Organometallic fragments coordinated to a multiisocyanide ligand and their physical properties

Article abstract of DOI:10.1021/ic0620900

Preparation of a triisocyanide ligand, 1,3,5-tris[(4-isocyano-3,5- diisoproyl-phenyl)ethynyl]benzene (5), is presented. Ligand 5 is obtained in three steps in 76% overall yield. Reaction of 5 with (η⁵- Cp*)Rh(Cab^s,s′)(Cab^s,s

Full text of DOI:10.1021/ic0620900

Inorg. Chem. 2007, 46, 2787−2796
Organometallic Fragments Coordinated to a Multiisocyanide Ligand and
Their Physical Properties
Jong Hyub Paek, Kyu Ho Song, Il Jung, Sang Ook Kang,* and Jaejung Ko*
Department of Chemistry, Korea UniVersity, Jochiwon, Chungnam 339-700
Received November 2, 2006
Preparation of a triisocyanide ligand, 1,3,5-tris[(4-isocyano-3,5-diisoproyl-phenyl)ethynyl]benzene (5), is presented.
Ligand 5 is obtained in three steps in 76% overall yield. Reaction of 5 with (
η
5-Cp*)Rh(Cabs,s’)(Cabs,s’
)
1,2-
i
S2C2B10H10-S,S
′
) produced the rhodadithiolene adduct [
{
(
η
5-Cp*)Rh(Cabs,s’)(CNC6H2 Pr2-2,6-C
t
C-3)
}
3C6H3-1,3,5]
C-3) 3C6H3-
3C6H3-1,3,5]
of trichromium
complex 8 occurs in the plane of the bridge and the gold center has a slightly bent linear configuration with a
Cl(1) Au(1) C(21) angle of 175.4(4) . The rhenation and platination of 5 employing [Re(bpy)(CO)3(AN)]PF6 (AN
acetonitrile) and [(C∧N∧N)PtCl] ((HC∧N∧N)
6-phenyl-2,2 -bipyridine) yielded the luminescent Re(I) and Pt(II)
complexes. Full characterization includes structural study of complexes 2, 8, and 9.
i
(6). Ligand 5 reacts with Cr(CO)5(THF) to give the triisocyanide complex [
1,3,5] (8) and with [AuCl(SMe2)] to give the triisocyanide complex [
(9). As revealed by a single-crystal X-ray diffraction study, the C(9)
{
Cr(CO)5(CNC6H2 Pr2-2,6-C
t
}
i
{
−
AuCl(CNC6H2 Pr2-2,6-C
N(3) C(61) angle of 5.9°
tC-3)}
−
−
−
°
)
)
′
Introduction
Transition-metal complexes of organic isocyanides are of
long-standing importance in organic and organometallic
syntheses, catalysis, materials science, diagnostic medicine,1
building blocks for molecular self-assembly,2 and organo-
metallic polymers.3 They are also of great current interest
in photochemistry4 and surface chemistry,5 where their
bonding on transition metals has been addressed using
multidentate isocyanides. Isocyanide ligands are unique in
their ability to coordinate to transition metals encompassing
Figure 1. Triisocyanide ligand 5.
* To whom correspondence should be addressed. E-mail: jko@
korea.ac.kr (J.K.).
the various oxidation states.6 Isocyanides stabilize not only
low-valent complexes by participating as π-acceptor ligands,
but also coordinate to high-valent transition metals as strong
σ donors. The most important electronic element of metal
isocyanides is the presence of metal-carbon multiple bonds
(1) (a) Weber, L. Angew. Chem., Int. Ed. 1998, 37, 1515. (b) Carnahan,
E. M.; Protasiewicz, J. D.; Lippard, S. J. Acc. Chem. Res. 1993, 26,
90. (c) Sharma, V.; Piwnica-Worms, D. Chem. ReV. 1999, 99, 2545.
(d) Robinson, R. E.; Holovics, T. C.; Deplazes, S. F.; Lushington, G.
H.; Powell, D. R.; Barybin, M. V. J. Am. Chem. Soc. 2003, 125, 4432.
(2) (a) Mayr, A.; Guo, J. Inorg. Chem. 1999, 38, 921. (b) Philp, D.;
Stoddart, J. F. Angew. Chem., Int. Ed. 1996, 35, 1154. (c) Burrows,
A. D.; Chan, C.-W.; Chowdhry, M. M.; McGrady, J. E.; Mingos, D.
M. Chem. Soc. ReV. 1995, 329.
(3) (a) Turcotte, M.; Harvey, P. D. Inorg. Chem. 2002, 41, 2971. (b) Fortin,
D.; Drouin, M.; Harvey, P. D. Inorg. Chem. 2000, 39, 2758. (c)
Guitard, A.; Mari, A.; Beauchamp, A. L.; Dartiguenave, Y.; Dart-
iguenave, M. Inorg. Chem. 1983, 22, 1603. (d) Fortin, D.; Drouin,
M.; Turcotte, M.; Harvey, P. D. J. Am. Chem. Soc. 1997, 119, 531.
(4) (a) Villegas, J. M.; Stoyanov, S. R.; Huang, W.; Lockyear, L. L.;
Reibenspies, J. H.; Rillema, D. P. Inorg. Chem. 2004, 43, 6383. (b)
Coppens, P.; Gerlits, O.; Vorontsov, I. I.; Kovalersky, A. Y.; Chen,
Y.-S.; Graber, T.; Gembicky, M.; Novozhilova, I. V. Chem. Commun.
2004, 2144.
(5) (a) Siemeling, U.; Rother, D.; Bruhn, C.; Fink, H.; Weidner, T.; Tra¨ger,
F.; Rothenberger, A.; Fenske, D.; Priebe, A.; Maurer, J.; Winter, R.
J. Am. Chem. Soc. 2005, 127, 1102. (b) Murphy, K. L.; Tysoe, W. T.;
Bennett, D. W. Langmuir. 2004, 20, 1732. (c) McCreery, R. L. Chem.
Mater. 2004, 16, 4477. (d) Seminario, J. M.; Zacarias, A. G.; Tour, J.
M. J. Am. Chem. Soc. 1999, 121, 411.
(6) (a) Barybin, M. V.; Young, V. G., Jr.; Ellis, J. E. J. Am. Chem. Soc.
1998, 120, 429. (b) Barybin, M. V.; Young, V. G., Jr.; Ellis, J. E. J.
Am. Chem. Soc. 1999, 121, 9237. (c) Szalda, D. J.; Dewan, J. C.;
Lippard, S. J. Inorg. Chem. 1981, 20, 3851. (d) Nielson, R. M.;
Wherland, S. Inorg. Chem. 1985, 24, 1803.
10.1021/ic0620900 CCC: $37.00
Published on Web 02/13/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 7, 2007 2787

Paek et al.
Figure 2. Molecular structure of complex 2 with thermal ellipsoids drawn at the 50% probability level. Hydrogen atoms are omitted for clarity. Selected
bond distances (Å) and angles (deg): Rh-C(13) ) 1.927(3), N-C(13) ) 1.150(3), N-C(14) ) 1.408(3), C(17)-C(26) ) 1.429(3), C(26)-C(27) ) 1.195-
(4), N-C(13)-Rh ) 175.1(2), C(13)-N-C(14) ) 173.8(3), C(17)-C(26)-C(27) ) 177.6(3).
Table 1. Selected Crystallographic Data of Complexes 2, 8, and 9
compound
empirical formula
fw
cryst syst
space group
a (Å)
2
8
9
C54H82B20N2S4Rh2
1309.48
orthorhombic
Pbca
17.2591(7)
20.7769(9)
20.9540(9)
90
90
90
7513.9(6)
4
1.158
C66H51N3O15Cr3
1282.10
triclinic
C51H51Cl3N3Au3
1403.20
monoclinic
C2/c
22.5803(13)
18.6604(12)
30.452(2)
90
105.370(2)
90
12372.3(13)
8
P-1
14.9119(11)
14.9973(11)
18.7576(14)
73.2550(10)
69.3830(2)
69.6590(2)
3615.2(5)
2
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
vol. (Å3)
Z
D
calcd, (g/cm3)
1.178
1.507
F(000)
2696
1320
5328
cryst size, mm
θ range
no. of rflns collected
no. of indep rflns
refinement method (I > 2σ(I))
0.24 × 0.16 × 0.12
1.94-28.31
74 860
0.28 × 0.23 × 0.17
1.18-28.37
49 400
0.39 × 0.27 × 0.23
1.39-28.34
40 930
9333
17 854
15 417
R1 ) 0.0408
wR2 ) 0.1207
1.144
R1 ) 0.0584
wR2 ) 0.1557
0.884
R1 ) 0.0606
wR2 ) 0.1473
0.713
goodness of fit on F2
via back-bonding.7 Such metal-carbon π interactions provide
the stability of metal-isocyanides and electronic interactions
between the metal center and isocyanide ligands.7b Therefore,
by introducing suitably functionalized isocyanides, such
isocyanide metal complexes can be induced to undergo self-
assembly with the geometric and electronic information
stored in them, together with dimers and oligomers with
photophysical properties.
Mayr and co-workers2a,8 recently prepared various metal
complexes of isocyanides with nitrogen donor groups and
hydrogen-bonding groups, which can be utilized as building
blocks for self-assembly. They also found the functionalized
derivatives of 2,6-diisopropylphenylisocyanide to be useful
due to the relatively good solubility. Puddephatt and co-
workers reported that the gold and platinum complexes
reacted with diisocyanide ligands to form covalently linked
network polymers.9
of type 5 (Figure 1) has not been previously known, and the
ligand is suitable to coordinate to a variety of metal
complexes with novel properties, although the directional
diisocyanides have been well documented to afford organo-
metallic dimers and oligomers.10 Of particular importance
is isocyanide ligation to the luminescent metal complexes.
There has been interest in multinuclear metal complexes with
chromophoric units. The Lees11 and Che groups12 reported
the photophysics of luminescent trinuclear metal complexes
containing (diimine)Re(CO)3 and [(C∧N∧N)Pt]+ chromo-
phores bridged by tribranched ligands. We envisioned that
the tritopic ligand 5 would be able to coordinate to
luminescent metal complexes and have photophysical prop-
erties. Here we describe the novel synthesis of 1,3,5-tris[(4-
isocyano-3,5-diisopropylphenyl)ethynyl]benzene 5. The iso-
lation and physical properties of the Rh(I), Cr(I), Au(I), Re(I),
and Pt(II) metal complexes containing 5 are described.
During the course of our studies concerning the multi-
functional isocyanides, we found that the triisocyanide ligand
(9) (a) Irwin, M. J.; Manojlovic´-Muir, L.; Muir, K. W.; Puddephatt, R.
J.; Yufit, D. S. Chem. Commun. 1997, 219. (b) Irwin, M. J.; Vittal, J.
J.; Puddephatt, R. J. Organometallics 1997, 16, 3541.
(10) Fournier, E.; Sicard, S.; Decken, A.; Harvey, P. D. Inorg. Chem. 2004,
43, 1491.
(11) (a) Sun, S.-S.; Robson, E.; Dunwoody, N.; Silva, A. S.; Brinn, I. M.;
Lees, A. J. Chem. Commun. 2000, 201. (b) Sun, S.-S.; Lees, A. J.
Organometallics 2002, 21, 39.
(7) (a) Johnston, R. F. J. Coord. Chem. 1994, 31, 57. (b) Grubisha, D.
S.; Rommel, J. S.; Lane, T. M.; Tysoe, W. T.; Bennett, D. W. Inorg.
Chem. 1992, 31, 5022.
(8) (a) Lu, Z.-L.; Mayr, A.; Cheung, K.-K. Inorg. Chim. Acta. 1999, 284,
205. (b) Lau, K. Y.; Mayr, A.; Cheung, K.-K. Inorg. Chim. Acta. 1999,
285, 223.
(12) Lu, W.; Zhu, N.; Che, C.-M. Chem. Commun. 2002, 900.
2788 Inorganic Chemistry, Vol. 46, No. 7, 2007

Fragments Coordinated to a Multiisocyanide Ligand
Scheme 1. Preparation of Complex 2a
a (i) (η5-Cp*)Rh(Cabs,s’), toluene.
Scheme 2. Synthesis of the Triisocyanide Ligand 5a
a (i) Pd(PPh3)4, CuI, THF/NEt3 (1:1); (ii) HCHO, acetic anhydride; (iii) triphosgene, THF.
Results and Discussion
formula. The solid-state structure of 2 is consistent with its
assigned solution structure (Figure 2). The crystallographic
data and processing parameters are given in Table 1. All of
the rhodium centers adopt a three-legged piano-stool con-
formation. The molecule of 2 possesses a crystallographic
inversion (symmetry code: 2 - x, 1 - y, 1 - z) that the
middle of the diyne unit goes through. The Rh-C(13) bond
length is 1.927(3) Å, which is within the ranges established
for the respective types of isocyanide metal complex. The
bond angels Rh-C(13)-N and C(17)-C(26)-C(27) are
175.1(2)° and 177.6(3)°, respectively. Although all are close
to linear, the distortion from the ideal angel of 180° is greater
than those for other transition-metal complexes.14
Synthesis of the Triisocyanide Ligand. The triisocyanide
ligand 5 can be prepared in three steps, as shown in Scheme
2. In each step the reaction proceeds smoothly and the
product can be obtained in high yield. In the first step,
substitution of the iodide in 4-iodo-2,6-diisopropylaniline by
the ethynyl group to afford 3 is achieved by Sonogashira
cross-coupling reaction in the presence of catalytic
Synthesis of Dimetallic Rhodium(I) Complexes. The
diisocyanide ligand 1 can be prepared by the oxidative
homocoupling reaction of 4-isocyanophenylacetylene. The
coupling reaction of acetylene was readily accomplished with
high yield in the presence of cupric chloride and sodium
acetate. Ligand 1 is a crystalline solid that is stable in air.
The 1H and 13C NMR spectra support the proposed structure.
Ligand 1 was found to be a good model to use as a building
block for discrete multicluster assembly. Stirring a mixture
of (η5-Cp*)Rh(Cabs,s’)13 and 1 in toluene at room temperature
for 2 h produced an orange solution of 2 in a yield
of 92%, which has been characterized by single-crystal
crystallography, NMR, IR, and elemental analysis (Scheme
1). As previously reported by us, the 16-electron cobalt
complex (η5-Cp)Co(Cabs,s’) acts as a Lewis acid and forms
1:1 adducts with tert-butyl isocyanide.13 Formation of 2 is
confirmed by the appearance of the 1H NMR signals at 7.39,
3.51, 1.81, and 1.32 ppm, which are ascribed to the aromatic,
isopropyl, and Cp* ligand, respectively. 13C NMR spectros-
copy and mass spectrometry also support the proposed
(14) (a) Hahn, F. E.; Lu¨gger, T. J. Organomet. Chem. 1994, 481, 189. (b)
Bailey, N. A.; Walker, N. W.; Williams, J. A. W. J. Organomet. Chem.
1972, 37, C49. (c) Che, C.-M.; Herbstein, F. H.; Schaefer, W. P.;
Marsh, R. E.; Gray, H. B. Inorg. Chem. 1984, 23, 2572.
(13) Won, J.-H.; Kim, D.-H.; Kim, B. Y.; Kim, S.-J.; Lee, C.; Cho, S.;
Ko, J.; Kang, S. O. Organometallics 2002, 21, 1443.
Inorganic Chemistry, Vol. 46, No. 7, 2007 2789

Paek et al.
Scheme 3. Preparation of Complexes 6 and 7a
a (i) (η5-Cp*)Rh(Cabs,s’), toluene; (ii) [(η5-Cp*)RhCl2]2, CH2Cl2; (iii) LiS2C2B10H10.
Scheme 4. Preparation of Complex 8
Two singlets (7.71 and 7.32 ppm) in the 1H NMR spectrum
and six singlets (145.5-116.8 ppm) in the 13C NMR
spectrum could be assigned to the aromatic groups. The 13
C
NMR resonances of isocyanide groups are generally of low
intensity.16 For 5, this resonance occurs at δ 170.3. The
alkynyl group in 5 gives rise to characteristic 13C NMR
resonances at 90.3 and 89.2 ppm. These values are compa-
rable to those observed for the arylisocyanides.17 The
isocyanide 5 exhibits a strong IR absorption band at 2109
cm-1 for the CtN triple bond.
Synthesis of Trimetallic Rhodium(I) Complexes. Tri-
isocyanide 5 was found to be a good scaffold to incorporate
triorganometallic fragments because metal complexes of 5
possess higher solubility than other metal complexes of
isocyanides without alkyl substituents and have three iso-
cyanide groups. For example, the new rhodium complex 6
was readily prepared from the reaction between the mono-
meric rhodium complex, (η5-Cp*)Rh(Cabs,s’), and the triiso-
cyanide ligand 5 (Scheme 3). In addition, the coordinatively
unsaturated 16-electron iridadithiolene complex (η5-Cp*)Ir-
(Cabs,s’) readily reacted with alkynes to afford the new class
of addition products.18 The structure of 6 was determined
on the basis of NMR spectroscopy, IR, and mass spectros-
copy, as well as elemental analysis. The initial indication of
amounts of Pd(PPh3)4 and copper iodide. Formylation of
3 with formic acid and acetic anhydride affords the forma-
mide 4. Triisocyanide ligand 5 was prepared by the
dehydration reaction of 4 with triphosgene/triethylamine.15
A similar preparation of functionalized derivatives of 2,6-
diisopropylphenylisocyanide has been reported by the Mayr
group.8 Ligand 5 is a crystalline white solid that is stable
and soluble in toluene, THF, and CH2Cl2. Spectroscopic data
for 5 are completely consistent with its proposed structure
(Scheme 2).
A parent ion in the mass spectrum of 5 was observed at
m/z 705. The H NMR spectrum of 5 contained a methine
resonance (3.36 ppm) and a methyl resonance (1.31 ppm).
1
(16) Lentz, D. Angew. Chem., Int. Ed. 1994, 33, 1315.
(17) Yang, L.; Cheung, K.-K.; Mayr, A. J. Organomet. Chem. 1999, 585,
26.
(18) Bae, J.-Y.; Lee, Y.-J.; Kim, S.-J.; Ko, J.; Cho, S.; Kang, S. O.
Organometallics 2000, 19, 1514.
(15) Eckert, H.; Forster, B. Angew. Chem., Int. Ed. 1987, 26, 894.
2790 Inorganic Chemistry, Vol. 46, No. 7, 2007

Fragments Coordinated to a Multiisocyanide Ligand
Scheme 5. Preparation of Complexes 9 and 10a
a (i) Au(SMe2)Cl, CH2Cl2; (ii)NaSC6H5, THF.
Scheme 6. Preparation of Complexes 11 and 12a
a (i) [Re(bpy)(CO)3(CH3CN)]PF6, THF; (ii) (C∧N∧N)PtCl, LiClO4.
the trinuclear rhodium complex stemmed from the observa-
tion of a parent ion in the mass spectrum at m/z 2044.
Complex 6 exhibited a strong CtN triple-bond stretching
absorption at 2154 cm-1 in the IR spectrum, and this
wavelength is normal for a terminal Rh-CNR ligand. The
13C NMR spectrum of 6 indicated a signal at δ 173.2 due to
an isocyanide group and two signals at δ 91.2 and δ 89.9
due to an alkynyl group. The 11B NMR spectrum consists
of three sets of broad resonances at -6.4, -10.2, and -16.2
ppm. All resonances are split into a B-H coupled doublet.
The trirhodium complex 6 can be prepared by an alternative
procedure in two steps. In the first step, the rhodium dimer
[Cp*RhCl2]2 is easily cleavaged by ligand 5 to afford the
trirhodium dichloride complex 7. Such cleavage reaction has
been observed for the reaction between the rhodium dimer
[Cp*RhCl2]2 and bidentate diisocyanide.19 The reaction of
7 with the dilithium salt Li2Cabs,s20 afforded a 62% yield of
6 (Scheme 3). Analytical and spectroscopic data support the
formulation of 6.
Synthesis of Trimetallic Chromium Complex. Treatment
of 3 equiv of in-situ-generated Cr(CO)5(THF)21 to 5 gave
its trichromium adduct 8 in 70% yield (Scheme 4). The
1H NMR and 13C NMR spectra of 8 indicated formation
of highly symmetrical structure and displayed spectroscopic
differences from its monomeric subunit. Complex 8
exhibits a strong IR absorption at 2121 cm-1 for the CtN
triple bond. The CtN stretching frequency in 8 under-
goes about 10 cm-1 shifts to higher frequency upon
bonding to the Cr(CO)5 fragment due to the NC(σ) f M
interaction.
The structure of 8 was unambiguously established by
single-crystal X-ray analysis and is shown in Figure 3. The
average isocyanide carbon-chromium bond length is 1.96
Å. The Cr-C distances are longer than the corresponding
bonds of [Cr(CO)5]2(µ-CN azulene NC)22 and [Cr(CO)5]2-
(µ-CNfcNC).5a The Cr-C back-bondings in 8 are weaker
than those in [Cr(CO)5]2(µ-CNfcNC). The C(9)-N(3)-C(61)
(19) Suzuki, H.; Tajima, N.; Tatsumi, K.; Yamamoto, Y. Chem. Commun.
2000, 1801.
(21) Herrmann, W. A.; Zybill, C. In Synthetic Methods of Organometallic
and Inorganic Chemistry (Herrmann/Brauer); Herrmann, W. A.,
Salzer, A., Eds.; Thieme: Stuttgart, 1996; Vol. 1, p117.
(20) Smith, H. D., Jr.; Obenland, C. O.; Papetti, S. Inorg. Chem. 1966, 5,
1013.
Inorganic Chemistry, Vol. 46, No. 7, 2007 2791

Paek et al.
Table 2. Absorption and Emission Data at 298 Ka
absorption
max, nm (ꢀ, 104 M-1 cm-1
)
λ
em, nm Φem
τ, ns
<1
b
compds
λ
5c
10
225 (3.44) 305 (3.84) 326 (5.24)
282 (4.26) 302 (4.63) 318 (6.26)
342 (1.52)
225 (7.48) 288 (9.63) 312 (9.06)
352 (1.84)
430
612
604d
475
568
542
0.024
0.0008 124
11
12
0.051
0.052
78
278
230 (7.64) 292 (9.63) 325 (10.12)
363 (3.32)
a The excitation wavelength is 350 nm in CH2Cl2/DMF. b The emission
quantum yields were determined using [Ru(bpy)3](PF6)2 (Φ ) 0.029).32
c The excitation wavelength is 330 nm. d The solid-state emission data taken
at 77 K.
complex. Treatment of 5 with the gold complex (Me2S)-
AuCl involves formation of a trinuclear gold complex 9
(Scheme 5). The reaction is quantitative and rapid at room
temperature. In the IR spectrum a strong band for υ(CtN)
stretching was observed at 2202 cm-1. The peak appears at
higher frequency compared with that of the ligand (2109
cm-1). The increase of ca. 100 cm-1 in the CN stretching
frequency of gold isocyanide is well documented and
probably attributable to σ donation of the carbon lone
pair to Au.24 The 13C NMR spectrum displays distinct
resonances for the isocyanide group at 170.8 ppm and the
alkynyl group at 90.4 and 89.9 ppm. 1H NMR spectrum and
mass spectrum also support the proposed formula. The solid-
state structure of 9 is consistent with its assigned solution
structure.
Figure 3. ORTEP drawing of complex 8 with thermal ellipsoids drawn
at the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond distances (Å) and angles (deg): C(9)-N(3) ) 1.408(3),
N(3)-C(61) ) 1.151(3), C(61)-Cr(3) ) 1.968(3), Cr(3)-C(65) ) 1.895-
(4), C(65)-O(12) ) 1.139(4), Cr(3)-C(64) ) 1.882(3), C(64)-(O13) )
1.136(4), C(9)-N(3)-C(61) ) 174.1(3), N(3)-C(61)-Cr(3) ) 173.1(3),
C(61)-Cr(3)-C(65) ) 93.79(13).
An X-ray diffraction study on 9 confirmed that the
complex has the expected linear geometry. The molecular
structure of 9 is shown in Figure 4. The Au-Cl distance in
LAuCl complexes is quite sensitive to the trans influence of
L. The Au-Cl bond distance (2.239(3) Å) in 9 is signifi-
cantly shorter than the corresponding in Cl-Au-PPh3 of
2.279(3) Å.25 This is in agreement with the greater trans
influence of PPh3 than that of an isocyanide. The bond angles
Cl(1)-Au(1)-C(21), Au(1)-C(21)-N(1), and C(21)-N(1)-
Cl(2) are 175.4(4)°, 175.1(12)°, and 172.7(13)°, respectively.
Although similar distortion is observed in complex 2, the
distortion is greater than those for other gold(I) complexes.26
The overall result is that the molecule of 9 has a little bent
rather than linear geometry. Complex 9 is readily converted
to the gold(I) thiolate of triisocyanide by the reaction between
9 and sodium phenylthiolate (Scheme 5). Its composition is
readily confirmed by analytical and spectroscopic data. A
similar gold(I) selenolate complex has been reported by
reaction of [Au2Cl2(µ-dppf)] with PhSeSiMe3.27
Figure 4. ORTEP drawing of complex 9 with thermal ellipsoids
drawn at the 50% probability level. Hydrogen atoms are omitted for
clarity. Selected bond distances (Å) and angles (deg): Au(1)-C(21) )
1.846(15), Au(1)-Cl(1) ) 2.239(3), C(7)-C(8) ) 1.187(12), N(1)-C(21)
) 1.218(15), C(21)-Au(1)-Cl(1) ) 175.4(4), Au(1)-C(21)-N(1) )
175.1(12).
Isocyanide Ligation at Luminescent Re(I) and Pt(II)
Complexes. As there has been considerable interest in
polynuclear metal complexes bearing multiluminescent units
angle of 5.9° occurs in the plane of the bridge and was
attributed a slight M(dπ) f CNR back-bonding.
Synthesis of Trimetallic Gold(I) Complexes. As the
monomeric gold(I) complexes of isocyanides have been
prepared by reaction of (dimethylsulfide)gold(I) chloride with
the corresponding isocyanides,23 we attempted a similar
reaction in anticipation of synthesizing the trinuclear gold
(24) (a) Sarapu, A. C.; Fenske, R. F. Inorg. Chem. 1975, 14, 247. (b) Jia,
G.; Payne, N. C.; Vittal, J. J.; Puddephatt, R. J. Organometallics 1993,
12, 4771.
(25) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. ReV. 1973,
10, 335.
(26) Humphrey, S. M.; Mack, H.-G.; Redshaw, C.; Elsegood, M. R. J.;
Young, K. J. H.; Mayer, H. A.; Kaska, W. C. Dalton Trans. 2005,
439.
(27) Canales, S.; Crespo, O.; Gimeno, M. C.; Jones, P. G.; Laguna, A.
Inorg. Chem. 2004, 43, 7234.
(22) Holovics, T. C.; Robinson, R. E.; Weintrob, E. C.; Toriyama, M.;
Lushington, G. H.; Barybin, M. V. J. Am. Chem. Soc. 2006, 128, 2300.
(23) Schneider, W.; Angermaier, K.; Sladek, A.; Schmidbauer, H. Natur-
forsch. 1996, 51b, 790.
2792 Inorganic Chemistry, Vol. 46, No. 7, 2007

Fragments Coordinated to a Multiisocyanide Ligand
Figure 5. UV-vis absorption and emission spectrum of 11 (a) and 12 (b) in CH2Cl2/DMF at 298 K (λem) 350 nm, normalized intensity, concentration
) 1.0 × 10-5 M). Excitation spectra monitored at (a) 560 and (b) 570 nm.
capable of performing light-induced processes, we attempted
to synthesize such complexes using the multidentate isocya-
nide ligand. The trinuclear Re(I) complex 11 can be prepared
by refluxing [Re(bpy)(CO)3(CH3CN)]PF6 with 5 in THF and
purified by crystallization from CH2Cl2/Et2O solution (Scheme
6). The identity of the new rhenium compound has been
established by NMR, IR, FAB-MS spectrometry, and el-
emental analysis. Compound 11 shows a strong CtN
absorption at 2196 cm-1 and three strong CtO stretching
absorptions at 2062 and 1902 cm-1. The observation of two
strong bands in the CtO stretching mode confirms that the
three carbonyl groups are in a facial arrangement with C3V
local symmetry.11a,28 The FAB-MS spectrum of 11 exhibits
a peak at m/z 1879 displaying the expected isotopic profile
of the [M - 2PF6]+ cation. As the facile displacement of
the chloride group from [(C∧N∧N)PtCl] (HC∧N∧N) 6-phen-
yl-2,2′-bipyridine) by isocyanide has been well documented,29
we thought that the reaction of [(C∧N∧N)PtCl] with triiso-
cyanide ligand 5 occurred to afford the trinuclear platinum
complex. As expected, we prepared the trinuclear complex
with three [(C∧N∧N)Pt] moieties by coordinating to the
triisocyanide ligand. Complex 12 is air and moisture stable
at room temperature. The FAB-MS spectrum of 12 reveals
a peak at m/z 2181 corresponding to [M+ - ClO4]. The
characteristic IR absorption for υ(CtN) in 12 appears at
2155 cm-1, which is comparable to that of [(C∧N∧N)Pt-
at 342 nm in DMF, 348 nm in MeOH, and 368 nm in THF.
The bathochromic shift with decreasing solvent polarity
indicates additional support for the assignment to the MLCT
bond. The different MLCT bands of compounds 10-12
associated with transitions to the diimine or C∧N∧N ligands
and free ligand are substantially overlapping, and it is not
possible to assign their accurate positions.
All complexes 10-12 are emissive in solution at room
temperature. Complex 12 in CH2Cl2/DMF solution at 298
K shows a broad emission band (λmax) 542 nm) in the region
of 500-700 nm, while complex 11 (λmax) 568 nm) under
the same condition exhibits a much broader emission band
with a shoulder peak at 475 nm relative to complex 12. The
nature of these emission bands can be assigned to a MLCT
excited state.30 Similar assignments in absorption and emis-
sion have been described for the related acetylide complexes,
such as those of Pt(II) and Re(I), which were isoelectronic
to the isocyanide.31 Measurement of the solid-state emission
spectrum of 10 at 77 K revealed a broad featureless band
centered at 604 nm. A lifetime of 124 ns for the emission
band is detected. The relatively long lifetime of the 604 nm
emission is consistent with its assignment to a triplet metal-
centered state. The emission spectra of 11 (Figure 5a) and
12 (Figure 5b) exhibit a broad center at 568 and 542 nm,
respectively, which is attributable to the triplet MLCT
emission, typical of [(bpy)Re(CO)3]11b and Pt(II)(diimine)
complexes.30 Of note is that the high emission quantum yield
of 11 and 12 may be rationalized by the strong ligand field
of isocyanide which increases the energy of ligand-field
excited states. Similar phenomena were observed in the Pt-
(II) complexes with isocyanide ligands.29b
1
(CtNtBu)]ClO4 (2207 cm-1).29a All H and 13C NMR data
of 12 are consistent with the proposed molecular structure.
Photophysical Properties. The photophysical parameters
obtained from compounds 10-12 and free ligand 5 are
summarized in Table 2. Ligand 5 exhibits three intense bands
in the 225-320 nm region. The absorption spectra of
complexes 10-12 shows a series of intense absorptions at
<330 nm which can be assigned to π f π* transitions
localized on C∧N∧N or diimine ligands and free ligand. The
lower energy bands which appear from ∼340 nm and extend
past 410 nm are assigned to M f ligand (M ) Au, Re, Pt)
charge-transfer (MLCT) absorption bands with reference to
previous spectroscopic work on related complexes.9b,11,29
Weak bands at 352 (11) and 363 nm (12) with extinction
coefficients (ꢀ) on the order of 104 M-1 cm-1 and the close
resemblance of excitation spectra at 345 (11) and 352 nm
(12) to the low-energy tail at ca. 400-500 nm in the
electronic absorption spectrum are supportive of a MLCT
origin. In the case of 11, a solvent-sensitive band maximizes
Conclusions
In summary, a novel triisocyanide ligand 5 was prepared.
The ligand was found to be an effective reactant to coordinate
(28) Gamelin, D. R.; George, M. W.; Glynn, P.; Grevels, F.-W.; Johnson,
F. P. A.; Klotzbu¨cher, W.; Morrison, S. L.; Russell, G.; Schaffner,
K.; Turner, J. J. Inorg. Chem. 1994, 33, 3246.
(29) (a) Lai, S.-W.; Chan, M. C.-W.; Cheung, K.-K.; Che, C.-M. Orga-
nometallics 1999, 18, 3327. (b) Lai, S.-W.; Lam, H.-W.; Lu, W.;
Cheung, K.-K.; Che, C.-M. Organometallics 2002, 21, 226.
(30) Chan, S.-C.; Chan, M. C. W.; Wang, Y.; Che, C.-M.; Cheung, K.-K.;
Zhu, N. Chem. Eur. J. 2001, 7, 4180.
(31) (a) Yam, V. W.-W.; Tao, C.-H.; Zhang, L.; Wong, K. M.-C.; Cheung,
K.-K. Organometallics 2001, 20, 453. (b) Tao, C.-H.; Zhu, N.; Yam,
V. W.-W. Chem. Eur. J. 2005, 11, 1647. (c) Chong, S. H.-F.; Lam, S.
C.-F.; Yam, V. W.-W.; Zhu, N.; Cheung, K.-K. Organometallics 2004,
23, 4924.
Inorganic Chemistry, Vol. 46, No. 7, 2007 2793

Paek et al.
temperature. The solution was stirred for 2 h. The pure complex 2
was isolated by silica gel chromatography (eluent: CH2Cl2/hexane
) 1:6) as an orange crystalline solid in 92% yield. mp: 282 °C.
1H NMR(CDCl3): δ 7.39 (s, 4H), 3.51 (h, 4H, JHH ) 6.6 Hz, CH),
1.81 (s, 30H), 1.32 (d, 24H, JHH ) 6.6 Hz, CH3). 13C{1H} NMR
(CDCl3): δ 172.8, 146.3, 135.7, 127.7, 126.2, 122.9, 103.0, 94.0,
81.8, 30.1, 23.6, 9.4. IR (KBr pellet, cm-1): 2085 (υ(CtC)), 2578
(υ(B-H)), 2162 (υ(CtN)). FAB-MS: m/z 1113 [M+]. Anal. Calcd
For C62H94B20N2O2S4Rh2: C, 53.95; H, 5.61. Found: C, 53.56; H,
5.32.
to various metal complexes through the isocyanide ligation.
Ligand 5 readily reacts with 16-electron rhodium complex,
(η5-Cp*)Rh(Cabs,s’) to afford the trimetallic addition product
6. Such trirhodium
complex can also be prepared by the cleavage reaction
between the rhodium dimer [Cp*RhCl2]2 and 5, followed
by the reaction of Li2Cabs,s’. The trimetallic chromium
complex 8 shows slightly weak Cr f CtN back-bonding.
Trimetallic gold complex bearing ligand 5 can be prepared
by the displacement reaction of (dimethylsulfide)gold(I)
chloride with 5. The trimetallic Re(I) and Pt(II) complexes
of 5 exhibit interesting photophysical properties. The emis-
sion spectra of both complexes exhibit a broad band centered
at 540-570 nm, due to the triplet MLCT emission. Work
will involve the synthesis of a hexaisocyanide ligand,
multiisocyanide with porphyrin unit, and their metal com-
plexes.
1,3,5-Tris[(4-amino-3,5-diisopropylphenyl)ethynyl]benzene (3).
A mixture of triethynylbenzene (0.15 g, 1 mmol), 2,6-diisopropyl-
4-iodoaniline (1.52 g, 5 mmol), Pd(PPh3)4 (0.10 g, 0.09 mmol),
CuI (0.017 g, 0.09 mmol), and degassed NEt3 (10 mL) in THF (10
mL) in a Schlenk flask was heated to reflux for 72 h. The resulting
reaction mixture was extracted with CH2Cl2. Compound 3 was
purified by chromatography on silica gel using CH2Cl2/hexane (1:
1
1) as the eluent in 72% yield. mp: 165 °C. H NMR (CDCl3): δ
7.58 (s, 3H), 7.22 (s, 6H), 3.92 (br, 6H, NH2), 2.88 (h, 6H, JHH
)
6.6 Hz, CH), 1.29 (d, 36H, JHH ) 6.6 Hz, CH3). 13C{1H} NMR
(CDCl3): δ 141.8, 132.3, 130.6, 124.6, 117.4, 112.2, 93.8, 86.0,
28.3, 22.5. IR (KBr pellet, cm-1): 2123(υ(CtC)). Anal. Calcd for
C48H57N3: C, 85.28; H, 8.50. Found: C, 85.15; H, 8.37.
Experimental Section
All experiments were performed under a nitrogen atmosphere
in a Vacuum Atmospheres drybox or by standard Schlenk tech-
niques. THF, toluene, diethyl ether, and hexane were distilled from
sodium benzophenone. Methylene chloride, CHCl3, MeOH, and
1,3,5-Tris[(4-formamido-3,5-diisopropylphenyl)ethynyl]ben-
zene (4). A mixture of acetic anhydride (3 mL) and formic acid (3
mL) was heated for 2 h at 50-60 °C. Then the solution was cooled
to room temperature. Compound 3 (0.45 g, 0.67 mmol) dissolved
in diethyl ether (20 mL) was slowly added to this solution. The
resulting solution was stirred for 12 h at room temperature and
neutralized with aqueous sodium carbonate. The organic phase was
dried over MgSO4. After filtration and evaporation of the solvent,
the product 4 was obtained as a white solid in 85% yield. mp:
1
EtOH were distilled under nitrogen from P2O5. The H, 13C, and
11B NMR spectra were recorded on a Varian Mercury 300
spectrometer operating at 300.00, 75.44, and 96.00 MHz, respec-
tively. 11B NMR chemical shifts are reported relative to BF3‚
O(C2H5)2, used as an external reference, with a negative sign
indicating an upfield shift. The absorption spectra were recorded
on a Perkin-Elmer Lambda 25 UV-visible spectrophotometer. IR
spectra were recorded on a Biorad FTS-165 spectrometer. Mass
spectra were recorded on a JEOL JMS-SX 102A instrument.
Elemental analyses were performed with a Carlo Elba Instruments
CHNS-O EA 1108 analyzer. Triphosgene, acetic anhydride, formic
acid, 2,6-diisopropyl-4-iodoaniline, and chloro(dimethylsulfide)-
gold(I) were purchased from Aldrich Chemical Co. 1,3,5-Triethy-
nylbenzene,33 (η5-Cp*)Rh(Cabs,s’),13 [Re(bpy)-(CO)3-(AN)]PF6,34
1
208 °C. H NMR (CDCl3): δ 8.49 (s, 3H, CHO), 7.71 (s, 3H),
7.31 (s, 6H), 6.74 (s, 3H, NH), 3.21 (h, 6H, JHH ) 6.6 Hz, CH),
1.24 (d, 36H, JHH ) 6.6 Hz, CH3). 13C{1H} NMR (CDCl3): δ 163.8,
147.1, 130.5, 129.2, 127.8, 124.2, 123.4, 90.4, 88.3, 28.6, 23.4. IR
(KBr pellet, cm-1): 1684 (υ(CdO)), 2088 (υ(CtC)). Anal. Calcd
for C51H57N3O3: C, 80.60; H, 7.56. Found: C, 80.38; H, 7.45.
1,3,5-Tris[(4-isocyano-3,5-diisopropylphenyl)ethynyl]ben-
zene (5). To a stirred THF solution (20 mL) of 2 (0.24 g, 0.31
mmol) and NEt3 (5 mL) was added a solution of triphosgene (0.18
g, 0.60 mmol) in THF (10 mL) at -78 °C. The mixture was warmed
to room temperature and stirred for 12 h. The mixture was
evaporated under reduced pressure to remove THF and NEt3. The
reaction mixture was extracted with CHCl3. Compound 5 was
purified by chromatography on silica gel using CH2Cl2/hexane (1:
(C∧N∧N)PtCl,35 and Li2(Cabs,s’ 20
literature methods.
)
were prepared according to
1,4-Bis(4-isocyano-3,5-diisopropylpheny)buta-1,3-diyne (1). A
mixture of 4-isocyanophenylacetylene (0.24 g, 0.31 mmol), CuCl2
(0.083 g, 0.62 mmol), and NaOAc (0.13 g, 0.62 mmol) in THF
(10 mL) in a Schlenk flask was heated to reflux for 12 h. The THF
was then evaporated in vacuo. The residue was extracted with CH2-
Cl2. The pure product was isolated by column chromatography on
silica gel using CH2Cl2/hexane (1:1) as the eluent in 84% yield.
1
1) as the eluent in 72% yield. mp: 236 °C. H NMR (CDCl3): δ
7.71 (s, 3H), 7.32 (s, 6H), 3.36 (h, 6H, JHH ) 6.9 Hz, CH), 1.31
(d, 36H, JHH ) 6.9 Hz, CH3). 13C{1H} NMR (CDCl3): δ 170.3,
145.5, 130.8, 123.9, 123.0, 118.3, 116.8, 90.3, 89.2, 28.2, 22.5. IR
(KBr pellet, cm-1): 2091 (υ(CtC)), 2109 (υ(CtN)). FAB-MS:
m/z 705 [M+]. Anal. Calcd for C51H51N3: C, 86.77: H, 7.28.
Found: C, 86.33; H, 7.14.
[{(η5-Cp*)Rh(Cabs,s)(CNC6H2iPr2-2,6-CtC-3)}3C6H3-1,3,5] (6).
(A) To a stirred toluene solution (5 mL) of 5 (0.049 g, 0.07 mmol)
was added (η5-Cp*)Rh(Cabs,s’) (0.10 g, 0.22 mmol) dissolved in
toluene (5 mL) at 0 °C. The solution was allowed to warm to room
temperature. The solution was stirred for 3 h. The pure compound
6 was isolated by silica gel chromatography (eluent: CH2Cl2/hexane
(1:10)) as a yellow solid in 92% yield.
1
mp: 236 °C. H NMR (CDCl3): δ 7.32 (s, 4H), 3.35 (h, 4H, JHH
) 6.6 Hz, CH), 1.27 (d, 24H, JHH ) 6.6 Hz, CH3). 13C{1H} NMR
(CDCl3): δ 170.9, 145.6, 145.4, 128.1, 127.2, 122.7, 125.0, 81.9,
30.4, 22.6. IR (KBr pellet, cm-1): 2050 (υ(CtC)), 2124 (υ(Ct
N)). Anal. Calcd for C30H32N2: C, 85.67; H, 7.67. Found: C, 85.34;
H, 7.71
i
[{((η5-Cp*)Rh(Cabs,s)(CNC6H2 Pr2-2,6))2-CtC}-1,2] (2). To
a stirred toluene solution (5 mL) of 1 (0.049 g, 0.07 mmol) was
added (η5-Cp*)Rh(Cabs,s’) (0.1 g 0.22 mmol) dissolved in toluene
(5 mL) at 0 °C. The solution was allowed to warm to room
(32) Caspar, J. V.; Meyer, T. J. J. Am. Chem. Soc. 1983, 105, 5583.
(33) Leininger, S.; Stang, P. J.; Huang, S. Organometallics 1998, 17, 3981.
(34) Caspar, J. V.; Meyer, T. J. J. Phys. Chem. 1983, 87, 952.
(35) Cheung, T. C.; Cheung, K. K.; Peng, S. M.; Che, C. M. J. Chem.
Soc., Dalton Trans. 1996, 1645.
(B) An alternative procedure of complex 6 from complex 7: To
a stirred THF solution (5 mL) of Li2Cabs,s’ (0.01 g, 0.045 mmol)
was added complex 7 (0.05 g, 0.03 mmol) dissolved in THF (5
2794 Inorganic Chemistry, Vol. 46, No. 7, 2007

Fragments Coordinated to a Multiisocyanide Ligand
mL) at 0 °C. The solution was stirred for 6 h at 0 °C. Purification
of complex 6 was described above (A). The isolated yield was 62%.
mp: 280 °C. 1H NMR (CDCl3): δ 7.76 (s, 3H), 7.39 (s, 6H), 3.53
(h, 6H, JHH ) 6.9 Hz, CH), 1.82 (s, 45H), 1.35 (d, 36H, JHH ) 6.9
Hz, CH3). 13C{1H} NMR (CDCl3): δ 173.2, 146.4, 136.1, 127.6,
124.5, 123.9, 103.1, 93.5, 91.2, 89.9, 28.9, 22.9, 9.5. 11B NMR
(CDCl3): δ -6.4 (d, 5B, JBH ) 135 Hz), -10.2 (d, 3B, JBH ) 120
Hz), -16.2 (d, 2B, JBH ) 140 Hz). IR (KBr pellet, cm-1): 2093
(υ(CtC)), 2154 (υ(CtN)), 2582 (υ(B-H)). FAB-MS: m/z 2044
[M+]. Anal. Calcd for C126 H135N3S6Rh3: C, 69.02; H, 6.21.
Found: C, 68.78; H, 6.09.
Hz, CH3). 13C{1H} NMR (CDCl3): δ 171.2, 156.8, 146.6, 146.0,
134.1, 131.7, 128.6, 127.4, 125.9, 123.7, 122.3, 90.5, 89.7, 30.9,
23.7. IR (KBr pellet, cm-1): 2096 (υ(CtC)), 2186 (υ(CtN)). Anal.
Calcd for C69H66N3S3Au3: C, 51.01: H, 4.10. Found: C, 50.84;
H, 4.02.
i
[{Re(bpy)(CO)3(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5]-
(PF6)3 (11). A mixture of [Re(bpy)(CO)3(CH3CN)]PF6 (0.14 g, 0.23
mmol) and 5 (0.05 g, 0.07 mmol) in THF (20 mL) was heated to
reflux under nitrogen for 12 h. The solvent was removed in vacuo
and washed with ethanol (3 mL × 3). The pure product 11 was
obtained by crystallization by vapor diffusion of Et2O into a CH2-
Cl2 solution of the product as a pale yellow crystal in 43% yield.
[{(η5-Cp*)RhCl2(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5] (7). To
i
1
a stirred CH2Cl2 solution (10 mL) of [Cp*RhCl2]2 (0.05 g, 0.081
mmol) was added ligand 5 (0.038 g, 0.054 mmol) in CH2Cl2 (10
mL) at room temperature. The solution was stirred for 1 h. The
solvent was removed in vacuo and washed with Et2O (20 mL).
The pure product 7 was obtained by recrystallization with CH2-
Cl2/hexane as an orange solid in 82% yield. mp: 327 °C. 1H NMR
(CDCl3): δ 7.72 (s, 3H), 7.33 (s, 6H), 3.46 (h, 6H, JHH ) 6.6 Hz,
CH), 1.85 (s, 45H), 1.32 (d, 36H, JHH ) 6.6 Hz, CH3). 13C{1H}
NMR (CDCl3): δ 172.4, 144.8, 137.2, 126.8, 124.2, 123.7, 104.6,
93.2, 90.6, 89.2, 27.4, 22.4, 9.8. IR (KBr pellet, cm-1): 2096 (υ-
(CtC)), 2160 (υ(CtN)). Anal. Calcd for C81H96N3Cl6Rh3: C,
59.57; H, 5.93. Found: C, 59.38; H, 5.81.
mp: 168 °C. H NMR (CDCl3): δ 9.07 (d, 6H, JHH ) 4.2 Hz),
8.20 (d, 6H, JHH ) 7.5 Hz), 8.08 (m, 6H), 7.71 (s, 3H), 7.55 (m,
6H), 7.37 (s, 6H), 3.12 (h, 6H, JHH ) 6.6 Hz, CH), 1.25 (d, 36H,
JHH ) 6.6 Hz, CH3). 13C{1H} NMR (CDCl3): δ 196.1, 191.9, 156.0,
154.8, 147.6, 146.9, 140.3, 140.0, 127.8, 127.4, 123.6, 123.2, 122.6,
91.8, 89.6, 30.7, 22.7. IR (KBr pellet, cm-1): 1902, 2062 (υ(Ct
O)), 2092 (υ(CtC)), 2196 (υ(CtN)). FAB-MS: m/z 1879 [(M -
2PF6)]+. Anal. Calcd for C90H84F18N9O9P3Re3: C, 44.31; H, 3.39.
Found: C, 44.51; H, 3.47.
i
[{Pt((N∧N∧C))(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5]-
(ClO4)3 (12). To a stirred solution of [(C∧N∧N)PtCl] (0.20 g, 0.44
mmol) in CH3CN (10 mL) and CH2Cl2 (10 mL) was added 5 (0.103
g, 0.146 mmol) in CH2Cl2 (5 mL) at room temperature. The color
of the mixture changed to red after 30 min. The solution was stirred
for 2 h. To that solution was added excess LiClO4 in CH3CN (15
mL). On addition of Et2O (20 mL) to that solution, the yellow
product 12 precipitated out. The product was collected and washed
with Et2O (10 mL × 3) in 72% yield. mp: 276 °C. 1H NMR (CD2-
Cl2): δ 8.62 (d, 6H, JHH ) 7.5 Hz), 8.44 (m, 6H), 8.16 (d, 6H, JHH
) 6.6 Hz), 7.87 (m, 6H), 7.75 (m, 6H), 7.69 (s, 3H), 7.35 (s, 6H),
7.20 (d, 3H, JHH ) 6.9 Hz), 3.35 (h, 6H, JHH ) 6.9 Hz, CH), 1.36
(d, 36H, JHH ) 6.9 Hz, CH3). 13C{1H} NMR (CD2Cl2): δ 164.0,
156.5, 155.1, 146.9, 145.8, 144.0, 143.6, 142.2, 141.7, 137.6, 137.1,
134.7, 134.5, 129.3, 127.4 127.1, 126.7, 126.0, 124.9, 124.2, 123.3,
120.9, 120.5, 90.3, 89.9, 30.2, 21.9. IR (KBr pellet, cm-1): 2093
(υ(CtC)), 2155 (υ(CtN)). FAB-MS: m/z 2181 [M - ClO4]+.
Anal. Calcd for C99H84N9Cl3O12Pt3: C, 59.90; H, 4.27. Found: C,
59.98; H, 4.34.
i
[{Cr(CO)5(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5] (8). A stirred
THF solution (30 mL) of Cr(CO)6 (0.096 g, 0.43 mmol) was
irradiated using a Hg immersion lamp (150 W) at room temperature
for 3.5 h until the solution turned orange. Then ligand 5 (0.10 g,
0.14 mmol) in THF (5 mL) was added to the orange solution. The
solution was stirred for 30 min at room temperature. The solvent
was evaporated in vacuo, and excess Cr(CO)6 was removed by
vacuum sublimation. The pale yellow residue was extracted with
diethyl ether (20 mL × 3). Compound 8 was purified by
chromatography on silica gel using CH2Cl2/hexane (1:3) as an eluent
1
in 70% yield. mp: 176 °C. H NMR (CDCl3): δ 7.72 (s, 3H),
7.33 (s, 6H), 3.26 (h, 6H, JHH ) 7.2 Hz, CH), 1.35 (d, 36H, JHH
)
7.2 Hz, CH3). 13C{1H} NMR (CDCl3): δ 214.5, 214.2, 170.3, 145.5,
134.5, 128.4, 126.9, 124.4, 123.9, 90.3, 89.2, 29.9, 22.6. IR (KBr
pellet, cm-1): 2121 (υ(CtN)), 2090 (υ(CtC)), 2051 (υ(CtO)),
1957 (υ(CtO)). Anal. Calcd for C64H47Cr3N3O15: C, 61.30; H,
3.78. Found: C, 60.81; H, 3.61.
Emission and Lifetime Measurements. Emission spectra were
recorded on a Perkin-Elmer LS-50 spectrophotometer with a
Hamamatsu R928 photomultiplier. Luminescence lifetimes were
measured with a Quanta Ray DCR-3 pulsed Nd:YAG laser system
(355 nm, time resolution, 0.5 ns). Luminescence quantum yields
were performed on a Perkin-Elmer LS-50 spectrophotometer using
the method of Demas and Crosby with [Ru(bpy)3]2+ 36 as the
quantum yield standard (Φ ) 0.029).
i
[{AuCl(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5] (9). To a stirred
CH2Cl2 solution (10 mL) of Au(SMe2)Cl (0.026 g, 0.009 mmol)
was added ligand 5 (0.021 g, 0.003 mmol) in CH2Cl2 (10 mL) at
room temperature. The solution was stirred for 6 h. The solvent
was removed in vacuo and washed with Et2O (10 mL × 3). The
pure product 9 was obtained by recrystallization with CH2Cl2/Et2O
1
as a white crystalline solid in 84% yield. mp: 361 °C. H NMR
(CD2Cl2): δ 7.73 (s, 3H), 7.41 (s, 6H), 3.24 (h, 6H, JHH ) 6.9 Hz,
CH), 1.29 (d, 36H, JHH ) 6.9 Hz, CH3). 13C{1H} NMR (CD2Cl2):
δ 170.8, 147.0, 136.2, 127.6, 126.2, 123.8, 122.1, 90.4, 89.9, 30.2,
22.0. IR (KBr pellet, cm-1): 2090 (υ(CtC)), 2202 (υ(CtN)). Anal.
Calcd for C51H51N3Cl3Au3: C, 43.65: H, 3.66. Found: C, 43.41;
H, 3.52.
X-ray Crystallography. Suitable crystals of 2, 8, and 9 were
grown by THF/hexane, CH2Cl2/hexane, and CH2Cl2/Et2O, respec-
tively. All X-ray data of compounds 2, 8, and 9 were collected
using graphite-monochromated Mo KR radiation (λ ) 0.7173 Å)
with a Bruker AXS SMART CCD area-detector diffractometer. The
orientation matrix and unit cell parameters of 2, 8, and 9 were
determined by least-squares analyses of the setting angles of the
range 3.88° < 2θ < 56.62°, 2.36° < 2θ < 56.74°, and 2.78° < 2θ
< 56.68° with 8803, 8144, and 4445 reflections, respectively. Three
check reflections were measured every 100 reflections throughout
data collection and showed no significant variation in intensity.
Intensity data were collected with Ψ-scan data. All calculations
were carried out with the SHELXL-97 program. The structure was
i
[{AuSPh(CNC6H2 Pr2-2,6-CtC-3)}3C6H3-1,3,5] (10). Under
nitrogen NaSC6H5 (0.016 g, 0.121 mmol) was added to a stirred
THF (10 mL) and MeOH (10 mL) solution of 9 (0.053 g, 0.0378
mmol). After stirring for 1 h, the solution was evaporated and
washed with MeOH (5 mL × 2). The pure product 10 was obtained
by recrystallization with CH2Cl2/Et2O as an orange crystal in 84%
1
yield. mp: 324 °C. H NMR (CDCl3): δ 7.76 (s, 3H), 7.68 (d,
6H, JHH ) 6.6 Hz), 7.35 (s, 6H), 7.13 (m, 6H), 7.02 (t, 3H, JHH
6.6 Hz), 3.27 (h, 6H, JHH ) 6.6 Hz, CH), 1.33 (d, 36H, JHH ) 6.6
)
(36) Demas, J. N.; Crosby, G. A. J. Phys. Chem. 1971, 75, 991.
Inorganic Chemistry, Vol. 46, No. 7, 2007 2795

Paek et al.
solved by the direct method. All non-hydrogen atoms were refined
anisotropically. All hydrogen atoms were included in the calculated
positions. The SQUEEZE procedure in PLATON takes care of the
contribution of disordered solvents such as THF (complex 2),
hexane (complex 8), and diethyl ether (complex 9) to the calculated
structure factors by back-Fourier transformation of the continuous
density found in a masked region of the difference map. The masked
region is defined as the solvent accessible void left by the ordered
part of the structure.37
Acknowledgment. We are grateful for the KOSEF
through the National Research Laboratory (NRL2005)
program and the second stage of the BK-21 project in 2006.
Supporting Information Available: Crystallographic data in
CIF format for 2, 8, and 9. This material is available free of charge
via the Internet at http://pubs.acs.org.
IC0620900
(37) See the SQUEEZE instruction at http://www.cryst.chem.uu.nl/platon.
2796 Inorganic Chemistry, Vol. 46, No. 7, 2007