New benzotriazole derivative as multifunctional ligands

Article abstract of DOI:10.1016/S0022-328X(02)01669-8

A series of new multifunctional ligands based on the benzotriazole unit has been synthesized by condensation of hydroximethylbenzotriazole with carboxylic acid derivatives of pyridine, triphenylphosphine, ferrocene and thiophene. The coordination properti

Full text of DOI:10.1016/S0022-328X(02)01669-8

Journal of Organometallic Chemistry 658 (2002) 251ꢀ258
/
www.elsevier.com/locate/jorganchem
New benzotriazole derivatives as multifunctional ligands
Christophe M. Thomas, Bruno Therrien, Antonia Neels, Helen Stœckli-Evans,
Georg Suss-Fink *
¨
Institut de Chimie, Universite´ de Neuchaˆtel, Case Postale 2, Avenue de Bellevaux 51, CH-2007, Neuchaˆtel, Switzerland
Received 13 March 2002; received in revised form 31 May 2002; accepted 7 June 2002
Abstract
A series of new multifunctional ligands based on the benzotriazole unit has been synthesized by condensation of
hydroximethylbenzotriazole with carboxylic acid derivatives of pyridine, triphenylphosphine, ferrocene and thiophene. The
coordination properties of these ligands towards cobalt, rhodium and iridium have been studied. # 2002 Elsevier Science B.V. All
rights reserved.
Keywords: Rhodium; Phosphine ligands; Benzotriazole
1. Introduction
unit that can be used to improve the activity of late
transition metal catalysts in the carbonylation of
methanol. One important property of these potentially
multidentate ligands is that they can stabilize metal ions
in a variety of oxidation states and geometries.
Nitrogen donor ligands are widely used in coordina-
tion chemistry [1]. Apart from the classical amine
ligands such as ammonia and ethylene diamine, the
most common nitrogen-containing ligand systems are
heterocycles such as pyridine(a), pyrazine(b), bipyridi-
ne(c), oxazoline(d) (Scheme 1) and derivatives thereof [2ꢀ
6]. Complexes of these ligands are known with almost all
transition metals [7ꢀ11].
/
2. Results
/
The new benzotriazole ligands 1ꢀ5 are easily acces-
/
Surprisingly benzotriazole(e) and its derivatives are
less frequently encountered in coordination chemistry:
Only a few complexes were known so far [12]. Recently
we reported the synthesis of thiophene-2,5-di(carboxy-
latomethylenebenzotriazole) as a new multifunctional
ligand for the rhodium-catalysed carbonylation of
methanol, from the reaction mixture the macrocyclic
sible by classical condensation methods [15] from
hydroximethylbenzotriazole and the corresponding
mono- or diacids (Scheme 2). They can be isolated
with good yields as micro-crystalline powders; 1 can be
recrystallised from ethyl acetateꢀ
less, air-stable crystals and 2 can be recrystallised from
acetoneꢀhexane to give orangeꢀred, air-stable crystals.
/
hexane to give colour-
/
/
The molecular structure of the ligand 1 is depicted in
Fig. 1. The pyridine ring is almost planar, the ring atoms
being formally sp2 hybridised. In accordance with the
rhodium
[Rh2(CO)2I6(C6H4N3CH2CO2C4H2S-
CO2CH2C6H4N3)]2 complex was isolated and charac-
terised [13]. We also found this ligand to react with
cobalt iodide to give the polymeric complex
aromaticity, the CÃ
ring are shorter [C(9)Ã
1.383(4), C(9)ÃN(4) 1.338(3) A] than those in the
benzotriazole ring [C(1)ÃC(2) 1.391(3), C(1)ÃC(6)
1.396(3), C(4)ÃC(5) 1.408(3), C(1)Ã
The two nitrogenÃnitrogen distances of the benzotria-
zole unit are in line with the lengths of a single and a
double bond [N(2)ÃN(3) 1.301(2), N(1)ÃN(2) 1.367(3)
O(1) bond distance [1.203(2) A] and the
/
C and CÃ
/
N distances in the pyridine
/
C(10) 1.381(3), C(10)Ã
/C(11)
[CoI2(C6H4N3CH2CO2C4H2SCO2CH2C6H4N3)] [14].
With the catalytic perspective in mind, we decided to
synthesize new ester ligands based on the benzotriazole
˚
/
/
/
˚
N(1) 1.369(3) A].
/
/
/
* Corresponding author. Tel.:
7182511
E-mail address: georg.suess-fink@unine.ch (G. Suss-Fink).
ꢁ
/
41-32-7182405; fax:
ꢁ/41-32-
/
/
˚
˚
A]. The C(8)Ã
/
¨
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 6 9 - 8

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C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ258
/
Scheme 1.
Table 1
Selected bond lengths (A) for 1
˚
C(9)ÃC(10)
C(10)ÃC(11)
C(9)ÃN(4)
C(1)ÃC(2)
C(1)ÃC(6)
C(1)ÃN(1)
1.381(3)
1.383(4)
1.338(3)
1.391(3)
1.396(3)
1.369(3)
N(2)ÃN(3)
N(1)ÃN(2)
C(8)ÃO(1)
C(8)ÃO(2)
1.301(2)
1.367(3)
1.203(2)
1.346(2)
˚
C(9) 1.456(2) A]
function and the Cp ring [C(8)Ã
/
Fig. 1. Molecular structure of (C6H4N3CH2CO2C5H4N) (1).
corresponds to a CÃC single bond.
/
˚
O(2) bond distance [1.346(2) A] are similar to
The methylenebenzotriazole substituent is rotated out
of the ester plane by 79.458, allowing no efficient
interaction between the p-system of the Cp ring and
the benzotriazole moiety. A similar behavior has been
observed for benzoylferrocene [19], where the solid state
structure shows the phenyl ring rotated out of the Cp
plane by 40.48; steric interference does not allow
coplanarity of the Cp and Ph groups [19]. Similar steric
problems are most likely responsible for the arrange-
C(8)Ã
/
those reported for other pyridine esters [16,17] (Table 1).
Selected bond distances and angles for 2 are given in
Table 2. The molecular structure of ligand 2 is given in
Fig. 2. The ferrocene moiety is in the eclipsed con-
formation. In each molecule, the Cp rings are almost
parallel to each other (angle between the two Cp planes:
5.308). The ironÃ
compare well with those of other ferrocene structures
[18]. Interestingly, the carbonÃcarbon bond distances in
the substituted Cp ring [C(9)ÃC(13) 1.430(3), C(9)Ã
C(10) 1.433(2) A] are longer than those in the unsub-
stituted Cp ring [C(14)ÃC(18) 1.409(4), C(14)ÃC(15)
1.403(3) A], as it has been observed in similar cases [18].
The carbonÃcarbon distance between the carbonyl
/carbon distances are as expected and
ment of the benzotriazole substituent. The C(8)Ã
/
O(1)
bond of 1.211(2) A is shorter than those observed for
/
˚
/
/
˚
ferrocenecarboxylic acid [20] (1.261(15) A) and ferroce-
˚
nedicarboxylic acid (1.228(3) A) [21]. However, it is also
˚
/
/
˚
longer than those of other ferrocenecarboxylic esters,
such as 2-(1-hydroxyethyl)-1-ferrocenecarboxylic acid
/
Scheme 2.

C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ
/258
253
Table 2
Selected bond lengths (A) for 2
Co(1)Ã
/
I(1), N(23)Ã
/
Co(1)Ã
/
I(2), N(3)Ã
/
Co(1)Ã
/
I(1), N(3)Ã
/
˚
Co(1)Ã
/
I(2), I(1)Ã
/
Co(1)Ã
/I(2) (103.5(2), 106.99(17),
113.42(17), 104.65(15), 110.97(15), 116.20(4)8, respec-
tively) are not far from the ideal tetrahedral angle. The
C(9)ÃC(13)
C(9)ÃC(10)
C(14)ÃC(18)
C(14)ÃC(15)
1.430(3)
1.433(2)
1.409(4)
1.403(3)
C(8)ÃO(2)
C(8)ÃC(9)
C(8)ÃO(1)
1.363(2)
1.456(2)
1.211(2)
two cobaltÃ
Co(1)ÃN(23) 2.044(5) A] and the two cobaltÃ
bonds [Co(1)ÃI(1) 2.5510(11), Co(1)ÃI(2) 2.5692(11) A]
/
nitrogen bonds [Co(1)Ã
/
N(3) 2.033(5),
˚
/
/iodine
˚
/
/
are almost equal in length and are normal for this kind
of complexes [25,26]. Some deviation from regular
tetrahedral geometry is indicated by the relatively large
I(1)Ã
Co(1)Ã
iodine presumably are responsible for the observed
distortion [27]. The two CÄO bond distances (C(8)Ã
O(1) 1.197(8), C(28)ÃO(21) 1.195(8) A) are shorter
/
Co(1)Ã
/
I(2) and corresponding small N(23)Ã
/
/
N(3) angles. Interligand repulsions between the
/
/
˚
/
˚
than this in the free ligand (1.211(2) A). Selected bond
distances and angles for 6 are given in Table 3. The
molecular structure of ligand 6 is given in Fig. 3.
Fig. 2. Molecular structure of (C6H4N3CH2CO2C5H4FeC5H5) (2).
Compound 4 was found to coordinate easily to
iridium through the 3-N atom of the benzotriazole
unit. The reaction of 4 with [Ir(m-Cl)(cod)]2 in toluene
at 110 8C in a carbon monoxide atmosphere gives
˚
O 1.205(4) A] [22] and 3-(diphenylpho-
methyl ester [CÄ
/
sphino)-1-ferrocenecarboxylic acid methyl ester [CÄ
/
O
˚
1.204(3) A] [23]. The C(8)Ã
/
O(2) bond distance [1.363(2)
quantitatively
the
iridium(I)
complex
solid
˚
A] is about 0.06 A shorter than that of ferrocenecar-
˚
[IrCl(CO)(4)]2 (7) as an air-stable orange solid (Scheme
4). Micro-analytical and NMR data are consistent with
the composition proposed, the dimeric nature of the
molecule clearly follows from the ESI mass spectrum
which shows the molecular peak at m/z 1380. Complex
7 exhibits two strong n(CO) absorptions at 2074 and
1994 cmꢂ1 in the infrared spectrum, as expected for a
cisoid arrangement of the two terminal carbonyl ligands
[28].
The phosphine derivative 5 reacts with [RhCl(CO)2]2
to give the diphosphine complex [C6H4N3CH2CO2-
C6H4P(C6H5)2]2Rh(CO)Cl (8) in high yield (Scheme 5).
The product is very easily isolated by evaporation of the
solvent and washing of the residues with ether. Com-
pound 8 exhibits, as expected, only one strong n(CO)
absorption in the infrared spectrum, the monomeric
˚
boxylic acid benzotriazole ester [1.427(2) A], which is
known to have a weak and reactive ester bond,
facilitating the amidation in the peptide-coupling reac-
tions [24]. These findings are in line with the stability of
the ester bond observed for 2.
Compound 2 was found to coordinate easily to cobalt
through the 3-N atom of the triazole unit. The reaction
of 2 with CoI2 in dichloromethane at room temperature
gives quantitatively the cobalt(II) complex [CoI2(2)2] (6)
as an air-stable green solid (Scheme 3). This compound
is moderately soluble in acetone and toluene, but only
sparingly soluble in alcohols and insoluble in alkanes; 6
can be recrystallised from dichloromethane/hexane to
give green, air-stable crystals.
The single-crystal X-ray structure analysis reveals that
the cobalt(II) centre is tetrahedrally coordinated to two
iodine atoms and to the 3-N nitrogen atoms of two
Table 3
˚
Selected bond lengths (A) and angles (8) for complex 6
triazole ligands. The angles N(23)Ã
/
Co(1)Ã
/
N(3), N(23)Ã
/
Bond lengths
Co(1)ÃN(3)
Co(1)ÃN(23)
Co(1)ÃI(1)
Co(1)ÃI(2)
C(8)ÃO(1)
1.430(3)
1.433(2)
1.409(4)
1.403(3)
1.197(8)
1.195(8)
C(28)ÃO(21)
Bond angles
N(23)ÃCo(1)ÃN(3)
N(23)ÃCo(1)ÃI(1)
N(23)ÃCo(1)ÃI(2)
N(3)ÃCo(1)ÃI(1)
N(3)ÃCo(1)ÃI(2)
I(1)ÃCo(1)ÃI(2)
103.5(2)
106.99(17)
113.42(17)
104.65(15)
110.97(15)
116.20(4)
Scheme 3.

254
C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ258
/
Scheme 5.
spectrum (see Section 5), which appears as a doublet due
to coupling of the phosphorus atoms to 103Rh (Iꢃ/21), in
agreement with the trans-P,P coordination. This is in
agreement with the NMR observations for similar b-
ketophosphine complexes reported by Shaw and cow-
orkers [29]. Final structural proof was obtained by a
single-crystal X-ray structure analysis; the molecular
structure of 8 is depicted in Fig. 4, important bond
lengths and angles are given in Table 4.
Fig. 3. Molecular structure of CoI2(C6H4N3CH2CO2C5H4FeC5H5)
(6).
The single-crystal X-ray structure analysis of 8 shows
the rhodium atom carrying two phosphine ligands in
trans position, one carbonyl ligand and one chloride.
The metal atom is in a square-planar environment, the
angles C(27)Ã
Rh(1)ÃP(1), P(1)Ã
being 178.2(2), 91.1(3), 88.9(3), 88.62(7), 91.38(7)8,
/
Rh(1)Ã
/
Cl(1), P(1a)Ã
/
Rh(1)Ã
/
C(27), C(27)Ã
/
/
/
Rh(1)Ã
/
Cl(1), Cl(1)Ã
/
Rh(1)ÃP(1a)
/
˚
P lengths of 2.32 A (Table
respectively. The two RhÃ
4) compare well with the analogous triphenylphosphine
complex [30ꢀ32]. The least-square planes of the benzo-
Cl
/
/
triazole rings are tilted toward the RhÃ
/
PÃ
/
COÃ
/
PÃ
/
least-square plane by about 71.28.
3. Discussion
Of the five new ligands based on the benzotriazole
unit synthesized, the phosphine ligand 5 is of particular
interest with respect to its donorꢀacceptor properties,
/
which can be studied in the case of the rhodium complex
[Rh(5)2(CO)Cl] (8). Since monocarbonyl complexes
provide easy-to-interpret infrared spectra with a single
carbonyl band, complexes of this type have found wide
applications as probes for the electronic properties of
donor ligands [33]. The extensive literature available
Scheme 4.
nature of these complexes can be deduced from the mass
spectra. It shows only one resonance for the two
equivalent phosphorus atoms in the 31P{1H}-NMR
[34ꢀ37] allows a rapid evaluation of the electronic
properties of a new ligand. Thus, for 8 the CO band is
detected at 1949 cmꢂ1, which is about 16 cmꢂ1 lower in
/

C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ
/258
255
Moreover, the overall structural features of 8 being as
expected (square-planar coordination, trans dipho-
sphine configuration), the bond lengths involving the
rhodium atom are of particular interest. A comparison
of bond lengths in 8 with those of other trans-
Rh(PR3)2(CO)Cl structures [40] shows that 8 has the
˚
C carbonyl bond [1.722(7) A] observed for
shortest RhÃ
/
this type of complexes. Although the differences in bond
lengths are small, these trends are consistent for all
structurally characterized Rh(PR3)2(CO)Cl complexes.
The short RhÃ/C bond in 8 is consistent with the low-
energy nCO absorption in the infrared spectrum. Since
the phosphine ligand 5 is electron-rich and therefore a
good s-donor ligand, the structure of 8 suggests that the
long RhÃP distance may result from a reduced p-back-
/
bonding from rhodium to phosphorus. The good s-
donor and poor p-acceptor character of ligand 5 is also
reflected in the rhodiumÃ
/
chlorine bond length. As the
rhodium atom has a 16 electrons configuration, the
reduced electron density at the metal is compensated in
such complexes by enhanced donation of electrons from
the chlorine lone pairs [41], which causes in general a
shortening of the RhÃ
/
Cl bond. However, since 5 is a
˚
Cl bond [2.391(2) A] in 8
good s-donor ligand, the RhÃ
/
˚
is longer than in Rh[P(N-pyrrolyl)3]2Cl(CO) [2.350(4) A]
and comparable to that of [P(tBu)3]2Rh(CO)Cl [2.389(2)
Fig. 4. Molecular
CO2C6H4P(C6H5)2]2 (8).
structure
of
Rh(CO)Cl[C6H4N3CH2-
˚
˚
C distance [1.722(7) A] in 8 is shortened due
A]. The RhÃ
/
to enhanced p-back-bonding to the carbonyl, as demon-
strated by the carbonyl stretching frequency at 1949
cmꢂl. Hence, ligand 5 compares to tri-tert-butylpho-
sphine and not to triphenylphosphine as far as its
Table 4
˚
Selected bond lengths (A) and angles (8) for complex 8
donorꢀacceptor properties are concerned.
/
Bond lengths
P(1)ÃRh(1)
C(8)ÃO(1)
C(27)ÃO(3)
2.3223(6)
1.205(3)
1.190(7)
4. Conclusion
Bond angles
C(27)ÃRh(1)ÃCl(1)
P(1a)ÃRh(1)ÃC(27)
C(27)ÃRh(1)ÃP(1)
P(1)ÃRh(1)ÃCl(1)
Cl(1)ÃRh(1)ÃP(1a)
178.2(2)
91.1(3)
88.9(3)
The aim of this work was the synthesis of new
nitrogen-donor ligands and to study their ability to
coordinate as ligand to transition metals. A high-yield
route was developed to synthesize different ester deri-
vatives of benzotriazole. The coordination chemistry of
these multifunctional ligands studied with Rh(I), Ir(I)
and Co(II) centers shows that ligands 2 and 4 are
modentate using the 3-N atom of the benzotriazole unit
for coordination, while 5 coordinates through the
phosphorus atom. Compounds 1 and 3 were not found
to be useful as ligands for these metals.
88.62(7)
91.38(7)
energy than that of the triphenylphosphine complex
[Rh(PPh3)2(CO)Cl] [34], but 7 cmꢂ1 higher in energy
than that of [Rh(PR2R?)2(CO)Cl] (Rꢃ
/
N-pyrrolidinyl,
R?ꢃtert-butyl), containing a very electron-rich phos-
/
phine ligand [37]. The nCO value for 8 is significantly
lower than those of most electron-rich alkylphosphine
complexes [Rh(PR3)2(CO)Cl] (Rꢃ
/
Me: nCO 1960, Rꢃ
/
Et: nCO 1956) [37,38] which are often used in catalysis.
Tri-tert-butylphosphine, which is generally thought of
as one of the most electron-donating phosphines,
actually forms a tetrahedral complex [Rh(PtBu3)2-
(CO)Cl] and cannot be directly compared [39]. Given
this comparison, the phosphine 5 can be considered as a
strong donor ligand.
5. Experimental
Solvents were dried and distilled under nitrogen prior
to use. All reactions were carried out under nitrogen,
using standard Schlenk techniques. The compounds 4
[13], [IrCl(cod)]2 [42], and [RhCl(CO)2]2 [43] were
prepared as described previously. All other reagents

256
C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ258
/
were purchased (Fluka) and used as received. Nuclear
magnetic resonance spectra were recorded using a
Varian Gemini 200 BB instrument or a Bruker AMX
400 spectrometer and referenced by using the resonances
of residual protons in the deuterated solvents. 1H-NMR:
internal standard solvent, external standard Me4Si; 13C-
NMR: internal standard solvent, external standard
Me4Si; 31P-NMR: external standard 85% H3PO4. Infra-
The product was isolated from the third fraction by
evaporation of the solvent, giving 1.3 g (58%) of 2 as an
orange solid. Crystals suitable for X-ray diffraction
analysis were grown by slow evaporation of a 1:1
C3H6Oꢀ
/
C6H14
solution.
Anal.
Calc.
for
C18H15Fe1N3O2 (361.2): C, 59.9; H, 4.2. Found: C,
60.1; H, 4.3%; IR (KBr): 3118vw, 3040vw, 2928m,
1708vs (CÄ
/
O ester), 1459s, 1276m, 1108s, 967m, 746m
1
red spectra were recorded with a Perkinꢀ
/
Elmer 1720X
cmꢂ1; ESI-MS: m/z: 361 [M]ꢁ; H-NMR (200 MHz,
d6-C3H6O, 21 8C): d 8.10 (d, 1H, ArH), 7.93 (d, 1H,
ArH), 7.62 (t, 1H, ArH), 7.44 (t, 1H, ArH), 6.82 (s, 2H,
FT-IR spectrometer. Microanalyses were carried out by
the Laboratory of Pharmaceutical Chemistry, Univer-
sity of Geneva, Switzerland.
Ã
/
CH2), 4.82 (t, 2H, CpH), 4.44 (t, 2H, CpH), 3.90 (s,
5H; CpH); 13C-NMR (50 MHz, d6-C3H6O, 21 8C): d
171.30, 147.30, 146.39, 133.06, 133.03, 128.67, 124.93,
120.34, 110.74, 72.46, 72.43, 70.76, 70.16, 70.03, 70.00,
69.95, 69.01, 68.98, 67.62.
5.1. (C6H4N3CH2CO2C5H4N) (1)
A solution of 2-pyridinecarboxylic acid (826 mg, 6.71
mmol), N,N-dicyclohexylcarbodiimide (2.7 g, 13.1
mmol), 4-(dimethylamino)pyridine (122 mg, 1 mmol),
4-pyrrolidinopyridine (148 mg, 1 mmol) and hydroxy-
methylbenzotriazole (1.1 g, 7.4 mmol) in CH2Cl2 (40 ml)
was allowed to stand at room temperature (r.t.) under
nitrogen, until the esterification was complete. The
resulting solution was filtered through Celite to remove
N,N-dicyclohexyl urea, and the filtrate was concen-
trated under reduced pressure. The residue was chro-
matographed on a silica gel column (150 g), eluting with
5.3. (C6H4N3CH2CO2C5H4Fe)2 (3)
A solution of ferrocenedicarboxylic acid (1.7 g, 6.59
mmol), N,N-dicyclohexylcarbodiimide (5.5 g, 26.6
mmol), 4-(dimethylamino)pyridine (122 mg, 1 mmol),
4-pyrrolidinopyridine (148 mg, 1 mmol) and hydroxy-
methylbenzotriazole (1.94 g, 13.04 mmol) in CH2Cl2 (40
ml) was allowed to stand at r.t. under nitrogen, until the
esterification was complete. The resulting solution was
filtered through Celite to remove N,N-dicyclohexyl
urea, and the filtrate was concentrated under reduced
pressure. The residue was chromatographed on a silica
EtOAcꢀC6H14 (1/1). The product was isolated from the
/
third fraction by evaporation of the solvent, giving 1.1 g
(65%) of 1 as a white solid. Crystals suitable for X-ray
diffraction analysis were grown by slow evaporation of a
gel column (150 g), eluting with C3H6OꢀC6H14 (1/1).
/
1:1 EtOAcꢀ
/
C6H14 solution. Anal. Calc. for C13H10N4O2
The product was isolated from the fourth fraction by
evaporation of the solvent, giving 1.3 g (51%) of 3 as an
orange solid. Anal. Calc. for C26H20Fe2N6O4 (592.2): C,
52.7; H, 3.4. Found: C, 52.9; H, 3.5%; IR (KBr):
(254.2): C, 61.4; H, 4.0. Found: C, 61.1; H, 4.3%; IR
(KBr): 3283m, 3071vw, 3050vw, 3002vw, 2927s, 2852m,
2119vw, 1695vs (CÄ
1584vw, 1519s, 1432m, 1349m, 1119m, 748m, 694m
cmꢂ1; ESI-MS: m/z: 254 [M]ꢁ; H-NMR (200 MHz,
/
O ester), 1645s (CÄ/O amide),
3100vw, 3050vw, 2927s, 1723vs (CÄ
/
O ester), 1452m,
1270s, 1155m, 1102s, 968m cmꢂ1; ESI-MS: m/z: 592
1
1
d6-C3H6O, 21 8C): d 8.60 (d, 1H, ArH), 8.10 (d, 1H,
ArH), 7.93 (d, 1H, ArH), 7.65 (t, 1H, ArH), 7.62 (t, 1H,
ArH), 7.44 (t, 1H, ArH), 7.28 (t, 2H, ArH), 6.82 (s, 2H,
[M]ꢁ; H-NMR (200 MHz, d6-C3H6O, 21 8C): d 8.10
(d, 4H, ArH), 7.71 (t, 2H, ArH), 7.51 (t, 2H, ArH), 6.89
(s, 4H, Ã
/
CH2), 4.66 (t, 4H, CpH), 4.19 (t, 4H, CpH);
Ã
/
CH2); 13C-NMR (50 MHz, d6-C3H6O, 21 8C): d
13C-NMR (50 MHz, d6-C3H6O, 21 8C): d 171.30,
147.30, 146.39, 133.06, 133.03, 128.67, 124.93, 120.34,
110.74, 72.46, 72.43, 70.76, 70.16, 70.03, 70.00, 69.95,
69.01, 68.98, 67.62.
164.40, 150.46, 146.63, 146.36, 137.48, 133.13, 128.81,
127.94, 126.11, 124.88, 120.26, 110.55, 69.11.
5.2. (C6H4N3CH2CO2C5H4FeC5H5) (2)
5.4. [C6H4N3CH2CO2C6H4P(C6H5)2] (5)
A solution of ferrocenecarboxylic acid (1.4 g, 6.54
mmol), N,N-dicyclohexylcarbodiimide (2.7 g, 13.1
mmol), 4-(dimethylamino)pyridine (122 mg, 1 mmol),
4-pyrrolidinopyridine (148 mg, 1 mmol) and hydroxy-
methylbenzotriazole (1.04 g, 7.04 mmol) in CH2Cl2 (40
ml) was allowed to stand at r.t. under nitrogen, until the
esterification was complete. The resulting solution was
filtered through Celite to remove N,N-dicyclohexyl
urea, and the filtrate was concentrated under reduced
pressure. The residue was chromatographed on a silica
A solution of 2-diphenylphosphinobenzoic acid (1.4 g,
4.6 mmol), N,N-dicyclohexylcarbodiimide (1.3 g, 6.3
mmol), 4-(dimethylamino)pyridine (122 mg, 1 mmol), 4-
pyrrolidinopyridine (148 mg, 1 mmol) and hydroxy-
methylbenzotriazole (750 mg, 5.0 mmol) in CH2Cl2 (40
ml) was allowed to stand at r.t. under nitrogen, until the
esterification was complete. The resulting solution was
filtered through Celite to remove N,N-dicyclohexyl
urea, and the filtrate was concentrated under reduced
pressure. The residue was chromatographed on a silica
gel column (150 g), eluting with C3H6OꢀC6H14 (1/4).
/

C.M. Thomas et al. / Journal of Organometallic Chemistry 658 (2002) 251ꢀ
/258
257
gel column (150 g), eluting with Et2Oꢀ
/
C6H14 (1/1). The
for 2 h. Then the solvent was removed under reduced
pressure. The resulting yellow solid was washed with
ether (10 ml) and dried under vacuum (210 mg, 0.20
mmol, 78%). Anal. Calc. for C53H40Cl1N6O5P2Rh1
(1041.2): C, 61.1; H, 3.9. Found: C, 61.5; H, 4.1%; IR
product was isolated from the third fraction by evapora-
tion of the solvent, giving 1.3 g (65%) of 5 as a white
solid. Anal. Calc. for C26H20N3O2P1 (437.4): C, 71.4; H,
4.6. Found: C, 71.1; H, 4.3%; IR (KBr): 3051vw, 2927s,
2852m, 1723vs (CÄ
1049m, 984m, 695s cmꢂ1; ESI-MS: m/z: 437 [M]ꢁ; 1H-
NMR (200 MHz, d6-C3H6O, 21 8C): d 8.06ꢀ7.46 (m,
1H; ArH), 6.94 (s, 2H, Ã
CH2); 13C-NMR (50 MHz, d6-
C3H6O, 21 8C): d 165.76, 146.36, 142.10 (d, JCÃP 28.1
Hz), 137.58 (d, JCÃP 11.0 Hz), 134.68, 134.13 (d,
20.7 Hz), 133.10 (d, JCÃP 14.6 Hz), 132.19 (d,
/
O ester), 1584vw, 1434m, 1244s,
(KBr): 3058m, 2926m, 1949vs, 1730vs (CÄ
/
O ester),
1480w, 1452vw, 1435s, 1275s, 1156m, 1096s, 1055m,
986m, 962m, 743s, 696s cmꢂ1; ESI-MS: m/z: 844 [Mꢂ
/
/
1
/
Cl]ꢁ; H-NMR (200 MHz, d6-C3H6O, 21 8C): d 8.04
(m, 4H, ArH), 7.83 (m, 8H, ArH), 7.45 (m, 22H, ArH),
ꢃ
/
ꢃ
/
7.17 (m, 2H, ArH), 6.74 (s, 4H, Ã
/
CH2); 13C-NMR (50
1
JCÃP
JCÃP
JCÃP
ꢃ
/
ꢃ
/
MHz, d6-C3H6O, 21 8C): d 188.20 (dt, JPÃRh
ꢃ65 Hz
/
2
ꢃ
/
18.3 Hz), 131.67, 131.62, 129.10, 128.80 (d,
7.3 Hz), 128.62, 124.73, 120.19, 110.48, 68.73;
d, JCÃP
ꢃ22 Hz, carbonyl ligand), 171.25, 153.62,
/
ꢃ
/
144.80, 144.42, 138.54ꢀ
/
125.20, 68.62, 49.92; 31P-NMR
31P-NMR (81 MHz, d6-C3H6O, 21 8C): ꢂ
/2.7 (s).
(81 MHz, d6-C3H6O, 21 8C): 33.7 (d, J(103RhÃ
/
31P)ꢃ
/
1
136 Hz).
5.5. CoI2(C6H4N3CH2CO2C5H4FeC5H5)2 (6)
A solution of CoI2 (200 mg, 0.62 mmol) in CH2Cl2 (10
ml) was added dropwise to a solution of ferrocene(car-
boxylato-methylenebenzotriazole) (431 mg, 1.25 mmol)
in the same solvent (10 ml). The resulting solution was
stirred at room temperature for 1 h. The product
precipitated as green solid, which was filtered off,
washed with C6H14 (20 ml) and dried in vacuo (174
mg, 75%). Crystals suitable for X-ray diffraction analy-
6. Supplementary material
Lists of atomic coordinates, anisotropic displacement
parameters and crystallographic data (excluding struc-
ture factors) have been deposited with the Cambridge
Crystallographic Data Centre, CCDC nos. 179635,
179636, 179637 and 179638 for compounds 1, 2, 6 and
8. Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
sis were grown by slow evaporation of a 1:3 C3H6Oꢀ
/
C6H14 solution. Anal. Calc. for C36H30Co1Fe2I2N6O4
(1035.1): C, 41.8; H, 2.9. Found: C, 41.5; H, 3.1%; IR
Cambridge CB2 1EZ, UK (Fax: ꢁ44-1223-336033; e-
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
/
(KBr): 3092m, 3030vw, 1723vs (CÄ
/
O ester), 1455m,
1269s, 1199m, 782m, 481m cmꢂ1; ESI-MS: m/z: 1035
[M]ꢁ.
Acknowledgements
5.6. [Ir(CO)Cl(C6H4N3CH2CO2C4H2SCO2-
CH2C6H4N3)]2 (7)
Financial support (Project no 20-61227.00) of this
work from the Swiss National Science Foundation is
gratefully acknowledged.
A solution of [IrCl(cod)]2 (175 mg, 0.26 mmol) and
thiophene-2,5-di(carboxylatomethylenebenzotriazole)
(248 mg, 0.57 mmol) in C6H5CH3 (20 ml) was stirred at
reflux for 12 h under 1 bar of carbon monoxide. The
solution was filtered then evaporated to dryness. The
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