
goodness-of-fit on F2a
final R indicesb [I > 2σ(I)]
R1
1.233
0.0248
wR2
0.0844
0.0258
0.0363
0.0200
0.1075
0.0339
0.0389
0.0186
0.1265
0.0434
R indices (all data)
R1
wR2
0.0879
0.0374
0.1153
0.0397
0.1317
9
10
11
12
formula
fw
C37H31AuFeN3P
801.43
C30H49AuN3PSi
707.75
C39H49AuN3P
787.75
C37H47AuN3P
761.71
cryst syst
space group
a, A
b, A
c, A
R, deg
β, deg
monoclinic
P21/c
23.71(2)
9.026(9)
29.77(3)
monoclinic
P21/c
15.331(4)
10.891(3)
19.294(5)
triclinic
P1
monoclinic
P21/c
12.2523(18)
15.205(2)
18.003(3)
10.7229(10)
11.9560(11)
15.4679(14)
92.985(1)
108.423(1)
113.359(1)
1691.0(3)
2
1.547
100(2)
4.429
796
0.38 ꢀ 0.18 ꢀ 0.07
1.42, 26.96
18 921
6689
397
1.240
0.0265
0.0291
0.0736
0.0797
91.702(10)
104.821(2)
108.110(1)
γ, deg
cell volume, A3
Z
6368(10)
8
1.672
100(2)
5.138
3152
0.35 ꢀ 0.32 ꢀ 0.10
0.86, 27.50
54 027
14 504
775
3114.3(13)
4
1.509
296(2)
4.836
1432
0.27 ꢀ 0.20 ꢀ 0.11
1.37, 26.99
31 641
6594
329
1.192
3187.6(8)
4
1.587
100(2)
4.696
1536
0.37 ꢀ 0.10 ꢀ 0.10
1.75, 27.01
34 007
6108
379
0.979
Dcalcd, Mg, m-3
T, K
μ, mm-1
F(000)
cryst size, mm3
θ
min, θmax, deg
no. of reflns collected
no. of indep reflns
no. of refined params
goodness-of-fit on F 2a
final R indicesb [I > 2σ(I)] R1
wR2
1.074
0.0216
0.0481
0.0268
0.0545
0.0666
0.2055
0.0817
0.2397
0.0368
0.0415
0.1179
0.1219
R indices (all data) R1
wR2
P
P
P
P
a GOF = [ w(Fo2 - Fc2)2/(n - p)]1/2; n = number of reflections, p = number of parameters refined. b R1 = ( Fo|- |Fc )/ |Fo|; wR2 = [ w(Fo
-
2
P
4 1/2
Fc2)2/ wFo
]
.
collected, dried, and recrystallized by vapor diffusion of pentane
into a filtered, saturated chloroform solution. The resultant
solid was extracted into benzene and filtered, and the benzene
removed by rotary evaporation to yielded a residue, which was
triturated with pentane. The resultant white solid was collected
and dried. Yield: 18 mg (21%). 1H NMR (C6D6): δ 7.48-7.61
(m, 6H), 6.90-7.10 (m, 9H), 3.69 (s, 1H, CO2CH3), 2.70 (s, 6H,
admantyl), 1.94 (s, 3H, adamantyl), 1.48 (s, 6H, adamantyl)
ppm. 31P{1H} NMR (C6D6): δ 42.5 (s) ppm. IR (KBr): 1705
(vs, νCdO) cm-1. HR-MS (ESþ): calcd m/z = 720.2053 (M þ
H)þ; found m/z = 720.2115.
X-ray Structure Determination. New compounds were crys-
tallized by pentane diffusion into saturated benzene solutions.
Single-crystal X-ray data were collected on a Bruker AXS
SMART APEX II CCD diffractometer using monochroma-
tic Mo KR radiation with the omega scan technique. The
unit cells were determined using SMART97 and SAINTþ.98
(97) Bruker Advanced X-ray Solutions. SMART for WNT/2000
(Version 5.628); Bruker AXS Inc.: Madison, WI, 1997-2002.
(98) Bruker Advanced X-ray Solutions. SAINT (Version 6.45);
Bruker AXS Inc.: Madison, WI, 1997-2003.

6178 Organometallics, Vol. 28, No. 21, 2009
Partyka et al.
Data collection for all crystals was conducted at 100 K (-173.5 °C).
All structures were solved by direct methods and refined by
full matrix least-squares against F2 with all reflections using
SHELXTL.99 Refinement of extinction coefficients was found
to be insignificant. All non-hydrogen atoms were refined aniso-
tropically. All hydrogen atoms were placed in standard calculated
positions, and all hydrogen atoms were refined with an isotropic
displacement parameter 1.2 times that of the adjacent carbon.
Computations. Spin-restricted density-functional theory com-
putations were performed within the Gaussian 03 program
suite.100 Calculations employed the modified Perdew-Wang
exchange functional of Adamo and Barone101 and the original
Perdew-Wang correlation functional.102 Nonmetal atoms were
described with the TZVP basis set of Godbelt, Andzelm, and co-
workers.103 Gold orbitals were described with the Stuttgart
effective core potential and the associated basis set,104 which
was contracted as follows: Au, (8s,6p,5d) f [7s,3p,4d].105
Relativity with the Stuttgart ECP and its associated basis set is
introduced with a potential term (i.e., a one-electron operator)
that replaces the two-electron exchange and Coulomb operators
resulting from interaction between core electrons and between
core and valence electrons. In this way relativistic effects,
especially scalar effects, are included implicitly rather than as
four-component, one-electron functions in the Dirac equation.
Geometries were optimized without imposed symmetry, and
harmonic frequency calculations find all structures to be poten-
tial energy minima. Calculations on triplet states were spin-
unrestricted. Vertical excitation energies were calculated using a
TDDFT implementation described by Scuseria and co-work-
ers.106 All calculated properties reported here include implicit
THF solvation (ε = 7.58, 298.15 K), which was incorporated in
single-point calculations of the gas-phase geometries with To-
masi’s polarizable continuum model (PCM).107,108 The stability
of each converged density was confirmed by calculation of the
eigenvalues of the A matrix.109,110 Percentage compositions of
molecular orbitals, overlap populations, and bond orders be-
tween fragments were calculated using the AOMix program of
Gorelsky.111,112
Results and Discussion
Syntheses and Spectroscopy. Reaction of an (N-heterocyc-
lic carbene)gold(I) 2-naphthyl alkynyl precursor with 3 equiv
of benzyl azide in the presence of 10 mol % [Cu(Me-
CN)4](PF6) at room temperature for 12 h affords triazolate
1 in quantitative yield by 1H NMR, Scheme 1. Lower catalyst
loadings lead to incomplete conversion after 12 h. 1H NMR
diagnoses product formation, through a downfield shift of
the benzylic hydrogen resonances upon metalation. The
benzylic protons of 1 resonate at δ 5.65 ppm in C6D6 relative
to tetramethylsilane; those of benzyl azide, at 3.66 ppm.
Complex 1 is isolated in 96% yield by crystallization from
benzene/pentane solutions. An X-ray diffraction crystal
structure determination establishes its identity as the 1,4-
regioisomer, vide infra. Other triazolate complexes are pre-
pared in like manner. Another copper(I) source, CuI, is also
efficient in catalyzing the reaction, as specified in the synth-
esis of compound 13. Attempts at [3 þ 2] cycloaddition of
gold(I) alkynyls catalyzed by (THT)AuCl (THT=tetrahy-
drothiophene), AgOTf (OTf=triflate), or Cp*RuCl(COD)
(Cp*=η5-C5Me5, COD=(1Z,5Z)-cycloocta-1,5-diene) pro-
duced no discernible product; starting materials were recov-
ered.
Copper-catalyzed cycloaddition of azides to gold(I) alky-
nyls tolerates a range of functionalities on the alkynylgold(I)
reactant, Table 1. Triazolate complexes bearing alkyl and
trialkylsilyl (compounds 2, 10), an ester (3), polycyclic
hydrocarbon substituents (1, 12-14), phenyl groups and
substituted benzene rings (4-7, 11), ferrocenyl (9), and
thienyl (8, 15) readily form from (alkynyl)gold(I) precursors.
New compounds are characterized by nuclear magnetic
resonance spectroscopy and combustion analysis; X-ray
crystal-structure determinations of 1, 3-6, and 9-12 are
reported. Gold(I) triazolate complexes are isolated by crys-
tallization, and yields are somewhat wide-ranging; that of 10
is below 30%. An expectation of crystalline products sug-
gested the choice of benzyl azide in this work. Preliminary
experiments indicate that other azides also undergo copper-
catalyzed cycloaddition with gold(I) alkynyls. For example,
1-azidoadamantane reacts with alkynyl 16 to yield the alkyl
triazolate:
(99) Bruker Advanced X-ray Solutions. SHELXTL (Version 6.10);
Bruker AXS Inc.: Madison, WI, 2000.
(100) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; and Pople, J. A. Gaussian 03, Revision D.01; Gaussian, Inc.:
Wallingford, CT, 2004.
(101) Adamo, C.; Barone, V. J. Chem. Phys. 1998, 108, 664–675.
(102) Perdew, J. P.; Wang, Y. Phys. Rev. B 1992, 45, 13244–13249.
(103) Godbout, N.; Salahub, D. R.; Andzelm, J.; Wimmer, E. Can. J.
Chem. 1992, 70, 560–571.
(104) Dolg, M.; Wedig, U.; Stoll, H.; Preuss, H. J. Chem. Phys. 1987,
86, 866–872.
(105) (a) Basis sets were obtained from the EMSL Office of Science
Basis Set Exchange, https://bse.pnl.gov/bse/portal. (b) Feller, D.
J. Comput. Chem. 1996, 17, 1571–1586. (c) Schuchardt, K. L.; Didier, B.
T.; Elsethagen, T.; Sun, L.; Gurumoorthi, V.; Chase, J.; Li, J.; Windus, T. L.
J. Chem. Inf. Model 2007, 47, 1045–1052.
(106) Stratmann, R. E.; Scuseria, G. E.; Frisch, M. J. J. Chem. Phys.
1998, 109, 8218–8224.
Purification of 17 requires repeated washings and crystal-
lization, and its isolated yield is 21%, despite 31P NMR
(107) Miertus, S.; Scrocco, E.; Tomasi, J. Chem. Phys. 1981, 55, 117–129.
(108) Tomasi, J.; Mennucci, B.; Cammi, R. Chem. Rev. 2005, 105,
2999–3093.
(109) Seeger, R.; Pople, J. A. J. Chem. Phys. 1977, 66, 3045–3050.
(110) Bauernschmitt, R.; Ahlrichs, R. J. Chem. Phys. 1996, 104,
9047–9052.
(111) Gorelsky, S. I. AOMix: Program for Molecular Orbital Ana-
lysis; York University: Toronto, 1997, http://www.sg-chem.net.
(112) Gorelsky, S. I.; Lever, A. B. P. J. Organomet. Chem. 2001, 635,
187–196.

Article
Organometallics, Vol. 28, No. 21, 2009 6179
Figure 1. Crystal structures (100 K) of representative gold(I) triazolates: (a) 1; (b) 11. Hydrogen atoms are omitted for clarity; 50%
probability thermal ellipsoids are shown. A partial numbering system appears; unlabeled atoms are carbon.
Table 3. Luminescence Maxima (273 ( 2 K) of Emissive Com-
pounds in THF Solution
compound
λex (nm)
Eem (nm)
1
312
325
325
325
325
383, 498, 536, 579
363, 489, 522
390, 534, 570
390, 494, 533
385, 531, 561
11
12
13
14
Table 4. Emission Lifetimes τ and Quantum Yields Oem of
Luminescent Compounds in 2-MeTHF Solution (room
temperature) or Glass (77 K)
compound
T (K)
Emax (nm)
λ
em (nm)a
τ (ms)
jem
1
1
295
77
295
77
295
77
295
77
497
0.00092
495
515
540
490
540
19.1
11
11
12
12
13
13
14
14
522
530
532
531
0.0014
0.0025
0.0016
0.0028
0.260
0.277
5.06
Figure 2. Room-temperature absorption (blue) and emission
spectra (red, 312 nm excitation) of 1 in THF.
spectra that indicate quantitative product. Attempted reac-
tions of gold(I) alkynyls with phenyl azide led to recovery of
starting reagents with no evidence of product formation.
Table 2 compiles crystallographic data. Intermolecular
aurophilic interactions,113 where gold atoms approach with-
in 3.5 A of each other, are absent from the new structures,
nor do packing diagrams of the new complexes indicate
intermolecular π-π interactions. Metric data are similar to
those of related organogold complexes.43,45 Except for 9,
a single gold complex inhabits each asymmetric unit, in some
cases with benzene of crystallization. The asymmetric unit of
9 contains two crystallographically independent molecules.
The structures of 1 and 11, Figure 1, are representative. For
1, the gold-triazolato carbon bond distance is 2.015(3) A and
is nearly identical to the gold-carbene carbon length of
2.018(3) A. For comparison, the gold-carbon bond in (Ph3P)-
Au(4-tolyltriazole) measures 2.027(5) A;60 here a triazole nitro-
gen binds hydrogen, rather than an organic substituent. In the
295
77
0.401
a Wavelength at which emission lifetime data were collected.
structure of a two-coordinate (triphenylphosphine)gold(I) al-
lenoate complex, Hammond and co-workers report a 2.036(5)
A C-Au bond.114 Such bond lengths are expected for gold-
(I)-carbon single bonds.115,116 Gold(I) is two-coordinate
and virtually linear; the Ctriazolate-Au-Ccarbene angle is
175.06(13)°. The triazolate and naphthyl ring systems are
nearly coplanar; the dihedral angle between their (non-hydro-
gen-atom) mean planes is 5.50°. The triazolate linker moves
gold nearer the naphthyl fragment than in its alkynyl precursor.
In 1, gold is 3.593(4) A from the nearest naphthyl carbon atom;
(114) Liu, L.-P.; Mashuta, M. S.; Hammond, G. B. J. Am. Chem. Soc.
2008, 130, 17642–17643.
~
ꢀ
(115) Fananas-Mastral, M.; Aznar, F. Organometallics 2009, 28,
666–668.
(113) Schmidbaur, H.; Schier, A. Chem. Soc. Rev. 2008, 37, 1931–
1951.
(116) Shi, Y.; Ramgren, S. D.; Blum, S. A. Organometallics 2009, 28,
1275–1278.

6180 Organometallics, Vol. 28, No. 21, 2009
Partyka et al.
Figure 3. Kohn-Sham orbital correlation diagram of model complex 10. Fragments are the (N-heterocyclic carbene)gold(I) fragment
(left) and the naphthyl triazolate ligand, right (mpwpw91/Stuttgart ECP and basis on Au; TZVP on nonmetal atoms); implicit THF
solvation is included through a polarizable continuum model. Right: plots of selected orbitals (contour level 0.03 au).
Table 5. Calculated Energies, Orbital Compositions, and Oscillator Strengths f of Allowed Transitions beyond 300 nm for 10 Dissolved in
THF
no.
E (nm)
376.4
367.5
E (eV)
3.29
3.37
f
assignment
1
2
0.0992
0.0816
HOMOfLUMOþ1 (þ80%), HOMOfLUMO (11%), HOMOfLUMOþ2 (þ7%)
HOMOfLUMO (þ56%), HOMOfLUMOþ1 (þ14%), HOMO-1fLUMO (þ12%),
HOMOfLUMOþ2 (8%)
3
4
5
6
7
334.0
332.1
318.7
309.5
304.6
3.71
3.73
3.89
4.01
4.07
0.0025
0.2242
0.0418
0.1480
0.0009
HOMO-2fLUMO (þ96%)
HOMOfLUMOþ2 (þ56%), HOMO-1fLUMO (17%), HOMOfLUMO (þ14%)
HOMO-1fLUMOþ1 (þ83%), HOMO-1fLUMO (6%)
HOMOfLUMOþ3 (þ46%), HOMO-1fLUMO (30%), HOMOfLUMOþ2(8%)
HOMO-3fLUMO (þ98%)
in (SIPr)Au(2-ethynylnaphthalene), it is 4.621(5) A away.94
Metric parameters of 11 are similar.
average separation of 1400 cm-1. These vibronic spacings
suggest that ring-deformation modes are activated in the
excited states. Similar structure occurs in the triplet-state
emission of naphthalene embedded in sandwich adducts with
trinuclear gold117,118 and in the free hydrocarbon.119 Table 3
collects room-temperature emission maxima of luminescent
complexes in THF (tetrahydrofuran) solution.
Time-resolved measurements at 77 K find that the emis-
sions near 475 nm last from hundreds of microseconds to
tens of milliseconds. Table 4 collects luminescence lifetimes
and quantum yield data. Emission persists the longest for 1;
its lifetime is 19.1 ms (77 K). The long lifetimes indicate
triplet-state luminescence brought about by the heavy atom
Triazolate complexes bearing polycyclic aromatic hydro-
carbon fragments are luminescent. The 2-naphthyl-substi-
tuted triazolate 1 is typical. A combined absorption and
emission spectrum of 1 in tetrahydrofuran solvent appears in
Figure 2. The excitation spectrum of 1 parallels the absorp-
tion trace. Absorption sets in near 400 nm. A prominent
absorption maximizes at 312 nm, ε = 16 600 M-1 cm-1; a
shoulder is apparent at 325 nm. Higher-energy absorption
peaks occur between 250 and 275 nm.
Excitation of 1 at 312 nm elicits dual emission at room
temperature. The shorter-wavelength emission peaks are at
383 nm; the vibronic structure is partly resolved. This higher-
energy emission is unquenched on exposure to air. We
attribute the unquenched emission to ligand-centered fluor-
escence. A longer-wavelength, O2-quenchable emission rises
near 475 nm. The vibronic structure is clearly resolved with
maxima at 498, 536, and 579 nm, corresponding to an
(117) Mohamed, A. A.; Rawashdeh-Omary, M. A.; Omary, M. A.;
Fackler, J. P., Jr. Dalton Trans. 2005, 2597–2602.
(118) Omary, M. A.; Mohamed, A. A.; Rawashdeh-Omary, M. A.;
Fackler, J. P., Jr. Coord. Chem. Rev. 2005, 249, 1372–1381.
(119) Lakowicz, J. Principles of Fluorescence Spectroscopy; Kluwer/
Plenum: New York, 1999.

Article
Organometallics, Vol. 28, No. 21, 2009 6181
Figure 4. Selected optimized geometric parameters of singlet and triplet 10, with comparisons to the crystal structure of 1. Bond
distances, where indicated, are between non-hydrogen atoms. Legend: Gold, yellow; carbon, gray; nitrogen, blue; white, hydrogen;
boldface type, crystal structure of 1; sans serif, calculated geometry of singlet 10; blue italics, calculated geometry of triplet 10.
effect of gold. Quantum yields are in a range typical of
ligand-centered luminescence. The large number of available
rotors, some owing to the benzyl substituents, all contribute
to nonradiative decay.120 The new compounds, all diamag-
netic, lend themselves to density-functional theory calcula-
tions of the first several excited states.
strengths. Transitions are mostly composed of one-electron
promotions that mingle through configuration interaction.
The first singlet-singlet transition, calculated at 376 nm,
consists of an excitation from the HOMO to the LUMOþ1
(but with other contributions). It can be described as a
ligand-to-(metal-ligand) charge transfer from the naphthyl
triazolate to the (carbene)gold(I) fragment. The second
allowed transition is calculated at 368 nm. It consists of
more than four one-electron transitions in configuration
interaction; the major contributor (56%) is a LUMOr
HOMO excitation. The most intense transition, based on oscil-
lator strength, is computed at 332 nm. It is a majority (56%)
LUMOþ2rHOMO transition, with LUMOrHOMO-1
(17%) and LUMOrHOMO (14%) character. The exten-
sive configuration interaction among the first several
singlet-singlet transitions hinders a succinct description of
them. Suffice it to say that those involving the HOMO-1,
HOMO, LUMO, or LUMOþ2 have substantial participa-
tion from the naphthyl moiety.
Spin-unrestricted geometry optimization of the triplet
excited state converged on a structure closely similar to the
ground-state geometry. A harmonic frequency calculation
finds the optimized triplet to be an energy minimum. Calcu-
lated bond distances and angles show good agreement
with crystallographic values. The near-linearity of the
Ccarbene-Au-Ctriazole linkage is reproduced, as is the near-
coplanarity of the triazole and naphthyl rings. Figure 4
compares calculated ground- and triplet-state metrics to
the crystal structure of 1. The triplet-state structure is mini-
mally distorted relative to the (singlet) ground state.
Computations. Density-functional theory (DFT) calcula-
tions were undertaken to determine the orbital origins of the
new compounds’ absorption and emission. Calculations
were conducted on 10, where methyls substitute for the N-
2,6-diisopropylphenyl groups and the triazolate benzyl sub-
stituent of 1. Geometry optimization converged to an energy
minimum, as verified by a harmonic frequency calculation.
Figure 3 depicts a partial Kohn-Sham orbital energy-
level diagram of 10. The calculations include implicit THF
solvation through the polarized continuum model (PCM) of
Tomasi and co-workers.107,108 The calculations predict a
sizable gap (2.970 eV) between filled and unfilled levels.
Consistent with this prediction, naphthyl triazolate com-
plexes 1 and 13 are colorless when isolated and in solution.
Plots of selected orbitals appear at right in the figure.
Percentages of ligand character are indicated, in terms of
electron density.121 The naphthyl-triazolate ligand domi-
nates the frontier orbitals of 10. The highest occupied
Kohn-Sham orbital (HOMO) and the HOMO-1 are more
than 97% localized on the naphthyl-triazolate fragment. The
lowest unoccupied Kohn-Sham orbital (LUMO) resides
almost entirely on the naphthalene fragment. In contrast,
the LUMOþ1 is nearly three-quarters (N-heterocyclic
carbene)gold(I)-based (23.9% gold); the rest derives from
the triazolate ligand.
Time-dependent density-functional theory (TDDFT) cal-
culations were applied to the optical spectroscopy of 10.
Table 5 collects orbital compositions of allowed transitions
beyond 300 nm, along with their calculated oscillator
Conclusion
In summary, gold(I) alkynyls undergo copper-catalyzed
click chemistry with benzyl azide. Reactions proceed with
1,4-regioselectivity, affording triazolate products that retain
both azide and alkynyl substituents. This reaction contrasts
with our earlier noncatalytic reaction in protic solvents,60
where a hydrolyzable azide reacts with (alkynyl)gold(I)
(120) Anslyn, E. V.; Dougherty, D. A. Modern Physical Organic
Chemistry; University Science Books: Sausalito, CA, 2006; p 953.
(121) Mulliken, R. S. J. Chem. Phys. 1955, 23, 1833–1840.

6182 Organometallics, Vol. 28, No. 21, 2009
Partyka et al.
species in a net [3 þ 2] cycloaddition of HN3 across the
carbon-carbon triple bond. Nine new gold(I) triazolates are
structurally characterized. In no case are intermolecular
aurophilic interactions observed. Gold(I) triazolates bearing
photoactive substituents exhibit dual luminescence. Both
singlet- and triplet-state emissions are observed. Phospho-
rescence suggests a pseudoexternal heavy-atom effect, where
gold promotes intersystem crossing to reach an emissive,
ligand-centered triplet state.122 Vibronic splittings indicate
that ring deformation modes are activated in the lowest
triplet state. Density-functional theory calculations on a
representative naphthyl-triazolate complex find the frontier
orbitals to lie mostly on the conjugated triazolate ligand. The
first several optically allowed transitions have both intrali-
gand and ligand-to-metal character; configuration interac-
tion is extensive.
organogold product is crystallographically characterized.
Hammond and co-workers114,123 find that cyclization results
upon reaction of (triphenylphosphine)gold(I) cations with
carboethoxy-substituted allenes. Ring-closure affords five-
membered lactones with exocyclic carbon-gold bonds. One
representative is crystallographically authenticated.
The results herein demonstrate that metal alkynyls sup-
port copper-catalyzed cycloaddition with organic azides. It is
noteworthy that the phosphine and N-heterocyclic carbene
fragments are isolobal with the proton. Standard Pauling
electronegativities124 suggest that the carbon-gold σ-bond is
nonpolar. The copper-based protocol described here readily
attaches gold to azide-bearing materials now available from
recent efforts in click chemistry. Investigations of these
aurated materials are underway.
The copper-mediated [3 þ 2] cycloaddition is part of an
emerging trend where gold(I) alkynyls react with other
organometallics or with substrates under metal-ion catalysis.
Blum and co-workers116 report that PdCl2(PPh3)2 catalyzes
the syn-carboauration of electrophilic alkynes, with crystal
Acknowledgment. The authors thank the National
Science Foundation (grant CHE-0749086 to T.G.G.)
for support. T.G.G. is an Alfred P. Sloan Foundation
Fellow. The diffractometer at Case Western Reserve was
funded by NSF grant CHE-0541766. N.D. holds a Re-
public of Turkey Ministry of National Education fellow-
ship. T.S.T. acknowledges the Fannie and John Hertz
Foundation for a predoctoral fellowship. We thank
Professor D. G. Nocera (Massachusetts Institute of
Technology) for access to instrumentation.
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structures of two gold-bearing products. Fananas-Mastral
and Aznar115 describe carbene-transfer reactions from
chromium or tungsten centers to (N-heterocyclic carbene)-
gold(I) cations generated in situ by dehalogenation of the
corresponding (NHC)gold(I) chloride with AgSbF6; one
(122) Turro, N. J. In Modern Molecular Photochemistry; University
Science Books: Sausalito, CA, 1991; pp 191-195.
(123) Liu, L.-P.; Hammond, G. P. Chem. Asian J. 2009, 4, 1230–1236.
(124) Allred, A. L. J. Inorg. Nucl. Chem. 1961, 17, 215–221.
Supporting Information Available: Thermal ellipsoid projec-
tions for 3-6, 9, and 10. This material is available free of charge
via the Internet at http://pubs.acs.org.