The first metal complexes derived from 3,5-diethynylpyridine. X-ray crystal structure of [(AuPTo3)2{μ-(C=C)2Py}] (Py = pyridine-3,5-diyl; to = p-toly1)

Article abstract of DOI:10.1021/om049509j

The reactions of 3,5-diethynylpyridine (Py(C=CH)2) with PPN[Au(acac) ₂] (2.5:1; PPN = Ph₃P=N=PPh₃) or with [AuCl(SMe₂)] and NEt₃ (1:2:2) give respectively PPN[Au{C=C(Py)-C=CH}₂] (1) and [Au₂{μ-(C=C) ₂Py}]_n (2). Complex 2 reacts with monodentate ligands (1:2) or with 1,6-bis(diphenylphosphino)hexane (dpph, 1:1) to give neutral dinuclear complexes of the general formula [(AuL)₂{μ-(C=C) ₂Py}] (L = CN'Bu (3), PMe₃ (4), PPh₃ (5), PTo₃ (To = C_eH₄Me-4) (6); Au₂L ₂ = Au₂(μ-dpph) (7)). The reactions of 6 with the complexes [MCI] and TITfO (1:1:1) (TfO = CF₃SO₃) give the cationic trinuclear complexes [M{Py(C=CAuPTo₃)₂}]TfO (M = AuPTo₃ (8), cis-PtCl(PPh₃)₂ (9)). The crystal structure of complex 6 has been determined.

Full text of DOI:10.1021/om049509j

Organometallics 2004, 23, 5707-5712
5707
The First Metal Complexes Derived from
3,5-Diethynylpyridine. X-ray Crystal Structure of
[(AuPTo3)2{µ-(CtC)2Py}] (Py ) Pyridine-3,5-diyl;
To ) p-Tolyl)
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, Apartado 4021, Murcia 30071, Spain
Delia Bautista‡
SACE, Universidad de Murcia, Apartado 4021, Murcia 30071, Spain
Received July 2, 2004
The reactions of 3,5-diethynylpyridine (Py(CtCH)2) with PPN[Au(acac)2] (2.5:1; PPN )
Ph3PdNdPPh3) or with [AuCl(SMe2)] and NEt3 (1:2:2) give respectively PPN[Au{CtC(Py)-
CtCH}2] (1) and [Au2{µ-(CtC)2Py}]n (2). Complex 2 reacts with monodentate ligands (1:2)
or with 1,6-bis(diphenylphosphino)hexane (dpph, 1:1) to give neutral dinuclear complexes
of the general formula [(AuL)2{µ-(CtC)2Py}] (L ) CNtBu (3), PMe3 (4), PPh3 (5), PTo3 (To
) C6H4Me-4) (6); Au2L2 ) Au2(µ-dpph) (7)). The reactions of 6 with the complexes
[MCl] and TlTfO (1:1:1) (TfO ) CF3SO3) give the cationic trinuclear complexes
[M{Py(CtCAuPTo3)2}]TfO (M ) AuPTo3 (8), cis-PtCl(PPh3)2 (9)). The crystal structure of
complex 6 has been determined.
Introduction
diyndiyl subunits (Chart 1), from which some Re,10 Ru,11
and Pt12-14 complexes have been obtained and shown
to possess metallamacrocyclic structures and interesting
physical properties. However, although it was first re-
ported in 1978,15 there is no previous report on any
complex derived from 3,5-diethyndiylpyridine, which is
rather surprising in view of the tempting possibilities
this ligand offers as a potential building block for
multimetallic complexes, including metallamacrocycles
and polymers. Two platinum(II) complexes derived from
the monoalkyne HCtC(Py)CtCSiiPr3 have been re-
ported.14 On the basis of the related 2,5- or 2,6-di-
ethynylpyridine a series of monomeric and polymeric
organic compounds16,17 as well as some σ-acetylide com-
plexes of Ru, Os,18 and Pt17,19,20 and some π-complexes
Metal complexes with bridging -CtC(Ar)CtC- spac-
ers (Ar being an aromatic ring) have been shown to
possess electrical conductivity, nonlinear optical, or
liquid crystalline properties derived from the extended
electronic conjugation they display.1 The (arenediethy-
nyl)gold(I) complexes reported so far include the Ar
groups C6H4-1,3,2 C6H4-1,4,1 (C6H3Me-5)-1,3, (C6H2Me2-
2,5)-1,4,3 (C6HMe3-2,4,6)-1,3, C6Me4-2,3,5,6,2 and dif-
ferent fluorene-2,7-diyl4 derivatives, many of which are
luminescent. Among them only a few, described
by Puddephatt5 and by us,2,6 are m-arenediethynyl
derivatives; four of these derivatives have been char-
acterized by X-ray diffraction methods, namely [(AuL)2-
{(CtC)2Ar-1,3}] (Ar ) C6H4, C6HMe3-2,4,6, L ) PPh3;
Ar ) C6H3Me-5, L ) PPh2Me, P(OMe)3). Apart from
these, the crystal structures of only three other arene-
diethynyl complexes of any element (Ru,7 Pt,8 and Fe9)
have been reported.
(7) Whittall, I. R.; Humphrey, M. G.; Houbrechts, S.; Maes, J.;
Persoons, A.; Schmid, S.; Hockless, D. C. R. J. Organomet. Chem. 1997,
544, 277.
(8) Onitsuka, K.; Fujimoto, M.; Ohshiro, N.; Takahashi, S. Angew.
Chem., Int. Ed. 1999, 38, 689.
3,5-Diethynylpyridine has been used for the synthesis
of some fully conjugated ligands containing pyridine-
(9) Weyland, T.; Costuas, K.; Toupet, L.; Halet, J. F.; Lapinte, C.
Organometallics 2000, 19, 4228.
(10) Sun, S. S.; Lees, A. J. Organometallics 2001, 20, 2353.
(11) Campbell, K.; McDonald, R.; Tykwinski, R. R. J. Org. Chem.
2002, 67, 1133.
† E-mail: jvs1@um.es (J.V.), mch@um.es (M.-T.C.). WWW: http://
www.um.es/.
(12) Campbell, K.; Kuehl, J.; Ferguson, M. J.; Stang, P. J.; Tykwin-
ski, R. R. J. Am. Chem. Soc. 2002, 124, 7266. Campbell, K.; McDonald,
R.; Ferguson, M. J.; Tykwinski, R. R. Organometallics 2003, 22, 1353.
(13) Bosch, E.; Barnes, C. L. Organometallics 2000, 19, 5522.
(14) Campbell, K.; McDonald, R.; Ferguson, M. J.; Tykwinski, R. R.
J. Organomet. Chem. 2003, 683, 379.
‡ E-mail: dbc@um.es.
(1) Jia, G. C.; Puddephatt, R. J.; Scott, J. D.; Vittal, J. J. Organo-
metallics 1993, 12, 3565.
(2) Vicente, J.; Chicote, M. T.; Alvarez-Falco´n, M. M.; Abrisqueta,
M. D.; Herna´ndez, F. J.; Jones, P. G. Inorg. Chim. Acta 2003, 347, 67.
(3) Irwin, M. J.; Vittal, J. J.; Puddephatt, R. J. Organometallics
1997, 16, 6, 3541.
(15) Shvartsberg, M. S.; Moroz, A. A.; Kozhevnikova, A. N. Izv. Akad.
Nauk SSSR, Ser. Khim. 1978, 4, 875.
(4) Wong, W. Y.; Choi, K. H.; Lu, G. L.; Shi, J. X.; Lai, P. Y.; Chan,
S. M.; Lin, Z. Y. Organometallics 2001, 20, 5446.
(5) MacDonald, M. A.; Puddephatt, R. J.; Yap, G. P. A. Organome-
tallics 2000, 19, 2194.
(6) Vicente, J.; Chicote, M. T.; Abrisqueta, M. D.; AÄ lvarez-Falco´n,
M. M. J. Organomet. Chem. 2002, 663, 40.
(16) Naka, K.; Uemura, T.; Chujo, Y. Macromolecules 2000, 33, 4733.
(17) Bunten, K. A.; Kakkar, A. K. Macromolecules 1996, 29, 2885.
(18) Colbert, M. C. B.; Lewis, J.; Long, N. J.; Raithby, P. R.; Younus,
M.; White, A. J. P.; Williams, D. J.; Payne, N. N.; Yellowlees, L.;
Beljonne, D.; Chawdhury, N.; Friend, R. H. Organometallics 1998, 17,
3034.
10.1021/om049509j CCC: $27.50 © 2004 American Chemical Society
Publication on Web 10/20/2004

5708 Organometallics, Vol. 23, No. 24, 2004
Vicente et al.
Chart 1a
(PTo3)] and cis-[PtCl2(PPh3)2] were prepared by adding 1 or 2
equiv of the appropriate phosphine to [AuCl(SMe2)] and [PtCl2-
(NCPh)2],29 respectively. TlTfO (TfO ) CF3SO3) was obtained
by reacting in water Tl2CO3 and HTfO (1:2) after evaporation
of the solvent and recrystallization of the residue from acetone
and Et2O. All other chemicals were obtained from commercial
sources and used as received. The solvents were distilled before
use.
Synthesis of PPN[Au{CtC(Py)CtCH}2] (1). A solution
of PPN[Au(acac)2] (676 mg, 0.72 mmol) in acetone (15 mL) was
slowly dropped over a solution of 3,5-diethynylpyridine (23 mg,
1.8 mmol) in the same solvent (10 mL). The mixture was
stirred for 8 h and filtered through Celite and the solution
concentrated to dryness. The residue was stirred with Et2O/
CH2Cl2 (14:1, 3 × 45 mL), and the colorless microcrystalline
solid was filtered and dried under reduced pressure (ca. 1
mbar) for 1 h to give 1‚H2O‚Et2O. Yield: 592 mg, 76%. Mp:
133 °C. Anal. Calcd for C58H50AuN3O2P2: C, 64.50; H, 4.67;
N, 3.89. Found: C, 64.49; H, 4.28; N, 3.93. IR (cm-1): ν(CH)
3294 (w), 3232 (w); ν(CtC) 2106 (s). ΛM (Ω-1 cm2 mol-1): 81.
1H NMR (200 MHz, CDCl3): δ 8.51 (m, 2 H, py), 8.35 (m, 2 H,
py), 8.23 (m, 2 H, py), 7.69-7.28 (m, 30 H, PPN), 3.5 (q, 4 H,
CH2, Et2O, 3JHH ) 7 Hz), 3.11 (s, 2 H, CH), 1.66 (s, 2 H, H2O),
a Legend: (A) X ) CtC, Y ) Ph2CdC, -Z- ) -[M]-; (B)
X ) CtC, CtCCtC, Y ) C6H4-1,3 and X ) CtCCtC, Y )
R2CdC (R ) Me, Ph).
of Co21 have been described, which exhibit interesting
optical and conductivity properties that in some cases
are affected by quaternization of the pyridine nitrogen.17
The crystal structure of a hexanuclear metallamacro-
cyclic complex of platinum containing C5H3N(CtC)2-2,6
ligands20 represents the only example of a diethyndiylpy-
ridine complex to be fully characterized.
3
1.25 (t, 6 H, Me, Et2O, JHH ) 7 Hz). 31P{1H} NMR (81 MHz,
CDCl3): δ 21.1 (s, PPN). 13C{1H} NMR (50 MHz, CDCl3): δ
152.6, 148.1, 141.5, 140.0, 133.8 (m, p-CH, PPN), 132.0 (m,
m-CH, PPN), 129.6 (m, o-CH, PPN), 126.8 (m, i-C, PPN), 123.4,
117.9, 98.0 (CtC), 80.6 (CtCH), 79.7 (tCH), 65.91 (CH2,
Et2O), 15.20 (Me, Et2O). MS-FAB- (m/z, %): 449 (M-, 100%).
We have given different accounts on the “acac
method”22 which, on the basis of the ability of (acetyl-
acetonato)gold(I) complexes of the types [Au(acac)2]-
and [Au(acac)L] to deprotonate substrates containing
at least an acidic hydrogen atom, led to a variety of
complexes, including alkynylgold(I) derivatives.2,6,23-25
In this paper we report on the use of 3,5-diethynylpy-
ridine to prepare a family of complexes of the types
[Au{CtC(Py)CtCH}2]-, [Au2{µ-(CtC)2Py}]n, [(AuL)2-
{µ-(CtC)2Py}], and [M{Py(CtCAuPTo3)2}]+ (M )
AuPTo3, cis-PtCl(PPh3)2), which display all the potential
coordination modes of the versatile 3,5-diethynylpyri-
dine ligand.
Synthesis of [Au2{(CtC)2Py}]n (2). A mixture of 3,5-
diethynylpyridine (198 mg, 1.6 mmol), [AuCl(SMe2)] (917 mg,
3.11 mmol), and NEt3 (0.46 mL, 3.26 mmol) in CH2Cl2 (20 mL)
was stirred for 0.5 h. The suspension was filtered and the solid
washed successively with CH2Cl2 (4 × 10 mL) and Et2O (10
mL) and dried under vacuum (ca. 1 mbar) for 1 h to give 2 as
a bright yellow powder. Its insolubility in all common solvents
impeded measuring its NMR spectra or recrystallizing it to
improve the elemental analysis (see Results and Discus-
sion). Yield: 802 mg, 97%. Mp: 115 °C dec. Anal. Calcd for
C9H3Au2N: C, 20.83; H, 0.58; N, 2.70. Found: C, 22.15; H,
0.97; N, 3.06. IR (cm-1): ν(CtC) 2114 (w).
Synthesis of [(AuL)2{µ-(CtC)2Py}] (L ) tBuNC (3),
PMe3 (4), PPh3 (5), PTo3 (6); Au2L2 ) Au2(µ-dpph) (7)). To
a suspension of 2 (3, 286 mg, 0.55 mmol; 4, 213 mg, 0.41 mmol;
5, 120 mg, 0.23 mmol; 6, 277 mg, 0.53 mmol; 7, 243 mg, 0.47
mmol) in CH2Cl2 (3, 10 mL; 4 and 5, 20 mL; 6, 30 mL; 7, 15
mL) was added the appropriate ligand (3, tBuNC 0.25 mL, 2.2
mmol; 4, PMe3 1 M in toluene, 2 mL, 2 mmol; 5, PPh3 127 mg,
0.49 mmol; 6, PTo3 325 mg, 1.07 mmol; 7, dpph 213 mg, 0.47
mmol). The reaction mixture was stirred for 1 h at room
temperature (4, under an N2 atmosphere) or refluxed for 4 h
(7) and filtered through Celite. The solvent was removed under
vacuum to 1 mL (4) or 3 mL (7) or to dryness (3, 5, 6). When
n-hexane (3, 4, 10 mL) or Et2O (5, 7, 20 mL) or a 1:1 mixture
of both solvents (6, 20 mL) was added and the mixture was
stirred for a few minutes, a suspension resulted, which was
filtered. The solid was washed with the same solvent (2 × 5
mL) and air-dried to give a bright yellow (3‚0.5Et2O) or pale
yellow (4, 5‚H2O, 6) or white (7‚H2O) powder.
Experimental Section
IR spectroscopy, mass spectrometry (FAB+/-), elemental
analyses, conductance measurements in acetone, and melting
point determinations were carried out as described elsewere.26
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, and 400 MHz spectrometers.
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 3,5-diethynylpyridine,13 PPN[Au-
(acac)2],27 and [AuCl(SMe2)]28 were previously reported. [AuCl-
(19) Chawdhury, N.; Ko¨hler, A.; Friend, R. H.; Younus, M.; Long,
N. J.; Raithby, P. R.; Lewis, J. Macromolecules 1998, 31, 722.
(20) Leininger, S.; Schmitz, M.; Stang, P. J. Org. Lett. 1999, 1, 1921.
(21) Dana, B. H.; Robinson, B. H.; Simpson, J. J. Organomet. Chem.
2002, 648, 251.
(22) Vicente, J.; Chicote, M. T. Coord. Chem. Rev. 1999, 193-195,
1143.
(23) Vicente, J.; Chicote, M. T.; Abrisqueta, M. D. J. Chem. Soc.,
Dalton Trans. 1995, 497. Vicente, J.; Chicote, M. T.; Abrisqueta, M.
D.; Jones, P. G. Organometallics 1997, 16, 5628.
(24) Vicente, J.; Chicote, M.-T.; Abrisqueta, M.-D.; Guerrero, R.;
Jones, P. G. Angew. Chem., Int. Ed. 1997, 36, 1203.
(25) Vicente, J.; Chicote, M. T.; AÄ lvarez-Falco´n, M. M.; Fox, M. A.;
Bautista, D. Organometallics 2003, 22, 4792.
(26) 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.
3‚0.5Et2O: yield 276 mg, 73%. Mp: 140 °C. Anal. Calcd for
C21H26Au2N3O0.5: C, 34.92; H, 3.63; N, 5.82. Found: C, 34.80;
H, 3.48; N, 6.35. IR (cm-1): ν(CtN) 2230 (s); ν(CtC) 2120 (w).
4
1H NMR (200 MHz, CDCl3): δ 8.44 (d, 2 H, py, JHH ) 2 Hz),
4
3
7.69 (t, 1 H, py, JHH ) 2 Hz), 3.1 (q, 2 H, CH2, Et2O, JHH
)
7 Hz), 1.57 (s, 18 H, tBu), 1.4 (t, 3 H, Me, Et2O, 3JHH ) 7 Hz).
13C{1H} NMR (50 MHz, CDCl3): δ 150.3, 146.4 (CN), 141.6,
(27) Vicente, J.; Chicote, M. T. Inorg. Synth. 1998, 32, 172.
(28) Tamaki, A.; Kochi, J. K. J. Organomet. Chem. 1974, 64, 411.
(29) Doyle, J. R.; Slade, P. E.; Jonassen, H. B. Inorg. Synth. 1960,
6, 128.

Metal Complexes of 3,5-Diethynylpyridine
Organometallics, Vol. 23, No. 24, 2004 5709
Table 1. Crystal Data for Complex 6
126.6, 121.0, 99.2 (CtC), 59.0 (CH2, Et2O), 58.6 (CMe3), 29.6
(CMe3), 8.9 (Me, Et2O).
formula
fw
cryst size (mm)
cryst syst
space group
a (Å)
C51H45Au2NP2
4: yield 191 mg, 69%. Mp: 293 °C dec. Anal. Calcd for
1127.75
0.34 × 0.28 × 0.06
monoclinic
P21/c
C15H21Au2NP2: C, 26.84; H, 3.15; N, 2.09. Found: C, 26.88;
1
H, 3.13; N, 2.08. IR (cm-1): ν(CtC) 2098 (w). H NMR (200
4
MHz, CDCl3): δ 8.47 (d, 2 H, py, JHH ) 2 Hz), 7.73 (t, 1 H,
py, 4JHH ) 2 Hz), 1.55 (d, 18 H, PMe3, 2JHP ) 10 Hz). 31P{1H}
NMR (81 MHz, CDCl3): δ 1.36 (s).13C{1H} NMR (50 MHz,
CDCl3): δ 150.5 (py), 141.5 (py), 121.2 (d, CCAu, 3JCP ) 5 Hz),
9.9851(6)
23.4212(19)
19.0934(15)
90
91.270(6)
90
4464.1(6)
4
1.678
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
2
1
100.7 (d, CAu, JCP ) 30 Hz), 15.7 (d, PMe3, JCP ) 35 Hz).
5‚H2O: yield 161 mg, 67%. Mp: 115 °C. Anal. Calcd for
C45H35NAu2OP2: C, 50.91; H, 3.32; N, 1.32. Found: C, 50.79;
H, 3.39; N, 1.27. IR (cm-1): ν(CtC) 2112 (s). 1H NMR (400
Z
F
λ (Å)
calcd (Mg m-3
)
4
MHz, CDCl3): δ 8.55 (d, 2 H, py, JHH ) 2 Hz), 7.83 (t, 1 H,
py, 4JHH ) 2 Hz), 7.57-7.45 (m, 30 H, PPh3), 1.66 (s, 2 H, H2O).
31P{1H} NMR (162 MHz, CDCl3): δ 42.61 (s). 13C{1H} NMR
(50 MHz, CDCl3): δ 150.7 (py), 141.5 (py), 137.5 (py), 134.3
0.710 73
173(2)
T (K)
F(000)
2184
µ(Mo KR) (mm-1
θ range (deg)
abs cor
)
6.671
2
4
(d, o-CH, PPh3, JCP ) 14 Hz), 131.6 (d, p-CH, PPh3, JCP ) 3
3.05-25.00
ψ scans
8437
Hz,), 129.6 (d, i-C, PPh3, 1JCP ) 56 Hz), 129.2 (d, m-CH, PPh3,
3JCP ) 11 Hz), 121.2 (d, CCAu, JCP ) 3 Hz), 100.2 (d, CAu,
3
no. of rflns coll
2JCP ) 27 Hz).
no. of indep rflns
Rint
7835
0.0407
6: yield 488 mg, 82%. Mp: 206 °C dec. Anal. Calcd for
transmissn
0.997 05/0.449 49
7835/18/505
0.0403
C51H45Au2NP2: C, 54.31; H, 4.02; N, 1.24. Found: C, 54.14;
1
no. of data/restraints/params
R1 (I > 2σ(I))a
wR2 (all rflns)b
H, 4.30; N, 1.33. IR (cm-1): ν(CtC) 2112 (w). H NMR (200
4
MHz, CDCl3): δ 8.55 (d, 2 H, py, JHH ) 2 Hz), 7.82 (t, 1 H,
0.0668
py, 4JHH ) 2 Hz), 7.47-7.37 (m, 12 H, PTo3), 7.25-7.21 (m, 12
H, PTo3), 2.39 (s, 18 H, Me). 31P{1H} NMR (81 MHz, CDCl3):
δ 41.22 (s). 13C{1H} NMR (50 MHz, CDCl3): δ 150.7, 141.9 (d,
a R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). b wR2
2
) [∑[w(Fo2 - Fc )2]/∑[w(Fo2)2]0.5 for all reflections; w-1 ) σ2(F2) +
2
(aP)2 + bP, where P ) (2Fc + Fo2)/3 and a and b are constants
4
2
p-CH, PTo3, JCP ) 2 Hz), 141.5, 134.1 (d, o-CH, PTo3, JCP
)
set by the program.
3
14 Hz), 129.8 (d, m-CH, PTo3, JCP ) 12 Hz), 126.6 (d, i-C,
1
5
PTo3, JCP ) 58 Hz), 121.2, 21.5 (d, Me, JCP ) 1 Hz).
7‚H2O: yield 226 mg, 49%. Mp: 131 °C dec. Anal. Calcd for
C39H37Au2NOP2: C, 47.24; H, 3.76; N, 1.41. Found: C, 47.05;
vacuum, and the residue was stirred with CHCl3 (20 mL). The
resulting suspension was filtered through Celite, the solution
concentrated to dryness, and the solid residue stirred with
n-pentane (25 mL). The suspension was filtered and the solid
dried under reduced pressure (ca. 1 mbar) for 1 h to give a
microcrystalline pale yellow powder. Yield: 365 mg, 90%.
Mp: 142 °C dec. Anal. Calcd for C88H75Au2ClF3NO3P4PtS: C,
52.02; H, 3.72; N, 0.69. Found: C, 52.08; H, 3.78; N, 0.89. IR
(cm-1): ν(CtC) 2114 (s); ν(PtCl), 318(s). ΛM (Ω-1 cm2 mol-1):
H, 3.41; N, 1.52. IR (cm-1): ν(CtC) 2106 (w). H NMR (400
1
4
MHz, CDCl3): δ 8.52 (d, 2 H, py, JHH ) 2 Hz), 7.79 (m, 1 H,
py), 7.68-7.44 (m, 20 H, Ph), 2.37 (m, 4 H, CH2), 1.66 (s, 2 H,
H2O), 1.59 (m, 4 H, CH2), 1.43 (m, 4 H, CH2). 31P{1H} NMR
(162 MHz, CDCl3): δ 37.35 (s). 13C{1H} NMR (75 MHz,
CDCl3): δ 150.5, 141.5, 133.3 (d, m-CH, Ph, 3JCP ) 8 Hz), 131.6
(m, p-CH, Ph), 130.3 (d, i-C, Ph, 1JCP ) 53 Hz), 129.2 (d, o-CH,
1
2
146. H NMR (300 MHz, CDCl3): δ 8.17 (m, 2 H, py), 7.48-
Ph, JCP ) 15 Hz), 121.2 (s, CCAu), 100.1 (s, CAu), 30.3 (d,
7.14 (m, 55 H, PTo3 + PPh3 + py), 2.42 (s, 18 H, Me). 31P{1H}
NMR (121 MHz, CDCl3): δ 40.22 (s, AuPTo3), 16.67 (d, PtPPh3,
CH2, 2JCP ) 15 Hz), 27.8 (d, CH2, 1JCP ) 34 Hz), 25.3 (d, CH2,
3JCP ) 3 Hz). MS-FAB+ (m/z, %): 974 (M+, 6%), 651 (Audpph+,
36%).
2
1
1JPPt ) 3655 Hz, JPP ) 18 Hz), 4.74 (d, PtPPh3, JPPt ) 3240
Hz, JPP ) 18 Hz). MS-FAB+ (m/z, %): 1881 (M+, 26%).
2
Synthesis of [(AuPTo3){Py(CtCAuPTo3)2}]TfO (8). A
mixture of 6 (213 mg, 0.19 mmol), [AuClPTo3] (107 mg, 0.20
mmol), and TlTfO (71 mg, 0.20 mmol) in dry THF (20 mL)
was stirred under a nitrogen atmosphere for 0.5 h and then
concentrated to dryness under reduced pressure. The residue
was stirred with CHCl3 (30 mL), and the suspension was
filtered through Celite. The solution was concentrated to
dryness, the residue stirred with n-pentane (2 × 20 mL), the
suspension filtered, and the solid air-dried to give 8 as a
microcrystalline bright yellow powder. Yield: 242 mg, 72%.
Mp: 130 °C. Anal. Calcd for C73H66Au3F3NO3P3S: C, 49.31;
H, 3.74; N, 0.79. Found: C, 49.53; H, 3.91; N, 0.66. IR (cm-1):
ν(CtC) 2114 (w). ΛM (Ω-1 cm2 mol-1): 105. 1H NMR (300 MHz,
X-ray Structure Determination for Complex 6. The
crystals were mounted in inert oil on a glass fiber and
transferred to the diffractometer (Siemens P4 with LT2 low-
temperature attachment). Crystal data and refinement details
are presented in Table 1. The unit cell parameters were
determined from a least-squares fit of 88 accurately centered
reflections (14.1° < 2θ < 25.8°). The structure was solved by
the heavy-atom method and refined anisotropically on F2
(program SHELX-97, G. M. Sheldrick. University of Go¨ttingen,
Go¨ttingen, Germany). The largest residual peak of 1.62 e was
1.13 Å from Au2. Hydrogen atoms were included using a riding
model.
4
CDCl3): δ 8.49 (br, 2 H, py), 7.84 (t, 1 H, py, JHH ) 1.8 Hz),
7.41-7.22 (m, 36 H, Ar, PTo3), 2.44 (s, 9 H, Me), 2.39 (s, 18 H,
Me). 31P{1H} NMR (162 MHz, CDCl3): δ 43.68 (s, CAuPTo3),
36.85 (br s, NAuPTo3). 13C{1H}-APT NMR (100 MHz, CDCl3):
δ 150.5, 143.3 (p-C, PTo3), 142.3 (p-C, PTo3), 133.9 (d, o-CH,
Results and Discussion
Synthesis. The reaction of 3,5-diethynylpyridine
with PPN[Au(acac)2] to give the anionic complex
PPN[Au{CtC(Py)CtCH}2] (1), in which gold coordi-
nates to two monoanionic HCtC(Py)CtC- (Py ) pyri-
dine-3,5-diyl) ligands, requires the use of an excess of
the dialkyne over the stoichiometric 2:1 molar ratio
(Scheme 1) in order to prevent the formation of insoluble
oligomers of the type (PPN)n[Au{(CtC)2Py}]n. The
complex [Au2{(CtC)2Py}]n (2) was obtained by reacting
3,5-diethynylpyridine with [AuCl(SMe2)] and NEt3
2
PTo3, JCP ) 14 Hz), 133.7 (m, o-CH, NAuPTo3), 130.5 (m,
m-CH, NAuPTo3), 129.9 (d, m-CH, PTo3, 3JCP ) 12 Hz,), 125.7
1
(d, i-C, PTo3, JCP ) 61 Hz), 124.2 (m, i-C, NAuPTo3), 121.5,
21.5 (Me, PTo3), 21.4 (Me, PTo3). MS-FAB+ (m/z, %): 1628 (M+,
27%).
Synthesis of [{cis-PtCl(PPh3)2}{Py(CtCAuPTo3)2}]TfO
(9). A mixture of 6 (230 mg, 0.2 mmol), cis-[PtCl2(PPh3)2] (161
mg, 0.2 mmol), and TlTfO (72 mg, 0.2 mmol) in acetone (25
mL) was stirred for 1.25 h. The solvent was removed under

5710 Organometallics, Vol. 23, No. 24, 2004
Vicente et al.
Scheme 1a
purification of 2, since it is a stable compound from
which pure derivatives can be obtained.
Thus, complex 2 reacts with monodentate L ligands
in a 1:2 molar ratio or with 1,6-bis(diphenylphosphino)-
hexane (1:1) to give neutral dinuclear complexes of the
general formula [(AuL)2{µ-(CtC)2Py}] (L ) CNtBu (3),
PMe3, (4), PPh3 (5), PTo3 (6); Au2L2 ) Au2(µ-dpph) (7)).
Addition of the appropriate ligand to suspensions of 2
in dichloromethane caused the immediate formation of
solutions from which the neutral complexes were iso-
lated in 50-80% yield upon concentration and addition
of Et2O or n-hexane.
The reaction of 6 and [AuCl(PTo3)] (1:1) in the pres-
ence of TlTfO (TfO ) CF3SO3) produces the immediate
precipitation of TlCl. After filtration, a solution was ob-
tained from which the trinuclear complex [(AuPTo3)-
{Py(CtCAuPTo3)2}]TfO (8) was isolated in 72% yield,
as the result of coordination of the pyridinic nitrogen
present in the metalloligand complex 6 to the AuPTo3
fragment generated in situ. The homologous reaction
between 3 and [AuCl(SMe2)] (1:1) did not produce the
expected neutral trinuclear derivative. Instead, precipi-
tation of the polymeric complex 2 took place and [AuCl-
(CNtBu)] was identified in the mother liquor. This result
prompted us to attempt the synthesis of the penta-
nuclear complex [Au{Py(CtCAuPTo3)2}2]TfO by react-
ing 6 with [AuCl(SMe2)] and TlTfO (2:1:1). However,
precipitation of 2 took place again, and 8 was isolated
from the mother liquor. An attempt to coordinate gold-
(III) to the nitrogen atom present in 6 by reacting it with
[AuCl3(PPh3)] and TlTfO (1:1:1) gave a mixture of
products that we could not separate.
However, the reaction of 6 with [PtCl2(PPh3)2] and
TlTfO (1:1:1) caused the immediate precipitation of
TlCl, and the cationic complex [{cis-PtCl(PPh3)2}{Py-
(CtCAuPTo3)2}]TfO (9) (Scheme 1) was isolated from
the solution. A small amount (ca. 7%) of the isomer
containing the trans-PtCl(PPh3)2 fragment was evi-
denced by the 31P{1H} NMR spectrum. Although 9 is
stable in the solid state at low temperature, it decom-
poses after a few hours in solution to give [AuCl(PTo3)]
along with other unidentified species. In an attempt to
prepare the new dicationic heteronuclear derivatives
that would result from replacing both chloro ligands in
[PtCl2L2] by two molecules of the metalloligand 6, we
reacted it with [PtCl2(PPh3)2] and TlTfO (2.1:1:2).
Unfortunately, after 5 h of stirring 9 was the only
complex detected in the NMR of the reaction mixture,
apart from the excess of 6. An attempt to coordinate 6
to AgClO4 (2:1) gave an insoluble species that we could
not characterize.
We have also explored an alternative route to obtain
heteronuclear complexes derived from 3,5-diethynylpy-
ridine which would consist of coordinating first the
pyridinic nitrogen to different metal centers with the
purpose of replacing afterwards the acetylenic hydro-
gens by AuL fragments using the “acac method”.
However, the reactions of 3,5-diethynylpyridine with
AgClO4, AgTfO, [PdCl2(dtbipy)] (dtbipy ) 4,4′-di-tert-
butyl-2,2′-bipyridine), and [PtCl(PPh3)(dtbipy)]TfO led
to mixtures of complexes or to insoluble products that
we could not characterize.
a Legend: (i) +1/2PPN[Au(acac)2], -acacH; (ii) +2[AuCl-
(SMe2)], +2NEt3, -2SMe2, -2[NHEt3]Cl; (iii) +2L; (iv)
+[AuCl(PTo3)], +TlTfO, -TlCl; (v) +[PtCl2(PPh3)2], +TlTfO,
-TlCl.
(1:2:2) in dichloromethane upon replacement of both Cl
and SMe2 ligands from the coordination sphere of gold
by the dialkynediyl ligand generated by deprotonation
of the dialkyne with the amine. The insolubility of this
complex in all common organic solvents suggests it to
be a polymer in which gold would coordinate to the
doubly deprotonated Py(CtC)2 ligand and is likely to
complete its usual linear dicoordination with (CtC)fAu
interactions, as is assumed for related complexes.
However, in the case of 2 it cannot be discarded that
NfAu bonds also contribute to complete the dicoordi-
nation of gold. Complex 2 precipitates quantitatively in
the reaction mixture, while SMe2 and [NHEt3]Cl remain
soluble and are separated by filtration. The elemental
analyses of 2 are compatible with the presence of a
residual amount of NEt3 that we suggest would be
coordinated to the outer gold atoms in the polymer, since
it is not removed after drying under reduced pressure
for several hours. On the basis of the tendency of some
analytically pure alkynylgold polymers to explode on
contact,5,30 we decided not to attempt any further
(30) Hunks, W. J.; MacDonald, M. A.; Jennings, M. C.; Puddephatt,
R. J. Organometallics 2000, 19, 5063.

Metal Complexes of 3,5-Diethynylpyridine
Organometallics, Vol. 23, No. 24, 2004 5711
NMR Spectra. The heteroaromatic protons appear
in the 1H NMR spectra of complexes 1-9 in the ranges
8.44-8.55 ppm (d) and 7.69-7.83 ppm (t), only very
slightly shielded with respect to their homologues in the
free 3,5-diethynylpyridine ligand (at 8.65 and 7.85 ppm,
1
respectively). Additionally, the H NMR spectrum of 1
shows a singlet for the acetylenic protons at 3.11 ppm,
slightly shifted to high field with respect to the free
dialkyne (at 3.24 ppm), likely due to the anionic nature
of 1. The PTo3 methyl protons in 8 give rise to two
singlets. The singlet at 2.39 ppm corresponds to the
C-AuPTo3 fragments and is at higher field than that
due to the N-AuPTo3 moiety (at 2.44 ppm), in agree-
ment with the greater electronegativity of nitrogen with
respect to carbon.
The 31P{1H} NMR spectrum of complex 1 shows a
singlet at 21.1 ppm due to the PPN cation, while the
spectra for the neutral complexes 3-7 display one
singlet resonance (at 1.36 ppm (4, PMe3) or in the range
36-44 ppm (5-7, PAr3)) for the two equivalent phos-
phorus nuclei. In agreement with the 1H NMR, the
31P{1H} NMR spectrum of 8 shows two singlet reso-
nances with a 2:1 intensity ratio. The most intense one
(at 43.68 ppm) corresponding to two C-AuP fragments
is shifted to low field with respect to that due to the
N-AuP fragment (at 36.85 ppm), despite nitrogen being
more electronegative than carbon. This can be at-
tributed to the greater trans influence of carbon-donor
with respect to nitrogen-donor ligands. In fact, com-
plexes with the AuPPh3 fragment coordinated to the
nitrogen atom of different substituted pyridines or to
alkynyl groups show the 31P resonance at around 30
ppm35 or in the range 42-56 ppm,25,36 respectively. In
the 31P{1H} NMR spectrum of 9 the phosphine bonded
to gold gives a singlet resonance (see Experimental
Section), while those coordinated to platinum give two
doublets with 195Pt satellites, corresponding to the
isomer containing a cis-PtCl(PPh3)2 fragment. The
spectrum of 9 shows a small singlet with 195Pt satellites
at 14.86 ppm (JPtP ) 3677 Hz), compatible with the
formation of a small amount (ca. 7%) of the isomer
containing trans-PtCl(PPh3)2. Additionally, it shows a
minor signal at 32.4 ppm (s) that grows with the
acquisition time and is indicative of the formation of
[AuClPTo3] resulting from some decomposition process,
which impeded us measuring its 13C NMR spectrum.
The 13C{1H} NMR spectra of complexes 1 and 3-8
show the expected resonances (see Experimental Sec-
Figure 1. Ellipsoid representation of 6 (50% probability).
Selected bond lengths (Å) and angles (deg): Au(1)-C(10)
)
2.011(10), Au(1)-P(1) ) 2.269(2), C(9)-C(10) )
1.188(11), C(10)-Au(1)-P(1) ) 175.3(2), Au(2)-C(8) )
1.995(8), Au(2)-P(2) ) 2.269(2), C(7)-C(8) ) 1.183(11),
C(8)-Au(2)-P(2) ) 173.3(2).
Figure 2. Two different views of the aurophilic contacts
in 6 giving rise to infinite chains. The tolyl groups and
the hydrogen atoms have been omitted. Selected bond
lengths (Å) and angles (deg): Au(1)-Au(2)#1 ) 3.2265(5),
C(10)-Au(1)-Au(2)#1 ) 76.6(2), P(1)-Au(1)-Au(2)#1 )
108.01(6), C(8)-Au(2)-Au(1)#2 ) 76.1(2), P(2)-Au(2)-
Au(1)#2 ) 104.14(6).
Crystal Structure of [(AuPTo3)2{µ-(CtC)2Py}]
(6). The crystal structure of 6 (Figure 1, Table 1) shows
a dinuclear complex in which two AuPTo3 units are
coordinated to the ethynyl fragments of the 3,5-py-
ridinediethyndiyl ligand, both gold atoms being in
almost linear environments (C-Au-P ) 175.3(2), 173.3-
(2)°). A search of the Cambridge Structural Data Base31
reveals that the Au-C (2.011(10), 1.995(8) Å), Au-P
(2.269(2) Å), and CtC (1.183(11), 1.188(11) Å) bond
distances found in 6 are similar to the mean values
found for other alkynyl(phosphine)gold(I) dicoordinate
complexes (Au-C ) 2.004 Å, Au-P ) 2.278 Å, CtC )
1.195 Å). Additionally, the molecules of 6 are packed
through intermolecular aurophilic contacts (Au‚‚‚Au )
3.2265(5) Å) to give infinite chains (Figure 2). The
molecules arrange in the chain so that the linear
fragments CtCAuPTo3 of two vicinal molecules are
almost perpendicular (dihedral angle PAu‚‚‚AuP 89°).
This type of “pseudopolymerization” in the solid state
has been previously reported for other (alkynyl)gold(I)
complexes.5,32-34
(31) CSD Version November 2003.
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C.; Puddephatt, R. J. J. Organomet. Chem. 2003, 670, 27.
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Chem. 2003, 217. Irwin, M. J.; Jia, G.; Payne, N. C.; Puddephatt, R. J.
Organometallics 1996, 15, 51. Puddephatt, R. J. Chem. Commun. 1998,
1055. Irwin, M. J.; Manojlovic-Muir, L.; Muir, K. W.; Puddephatt, R.
J.; Yufit, D. S. Chem. Commun. 1997, 219. Puddephatt, R. J. Coord.
Chem. Rev. 2001, 216, 313. Liau, R. Y.; Schier, A.; Schmidbaur, H.
Organometallics 2003, 22, 3199.
(34) McArdle, C. P.; Irving, M. J.; Jennings, M. C.; Vittal, J. J.;
Puddephatt, R. J. Chem. Eur. J. 2002, 8, 723.
(35) Casas, J. E.; Gimeno, M. C.; Jones, P. G.; Laguna, A.; Laguna,
M. J. Chem. Soc., Dalton Trans. 1999, 2819. Crespo, O.; Gimeno, M.
C.; Laguna, A. J. Organomet. Chem. 1998, 561, 13. Barranco, E. N.;
Crespo, O.; Gimeno, M. C.; Jones, P. G.; Laguna, A.; Sarroca, C. Dalton
2001, 2523.
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16081. Hunks, W. J.; Macdonald, M. A.; Jennings, M. C.; Puddephatt,
R. J. Organometallics 2000, 19, 5063. Whittall, I. R.; Humphrey, M.
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1996, 15, 5738.

5712 Organometallics, Vol. 23, No. 24, 2004
Vicente et al.
tion). In those complexes containing CtC-AuPR3 frag-
ments the R- and â-carbons of the CtC subunits could
be assigned when the JCP coupling constants were
observed, on the basis of the admitted fact23,34,37,38 that
they are greater for the R-carbons. In all other cases,
no assignment has been made, since controversial data
can be found in the literature.38
NMR and analytical data prove that some complexes
crystallize with Et2O (3‚0.5Et2O) or H2O (5‚H2O, 7‚H2O).
IR Spectra. The infrared spectra of the ionic com-
plexes show characteristic bands of the corresponding
counterions (1, PPN;6 8, 9, TfO).39 All complexes show
one medium to weak band in the range 2098-2114 cm-1
assignable to the CtC stretching mode.40 This band was
expected32,41 to appear at lower wavenumber in the
polymeric complex 2 due to the (CtC)fAu bond com-
ponent, and its position should also change with the
electron density around the metal center. However, very
similar or identical values are found for complexes 1,
2, 7, and 8 (2106, 2114, 2106, and 2114 cm-1, respec-
tively), despite 1 being anionic, 2 polymeric, 7 neutral,
and 8 cationic. In the spectrum of complex 1 two bands
are observed (3294, 3232 cm-1) for the tC-H stretching
mode,40 as observed in other alkynylgold complexes with
two CtCH moieties.6 Additionally, complex 9 shows one
ν(PtCl) band and 3-9 show the bands characteristic of
the phosphine or isocyanide ligands they contain (see
Experimental Section).
FAB Mass Spectra. The FAB- (1) or FAB+ (7-9)
mass spectra measured show in all cases the corre-
sponding mass peak with relative intensity in the range
of 6% (7) to 100% (1). The spectra of complexes 7-9 are
dominated by the signals corresponding to the [AuPR3]+,
[Au(PR3)2]+, and [PtCl(PR3)2]+ fragments.
Conclusions
3,5-Diethynylpyridine has been used to prepare a
family of mono- (1), di- (2-7), and trinuclear (8, 9) homo-
or heteronuclear complexes containing σ monoalkynyl
(CtC(Py)CtCH, 1) or σ dialkynyl (µ-CtC(Py)CtC,
2-7) ligands. Furthermore, complex 6 is a metalloligand
from which homo- (8) or heterotrinuclear (9) complexes
can be obtained after coordination of a third metal
center to the pyridinic nitrogen atom.
Acknowledgment. We thank the Ministerio de
Ciencia y Tecnolog´ıa, FEDER (BQU2001-0133), for
financial support and Fundacio´n Se´neca (Comunidad
Auto´noma de la Regio´n de Murcia, Spain) for a grant
to M.M.A.F.
(37) McArdle, C. P.; Van, S.; Jennings, M. C.; Puddephatt, R. J. J.
Am. Chem. Soc. 2002, 124, 3959. Eisler, D.; Hong, W.; Jennings, M.
C.; Puddephatt, R. J. Organometallics 2002, 21, 3955.
(38) Naulty, R. H.; Cifuentes, M. P.; Humphrey, M. G.; Houbrechts,
S.; Boutton, C.; Persoons, A.; Heath, G. A.; Hockless, D. C. R.; Luther-
Davies, B.; Samoc, M. J. Chem. Soc., Dalton Trans. 1997, 4167. Hong,
X.; Cheung, K. K.; Guo, C.-X.; Che, C.-M. J. Chem. Soc., Dalton Trans.
1994, 1867.
Supporting Information Available: A crystallographic
file in CIF format for complex 6. This material is available
free of charge via the Internet at http://pubs.acs.org.
(39) Lawrance, G. A. Chem. Rev. 1986, 86, 17.
(40) Silverstein, R. M.; Bassler, G. C.; Morrill, T. C. Spectrometric
Identification of Organic Compounds, 4th ed.; 1981, p 110.
(41) Mingos, D. M. P.; Yau, J.; Menzer, S.; Williams, D. J. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1894.
OM049509J