New N-pyrazole, P-phosphinite hybrid ligands and corresponding Rh(I) complexes: X-ray crystal structures of complexes with [Rh, N, P-phosphinite, Cl, (CO)] core

Article abstract of DOI:10.1016/j.jorganchem.2008.03.010

Two new N-pyrazole, P-phosphinite hybrid ligands 3-(3,5-dimethyl-1H-pyrazol-1-yl)propyldiphenylphosphinite (L³) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L⁴) are presented. The reactivity of these ligands and two other ligands reported in the literature (3,5-dimethyl-1H-pyrazol-1-yl)methyldiphenylphosphinite (L¹) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L²) towards [RhCl(CO)₂]₂ (1) have been studied and complexes [RhCl(CO)L] (L = L² (2), L³ (3) and L⁴ (4)) have been obtained. For L¹ only decomposition products have been achieved. All complexes were fully characterised by analytical and spectroscopic methods and the resolution of the crystalline structure of complexes 2 and 3 by single-crystal X-ray diffraction are also presented. In these complexes, the ligands are coordinated via κ²(N,P) to Rh(I), forming metallocycles of seven (2 and 4) or eight (3) members and finish its coordination with a carbonyl monoxide and a trans-chlorine to phosphorus atom. In both complexes, weak intermolecular interactions are present. NMR studies of complexes 2-4 show the chain N-(CH₂)_x-O becomes rigid and the protons diastereotopic.

Full text of DOI:10.1016/j.jorganchem.2008.03.010

Journal of Organometallic Chemistry 693 (2008) 2132–2138
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
New N-pyrazole, P-phosphinite hybrid ligands and corresponding Rh(I)
complexes: X-ray crystal structures of complexes with [Rh, N, P-phosphinite,
Cl, (CO)] core
Sergio Muñoz a, Josefina Pons a, , Xavier Solans b,1, Merce Font-Bardia b, Josep Ros a,
*
*
a Departament de Química, Unitat de Química Inorgànica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
b Cristalꢀlografia, Minerologia i Depòsits Minerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 1 February 2008
Received in revised form 10 March 2008
Accepted 10 March 2008
Available online 15 March 2008
In memory of Prof. Xavier Solans i Huguet.
TwonewN-pyrazole,P-phosphinitehybridligands3-(3,5-dimethyl-1H-pyrazol-1-yl)propyldiphenylphosph-
inite (L3) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L4) are presented. The reactivity
of these ligands and two other ligands reported in the literature (3,5-dimethyl-1H-pyrazol-1-yl)meth-
yldiphenylphosphinite (L1) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L2) towards
[RhCl(CO)2]2 (1)havebeenstudiedandcomplexes[RhCl(CO)L](L = L2 (2),L3 (3)andL4 (4))havebeenobtained.
For L1 only decomposition products have been achieved. All complexes were fully characterised by analytical
and spectroscopic methods and the resolution of the crystalline structure of complexes2 and 3 bysingle-crys-
tal X-ray diffraction are also presented. In these complexes, the ligands are coordinated via j2(N,P) to Rh(I),
forming metallocycles of seven (2 and 4) or eight (3) members and finish its coordination with a carbonyl
monoxide and a trans-chlorine to phosphorus atom. In both complexes, weak intermolecular interactions
are present. NMR studies of complexes 2–4 show the chain N–(CH2)x–O becomes rigid and the protons
diastereotopic.
Keywords:
Pyrazole
Phosphinite
Hybrid ligands
Rhodium(I) complexes
X-ray structures
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
Alexandratos et al. have used phosphorylated calixarenes for the
selective complexation of metal ions in solution and onto inor-
During the last century the interest for the coordination and
the organometallic chemistry has increased impressively. The po-
tential applicability of complexes where the metal is coordinated
to organic ligands by a heteroatom (N, O, S, P, etc.) has focused
the interest of many laboratories [1]. In particular, hybrid ligands
(molecules with two or more different hetereoatoms) have been
studied for its potential hemilabile properties [2]. Our group has
previously reported several functionalized thioether-, amino-
and phosphino- containing pyrazole ligands: NSN [3], NSSN
[3a,4], NN0 [5], NN0N [5d,6] and NP [5c,7] and has studied their
reactivity with Pd(II), Pt(II) and Rh(I). It is well known, ligands
contain pyrazole group have been studied extensively in the last
decades and it has been used in many fields [8]. Moreover, during
the last years the phosphinite group [P(OR)R02] has experimented
an important attention in the coordination chemistry for its capa-
bility to modulate electronic and steric properties against phos-
phines and many utilities has been investigated [9].
ganic and organic polymers [9d]. Braunstein et al. focus their
studies in the hybrid and sometimes hemilabile ligands and its
applicability onto homogenous catalysis. Also, they take a look
on new applications like nanomaterials of magnetic and catalytic
interest by covalent anchoring of metal complexes and clusters
into mesoporous materials also are described [2c]. Mukaiyama
et al. have used phosphinites as intermediate species to prepare
chiral hydrosulphides, amines, nitriles and isocyanides from eas-
ily available chiral alcohols using a condensation reaction with
oxidation–reduction [9a]. Finally, it is explored the application
of phosphinite complexes in the asymmetric homogeneous catal-
ysis. Recently, Agbossou et al. [9c] and Castillon et al. [9b], and in
the 1990s RajanBabu [9e] have presented studies of phosphinite
complexes and studies in catalytic reactions.
Following the interest of hybrid ligands, our group has pub-
lished a paper with the synthesis and characterisation of two
newN-pyrazole, P-phosphinite ligands and its reactivity towards
Ru(II) [10]. In this paper we present the synthesis and characterisa-
tion of two new N-pyrazole, P-phosphinite hybrid ligands and
study of their coordination towards Rh(I). X-ray crystal structure
of two Rh(I) complexes with core [N, P-phosphinite, Cl, (CO)] are
presented.
* Corresponding authors. Fax: +34 93 581 2895.
E-mail address: Josefina.Pons@uab.cat (J. Pons).
1
Deceased on 3 September of 2007, during the writing of the manuscript.
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.03.010

S. Muñoz et al. / Journal of Organometallic Chemistry 693 (2008) 2132–2138
2133
The complexes 2–4 were characterised by elemental analysis,
mass spectrometry, conductivity measurements, IR and NMR spec-
troscopies. All NMR experiments were recorded in CDCl3 solution.
Elemental analysis of products 2–4 are consistent with a for-
mula [RhCl(CO)L]. MS–ESI(+) of all compounds gives peaks with
m/z values of 455 (100%) (2), 469 (100%) (3) and 579 (100%) (4),
attributable to [Rh(CO)L]+ (L = L2, L3 and L4). Molar conductance
of 10ꢁ3 M solutions of complexes 2–4 in acetone shows values be-
tween 2 and 17 Xꢁ1 cm2 molꢁ1, attributable to non-electrolyte
compounds [17]. The IR spectra of 2–4 do not show significant dif-
ferences respect to the free ligands. In complexes 2–4 the band m
(CO) at 2003 cmꢁ1 (2), 2003 cmꢁ1(3) and 1989 cmꢁ1 (4) is ob-
served. The 1H, 1H{31P}, 13C{1H} and 31P{1H} NMR spectra and other
NMR studies give information about the coordination and disposi-
tion of the ligands towards Rh(I). The values of 31P{1H} NMR show
phosphorus atom is connected to Rh(I). The spectra show a doublet
2. Results and discussion
2.1. Synthesis of the ligands
Ligands (3,5-dimethyl-1H-pyrazol-1-yl)methyldiphenylphosph-
inite
(L1)
and
2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl-
diphenylphosphinite (L2) were prepared as described in the
literature [10]. It is the first time 3-(3,5-dimethyl-1H-pyrazol-1-
yl)propyldiphenylphosphinite (L3) and 2-(3,5-diphenyl-1H-pyra-
zol-1-yl)ethyldiphenylphosphinite (L4) are described. The same
route is used for four ligands (Scheme 1). A small excess of freshly
distilled triethylamine is added to a dry THF solution of the appropri-
ate pyrazol-alcohol precursor: L1, (3,5-dimethyl-1H-pyrazol-1-
yl)methanol [11]; L2, 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol
[12]; L3, 3-(3,5-dimethyl-1H-pyrazol-1-yl)propanol [13] and L4, 2-
(3,5-diphenyl-1H-pyrazol-1-yl)ethanol [14]. An equivalent amount
ofdiphenylphosphinechlorideisadded andthesolutionisstirred for
12 h. Filtration and evaporation lead an oily product. The ligands L3
and L4 were characterised by elemental analysis, mass spectrometry
and IR, 1H, 13C{1H}, 31P{1H}, COSY, HSQC and NOESY NMR experi-
ments. All of them are in agreement with expected proposed ligands
[10,15]. The 31P{1H} NMR shows peaks at d = 114.3 ppm for L3 and
d = 116.7 ppm for L4 indicate the presence of the phosphinite group
[10,16].
at d = 125.9 ppm (1JRhP = 181.4 Hz) (2), d = 130.9 ppm (1JRhP
=
188.2 Hz) (3) and d = 125.5 ppm (1JRhP = 178.2 Hz) (4). Chemical
shifts and coupling constants agree with the values of other Rh,
P-phosphinite complexes described in the literature [16]. The 1H
and 13C{1H} NMR do not show important differences between
the spectra of free ligands and the complexes in the aromatic
and methyl regions. However, 1H NMR was studied in detail
(1H{31P}, COSY, HSQC and NOESY NMR experiments) to make the
assignment of the signals of the chain N–(CH2)x–O. As it can be ob-
served, when the ligands act as j2 to the metal the protons of the
chain become diastereotopics. Spectrum 1H NMR of 2 shows sig-
nals at d = [6.19 (1H), 4.00 (3H) ppm], spectrum of 3 shows signals
at d = [5.52 (1H), 4.47 (1H), 4.18 (1H), 3.58 (1H), 2.01 (2H) ppm]
and spectrum of 4 shows signals at d = [6.60 (1H), 4.35 (1H), 3.88
(2H) ppm]. HSQC and 1H{31P} NMR experiments show the signals
appear at d = [6.19, 4.00 (2); 5.52, 4.18 (3); 6.60, 4.35 (4) ppm] cor-
responds to protons N–CH2. NOE interaction between the signals at
d = [4.00 (2), 4.18 (3), 4.35 (4) ppm] and methyl linked to the pyr-
azole is observed. Also, X-ray diffraction of compounds 2 and 3
2.2. Synthesis and characterisation of the complexes
Treatment of [RhCl(CO)2]2 (1) with L2–L4 ligands in 1 metal/1
ligand ratio in dry CH2Cl2 lead to [RhCl(CO)L] (L = L2 (2), L3 (3)
and L4 (4)) complexes as a yellow powder with a moderate yield
for 2 (43%) and 3 (52%) and a yellowish-brown powder with a good
yield for 4 (86%) (Scheme 2 and Section 4). Reaction of L1 with 1
only products of decomposition are detected. The complexes 2–4
are air-stable. However, complex 4 is air-sensitive in solution and
decomposes after 48 h.
R
R
R
R
Et3N, dry THF
-Et3HNCl
O
P
N
N
+ Cl
H
P
O
N
N
x
x
L1: R=CH3, x=1
L2: R=CH3, x=2
L3: R=CH3, x=3
L4: R= C6H5, x=2
Scheme 1.
R
R
R
R
O
P
N
N
CO
CO
Cl
Cl
dry CH2Cl2
-CO
x
OC
O
P
N
N
1/2
+
Rh
Rh
x
OC
Rh
CO
Cl
[RhCl(CO)L] (L = L2-L4) (2-4)
Scheme 2.

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S. Muñoz et al. / Journal of Organometallic Chemistry 693 (2008) 2132–2138
Table 1
Selected bond lengths (Å) and angles (°) for 2 and 3
2
3
Rh–C(8)
Rh–N(1)
1.805(3)
2.109(2)
Rh–C(21)
Rh–N(1)
1.819(3)
2.125(3)
Rh–P
Rh–Cl
P–O(2)
C(8)–Rh–N(1)
C(8)–Rh–P
N(1)–Rh–P
C(8)–Rh–Cl
N(1)–Rh–Cl
O–P–Rh
2.2065(10)
2.3858(11)
1.6260(18)
176.84(9)
92.18(9)
90.36(7)
89.32(9)
88.25(7)
Rh–P
Rh–Cl
P–O(1)
C(21)–Rh–N(1)
C(21)–Rh–P
N(1)–Rh–P
C(21)–Rh–Cl
N(1)–Rh–Cl
O–P–Rh
2.2065(11)
2.3811(11)
1.617(2)
174.45(11)
93.66(10)
86.56(8)
90.87(10)
89.10(8)
114.05(9)
120.57(10)
114.23(10)
113.48(7)
116.78(9)
117.84(9)
C(9)–P–Rh
C(15)–P–Rh
C(9)–P–Rh
C(15)–P–Rh
between Rh and the main plane N1–P–CO–Cl [0.02 Å (2), 0.03 Å
(3)], the values of Cl–Rh–CO angles [89.32°(9) (2), 90.87°(10) (3)]
and the values of N1–Rh–P bite angles [90.36°(7) (2), 86.56°(8)
(3)]. All of them are in agreement with the ones found in the bib-
liography [18–20]. The phosphorus atom also differs from the ideal
tetrahedral geometry as it can be observed in the values of the O–
P–Rh angles [113.48°(7) (2), 114.05°(9) (3)], C(9)–P–Rh angles
[116.78°(9) (2), 120.57°(10) (3)] and C(15)–P–Rh angles
[117.84°(9) (2), 114.23°(10) (3)].
Fig. 1. ORTEP drawing of [RhCl(CO)L2] (2) showing all non-hydrogen atoms and the
atom-numbering scheme; 50% probability amplitude displacement ellipsoid
shown.
The bond distances Rh–N [2.109(2) Å (2), 2.125(3) Å (3)], Rh–Cl
[2.3858(11) Å (2), 2.3811(11) Å (3)] and Rh–CO [1.805(3) Å (2),
1.819(3) Å (3)] are in agreement with the values described in the
literature: Rh–N [2.110–2.200 Å], Rh–Cl [2.372–2.409 Å] and Rh–
CO [1.805–1.837 Å] [18–20]. The bond distances Rh–P
[2.2065(10) Å (2), 2.2065(11) Å (3)] are longer than the distances
described in the literature: Rh–P [2.154–2.186 Å] [18–20].
As our knowledge it is the first time Rh(I) structures with core:
N,P-phosphinite [P(OR1)(R2)2 where R1 is an alkylic chain and R2 is
–C6H5], Cl, CO have been described. Similar structures with other
phosphinite or phosphorus functional groups have been published
previously: phosphite [P(OR)3] [18], phosphonite [P(OR)2R] [19]
and phosphinite [P(OR1)(R2)2 where R1 is an alkylic or allylic chain
and R2 is N] [20].
Complex 2 shows weak intermolecular interactions Mꢀ ꢀ ꢀH and
M@C@Oꢀ ꢀ ꢀH typical from organometallic compounds [21]. The dis-
tance of Rhꢀ ꢀ ꢀH(19) is 3.133 Å and Rh@C@Oꢀ ꢀ ꢀH(11) is 2.582 Å, in
agreement with the values observed in the literature: [2.6–3.2 Å]
and [2.5–2.6 Å], respectively. Also a non-covalent interaction p–p
stacking is presented (Fig. 3). The angle between the centroids
formed by the two rings C15–C16–C17–C18–C19–C20 is 0° con-
firming a perfect face to face interaction. The distance between
their centroids is 3.917 Å. Similar values are found in the literature
[3.0–4.6 Å] [22]. However, only C16 and C17 build a parallel dis-
placed p–p stacking interaction. The distance between the pair of
carbons is 3.362 Å, in agreement with the interval found in the bib-
liography [3.3–3.8 Å] [22].
Fig. 2. ORTEP drawing of [RhCl(CO)L3] (3) showing all non-hydrogen atoms and the
atom-numbering scheme; 50% probability amplitude displacement ellipsoid
shown.
show a short distance between one proton of N–CH2 and the
CH3(5) moiety [2.578 Å (2), 2.193 Å (3)] (Figs. 1 and 2). This dis-
tance is shorter than the other proton of N–CH2 against CH3(5)
moiety [3.892 Å (2), 3.538 Å (3)].
The protons CH2–O appear at d = [4.00 (2), 4.47 and 3.58 (3),
3.88 (4) ppm]. Finally, the protons N–CH2–CH2–CH2–O of 3 appear
at d = 2.01 ppm.
In complex 3, a non-covalent CHꢀ ꢀ ꢀO interaction is observed
2.3. Crystal and molecular structure of complexes 2 and 3
(Fig. 4). The distance detected between H(5)ꢀ ꢀ ꢀO is 2.720 Å [23].
The structures of complexes 2 and 3 are confirmed by single-
crystal X-ray diffraction.
3. Conclusion
ORTEP pictures and selected bonds distances and and angles are
shown in Fig. 1 (2), Fig. 2 (3) and Table 1. The structures of com-
plexes 2 and 3 consist of discrete Rh(I) molecules. The metal is con-
nected to the pyrazole–phosphinite ligands via j2(N,P) building a
metallocycle ring of seven (2) and eight (3) members, and finishes
its coordination with a carbonyl monoxide and a trans-chlorine re-
spect phosphorus atom.
The present paper reports the synthesis and characterisation of
two new N-pyrazole, P-phosphinite hybrid ligands (L3 and L4). The
reaction of these ligands and two other ligands reported in the lit-
erature (L1 and L2) towards [RhCl(CO)2]2 (1) has been studied.
Complexes [RhCl(CO)L] (L = L2 (2), L3 (3) and L4 (4)) are obtained.
The coordination modes of the ligands (L2–L4) in complexes 2–4
do not depend neither on the groups of the pyrazole in 3,5-posi-
tions (methyl, phenyl) nor the length of the chain N–(CH2)x–O
Rh(I) has a slightly distorted square-planar geometry. The
distortion of the geometry is observed by the values of distances

S. Muñoz et al. / Journal of Organometallic Chemistry 693 (2008) 2132–2138
2135
Fig. 3. Two different views from the parallel displaced p–p stacking interactions of [RhCl(CO)L2] (2).
Fig. 4. View of CHꢀ ꢀ ꢀO interactions of complex [RhCl(CO)L3] (3).

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S. Muñoz et al. / Journal of Organometallic Chemistry 693 (2008) 2132–2138
when x = 2, 3. However, when x = 1 (L1) the formation of the corre-
sponding complex is not observed. Probably, the effect of the ring
size does not permit the formation of [RhCl(CO)L1]. This behaviour
has been observed previously in others ligands that contain only
one CH2 group between two heteroatoms [4b,4d,24].
Furthermore, few structures have been described in the litera-
ture with [Rh, N, P(phosphinite), Cl, (CO)] core. We have contrib-
uted with the resolution of the single-crystal X-ray diffraction of
two new Rh(I) complexes with this core.
d: 7.78–7.10 (m, 10H, C6H5), 5.66 (s, 1H, pz-CH), 3.97 (t, 2H,
3
3JHH = 7.1 Hz, pz-CH2–CH2–CH2–O), 3.77 (dt, 2H, JPH = 8.6 Hz,
3JHH = 5.9 Hz, pz-CH2–CH2–CH2–O), 2.12 (s, 3H, pz-CH3), 2.10 (m,
2H, pz-CH2–CH2–CH2–O), 2.04 (s, 3H, pz-CH3) ppm. 13C{1H} NMR
(CDCl3 at 298 K, 63 MHz) d: 147.8 (pz-CCH3), 142.2 (d,
1JPC = 18.2 Hz, O–P–C6H5), 139.3 (pz-CCH3), 134.3 (d, 1JPC = 16.8 Hz,
O–P–C6H5), 132.9–128.1 (C6H5), 105.1 (pz-CH), 67.4 (d,
2JPC = 19.7 Hz, pz-CH2CH2CH2–O), 45.5 (pz-CH2CH2CH2–O), 32.4
3
(d, JPC = 7.7 Hz, pz-CH2CH2CH2–O), 13.9 (pz-CH3), 11.3 (pz-CH3)
ppm. 31P{1H} NMR (CDCl3 at 298 K, 81 MHz) d: 114.3 (s, O–P–
(C6H5)2) ppm.
4. Experimental
4.2.2. Synthesis of 2-(3,5-diphenyl-1H-pyrazol-1-
yl)ethyldiphenylphosphinite (L4)
4.1. General details
Ligand L4 is prepared analogously L3 using 2-(3,5-diphenyl-1H-
All reactions were performed with the use of vacuum line and
Schlenk techniques. All reagents were commercial grade and were
used without further purification except triethylamine that was
purified by distillation in KOH. All solvents were dried and distilled
by standard methods. The elementals analysis (C, H, N) were carried
out by the staff of the Chemical Analyses Service of the Universitat
Autònoma de Barcelona on a Carlo Erba CHNS EA-1108 instrument
separated by chromatographic column and termoconductivity
detector. Conductivity measurements were performed at room
temperature in 10ꢁ3 M acetone solutions employing a CyberScan
CON 500 (Eutech instrument) conductimeter. Infrared spectra were
run on a Perkin–Elmer FT-2000 spectrophotometer as KBr pellets in
solid samples and with NaCl mulls in oily samples. The 1H, 1H{31P},
13C{1H} and 31P{1H} NMR spectra and COSY, HSQC and NOESY NMR
spectra were run on a NMR-FT Bruker AC-250 spectrometer and on
an Advance DRX500. All NMR experiments were recorded on CDCl3
solvent under nitrogen. 1H, 1H{31P} and 13C{1H} NMR chemical
shifts (d) were determined relative to internal TMS and are given
in ppm. 31P{1H} NMR chemical shifts (d) were determined relative
to external 85% H3PO4 and are given in ppm. Electrospray Mass
spectra (ESI+) were carried out by the staff of the Chemical Analysis
Service of the Universitat Autònoma de Barcelona on an Esquire
3000 ion trap mass spectrometer from Bruker Daltonics. Mass
experiments of the ligands were done on CH3CN, CH3OH or
CH3CN/CH3OH solvents. Mass spectra of the complexes were done
on CH3CN/CHCl3 solvents. The precursor complex [RhCl(CO)2]2 (1)
is commercially available. The (3,5-dimethyl-1H-pyrazol-1-yl)-
methanol, 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 3-(3,5-di-
methyl-1H-pyrazol-1-yl)propanol and 2-(3,5-diphenyl-1H-pyra-
zol-1-yl)ethanol were prepared as described in the literature
[11–14]. The (3,5-dimethyl-1H-pyrazol-1-yl)methyldiphenylphos-
phinite (L1) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenyl-
phosphinite (L2) ligands were prepared as described in the litera-
ture [10].
pyrazol-1-yl)ethanol
(3.78 mmol,
1.00 g),
triethylamine
(4.00 mmol, 0.56 mL) and PPh2Cl (3.81 mmol, 0.72 mL). L4 was ob-
tained as brownish-green oil (yield: 65%, 1.10 g). Anal. Calc. for
C
29H25N2OP: C, 77.66; H, 5.62; N, 6.25. Found: C, 77.53; H, 5.89; N,
6.24%. MS (ESI+): m/z (%) 449 (100%) [L4H]+, 247 (48%) [pz-
CH2CH2 + H+]. IR: (NaCl, cmꢁ1) 3055 m(C–H)ar, 2939 m(C–H)al, 1550
m(C@C/C@N)ar, 1482, 1435 d(C@C/C@N)ar, 1041 m(P–O–C), 739, 695
d(C–H)oop.
1H NMR (CDCl3 at 298 K, 250 MHz) d: 7.81–7.62 (d,
3JHH = 7.7 Hz, 2H, ortho-C6H5), 7.55–7.10 (m, 8H, C6H5), 6.50 (s, 1H,
pz-CH), 4.33 (m, 2H, pz-CH2–CH2–O), 4.20 (m, 2H, pz-CH2–CH2–O)
ppm. 13C{1H} NMR (CDCl3 at 298 K, 63 MHz) d: 151.4 (pz-CCH3),
146.1 (pz-CCH3), 135.9 (d, 1JPC = 7.2 Hz, C6H5), 135.6 (d, 1JPC = 7.2 Hz,
C6H5), 132.2–125.9 (C6H5), 103.9 (pz-CH), 67.0 (d, 2JPC = 18.7 Hz, pz-
CH2CH2–O), 50.7 (d, 3JPC = 8.6 Hz, pz-CH2CH2–O) ppm. 31P{1H} NMR
(CDCl3 at 298 K, 81 MHz) d: 116.7 (s, O–P–(C6H5)2) ppm.
4.3. Synthesis of the complexes
4.3.1. Complexes [RhCl(CO)L] (L = L2 (2), L3 (3) and L4(4))
The appropriate ligand (0.180 mmol: L1, 0.056 g; L2, 0.058 g; L3,
0.061 g; L4, 0.081 g), dissolved in dry CH2Cl2 (6 mL) was added to a
solution of the rhodium complex [RhCl(CO)2]2 (1) (0.090 mmol,
0.035 g) in dry CH2Cl2 (6 mL). The solutions changed to a slightly
yellowish-green colour immediately after the addition. After 12 h
the solutions were yellowish-brown in the reactions of L1, L2 and
L3 and brown in L4. The resulting solutions were concentrated till
5 mL. Cold diethyl ether was added dropwise to the solution of
L1, L2 and L3 to obtain a yellow pure solid. Hexane was added to
the solution of L4 to obtain a yellowish-brown pure solid.
The NMR spectra indicates [RhCl(CO)L] for L2 (2), L3 (3) and L4
(4) were obtained. In the reaction of L1 with [RhCl(CO)2]2 (1) only
products of decomposition of the ligand were observed (yields:
43%, 0.038 g (2), 52%, 0.047 g (3), 86%, 0.095 g (4)).
4.3.1.1. [RhCl(CO)L2] (2). Anal. Calc. for C20H21N2O2PClRh: C, 48.95;
H, 4.31; N 5.71. Found: C, 48.63; H, 4.08; N, 5.73%. Conductivity
(1.04 ꢂ 10ꢁ3 M in acetone): 2 Xꢁ1 cm2 molꢁ1. MS (ESI+): m/z (%)
455 (100%) [Rh(CO)L2]+. IR: (KBr, cmꢁ1) 3055 m(C–H)ar, 2915,
2878 m(C–H)al, 2003 m(CO), 1550 m(C@C/C@N)ar, 1469, 1432
4.2. Synthesis of the ligands
4.2.1. Synthesis of 3-(3,5-dimethyl-1H-pyrazol-1-
yl)propyldiphenylphosphinite (L3)
d(C@C/C@N)ar, 1052 m(P–O–C), 724, 699 d(C–H)oop.
1H NMR (CDCl3
A
solution of 3-(3,5-dimethyl-1H-pyrazol-1-yl)propanol
(6.48 mmol, 1.00 g) and triethylamine (6.78 mmol, 0.95 mL) in
20 mL of dry THF was prepared. PPh2Cl (6.51 mmol, 1.23 mL) dis-
solved in 10 mL of dry THF was slowly added at room temperature
and the mixture was stirred for 12 h. The triethylammonium chlo-
ride was formed and filtered off. Evaporation of the solvent in vac-
uum gave L3 as yellowish-brown oil (yield: 97%, 2.12 g). Anal. Calc.
for C20H23N2OP: C, 70.99; H, 6.85; N, 8.28. Found: C, 70.55; H, 6.44;
N, 8.31%. MS (ESI+): m/z (%) 345 (100%) [L3Li]+, 137 (83%)
[pz-CH2CH2CH2]+. IR: (NaCl, cmꢁ1) 3054 m(C–H)ar, 2949, 2928
m(C–H)al, 1552 m(C@C/C@N)ar, 1480, 1435 d(C@C/C@N)ar, 1048
at 298 K, 250 MHz): d = 7.86–7.27 (m, 10H, C6H5), 6.19 (m, 1H, pz-
CH2CH2–O), 5.81 (s, 1H, pz-CH), 4.00 (m, 3H, pz-CH2–CH2–O), 2.23
(s, 3H, pz-CH3), 2.15 (s, 3H, pz-CH3) ppm. 13C{1H} NMR (CDCl3 at
298K, 63 MHz) d: 151.6 (pz-CCH3), 140.6 (pz-CCH3), 133.5–128.7
2
(C6H5), 108.8 (pz-CH), 64.2 (d, JPC = 3.5 Hz, pz-CH2CH2–O), 48.0
3
(d, JPC = 5.2 Hz, pz-CH2CH2–O), 15.0 (pz-CH3), 11.6 (pz-CH3) ppm.
31P{1H} NMR (CDCl3 at 298 K, 81 MHz) d: 125.9 (d, 1JRhP = 181.4 Hz,
O–P–(C6H5)2) ppm.
4.3.1.2. [RhCl(CO)L3] (3). Anal. Calc. for C21H23N2O2PClRh: C, 49.97;
H, 4.59; N, 5.55. Found: C, 49.75; H, 4.52; N, 5.57%. Conductivity
m(P–O–C), 740, 697 d(C–H)oop.
1H NMR (CDCl3 at 298 K, 250 MHz)

S. Muñoz et al. / Journal of Organometallic Chemistry 693 (2008) 2132–2138
2137
(9.71 ꢂ 10ꢁ4 M in acetone): 2 Xꢁ1 cm2 molꢁ1. MS (ESI+): m/z (%)
4.4. X-ray crystal structures for complexes 2 and 3
469 (100%) [Rh(CO)L3]+. IR: (KBr, cmꢁ1) 3050 m(C–H)ar, 2959,
2945, 2915 m(C–H)al, 2003 m(CO), 1555 m(C@C/C@N)ar, 1437
Suitable crystals for X-ray diffraction of compounds [RhCl(CO)L]
(L = L2 (2) and L3 (3)) were obtained by slow diffusion of a CH2Cl2/
diethylether solution in 1:2 ratio. Prismatic crystals were selected
and mounted on a MAR 345 diffractometer with an image plate
detector. Unit cell parameters were determined from 6566 reflec-
tions for 2 and 2078 reflections for 3 (3 < h < 31°) and refined by
least-squares method. Intensities were collected with graphite
monochromatized Mo Ka radiation. 7173 reflections were mea-
sured in the range 3.21 6 h 6 29.09 for 2 which 3790 were non-
equivalent by symmetry (Rint (on I) = 0.026). Three thousand six
hundred and ninety three reflections were assumed as observed
applying the condition I > 2r(I). Ten thousand and five hundred
and six reflections were measured in the range 3.02 6 h 6 29.98
for 3 which 5427 were non-equivalent by symmetry (Rint (on
I) = 0.043). Five thousand and four hundred and seventeen reflec-
tions were assumed as observed applying the condition I > 2r(I).
Lorentz-polarization but no absorption corrections were made.
For 2 and 3, the structure was solved by direct methods, using
SHELXS-97 computer program [25] and refined by full-matrix least-
squares method with SHELXL-97 computer program [26], using
d(C@C/C@N)ar, 1055 m(P–O–C), 746, 701 d(C–H)oop.
1H NMR (CDCl3
at 298 K, 250 MHz) d: 7.66–7.26 (m, 10H, C6H5), 5.66 (s, 1H, pz-CH),
5.52 (m, 1H, pz–CH2–CH2–CH2–O), 4.47 (m, 1H, pz-CH2–CH2–CH2–
O), 4.18 (m, 1H, pz-CH2–CH2–CH2–O), 3.58 (m, 1H, pz-CH2–CH2–
CH2–O), 2.15 (s, 3H, pz-CH3), 2.08 (s, 3H, pz-CH3), 2.01 (m, 2H,
pz-CH2–CH2–CH2–O) ppm. 13C{1H} NMR (CDCl3 at 298 K,
63 MHz) d: 150.5 (pz-CCH3), 141.4 (pz-CCH3), 132.7–128.1
2
(C6H5), 108.4 (pz-CH), 66.0 (d, JPC = 1.2 Hz, pz-CH2CH2CH2–O),
3
49.1 (pz-CH2CH2CH2–O), 32.3 (d, JPC = 2.5 Hz, pz-CH2CH2CH2–O),
14.7 (pz-CH3), 12.0 (pz-CH3) ppm. 31P{1H} NMR (CDCl3 at 298 K,
1
81 MHz) d: 130.9 (d, JRhP = 188.2 Hz, O–P–(C6H5)2) ppm.
4.3.1.3. [RhCl(CO)L4] (4). Anal. Calc. for C30H25N2O2PClRh: C, 58.60;
H, 4.10; N, 4.56. Found: C, 58.52; H, 4.48; N, 4.34%. Conductivity
(1.02 ꢂ 10ꢁ3 M in acetone): 17 Xꢁ1 cm2 molꢁ1. MS (ESI+): m/z (%)
579 (100%) [Rh(CO)L4]+. IR: (KBr, cmꢁ1) 3056 m(C–H)ar, 2955 m(C–
H)al, 1989 m(CO), 1552 m(C@C/C@N)ar, 1436 d(C@C/C@N)ar, 1029
m(P–O–C), 764, 696 d(C–H)oop.
1H NMR (CDCl3 at 298 K, 250 MHz)
d: 7.92–7.85 (m, 2H, ortho-C6H5), 7.85–7.60 (m, 8H, C6H5), 6.60
(m, 1H, pz-CH2CH2–O), 6.50 (s, 1H, pz-CH), 4.35 (dd, 1H,
7173 reflections for 2 and 10506 for 3. The function minimised
P
3
2JHH = 15.0 Hz, JHH = 3.5 Hz, pz-CH2–CH2–O), 3.88 (m, 2H, pz-
was
w||Fo|2 ꢁ |Fc|2|2, where w = [r2(I) + (0.0617P)2 + 0.1036P]ꢁ1
,
CH2–CH2–O) ppm. 13C{1H} NMR (CDCl3 at 298 K, 63 MHz) d:
154.6 (pz-CC6H5), 146.5 (pz-CC6H5), 136.3-128.0 (C6H5), 108.2
and P = (|Fo|2 + 2|Fc|2)/3 for
2
and w = [r2(I) + (0.0232P)2 +
0.8872P]ꢁ1, and P = (|Fo|2 + 2|Fc|2)/3 for 3. All H atoms were com-
puted and refined, using a riding model, with an isotropic temper-
ature factor equal to 1.2 times the equivalent temperature factor of
the atom which is linked.
3
(pz-CH), 64.9 (pz-CH2CH2–O), 49.7 (d, JPC = 4.7 Hz, pz-CH2CH2–O)
ppm. 31P{1H} NMR (CDCl3 at 298 K, 81 MHz) d: 125.5 (d,
1JRhP = 178.2 Hz, O–P–(C6H5)2) ppm.
The parameters refined and other details concerning the refine-
ment of the crystal structures are gathered in Table 2.
Table 2
Supplementary material
Crystallographic data for [RhCl(CO)L2] (2) and [RhCl(CO)L3] (3)
CCDC 676215 and 676216 contain the supplementary crystallo-
graphic data for compound 2 and 3. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
2
3
Formula
C
20H21N2O2PClRh
C21H23N2O2PClRh
504.74
293(2)
0.71073
Triclinic, P1
Formula weight
Temperature (K)
Wavelength (Å)
System, space group
490.72
293(2)
0.71073
ꢀ
ꢀ
Triclinic, P1
Acknowledgements
Unit cell dimensions
a (Å)
b (Å)
c (Å)
a (°)
b (°)
c (°)
U (Å3)
Z
8.321(4)
10.996(5)
11.003(4)
11.120(4)
67.47(3)
61.46(3)
75.97(3)
1088.8(8)
2
1.540
0.999
512
11.549(4)
11.655(9)
111.09(2)
97.21(2)
93.66(2)
1029.5(10)
2
1.583
1.054
496
Support by the Spanish Ministerio de Educacion y Cultura (pro-
jecte CTQ2007-63913 BQU) is gratefully acknowledged.
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