New pentamethylcyclopentadienyl rhodium and iridium complexes containing arylazoimidazole ligands: Crystal and molecular structure of the complex [(η5-C5Me5)RhCl(Me-C6H 4-N{double bond, long}N-C3

Article abstract of DOI:10.1016/j.poly.2007.07.007

The dimeric [{(η⁵-C₅Me₅)M(μ-Cl)Cl}₂ ] complexes (η⁵-C₅Me₅ = pentamethylcyclopentadienyl; M = Rh and Ir) react with several arylazoimidazole (RaaiR′) ligands, viz., 2-(phenylazo)i

Full text of DOI:10.1016/j.poly.2007.07.007

Polyhedron 26 (2007) 5039–5044
www.elsevier.com/locate/poly
New pentamethylcyclopentadienyl rhodium and iridium
complexes containing arylazoimidazole ligands: Crystal
and molecular structure of the complex
[(g5-C5Me5)RhCl(Me–C6H4–N@N–C3H3N2)]+
a,b,
a
Padavattan Govindaswamy
*, Yurij A. Mozharivskyj c,1, Mohan Rao Kollipara
a
Department of Chemistry, North-Eastern Hill University, Shillong 793 022, India
ˆ ˆ
Institut de Chimie, Universite´ de Neuchatel, Case postale 158, CH-2009 Neuchatel, Switzerland
b
c
ABB 423, Department of Chemistry, McMaster University, 1280 Main Street West Hamilton, Ontario, Canada L8S 4M1
Received 27 April 2007; accepted 6 July 2007
Available online 15 August 2007
Abstract
The dimeric [{(g5-C5Me5)M(l-Cl)Cl}2] complexes (g5-C5Me5 = pentamethylcyclopentadienyl; M = Rh and Ir) react with several ary-
lazoimidazole (RaaiR0) ligands, viz., 2-(phenylazo)imidazole (Phai-H), 1-methyl-2-(phenylazo)imidazole (Phai-Me), 1-ethyl-2-(pheny-
lazo)imidazole (Phai-Et), 2-(tolylazo)imidazole (Tai-H), 1-methyl-2-(tolylazo)imidazole (Tai-Me) and 1-ethyl-2-(tolylazo)imidazole
(Tai-Et), to afford complexes of the type [(g5-C5Me5)MCl(RaaiR0)]+ where M = Rh or Ir; R, R0 = H (1, 7), R = H, R0 = CH3 (2, 8),
R = H, R0 = C2H5 (3, 9), R = CH3, R0 = H (4, 10), R, R0 = CH3 (5, 11), R = CH3, R0 = C2H5 (6, 12), respectively. These complexes
have been characterized by FT IR, FT NMR spectroscopy as well as by analytical data. The molecular structure of the hexafluorophos-
phate salt of the complex [(g5-C5Me5)RhCl(Me–C6H4–N@N–C3H3N2)]+ 4[PF6] has been established by single crystal X-ray diffraction
study.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Pentamethylcyclopentadienyl; Arylazoimidazole; Rhodium; Iridium
1. Introduction
[2]. Despite extensive studies on the complex [{(g5-
C5Me5)M(l-Cl)Cl}2], its reactivity with arylazoimidazole
ligands (RaaiR0) are yet to be explored. Recently, the
design of molecular architectures with imidazole ligands
has contributed to the understanding of biomolecular
interactions with metal ions in biology and provides mod-
els for the active sites of metalloproteins [3–6]. The mole-
cule bears the azoimine (–N@N–C@N–) functional
group, and is an efficient p-acid system for the stabilization
of low oxidation state metal ions. The chemistry of this
functional group with platinum is also known in detail
[7–9]. The ligands used in the present study are shown in
Scheme 1.
The dimeric chloro bridged complexes [{(g5-C5Me5)-
M(l-Cl)Cl}2] (M = Rh or Ir) have been the subject of
investigation by many research groups as these are very
useful starting materials [1]. The complexes undergo rich
variety of chemistry via the intermediacy of chloro bridge
cleavage reactions leading to the formation of series of
interesting neutral and cationic mononuclear complexes
*
´
Corresponding author. Address: Institut de Chimie, Universite de
Neuchaˆtel, Case postale 158, CH-2009 Neuchaˆtel, Switzerland. Tel.: +41
32 718 2499; fax: +41 32 718 2511.
We had reported previously the synthesis of cyclopenta-
dienyl and arene-ruthenium complexes containing N,N-
donor arylazoimidazole ligands [10]. We also reported
E-mail addresses: govinds77@rediffmail.com, govinds_catalyst@
yahoo.com (P. Govindaswamy).
1
X-ray crystallography.
0277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.07.007

5040
P. Govindaswamy et al. / Polyhedron 26 (2007) 5039–5044
3
N
N
4
5
+
11
7
10
N
2
M
R
N
N
Cl
Cl
1
9
6
M
RaaiR' /NH4PF6
MeOH
N
R'
Cl
R'
Cl
8
N
N
Cl
R, R' = H (Pai-H)
M
R, R' = H, CH3 (Phai-Me)
R, R' = H, C2H5 (Phai-Et)
R, R' = CH3, H (Tai-H)
R, R' = CH3 (Tai-Me)
R, R' = CH3, C2H5
R
R, R' = H; M = Rh (1), M = Ir (7)
M = Rh, Ir
R, R' = H, CH3; M = Rh (2), M = Ir (8)
R, R' = H, C2H5; M = Rh (3), M = Ir (9)
R, R' = CH3, H; M = Rh (4), M = Ir (10)
R, R' = CH3; M = Rh (5), M = Ir (11)
R, R' = CH3, C2H5; M = Rh (6), M Ir (12)
Scheme 1.
synthesis of cyclopentadienyl ruthenium [11], indenyl-ruthe-
nium [12] and arene-ruthenium [13] complexes with a
variety of nitrogen-based ligands. However, the analogous
pentamethylcyclopentadienyl rhodium(III) and iridium(III)
azo complexes have not been explored as much as the corre-
sponding isoelectronic cyclopentadienyl and arene-ruthe-
nium(II) complexes. As a part of our continuing study, we
would like to report herein the syntheses and characteriza-
tion of new cationic pentamethylcyclopentadienyl rho-
dium(III) and iridium(III) complexes with N,N-donor
arylazoimidazole ligands.
Scheme 2.
of the strong band at around 840 cmꢀ1 due to the m(P–F)
of the PFꢀ6 anion. The bands appearing at around 1600
and 1400 cmꢀ1 are assigned for m(C@N) and m(N@N), respec-
tively, of the ligand [15].
The 1H NMR spectrum of complexes shows a singlet for
the pentamethylcyclopentadienyl protons in the range
1.38–1.71 ppm, indicating downfield shift from the starting
dimeric complexes. A downfield shift in the position of the
pentamethylcyclopentadienyl protons might result from a
change in electron density on the metal center due to che-
lation of the arylazoimidazole ligand through its nitrogen
atoms. The N–H proton of complexes 1, 4, 7 and 10 is
exhibited a singlet in the range 8.2–9.2 ppm. The N-methyl
protons (N-Me) of complexes 2, 5, 8 and 11 appear as a sin-
glet at 3.82–4.19 ppm. The N-methylene proton (N-CH2)
of complexes 3, 6, 9 and 12 appears as a quartet in the
range 4.14–4.55 ppm. All these complexes show doublet
and multiplet in the range of 5.75–7.96 ppm due to the phe-
nyl protons of the azoimine ligand.
2. Results and discussion
1-Methyl-2-(arylazo)imidazole (aai-Me), 1-ethyl-2-(ary-
lazo)imidazole (aai-Et) and 2-(arylazo)imidazole (aai-H)
were synthesized by coupling the aryldiazonium ions with
imidazole in aqueous sodium carbonate solution (pH 7)
and purified by the reported method [26]. The alkylation
was carried out by adding alkyl halide in dry THF solution
to the corresponding 2-(arylazo)imidazole in the presence
of sodium hydride [14].
Six arylazoimidazole (RaaiR0) (see Scheme 1) ligands
have been used in this work. Ligands are unsymmetrical
N,N0-bidentate chelates, where N and N0 abbreviated to
N (imidazole) and N0 (azo) donor centers, respectively.
The pentamethylcyclopentadienyl rhodium and iridium
dimers [{(g5-C5Me5)M(l-Cl)Cl}2] where M = Rh and Ir
reacted with arylazoimidazoles (RaaiR0) in the presence
of ammonium salts in methanol to form mononuclear
cationic complexes having the general formula [(g5-C5Me5)
MCl(RaaiR0)]+ (C5Me5 = pentamethylcyclopentadienyl;
M = Rh or Ir) (Scheme 2). The cationic complexes 1–6
are orange, while the complexes 7–12 are brown in colour.
These complexes are non-hygroscopic, air-stable, shiny
crystalline solids. They are sparingly soluble in methanol
and benzene, soluble in dichloromethane, chloroform, ace-
tone, acetonitrile, and insoluble in hexane, petroleum ether
and diethyl ether.
The 31C {1H} NMR spectrum of complexes 1–6 and 7–
12 contain resonances for the pentamethylcyclopentadienyl
ring carbons at around 90 ppm. The resonance observed at
155 ppm may be due to the azoimine (C@N) carbon of the
ligand. The spectra also show resonances in the range of
122.1–162.2 ppm for the aromatic carbons and carbons
of imidazole C–H group.
2.1. Electronic spectra
The low spin d6 configuration of the mononuclear com-
plexes provides filled orbitals of proper symmetry, which
can interact with low lying p* orbitals of the arylazoimidaz-
ole ligands (RaaiR0). A band attributable to the MLCT
(t2g ! p*) transition is therefore expected in the electronic
spectra [16], where the transition energy of these bands var-
ies with the nature of the ligands acting as p-acceptors. The
presence of electron donating groups (H, CH3, C2H5) on
the imidazole nitrogen of the azoimine ligand should
decrease the energy of transition, causing a red shift in
The analytical data of these complexes are consistent
with the formulations (Table 1). The formation of cationic
complexes 1–6 and 7–12 are confirmed by the appearance

Table 1
Analytical,a FT IR, 1H NMRb and 13C NMR of complexes [1–12][PF6]
Complex
Analyses (%)
IR (KBr pellets (cmꢀ1))
1H NMR d [multiplicity, nH, J (Hz)]
13C NMR (d)
C
H
N
1
2
3
38.6
(38.5)
39.7
(40.0)
40.8
(40.8)
3.9
(3.9)
4.2
(4.2)
4.4
(4.3)
9.4
(9.3)
9.3
(9.1)
9.1
(9.1)
3204 (mN–H), 1639 (mC@N),
1434 (mN@N), 844 (mP–F)
1.38 (s, 15H, C5Me5), 6.97 (d, 2H, 3J = 7.5 Hz, Ph), 7.32–7.53 (m, 3H,
Ph), 7.69 (d, 1H, 3J = 6.4 Hz, CH), 8.24 (d, 1H, CH), 9.21 (s, 1H, NH)
8.96, 96.47, 122.41, 124.36, 127.32, 129.49,
131.16, 134.90, 151.18
8.91, 40.13, 92.92, 122.13, 126.42, 127.47,
130.27, 135.56, 142.55, 156.17
1633 (mC@N), 1427 (mN@N), 1.47 (s, 15H, C5Me5), 3.24 (s, 3H, CH3), 7.47 (d, 2H, 3J = 6.4 Hz, Ph),
850 (mP–F
)
7.52–7.77 (m, 3H, Ph), 8.02 (d, 1H, 3J = 7.2 Hz, CH), 8.46 (d, 1H, CH)
1633 (mC@N), 1434 (mN@N), 1.32 (s, 15H, C5Me5), 1.46 (t, 3H, 3J = 4.5 Hz, CH3), 4.42 (q, 2H, CH2), 8.91, 16.14, 44.16, 98.14, 122.19, 125.32,
844 (mP–F
)
7.07 (d, 2H, 3J = 6.2 Hz, Ph), 7.15–7.32 (m, 3H, Ph), 7.47 (d, 1H,
3J = 6.1 Hz, CH), 7.84 (d, 1H, CH)
127.62, 128.72, 133.74, 139.92, 146.11
4
5
6
39.7
(39.9)
4.2
(4.3)
9.3
(9.2)
3423 (mN–H), 1600 (mC@N),
1447 (mN@N), 850 (mP–F
1.71 (s, 15H, C5Me5), 2.53 (s, 3H, CH3), 6.79 (d, 2H, 3J = 6.1 Hz, Ph),
9.26, 15.79, 86.19, 124.68, 127.38, 130.92,
)
6.93 (d, 2H, Ph), 7.58 (d, 1H, 3J = 6.8 Hz, CH), 7.99 (d, 1H, CH), 8.16 (s, 131.17, 133.12, 136.19, 142.36
1H, NH)
40.8
(40.6)
4.4
(4.4)
9.1
(9.2)
1606 (mC@N), 1447 (mN@N), 1.39 (s, 15H, C5Me5), 2.14 (s, 3H, CH3), 3.42 (s, 3H, CH3), 7.18 (d, 2H, 8.90, 22.46, 42.34, 97.16, 126.32, 127.41,
844 (mP–F
)
3J = 6.8 Hz, Ph), 7.42 (d, 2H, Ph), 7.71 (d, 1H, 3J = 4.4 Hz, CH), 8.24 (d, 130.67, 132.31, 136.31, 141.46, 152.56
1H, CH)
41.8
(41.7)
4.6
(4.4)
8.9
(8.9)
1626 (mC@N), 1434 (mN@N), 1.48 (t, 3H, 3J = 6.9 Hz, CH3), 1.53 (s, 15H, C5Me5), 2.45 (s, 3H, CH3),
9.31, 16.09, 21.76, 43.93, 99.21 124.22,
129.11, 130.59, 131.03, 144.79, 150.30,
155.01
8.90, 92.86, 123.74, 124.29, 129.93, 130.42,
130.53, 133.17, 152.99
849 (mP–F
)
4.55 (q, 2H, CH2), 7.52 (d, 2H, 3J = 8.4 Hz, Ph), 7.86 (d, 2H, Hz, Ph),
8.01 (d, 1H, CH), 8.26 (d, 1H, CH)
1.47 (s, 15H, C5Me5), 7.13 (d, 2H, 3J = 8.2 Hz, Ph), 7.22–7.49 (m, 3H,
Ph), 7.82 (d, 1H, 3J = 8.1 Hz, CH), 8.47 (d, 1H, CH), 9.12 (s, 1H, NH)
7
8
9
33.6
(33.5)
34.6
(34.4)
35.6
(35.4)
3.4
(3.4)
4.2
(4.3)
3.8
(3.9)
8.2
(8.5)
8.1
(8.2)
7.9
(8.0)
3151 (mN–H), 1619 (mC@N),
1467 (mN@N), 850 (mP–F
)
1633 (mC@N), 1434 (mN@N), 1.53 (s, 15H, C5Me5), 3.36 (s, 3H, CH3), 7.69 (d, 2H, 3J = 6.9 Hz, Ph),
8.92, 39.89, 93.20, 124.46, 129.67, 130.01,
133.63, 151.68, 152.96, 160.96
844 (mP–F
)
7.78–7.82 (m, 3H, Ph), 7.98 (d, 1H, CH), 8.30 (d, 1H, CH)
1626 (mC@N), 1440 (mN@N), 1.36 (s, 15H, C5Me5), 1.52 (t, 3H, 3J = 6.1 Hz, CH3), 4.26 (q, 2H, CH2), 8.92, 14.13, 42.46, 94.36, 124.61, 126.52,
844 (mP–F
)
7.13 (d, 2H, 3J = 7.3 Hz, Ph), 7.23–7.41 (m, 3H, Ph), 7.53 (d, 1H,
3J = 7.14 Hz, CH), 7.91 (d, 1H, CH)
127.37, 130.49, 135.18, 146.63, 155.23
10
11
12
a
34.6
(34.6)
4.2
(4.6)
8.1
(8.7)
2925 (mN–H), 1606 (mC@N),
1394 (mN@N), 850 (mP–F
1.50 (s, 15H, C5Me5), 2.46 (s, 3H, CH3), 7.46 (d, 2H, 3J = 8.4 Hz, Ph),
8.93 21.63, 92.65, 124.38, 127.47, 130.17,
)
7.71 (d, 2H, Ph), 7.89 (d, 1H, 3J = 10.6 Hz, CH), 8.71 (d, 1H, CH), 9.07 130.32, 143.95, 150.93, 162.19
(s, 1H, NH)
35.6
(35.4)
3.8
(3.7)
7.9
(7.9)
1633 (mC@N), 1434 (mN@N), 1.41 (s, 15H, C5Me5), 2.06 (s, 3H, CH3), 3.53 (s, 3H, CH3), 7.09 (d, 2H, 8.97, 21.37, 44.08, 99.42, 122.28, 125.37,
844 (mP–F
)
3J = 6.4 Hz, Ph), 7.44 (d, 2H, Ph), 7.68 (d, 1H, 3J = 6.1 Hz, CH), 8.09 (d, 128.14, 130.36, 133.18, 139.92, 148.74
1H, CH)
9.18, 15.69, 22.43, 46.15, 97.43, 123.72,
4.44 (q, 2H, CH2), 7.31 (d, 2H, 3J = 6.6 Hz, Ph), 7.82 (d, 2H, Ph), 8.14 (d, 125.36, 128.93, 130.83, 133.68, 142.39,
1H, 3J = 5.6 Hz, CH), 8.32 (d, 1H, CH)
152.35
36.6
(36.6)
4.0
(4.1)
7.8
(7.7)
1637 (mC@N), 1434 (mN@N), 1.38 (s, 15H, C5Me5), 1.43 (t, 3H, 3J = 5.4 Hz, CH3), 2.26 (s, 3H, CH3),
844 (mP–F)
Calculated values are in parentheses.
In CDCl3; s, singlet; d, doublet; m, multiplet; J(H–H) in Hz.
b

5042
P. Govindaswamy et al. / Polyhedron 26 (2007) 5039–5044
Table 2
UV–Visible absorption data in dichloromethane at 298 K
Sl. no.
Complexes
kmax (nm)
1
2
3
4
5
6
7
8
9
[(g5-C5Me5)RhCl(Phai-H)]PF6
[(g5-C5Me5)RhCl(Phai-Me)]PF6
[(g5-C5Me5)RhCl(Phai-Et)]PF6
[(g5-C5Me5)RhCl(Tai-H)]PF6
[(g5-C5Me5)RhCl(Tai-Me)]PF6
[(g5-C5Me5)RhCl(Tai-Et)]PF6
[(g5-C5Me5)IrCl(Phai-H)]PF6
[(g5-C5Me5)IrCl(Phai-Me)]PF6
[(g5-C5Me5)IrCl(Phai-Et)]PF6
[(g5-C5Me5)IrCl(Tai-H)]PF6
[(g5-C5Me5)IrCl(Tai-Me)]PF6
[(g5-C5Me5)IrCl(Tai-Et)]PF6
415
407
410
423
665
408
414
446
452
436
407
407
326
370
391
365
406
395
388
393
375
397
333
333
358
364
313
364
312
321
316
309
317
311
311
335
311
10
11
12
MLCT maxima [17], while an electron withdrawing group
should increase the transition energy. The electronic spec-
tra of pentamethylcyclopentadienyl rhodium azoimine
complexes (1–6) with the formulations [g5-C5Me5RhCl-
(RaaiR0)]+ displayed very weak bands at 408–423 nm, a
medium absorption band at ꢁ390 nm and a very strong
absorption band at ꢁ330 nm (Table 2). The band at
390 nm has been assigned to a MLCT transitions [t2g
{Rh(III) ! p*(azoimine)}]. The kmax value of this band is
consistent with those of the azoimine ligand bound to the
complexes of rhodium [18].
The free ligand itself shows intraligand charge-transfer
transitions (n–p*, p–p*) of high intensity (e ꢁ 104–
105 Mꢀ1 cmꢀ1) at <400 nm. The transitions at ꢁ350 nm
and below are thus not considered further. Other two
transitions at longer wavelength region (410–460 nm and
370–390 nm) differ in their intensities. The first transition
(410–460 nm) is of moderate intensity and has been
assigned to the MLCT band dp(Rh) ! p*(azoimine) in
the complexes [19] or else from the hybrid orbitals com-
posed of dp(Rh) and p(Cp*) to the p*(azoimine) orbitals
of the ligand. The weak transition at ꢁ650 nm may orig-
inate from a singlet–triplet transition, particularly that
allowed by the strong spin–orbit coupling in rhodium
[20].
Fig. 1. ORTEP diagram of complex 4 at 50% probability level with
hydrogen atoms and hexafluorophosphate anion omitted for clarity.
˚
Selected bond lengths (A) and bond angles (ꢁ): Rh–N(1) 2.132(7), Rh–
N(32) 2.105(8), Rh–Cl 2.423(3), N(1)–N(2) 1.275(10), Rh–C* 1.795
˚
*
(
centroid is at x = 0.7413, y = 0.1825, z = 0.9899 at 1.795 A to Rh);
N(1)–Rh–N(32) 74.9(3), N(1)–Rh–Cl 92.5(2), N(32)–Rh–Cl 86.9(2).
the three-legged ‘piano-stool’ geometry. The metal is coor-
dinated to one g5-C5Me5 group, one chloride and two
nitrogen atoms of Tai-H which binds to the metal in a
bidentate chelating mode, as postulated from experimental
data.
The pentamethylcyclopentadienyl ligand is symmetri-
cally bound to the metal ion. All the Cp* atoms lie in a
plane, and indicated by the similar bond distances between
˚
carbons. The Rh–Cl bond length is 2.432(3) A which is
slightly longer than the other two-coordinated chelating
Schiff base rhodium complex [(g5-C5Me5)RhCl(C5H4N-2-
CH@N–C6H4-p-Cl)]+ [2.3756(7) A] [22].
˚
The Rh–N distances are unequal with Rh–N(1),
˚
˚
2.132(7) A and Rh–N(32), 2.105(8) A. This has been
observed in other complexes involving bidentate rhodium
terpyridine [(g5-C5Me5)RhCl(Ph-terpy)]BF4 [23]. Rho-
dium to pentamethylcyclopentadienyl ring centroid dis-
˚
Electronic spectra of iridium complexes (7–12) display
bands in the region ꢁ450 nm, ꢁ380 nm and ꢁ320 nm.
The broad medium intensity bands centering around
450 nm are assigned to MLCT bands arising from drift
of electron density from the filled Ir(III) ! dp(t2g) orbitals
to the low lying p* orbitals of the RaaiR0 ligand. The posi-
tion of this band is consistent with those in other metal-azo
complexes [21]. The band around 320 nm is assigned to an
MLCT transition [Ir(III) ! dp* on the Cp* ring].
tance is 1.759 A and is consistent with those reported
for the other rhodium(III) Cp* complexes [22]. The bond
angles N(1)–Rh–Cl and N(32)–Rh–Cl are 92.5(2) and
86.9(2), respectively, indicating a piano stool type of
structure at rhodium center. The N@N bond distance,
˚
N(1)–N(2) is 1.275(10) A which is longer than free ligand
˚
value [1.250(1) A] [24]. This refers to significant charge
delocalization from metal d-orbital, dp(Rh) ! p*(azo) in
the coordinated Tai-H.
2.2. Molecular structure of complex
[(g5-C5Me5)RhCl(Me–C6H4–N@N–C3H3N2)]+ (4)
3. Experimental
3.1. General remarks
The complex 4[PF6] crystallizes in the monoclinic P21/n
space group. The ORTEP drawing of the molecule along
with the atom-numbering scheme is shown in Fig. 1. The
asymmetric unit consists of a rhodium atom displaying
[{(g5-C5Me5)M(l-Cl)Cl}2] (M = Rh, Ir) [25] and
arylazoimidazole (RaaiR0) ligands [26] were prepared
according to published methods. All other reagents were

P. Govindaswamy et al. / Polyhedron 26 (2007) 5039–5044
5043
Table 3
commercially available and were used as received. UV/vis-
Crystal data and structure refinement for complex 4[PF6]
ible absorption spectra were recorded on a Hitachi – 300
spectrophotometer using precision cells made of quartz
Empirical formula
C20H25ClF6N4PRh
1
(1 cm). The H and 13C {1H}NMR spectra were recorded
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
604.77
293(2)
0.71073
Monoclinic
P21/n
in CDCl3 solvent with TMS as internal standard and
recorded on JEOL 500 (500 MHz) or Bruker ACF-300
(300 MHz) spectrometers, the coupling constants J are
given in Hz. Infrared spectra were recorded as KBr pellets
on a Perkin–Elmer-model-983 spectrophotometer. Microa-
nalyses were performed on a Perkin–Elmer-2400 CHN/O
analyzer, SAIF-NEHU, Shillong, India.
˚
Unit cell dimensions
˚
a (A)
8.386(9)
27.72(3)
10.717(12)
91.11(2)
˚
b (A)
˚
c (A)
b (ꢁ)
3.2. Synthesis of [(g5-C5Me5)RhCl(L)]PF6 {L = Phai-H
(1), Phai-Me (2), Phai-Et (3), Tai-H (4), Tai-Me (5),
Tai-Et (6)}
3
˚
Volume (A )
2491(5)
Z
4
Dcalc (Mg/m3)
1.613
0.917
1216
Absorption coefficient (mmꢀ1
F(000)
)
A mixture of [(g5-C5Me5)RhCl2]2 (100 mg, 0.16 mmol),
arylazoimidazole (RaaiR0) (0.36 mmol) and potassium
hexafluorophosphate (0.41 mmol) was stirred in dry meth-
anol (20 mL) at 0 ꢁC for 3 h. The solution becomes clear
before the product precipitates. After 3 h the orange solid
precipitated and the product was filtered, washed with
diethylether (3 · 10 ml) and then dried in vacuo to afford
70–80% yield of the complexes.
Crystal size (mm)
h Range for data collection (ꢁ)
Index ranges
0.15 · 0.10 · 0.07
1.47–28.26
ꢀ9 6 h 6 9,
ꢀ35 6 k 6 17
ꢀ13 6 l 6 4
7814
Reflections collected
Independent reflections [Rint
]
4514 [0.0796]
28.26, 73.2
Empirical
Completeness to theta (ꢁ, %)
Absorption correction
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Full-matrix least-squares on F2
4514/0/284
3.3. Synthesis of [(g5-C5Me5)IrCl(L)]PF6 {L = Phai-H
(7), Phai-Me (8), Phai-Et (9), Tai-H (10), Tai-Me (11),
Tai-Et (12)}
0.999
R1 = 0.0791, wR2 = 0.1360
R1 = 0.1839, wR2 = 0.1696
0.657 and ꢀ0.513
ꢀ3
˚
Largest difference peak and hole (e A
)
These compounds was prepared by the same procedure
as described above for [1–6][PF6] using [(g5-C5Me5)Ir
(l-Cl)(Cl)]2 (100 mg, 0.125 mmol), arylazoimidazole
(RaaiR0) (0.26 mmol) and potassium hexafluorophosphate
(0.41 mmol). Brown solid, Yield 65–75%.
Appendix A. Supplementary material
CCDC 272064 contains the supplementary crystallo-
graphic data for 4[PF6]. These data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK, fax:
(+44) 1223-336-033, or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.poly.2007.
07.007.
4. Structure analysis and refinement
X-ray quality crystals of the complex 4[PF6] were grown
by slow diffusion of hexane into dichloromethane solution.
An orange crystal of complex 4[PF6] was mounted on a
Bruker Apex CCD diffractometer in a full reciprocal sphere
equipped with CCD detector and used for data collection.
X-ray intensity data were collected with graphite mono-
˚
chromated Mo Ka radiation (0.71073 A) at 293(2) K, with
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