Iridium(III) and rhodium(III) cyclometalated complexes containing sulfur and selenium donor ligands

Article abstract of DOI:10.1016/j.jorganchem.2004.04.033

Treatment of [M(Buppy)₂Cl]₂ (M=Ir (1), Rh (2); BuppyH=2-(4′-tert-butylphenyl)pyridine) with Na(Et₂NCS₂), K[S₂P(OMe) ₂], and K[N(Ph₂PS)₂]₂ afforded monomeric [Ir(Buppy)₂ (S^∧S)] (S^∧S=Et₂NCS₂ (3), S₂ P(OMe)₂ (4), N(PPh₂S)₂ (5)) and [Rh(Buppy)₂(S^∧S)] (S^∧ S=Et₂NCS₂ (6), S₂P(OMe)₂ (7), N(PPh₂S)₂ (8)), respectively. Reaction of 1 with Na[N(PPh₂Se)₂] gave [Ir(Buppy)₂ {N(PPh₂Se)₂}] (9). The crystal structures of 3, 4, 7, and 8 have been determined. Treatment of 1 or 2 with AgOTf (OTf=triflate) followed by reaction with KSCN gave dinuclear [{M(Buppy)₂}₂(μ-SCN)₂] (M=Ir (10), Rh (11)), in which the SCN^- ligands bind to the two metal centers in a μ-S,N fashion. Interaction of 1 and 2 with [Et₄N]₂[WQ₄] gave trinuclear heterometallic complexes [{Ir(Buppy)₂}₂ (μ-WQ₄)] (Q=S (12), Se (13)) and [{Rh(Buppy)₂} ₂{(μ-WQ)₄}] (Q=S (14), Se (15)), respectively. Hydrolysis of 12 led to formation of [{Ir(Buppy)₂} ₂{W(O)(μ-S)₂(μ₃-S)}] (16) that has been characterized by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2004.04.033

Journal of Organometallic Chemistry 689 (2004) 2401–2410
www.elsevier.com/locate/jorganchem
Iridium(III) and rhodium(III) cyclometalated complexes
containing sulfur and selenium donor ligands
a
Man-Kit Lau , Ka-Man Cheung , Qian-Feng Zhang , Yinglin Song ,
a
a
b
c
Wing-Tak Wong , Ian D. Williams , Wa-Hung Leung
a
a,
*
a
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China
b
Department of Physics, Harbin Institute of Technology, Harbin 150001, PR China
c
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
Received 24 February 2004; accepted 27 April 2004
Abstract
Treatment of [M(Buppy)2Cl]2 (M ¼ Ir (1), Rh (2); BuppyH ¼ 2-(40-tert-butylphenyl)pyridine) with Na(Et2NCS2), K[S2P(OMe)2],
and K[N(Ph2PS)2]2 afforded monomeric [Ir(Buppy)2(S^S)] (S^S ¼ Et2NCS2 (3), S2P(OMe)2 (4), N(PPh2S)2 (5)) and [Rh(Bu-
ppy)2(S^S)] (S^S ¼ Et2NCS2 (6), S2P(OMe)2 (7), N(PPh2S)2 (8)), respectively. Reaction of 1 with Na[N(PPh2Se)2] gave [Ir(Bu-
ppy)2{N(PPh2Se)2}] (9). The crystal structures of 3, 4, 7, and 8 have been determined. Treatment of 1 or 2 with AgOTf
(OTf ¼ triflate) followed by reaction with KSCN gave dinuclear [{M(Buppy)2}2(l-SCN)2] (M ¼ Ir (10), Rh (11)), in which the SCNꢀ
ligands bind to the two metal centers in a l-S,N fashion. Interaction of 1 and 2 with [Et4N]2[WQ4] gave trinuclear heterometallic
complexes [{Ir(Buppy)2}2(l-WQ4)] (Q ¼ S (12), Se (13)) and [{Rh(Buppy)2}2{(l-WQ)4}] (Q ¼ S (14), Se (15)), respectively.
Hydrolysis of 12 led to formation of [{Ir(Buppy)2}2{W(O)(l-S)2(l3-S)}] (16) that has been characterized by X-ray diffraction.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Iridium(III); Rhodium(III); Cyclometalated complex; Sulfur ligands
1. Introduction
Mononuclear Ir(III) bis-cyclometalated complexes are
generally synthesized from dinuclear [Ir(ppy)2Cl]2. Sub-
stitution of [Ir(ppy)2Cl]2 with bidentate O,O or N,O li-
gands L^L afforded [Ir(ppy)2(L^L)], which have been
employed as dopants for OLEDs [13] and sensors for
singlet oxygen [18]. However, Ir(III) cyclometalated
complexes with chalcogen donor ligands have not been
well explored. Our interest in dithiolate ligands such as
dithiocarbamate [20] is stimulated by the fact that these
ligands are capable of stabilizing metal ions in unusual
oxidation states. For example, [Ir(R2NCS2)3] can be ox-
idized reversibly to [Ir(R2NCS2)3]þ [21]. Also of interest
are the tetrathio(seleno)tungstate(VII) anions [WQ4]2ꢀ
(Q ¼ S [22] or Se [23]) that binds to metal ions to give
heterometallic clusters. W(Mo)/M/S(Se) (M ¼ Cu, Ag,
Au and Pd) clusters are known to exhibit rich structural
chemistry and non-linear optical properties [22,23]. In
this paper, we report on the syntheses and crystal struc-
tures of cyclometalated Ir(III) and Rh(III) complexes
Luminescent complexes containing d6 transition metal
centers have attracted much attention due to their po-
tential applications to photocatalysis [1–3]. While exten-
sive works have been done on Ru(II) and Os(II)
complexes with polyimine ligands [1–3], the isoelectronic
Ir(III) analogues have received relatively less attention [4].
Recently, there is an increasing interest in the synthesis
and photophysical studies of Ir(III) complexes with cy-
clometalated ligands, notably 2-phenylpyridine (ppy)
[5–12], which have found applications as phosphors in
organic light emitting diodes (OLEDs) [13–16], sensors
[17,18], and luminescent labels for biomolecules [19].
* Corresponding author. Tel.: +(852)-23587360; fax: +(852)-2358-
1594.
E-mail address: chleung@ust.hk (W.-H. Leung).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.04.033

2402
M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
containing bidentate sulfur ligands and tetrathio(se-
leno)tungstate(VI) [WQ4]2ꢀ (Q ¼ S, Se).
7.19 (t, 2H, J ¼ 7 Hz, H6), 7.46 (d, 2H, J ¼ 8 Hz, H3),
7.68–7.81 (m, 4H, H4 and H5), 9.63 (d, 2H, J ¼ 5:6 Hz,
H7). MS (FAB): m=z 761 (Mþ).
4: Yield: 30 mg (63%). Anal. Calc. for C32H38N2S2O2
PIr: C, 49.92; H, 4.97; N, 3.64. Found: C, 49.91; H, 5.03;
N, 3.59%. 1H NMR (CDCl3): d 1.03 (s, 18H, t-Bu), 3.63
(s, 3H, CH3O), 3.68 (s, 3H, CH3O), 6.29 (d, 2H, J ¼ 2
Hz, H1), 6.84 (dd, 2H, J1 ¼ 2 Hz, J2 ¼ 6:6 Hz, H2), 7.21
(t, 2H, J ¼ 7:3 Hz, H6), 7.45 (d, 2H, J ¼ 8:2 Hz, H3),
7.71–7.82 (m, 4H, H4 and H5), 9.70 (d, 2H, J ¼ 6:2 Hz,
H7). 31P{1H} NMR (CDCl3): d 104.75 (s). MS (FAB):
m=z 770 (Mþ).
5: Yield (65%). Anal. Calc. for C54H52N3P2S2
Ir ꢁ H2O: C, 60.06; H, 5.00; N, 3.89. Found: C, 60.55; H,
4.84; N, 3.70%. 1H NMR (CDCl3): d 0.95 (s, 18H, t-Bu),
5.94 (d, J ¼ 2 Hz, 2H, H1), 6.28 (t, 2H, J ¼ 14:6 Hz,
H6), 6.84 (dd, 2H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H2), 6.97–7.02
(m, 4H, phenyl protons), 7.24 (t, 2H, J ¼ 1:6 Hz, H3),
7.34–7.72 (m, 10H, phenyl protons), 7.63–7.72 (m, 6H,
phenyl protons), 8.00–8.07 (m, 4H, H4 and H5), 9.12 (d,
2H, J ¼ 5:8 Hz, H7). 31P{1H} NMR (CDCl3): d 28.45
(s). MS (FAB): m=z 1061 (Mþ).
2. Experimental
2.1. General information
Solvents were purified by standard procedures and
distilled prior to use. The ligand 2-(40-tert-butylphe-
nyl)pyridine (BuppyH) was prepared by Pd-catalyzed
cross-coupling of 4-tert-butylphenylboronic acid and 2-
bromopyridine according to a literature method [24].
The atom labeling scheme for Buppyꢀ is shown below
4
5
3
6
7
t-Bu
2
N
1
[M(Buppy)2Cl]2 (M ¼ Ir (1), Rh (2)) were synthesized by
reactions of BuppyH with IrCl3 and RhCl3, respectively,
in alcohols as described elsewhere [25]. K[N(Ph2PQ)2]
(Q ¼ S [26] or Se [27]) and [Et4N]2[WQ4] (Q ¼ S [28] or
Se [29]) were synthesized according to literature meth-
ods. Other reagents were obtained from commercial
sources and used as received.
2.3. [Rh(Buppy)2(S^S)] (S^S ¼ Et2NCS2 (6), S2P-
(OMe)2 (7), N(PPh2S)2 (8))
These complexes were prepared similarly as for the Ir
analogues using 2 in place of 1, and recrystallized from
CH2Cl2/Et2O/hexane.
NMR spectra were recorded on a Bruker ALX 300
1
6: Yield: 23 mg (38%). Anal. Calc. for C35H42N3
S2Rh: C, 62.58; H, 6.30; N, 6.26. Found: C, 62.50; H,
6.32; N, 6.14%. 1H NMR (CDCl3): d 1.05 (s, 18H, t-Bu),
1.23–1.28 (m, 6H, CH2CH3), 3.62–3.66 (m, 2H,
CH2CH3), 4.02–4.09 (m, 2H, CH2CH3), 6.33 (s, 2H,
H1), 6.86 (dd, 2H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H2), 7.19–7.24
(m, 2H, H6), 7.49 (d, 2H, J ¼ 8 Hz, H3), 7.79 (d, 4H,
J ¼ 6 Hz, H4 and H5), 9.56 (d, 2H, J ¼ 7 Hz, H7). MS
(FAB): m=z 671 (Mþ).
spectrometer operating at 300 and 121.5 MHz for H
and 31P, respectively. Chemical shifts (d, ppm) were
referenced to SiMe4 (1H) and H3PO4 (31P). Infrared
spectra were recorded on a Perkin–Elmer 16 PC FT-IR
spectrophotometer and mass spectra on a Finnigan TSQ
7000 spectrometer. Elemental analyses were performed
by Medac Ltd., Surrey, UK.
2.2. [Ir(Buppy)2(S^S)] (S^S ¼ Et2NCS2 (3), S2P-
(OMe)2 (4), N(PPh2S)2 (5))
7: Yield: 30 mg (49%). Anal. Calc. for C32H38N2
1
S2O2PRh ꢁ H2O: C, 55.73; H, 5.66; N, 4.06. Found:
2
C, 55.97; H, 5.39; N, 4.10%. 1H NMR (CDCl3): d
1.03 (s, 18H, t-Bu), 3.63 (s, 3H, CH3O), 3.68 (s, 3H,
CH3O), 6.26 (s, 2H, H1), 6.91 (d, 2H, J ¼ 7 Hz, H2),
7.24 (t, 2H, J ¼ 6 Hz, H6), 7.50 (d, 2H, J ¼ 8 Hz,
H3), 7.79–7.84 (m, 4H, H4 and H5), 9.65 (d, 2H, J ¼ 6
Hz, H7). 31P{1H} NMR (CDCl3): d 103.88. MS
(FAB): m=z 680 (Mþ).
To a solution of 1 (ca. 0.04 mmol) in methanol (20
ml) was added the M[S^S] (M ¼ Na for Et2NCS2, K
for S2P(OMe)2 and N(SPPh2)2; 0.04 mmol) and the
mixture was stirred at room temperature for 3 h. The
solvent was pumped off, and the residue was washed
with methanol and Et2O and then extracted with
CH2Cl2. Recrystallization from CH2Cl2/Et2O/hexane
at room temperature in air afforded the yellow crys-
talline product.
8: Yield: 71 mg (75%). Anal. Calc. for
C54H52N3P2S2Rh: C, 66.73; H, 5.39; N, 4.32. Found: C,
1
66.58; H, 5.37; N, 4.10%. H NMR (CDCl3): d 0.97 (s,
3: Yield: 25 mg (53%). Anal. Calc. for C35H42N3S2
Ir ꢁ H2O: C, 54.54; H, 5.58; N, 5.45. Found: C, 54.45; H,
5.34; N, 5.19%. 1H NMR (CDCl3): d 1.03 (s, 18H, t-Bu),
1.21–1.27 (m, 6H, CH2CH3), 3.46–3.50 (m, 2H,
CH2CH3), 3.85–3.90 (m, 2H, CH2CH3), 6.36 (d, 2H,
J ¼ 2 Hz, H1), 6.81 (dd, 2H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H2),
18H, t-Bu), 5.93 (s, 2H, H1), 6.33 (t, 2H, J ¼ 7:0 Hz,
H6), 6.88 (d, 2H, J ¼ 10 Hz, H2), 6.97 (m, 4H, phenyl
protons), 7.33–7.51 (m, 10H, phenyl protons), 7.64–7.71
(m, 6H, phenyl protons), 8.04–8.12 (m, 4H, H4 and H5),
8.78 (d, 2H, J ¼ 5:8 Hz, H7). 31P{1H} NMR (CDCl3): d
34.80. MS (FAB): m=z 1065 (Mþ).

M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
2403
2.4. [Ir(Buppy)2{N(Ph2PSe)2}] (9)
Recrystallization from CH2Cl2/Et2O/hexane afforded
orange (12, yield: 37%) or red crystals (13, yield: 43%).
12: Despite two attempts, we were not able to obtain
satisfactory elemental analyses. The compound has been
characterized by NMR spectroscopy and mass spec-
To a solution of 1 (50 mg, 0.039 mmol) in MeOH (20
ml) were added 2 equiv. of K[N(Ph2PSe)2] (0.077 mmol)
and the mixture was stirred at room temperature over-
night. The solvent was pumped off and the residue was
washed with Et2O. Recrystallization from CH2Cl2/hex-
ane gave the yellow crystalline product. Yield: 31 mg
(69%). Anal. Calc. for C54H52N3P2Se2Ir: C, 55.29; H,
1
trometry. H NMR (CDCl3): d 1.05 (s, 36H, t-Bu), 6.39
(d, 4H, J ¼ 1:8 Hz, H1), 6.99 (t, 8H, J ¼ 15 Hz, H2),
7.55–7.63 (m, 8H, H3 and H5), 7.73 (d, 4H, J ¼ 7:8 Hz,
H4), 9.01 (d, 4H, J ¼ 6 Hz, H7). MS (FAB): m=z 1539
(Mþ + 1).
1
4.64; N, 3.59. Found: C, 55.79; H, 4.75; N, 3.43%. H
NMR (CDCl3): d 0.95 (s, 18H, t-Bu), 5.96 (s, 2H, H1),
6.25 (t, 2H, J ¼ 6:7 Hz, H6), 6.83 (d, 2H, J ¼ 8 Hz, H2),
7.01–7.06 (m, 4H, phenyl protons), 7.35–7.43 (m, 12H,
H3 and phenyl protons), 7.64–8.01 (m, 6H, phenyl
protons), 8.01–8.08 (m, 4H, H4 and H5), 9.20 (d, 2H,
J ¼ 5:4 Hz, H7). 31P{1H} NMR (CDCl3): d 16.72 (s).
MS (FAB): m=z 1155 (Mþ).
13: Anal. Calc. for C60H64N4Se4WIr2: C, 41.69; H,
1
3.70; N, 3.24. Found: C, 41.56; H, 3.74; N, 3.09%. H
NMR (CDCl3): d 1.04 (s, 36H, t-Bu), 6.37 (d, 4H,
J ¼ 1:8 Hz, H1), 6.91–6.97 (m, 8H, H2 and H6), 7.53–
7.61 (m, 8H, H3 and H5), 7.72 (d, 4H, J ¼ 8:2 Hz, H4),
9.18 (d, 4H, J ¼ 6 Hz, H7), MS (FAB): m=z 1727 (Mþ).
2.7. [{Rh(Buppy)2}2(WQ4)] (Q ¼ S (14), Se (15))
2.5. [{M(Buppy)2}2(l-SCN)2] (M ¼ Ir (10), Rh (11))
These were prepared similarly as for 12 and 13, re-
spectively, using 2 instead of 1. Recrystallization from
CH2Cl2/hexane gave yellow (14, yield: 40%) or red (15,
yield: 45%) crystals.
To a solution of 1 (40 mg, 0.031 mmol) in MeOH (20
ml) was added Ag(OTf) (OTf ¼ triflate, 0.062 mmol) and
the mixture was stirred at room temperature for 1 h and
filtered. To the red filtrate was added KSCN (10 mg,
0.062 mmol) and the mixture was stirred for 3 h and
evaporated to dryness by a rotavapor. The residue was
washed with hexane and Et2O, and then extracted with
CH2Cl2. Recrystallization from CH2Cl2/hexane gave
yellow crystals. Yield: 15 mg (34%). Complex 11 was
prepared by a similar procedure, employing 2 (34 mg)
instead of 1. Yield: 19 mg (41%)
14: Anal. Calc. for C60H64N4S4WRh2 ꢁ H2O: C,
52.28; H, 4.79; N, 4.07. Found: C, 52.23; H, 4.64; N,
4.01%. 1H NMR (CDCl3): d 1.03 (s, 36H, t-Bu), 6.30 (s,
4H, H1), 6.85–7.05 (m, 8H, H2 and H6), 7.55 (d, 4H,
J ¼ 4 Hz, H3), 7.61–7.72 (m, 8H, H4 and H5), 8.92 (d,
4H, J ¼ 5:6 Hz, H7). MS (FAB): m=z 1359 (Mþ).
15: Anal. Calc. for C60H64N4Se4WRh2: C, 46.04; H,
1
4.21; N, 3.58. Found: C, 46.19; H, 4.15; N, 3.53%. H
NMR (CDCl3): d 1.04 (s, 36H, t-Bu), 6.31 (s, 4H, H1),
6.85–7.00 (m, 8H, H2 and H6), 7.53 (d, 4H, J ¼ 8:2 Hz,
H3), 7.60–7.72 (m, 8H, H4 and H5), 9.04 (d, 4H, J ¼ 5:8
Hz, H7). MS (FAB): m=z 1546 (Mþ).
1
3
10: Anal. Calc. for C62H64N6S2Ir2 ꢁ hexane: C, 56.09;
H, 5.05; N, 6.13. Found: C, 56.15; H, 5.01; N, 6.07%. 1H
NMR (CDCl3): d 1.01 (s, 18H, t-Bu), 1.05 (s, 18H, t-Bu),
6.12 (d, 4H, J ¼ 12:6 Hz, H1), 6.86 (dd, 2H, J1 ¼ 1:8 Hz,
J2 ¼ 7:8 Hz, H2), 6.78 (dd, 2H, J1 ¼ 1:8 Hz, J2 ¼ 7:8 Hz,
H20), 7.04 (t, 4H, J ¼ 7:2 Hz, H6), 7.32–7.42 (m, 4H,
H3), 7.71–7.82 (m, 8H, H4 and H5), 9.14 (d, 2H, J ¼ 5:4
Hz, H7), 9.88 (d, 2H, J ¼ 5:4 Hz, H70). IR (KBr, cmꢀ1):
2132 (s) [m(CBN)]. MS (FAB): m=z 1341 (Mþ).
2.8. [{Ir(Buppy)2}2{WO(l-S)2(l3-S)}] (16)
Complex 12 was dissolved in CH2Cl2 and was left to
stand in air at )10 °C for ca. 1 month. The yellow
crystals formed were collected and washed with hexanes.
Yield: 10%. Anal. Calc. for C60H64N4OS3-
WIr2 ꢁ CH2Cl2: C, 45.60; H, 4.14; N, 3.49. Found: C,
11: Anal. Calc. for C62H64N6S2Rh2: C, 64.02; H,
1
5.54; N, 7.22. Found: C, 63.87; H, 5.15; N, 7.12%. H
NMR (CDCl3): d 1.03 (s, 36H, t-Bu), 5.30 (s, 4H, H1),
6.26 (d, 4H, J ¼ 2 Hz, H2), 6.90 (t, 4H, J ¼ 7:8 Hz, H6),
7.48 (d, 4H, J ¼ 2 Hz, H3), 7.79–7.87 (m, 8H, H4 and
H5), 9.64 (d, 4H, J ¼ 5:4 Hz, H7). IR (KBr, cmꢀ1): 2129
(s) [m(CBN)]. MS (FAB): m=z 1163 (Mþ).
1
45.12; H, 4.11; N, 3.44%. H NMR (CDCl3): d 1.03 (s,
36H, t-Bu), 6.33 (s, 4H, H1), 6.81–7.04 (m, 8H, H2 and
H6), 7.53 (m, 4H, H5), 7.69 (d, 8H, H4), 9.07 (d, 4H, H7).
IR (KBr, cmꢀ1): 881 [m(W@O)]. MS (FAB): m=z 1522
(Mþ + 1).
2.6. [{Ir(Buppy)2}2(WQ4)] (Q ¼ S (12), Se (13))
2.9. X-ray crystallography
To a solution of 1 (0.036 mmol) in CH2Cl2 (20 ml)
was added 1 equiv. of [Et4N]2[WQ4] (0.036 mmol) and
the mixture was stirred at room temperature overnight.
The solvent was pumped off and the residue was washed
with hexane and Et2O and then extracted with CH2Cl2.
Crystallographic data and experimental details for
complexes 3, 4, 7 ꢁ 4CH2Cl2, and 8 are summarized in
Table 1 and those for 10 ꢁ C6H14, 11 ꢁ C6H14 ꢁ 2H2O,
15 ꢁ 2C6H14, and 16 ꢁ 4CH2Cl2 ꢁ 0.5H2O in Table 2. In-
tensity data of all complexes were collected on a Bruker

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M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
Table 1
Crystallographic data and experimental details for [Ir(Buppy)2(Et2NCS2)] (3), [Ir(Buppy)2{S2P(OMe)2}] (4), [Rh(Buppy)2{S2P(OMe)2}] ꢁ 4CH2Cl2
(7 ꢁ 4CH2Cl2), and [Rh(Buppy)2{N(SPPh2)2}] (8)
3
4
7 ꢁ 4CH2Cl2
C33H40Cl2N2O2RhS2
8
Empirical formula
Formula weight
Crystal system
Space group
C32H38IrN2O2PS2
769.98
Triclinic
C35H42Ir N3S2
761.08
Monoclinic
C54H52N3P2RhS2
971.96
Monoclinic
765.57
Triclinic
ꢁ
ꢁ
P1
P21=n
P1
P21=n
ꢀ
a (A)
10.101(1)
11.477(1)
16.296(2)
107.96(1)
94.45(1)
113.11(1)
1609.8(4)
2
11.269(1)
20.186(2)
15.984(1)
9.6198(4)
12.1914(5)
16.3629(7)
91.390(1)
104.004(1)
111.713(1)
1716.0(1)
2
11.2789(6)
17.2900(9)
24.476(1)
ꢀ
b (A)
ꢀ
c (A)
a (°)
b (°)
c (°)
107.42(1)
101.088(1)
3
ꢀ
V (A )
3469.2(5)
4
4681.1(4)
4
1.387
Z
qcalc (g cmꢀ3
Temp (K)
F ð000Þ
)
1.588
298
1.457
298
1528
1.482
100
100
2016
768
4.369
788
0.854
l(Mo Ka) (mmꢀ1
)
4.006
20,672
7949
0.562
Reflection collected
Independent reflection
Rint
9865
6915
10,232
7548
28,191
10,991
0.0340
1.024
0.052
2.17
0.063, 0.072c
0.020
1.03
0.024, 0.030c
0.0117
1.040
Goodness-of-fit
R1,a wR2b (I > 2rðIÞ)
0.0266, 0.0689
0.0283, 0.0700
0.0354, 0.0779
0.0482, 0.0829
R1,a wR2b (all data)
P
P
a R1 ¼ jjFoj ꢀ jFcjj= jFoj.
P
P
2
2 1=2
b wR2 ¼ ½ wðjFo2j ꢀ jFc2jÞ = wjFo2j ꢂ
.
P
P
2
2 1=2
c Rw ¼ ½ wðjFoj ꢀ jFcjÞ = wjFoj ꢂ
.
Table 2
Crystallographic data and experimental details for [{Ir(Buppy)2}2(l-SCN)2] ꢁ C6H14 (10 ꢁ C6H14), [{Rh(Buppy)2}2(l-SCN)2] ꢁ C6H14 ꢁ 2H2O
(11 ꢁ C6H14 ꢁ 2H2O), [{Rh(Buppy)2}2(l-WSe4)] ꢁ 2C6H14 (15 ꢁ 2C6H14), and [{Ir(Buppy)2}2{WO(l-S)2(l3-S)}] ꢁ 4CH2Cl2 ꢁ 0.5H2O (16 ꢁ 4CH2Cl2 ꢁ
0.5H2O)
10 ꢁ C6H14
C74H92Ir2N6S2
11 ꢁ C6H14 ꢁ 2H2O
C74H96N6O2Rh2S2
15 ꢁ 2C6H14
C72H92N4Rh2Se4W
16 ꢁ 4CH2Cl2 ꢁ 0.5H2O
C64H73Cl8Ir2N4O1:5S3W
Empirical formula
Formula weight
Crystal system
Space group
1514.06
Monoclinic
P21=c
13.2267(6)
22.7050(11)
11.1233(5)
1371.51
Monoclinic
P21=c
13.223(5)
22.775(8)
11.125(4)
1719.01
Triclinic
1870.29
Triclinic
ꢁ
ꢁ
P1
P1
ꢀ
a (A)
12.002(2)
17.420(2)
18.182(3)
72.298(3)
83.184(3)
78.694(3)
3544.1(8)
2
15.42(1)
15.67(1)
15.70(1)
62.49(1)
84.29(1)
83.43(1)
3550(1)
2
ꢀ
b (A)
ꢀ
c (A)
a (°)
b (°)
c (°)
93.875(1)
94.848(7)
3
ꢀ
U (A )
3332.8(3)
2
1.509
3341.0(2)
2
1.363
Z
Dcalc (g cmꢀ3
T (K)
)
1.611
100(2)
1.749
100(2)
98(2)
1528
100(2)
1440
F ð000Þ
1704
4.175
1818
5.786
l (mmꢀ1
)
4.098
20,011
7754
0.607
20,347
7883
Reflection collected
Independent reflection
Rint
17,780
12,250
21,098
15,503
0.0333
1.042
0.0707
0.992
0.0807
0.904
0.0770
0.882
Goodness-of-fit
R1,a wR2b (I > 2rðIÞ)
0.0299, 0.0717
0.0377, 0.0749
0.0629, 0.1501
0.1105, 0.1730
0.0614, 0.1079
0.1000, 0.1346
0.0573, 0.0884
0.1032, 0.1503
R1,a wR2b (all data)
P
P
a R1 ¼ jjFoj ꢀ jFcjj= jFoj.
P
SMART APEX 1000 area-detector diffractometer using
P
2
2 1=2
b wR2 ¼ ½ wðjFo2j ꢀ jFc2jÞ = wjFo2j ꢂ
.
refined by full-matrix least-squares analyses on F2. Non-
hydrogen atoms were refined anisotropically. Hydrogen
atoms were placed in their calculated positions. Calcula-
graphite-monochromated Mo Ka radiation (k ¼ 0:70173
ꢀ
A). The structures were solved by direct methods and

M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
2405
tions were performed using the TEXSAN [30] (for 3 and 4)
and SHELXTL [31] (for other complexes) crystallographic
software packages.
for 9 was observed at d 16.72 that is more upfield than
that for the sulfide analogue 5.
The solid-state structures of 3, 4, 7 and 8 have been
unambiguously established by X-ray crystallography.
The corresponding crystal structures are shown in Figs.
1–4. Selected metrical parameters for these complexes
are compiled in Table 3 for comparison. In each of these
complexes, the geometry around the metal is distorted
octahedral with two mutually trans pyridyl groups and
the sulfur atoms being opposite to the phenyl rings. The
3. Results and discussion
3.1. Cyclometalated complexes containing sulfur donor
ligands
ꢀ ꢀ
Dinuclear [M(Buppy)2Cl]2 (M ¼ Ir 1, Rh 2) were
synthesized by refluxing IrCl3 and RhCl3 with 2-(40-tert-
butylphenyl)pyridine (BuppyH) in alcohol, respectively
[25]. As expected, treatment of [M(Buppy)2Cl]2 with
bidentate sulfur ligands resulted in cleavage of the
chloro bridges and formation of mononuclear com-
plexes. Scheme 1 summarizes the reactions of 1 and 2
with sulfur and selenium donor ligands. Treatment of 1
with NaS2CNEt2, K[S2P(OEt)2], and K[N(PPh2S)2] led
to formation of [Ir(Buppy)2(S^S)] (S^S ¼ Et2NCS2 (3),
PS2(OMe)2 (4), N(PPh2S)2 (5)). The corresponding Rh
(III) complexes [Rh(Buppy)2(S^S)] (S^S ¼ Et2NCS2 (6),
S2P(OMe)2 (7), N(PPh2S)2 (8)) were prepared similarly
from 2 and Na[S^S] or K[S^S]. The Ir diselenide com-
plex [Ir(Buppy)2{N(PPh2Se)2}] (9) was prepared from 1
and K[N(PPh2Se)2]. These complexes are soluble in
most organic solvents except hexanes, and are stable in
both the solid state and solution. They have been fully
characterized by spectroscopic methods and elemental
analyses. The 31P chemical shifts for complexes 4 (d
104.8) and 7 (d 103.9) and 5 (d 28.45) and 8 (d 34.80) are
typical for dithiophosphate [32] and imidodiphosphi-
nosulfide [33] complexes, respectively. The 31P resonance
average Ir–C (2.012(2) A for 3 and 2.024(2) A for 4) and
ꢀ
ꢀ
Ir–N (2.052(1) A for 3 and 2.054(2) A for 4) distances
are normal by comparison with other Ir(III) bis-ppy
complexes [9a,9b,9c]. The average Ir–S distances for 3
ꢀ
ꢀ
(2.478(2) A) and 4 (2.532(2) A) are longer than that in
ꢀ
[Ir(Et2NCS2)3] (2.367(3) A) [34] due to trans influence of
ꢀ
the phenyl groups. The average Rh–C (1.995(2) A for 7
ꢀ
and 2.003(1) A for 8) and Rh–N distances (2.046(2) and
ꢀ
2.054(1) A, respectively) are normal [35]. The Rh–S
N
Fig. 1. Perspective view of [Ir(Buppy)2(Et2NCS2)] (3).
Et
Et
C
C
S
S
M
N
C
N
N
M
N
N
M
N
N
M
N
C
C
S
S
OMe
OMe
Q
Q
Q
Q
C
C
M = Ir (3), Rh (6)
C
C
P
W
i
ii
v
M = Ir (4), Rh (7)
M = Ir, Q= S (12)
Q = Se (13)
M = Rh, Q = S (14)
Q = Se (15)
N
M
N
N
M
N
C
C
Cl
Cl
C
C
iii
M = Ir (1), Rh(2)
Ph
Ph
iv
N
M
N
C
Q
P
P
N
M
N
S
N
N
M
N
C
C
C
Q
N
S
C
C
Ph
C
N
Ph
C
M = Ir, Q = S (5)
M = Ir, Q = Se (9)
M = Rh, Q = S (8)
M = Ir (10)
M = Rh (11)
t-Bu
=
N
C
N
Buppy
Scheme 1.
Fig. 2. Perspective view of [Ir(Buppy)2{S2P(OMe)2}] (4).

2406
M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
As previously reported, 1 reacted with Ag(OTf) to
give the aquo compound [Ir(Buppy)2(H2O)2][OTf] and
AgCl [37]. Interaction of [Ir(Buppy)2(H2O)2][OTf] with
KSCN in MeOH gave dimeric [{Ir(Buppy)2}2(l-SCN)2]
(10) that has been characterized by X-ray crystallogra-
phy. The rhodium analogue [{Rh(Buppy)2}2(l-SCN)2]
(11) was prepared similarly and structurally character-
ized. The preparation of [Ir(ppy)(SCN)2]ꢀ from
[Ir(ppy)2Cl]2 and SCNꢀ has been reported recently [12].
Figs. 5 and 6 show the molecular structures of 10 and
11, respectively; selected bond lengths and angles are
listed in Table 4. In both structures, the asymmetric unit
consists of half of the molecule and is related by an in-
version center. The M–C and M–N(Buppy) distances in
both complexes are normal. The M–S distance for the
Fig. 3. Perspective view of [{Rh(Buppy)2}2{S2P(OMe)2}] (7).
ꢀ
Rh compound 11 (2.529(2) A) is slightly longer than
ꢀ
that in the Ir compound 10 (2.496(1) A). In both 10 and
11, the bridging SCNꢀ ligands bind to the two metal
centers in a l-S,N fashion. The M–S–CBN units are
approximately linear (the C–N–M angle of 165.1(3) and
164.1(4)° for 10 and 11, respectively) and the S–M–N#
(CS) angles (ꢀx þ 1, ꢀy þ 1, ꢀz þ 1) are close to 90°.
Fig. 4. Perspective view of [{Rh(Buppy)2}2{N(SPPh2)2}] (8).
ꢀ
distances for 7 (2.548(2) A) and 8 (2.487(2) A) are longer
ꢀ
ꢀ
than those in [Rh(Et2NCS2)3] (2.364(3) A) [36] due to
trans influence of the phenyl groups.
Fig. 5. Perspective view of [{Ir(Buppy)2}2(l-SCN)2] (10).
Table 3
ꢀ
Selected bond lengths (A) and angles (°) for [Ir(Buppy)2(Et2NCS2)] (3), [Ir(Buppy)2{S2P(OMe)2}] (4), [Rh(Buppy)2{S2P(OMe)2}] ꢁ 4CH2Cl2
(7 ꢁ 4CH2Cl2), and [Rh(Buppy)2{N(SPPh2)2}] (8)
3 (M ¼ Ir)
4 (M ¼ Ir)
7 ꢁ 4CH2Cl2(M ¼ Rh)
8 (M ¼ Rh)
Bond lengths
M–S
2.471(1)
2.484(1)
2.050(3)
2.053(3)
2.010(4)
2.013(4)
2.528(3)
2.535(3)
2.054(8)
2.054(8)
2.018(9)
2.030(9)
2.5284(4)
2.5674(5)
2.044(2)
2.047(2)
1.995(2)
1.996(2)
2.4761(5)
2.4986(6)
2.050(2)
2.058(2)
2.002(2)
2.003(2)
M–N
M–C
Bond angles
S(1)–M–S(2)
N(1)–M–N(2)
C–M–C0
71.20(4)
170.1(1)
91.1(1)
80.2(1)
80.1(1)
92.1(1)
93.8(1)
79.45(9)
170.8(3)
89.1(3)
80.0(4)
80.8(3)
92.9(3)
93.2(3)
79.40(1)
170.94(6)
89.49(7)
81.05(7)
81.16(6)
92.26(6)
92.62(6)
100.81(2)
171.79(7)
90.70(8)
80.73(8)
80.93(8)
92.15(8)
94.86(8)
C–M–N
C–M–N0

M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
2407
Fig. 7. Perspective view of [{Rh(Buppy)2}2(l-WSe4)] (15).
Fig. 6. Perspective view of [{Rh(Buppy)2}2(l-SCN)2] (11).
Table 4
Table 5
ꢀ
ꢀ
Selected bond lengths (A) and angles (°) for [{M(Buppy)2}2(l-
SCN)2] ꢁ (M ¼ Ir or Rh)
Selected bond lengths (A) and angles (°) for [{Rh(Buppy)2}2(l-WSe4)]
(15)
Bond lengths
10 (M ¼ Ir)
11 (M ¼ Rh)
W(1)–Se(1)
W(1)–Se(3)
W(1)–Rh(1)
Rh(1)–C(11)
Rh(2)–C(51)
Rh(1)–N(1)
Rh(2)–N(3)
Rh(1)–Se(1)
Rh(2)–Se(4)
2.335(1)
2.328(1)
3.031(1)
1.98(1)
W(1)–Se(2)
W(1)–Se(4)
W(1)–Rh(2)
Rh(1)–C(31)
Rh(2)–C(71)
Rh(1)–N(2)
Rh(2)–N(4)
Rh(1)–Se(2)
Rh(2)–Se(3)
2.322(1)
2.331(1)
3.049(1)
1.99(1)
Bond lengths
M(1)–S(1)
2.4957(8)
2.105(3)
2.052(3)
2.033(3)
2.018(3)
2.004(3)
2.5289(15)
2.125(4)
2.047(4)
2.029(4)
2.002(5)
1.988(5)
M(1)–N(1)a
M(1)–N(2)
M(1)–N(3)
M(1)–C(20)
M(1)–C(40)
2.04(1)
2.073(9)
2.04(1)
2.03(1)
2.061(9)
2.06(1)
2.545(2)
2.563(1)
2.558(2)
2.583(2)
Bond angles
N(3)–M(1)–N(2)
N(2)–M(1)–S(1)
N(3)–M(1)–S(1)
C(20)–M(1)–S(1)
C(40)–M(1)–S(1)
C(20)–M(1)–N(2)
C(40)–M(1)–N(2)
C(20)–M(1)–N(3)
C(40)–M(1)–N(3)
C(40)–M(1)–C(20)
172.6(1)
96.71(8)
90.19(8)
174.69(9)
85.91(9)
80.6(2)
172.2(2)
96.9(1)
90.3(1)
174.5(1)
86.2(2)
80.8(2)
96.4(2)
91.8(2)
81.1(2)
89.1(2)
Bond angles
Se(2)–W(1)–Se(3)
Se(3)–W(1)–Se(4)
Se(3)–W(1)–Se(1)
N(2)–Rh(1)–N(1)
Se(1)–Rh(1)–Se(2)
111.20(5)
109.45(4)
108.93(5)
168.9(4)
96.67(5)
Se(2)–W(1)–Se(4)
Se(2)–W(1)–Se(1)
Se(4)–W(1)–Se(1)
N(3)–Rh(2)–N(4)
Se(4)–Rh(2)–Se(3)
107.91(5)
109.85(5)
109.47(4)
167.0(4)
95.33(5)
97.5(1)
92.3(1)
C(11)–Rh(1)–C(31) 84.1(5)
C(71)–Rh(2)–C(51) 85.9(4)
W(1)–Se(2)–Rh(1)
W(1)–Se(4)–Rh(2)
W(1)–Se(1)–Rh(1)
W(1)–Se(3)–Rh(2)
Rh(1)–W(1)–Rh(2) 169.24(3)
76.64(5)
76.55(4)
76.61(5)
76.90(4)
80.3(1)
89.9(1)
a Symmetry operation: ꢀx þ 1, ꢀy þ 1, ꢀz þ 1.
Thus, the eight-membered M2(SCN)2 core in these
complexes can be roughly described as a rectangle.
organorhodium(III) compound containing the [WSe4]2ꢀ
anion. A trinuclear Rh/W/S complex [{(COD)Rh}2(l-
WS4)] (COD ¼ 1,5-cyclooctadiene) has been synthesized
by Rauchfuss and coworkers [39]. The solid-state
structure of 15 contains two symmetry-related {(Bu-
ppy)2Rh(l-Se)2} units with the W at the center of in-
version. The geometry around Rh is octahedral and that
around W is tetrahedral (average Se–W–Se bond an-
gle ¼ 109.47(5)°). The Rh–C and Rh–N distances are
3.2. Heterobimetallic complexes containing [WQ4]2ꢀ
(Q ¼ S or Se)
Treatment of 1 or 2 with 0.5 equiv. of [Et4N]2[WS4]
afforded the trinuclear heterobimetallic complexes
[{M(Buppy)2}2(l-WS4)] (M ¼ Ir (12), Rh (13)). Simi-
larly, reaction of 1 or 2 with [Et4N]2[WSe4] afforded
[{M(Buppy)2}2(l-WSe4)] (M ¼ Ir (14), Rh (15)). The
FAB mass spectra of complexes 12–15 display molecular
ion peaks corresponding to Mþ. A preliminary study
showed that 12 and 15 exhibit both non-linear absorp-
tion and non-linear refraction properties [38].
similar to those in 8. The average Rh–Se bond distance
ꢀ
of 2.562(2)
A
in 15 is longer than that in
[Cp*Rh(PMe3)(g2-C,Se–C4H4Se)] (Cp* ¼ g5-C5Me5)
ꢀ
(2.456(3) A) [40]. Similar to other trinuclear heterosele-
nometallic complexes [41,42], the Rh(1)ꢁ ꢁ ꢁW(1)ꢁ ꢁ ꢁRh(2)
unit in 15 is approximately linear (169.24(3)°).
Complex 15 has been characterized by X-ray dif-
fraction. Fig. 7 shows a perspective view of the molecule;
selected bond lengths and angles are listed in Table 5. To
our knowledge, this is the first structurally characterized
Attempts to grow X-ray quality crystals for 12 were
unsuccessful. However, recrystallization of 12 from
CH2Cl2 in air over a long period of time (>1 month)
afforded yellow crystals that were identified as the

2408
M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
ꢀ
A) is slightly longer than the W-(l-S) distance (average
ꢀ
2.242(3) A).
3.3. UV–Vis spectra
The UV–Vis spectral data for the Ir(III) and Rh(III)
cyclometalated complexes in CH2Cl2 are summarized in
Table 7. For the Ir complexes 3–5 and 10, the absorp-
tions in the higher energy region (ca. 245–374 nm) are
attributed to electronic transitions arising from the Bu-
ppy and bidentate sulfur ligands. Similar absorption
bands were found for the corresponding free S^S ligands
and unmetalated Buppy. For comparison, the ligand-
centered (LC) bands for [Ir(ppy)2(acac)] [9a] and
[Ir(Dtb)3] (Dtb ¼ dithiobenzoate) [20a] were observed at
250–360 and 288–340 nm, respectively. Similarly, the
absorptions at 245–290 nm for the Rh(III) analogues 6–
8 and 11 are assigned as LC (Buppy and S^S) bands.
Previously, the absorptions at 410 and 460 nm for
[Ir(tpy)2(acac)] (tpyH ¼ 2-(p-tolyl)pyridine) have been
assigned as the singlet and triplet MLCT
[dpðIrÞ ! pꢃðppyÞ] transitions, respectively. Thus, the
lower energy bands (kmax > 400 nm) for the Ir com-
plexes 3–5 and 10 are attributed to the MLCT [dpðIrÞ
! pꢃðBuppyÞ] transition that may be mixed with tran-
sition(s) arising from the Ir(S^S) moiety. The corre-
sponding absorptions for the Rh complexes 6–8 and 11
were found in shorter wavelengths (330–393 nm). Ad-
ditional works are required to unambiguously confirm
the origin of electronic transition for these lower energy
absorption bands. For the heterometallic Ir/W/S com-
plex 12, in addition to the LC absorptions, an intense
band at 483 nm (e ¼ 7:8 ꢄ 103 Mꢀ1 cmꢀ1) was observed.
This low energy band may be due to the LMCT
Fig. 8. Perspective view of [{Ir(Buppy)2}2(l3-WOS3)] (16).
[WOS3]2ꢀ-bridged trinuclear complex [{Ir(Buppy)2}2-
{WO(l-S)2(l3-S)}] (16) (Eq. (1))
O
W
S
N
Ir
N
Ir
S
N
C
S
H2O
S
S
S
S
C
C
C
C
N
W
ð1Þ
C
Ir
Ir
C
N
N
N
N
C
12
16
The IR spectrum of 16 shows a sharp peak at 881
cmꢀ1 assignable to the W@O stretch. It is believed that
the W@O group was formed by hydrolysis of a W@S
group in 12 during recrystallization [43]. The crystal
structure of 16 is shown in Fig. 8; selected bond lengths
and angles are listed in Table 6. The structure of 16
consists of two [Ir(Buppy)2]þ fragments bridged by a
[W(O)(l-S)2(l3-S)]2ꢀ ligand. A similar binding mode
has been found for related heterometallic Cu(Ag,Au)/
Mo(W)/S clusters containing the [W(S)(l-S)(l3-S)]2ꢀ
ꢀ
anion [44]. The average Wꢁ ꢁ ꢁIr separation is 2.912(2) A.
ꢀ
The average Ir–S distance is 2.467(2) A. The geometry
around W is tetrahedral with bond angles ranging from
106.6(3)° to 112.83(12)°. The W-(l3-S) distance (2.291(3)
Table 7
UV–Vis spectral data for cyclometalated Ir(III) and Rh(III) complexes
in CH2Cl2 at room temperature
Table 6
ꢀ
Selected bond lengths (A) and angles (°) for [{Ir(Buppy)2}2{WO(l-
S)2(l3-S)}] (16)
Complex
k )
max/nm (e/103 Mꢀ1 cmꢀ1
Bond lengths
3
245 (40.8), 290 sh (10.4), 365 (6.66), 400 sh (2.69), 455
(0.99)
W(1)–O(1)
W(1)–S(2)
Ir(1)–S(1)
Ir(2)–S(1)
Ir(1)–W(1)
Ir(1)–C(11)
Ir(2)–C(51)
Ir(1)–N(1)
Ir(2)–N(3)
1.740(7)
2.226(3)
2.461(3)
2.437(3)
2.910(2)
2.06(1)
W(1)–S(1)
W(1)–S(3)
Ir(1)–S(3)
Ir(2)–S(2)
Ir(2)–W(1)
Ir(1)–C(31)
Ir(2)–C(70)
Ir(1)–N(2)
Ir(2)–N(4)
2.291(3)
2.257(3)
2.484(3)
2.486(3)
2.914(2)
2.03(1)
4
5
262 (42.1), 290 sh (12.6), 350 (7.58), 400 sh (4.67), 450
(0.98)
263 (45.2), 347 sh (4.60), 374 (4.01), 399 sh (3.60), 451
(0.90)
6
7
8
9
245 (59.8), 285 sh (40.0), 393 (14.3)
246 (60.0), 276 sh (45.9), 330 (4.70)
245 (61.2), 290 sh (39.8), 377 (16.0)
256 (60.1), 289 sh (36.0), 357 sh (5.30), 380 (4.80), 403
(3.90)
2.03(1)
2.077(9)
2.101(9)
2.05(1)
2.060(9)
2.089(9)
Bond angles
O(1)–W(1)–S(2)
S(2)–W(1)–S(3)
S(2)–W(1)–S(1)
W(1)–S(1)–Ir(2)
Ir(2)–S(1)–Ir(1)
W(1)–S(3)–Ir(1)
S(1)–Ir(2)–S(2)
N(4)–Ir(2)–N(3)
108.5(2)
112.8(1)
109.6(1)
76.04(9)
129.0(1)
75.6(1)
O(1)–W(1)–S(3)
O(1)–W(1)–S(1)
S(3)–W(1)–S(1)
W(1)–S(1)–Ir(1)
W(1)–S(2)–Ir(2)
S(1)–Ir(1)–S(3)
N(2)–Ir(1)–N(1)
C(31)–Ir(1)–C(11)
106.6(3)
108.6(3)
110.6(1)
75.4(1)
10
246 (60.6), 276 sh (45.9), 363 (30.7)sh, 393 (7.50), 427
sh (4.60), 475 (1.00)
11
12
13
14
15
16
247 (58.4), 266 sh (27.7), 307 sh (25.8), 381 (8.0)
247 (55.4), 281 sh (684.3), 359 sh (2.90), 483 (7.80)
255 (61.6), 378 sh (29.0), 461 sh (5.62), 544 (9.65)
246 (60.9), 310 sh (32.1), 435 (6.92)
250 (61.8), 355 (27.8)sh, 438 (7.39) sh, 510 (6.10)
257 (64.1), 351 (7.27) sh, 481 (3.32)
76.20(9)
98.2(1)
97.1(1)
165.7(4)
167.0(3)
87.6(4)

M.-K. Lau et al. / Journal of Organometallic Chemistry 689 (2004) 2401–2410
2409
1.0
0.8
0.6
0.4
0.2
0.0
5. Supporting information available
Crystallographic data for complexes 3, 4, 7 ꢁ 4CH2Cl2,
8, 10 ꢁ C6H14, 11 ꢁ C6H14 ꢁ 2H2O, 15 ꢁ 2C6H14, and
16 ꢁ 4CH2Cl2 ꢁ 0.5H2O have been deposited with the
Cambridge Crystallographic Data Centre, CCDC Nos.
231906, 231905, 231908, 231907, 231903, 231904, and
231902, respectively, in CIF format. Copies of this in-
formation may be obtained free of charge from The Di-
rector, CCDC, 12 Union Road, Cambridge, CB2 1EZ,
UK (fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk).
400
450
500
550
600
650
Wavelength (nm)
Fig. 9. Emission spectrum for 3 in CH2Cl2 at room temperature (ex-
citation wavelength ¼ 455 nm).
Acknowledgements
The financial support from the Hong Kong Research
Grants Council and the Hong Kong University of Sci-
ence and Technology is gratefully acknowledged. We
thank Dr. Kenneth K.-W. Lo for helpful discussion and
reviewers for useful suggestions and comments.
[ppðSÞ ! dpðW Þ] together with MLCT [dpðIrÞ !
pꢃðBuppyÞ] transitions. It has been reported that the
LMCT
[ppðSÞ ! dpðWÞ]
bands
for
[WS4]2ꢀ
(kmax ¼ 392, 277 and 216 nm) [45] are red-shifted upon
coordination of transition metal ions [22,23]. Further
support for the LMCT [ppðSÞ ! dpðWÞ] contribution
to the 483-nm band comes from the observations that
this band is red-shifted to 544 nm upon substitution of
[WSe4]2ꢀ for [WS4]2ꢀ (complex 13) and blue-shifted to
435 nm upon substitution of Rh for Ir (complex 14).
However, this spectral assignment is only tentative.
Additional experimental works are required to confirm
the exact origin of electronic transition for these ab-
sorption bands.
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