Synthesis and characterization of tricarbonyl-molybdenum complexes bearing monoaza-trithia-macrocyclic ligands

Article abstract of DOI:10.1016/j.ica.2013.03.027

Novel tricarbonyl-molybdenum complexes bearing monoaza-trithia-macrocyclic ligands (LX^R), [Mo(CO)₃(LX^R)] (X = 12 or 14, R = H), and [Mo(CO)₃(L14^Py)Mo(CO)₄] have been synthesized to gain an understanding of the unique properties of macrocyclic ligands. X-ray structure analysis of [Mo(CO)₃(L14^H)] has revealed that intra- and intermolecular hydrogen bonds existed and these interaction regulated CO bond lengths. In addition, vibrational spectroscopy indicates that a specific hydrogen bonding interaction affects the strength of the binding of carbon monoxide molecules to the metal. In case of using L14 ^Py, it is expected that dinuclear molybdenum complex was generated.

Full text of DOI:10.1016/j.ica.2013.03.027

Inorganica Chimica Acta 401 (2013) 101–106
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis and characterization of tricarbonyl–molybdenum complexes
bearing monoaza-trithia-macrocyclic ligands
⇑
Takahiko Ogawa, Koji Koike, Jun Matsumoto, Yuji Kajita, Hideki Masuda
Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
a r t i c l e i n f o
a b s t r a c t
Novel tricarbonyl–molybdenum complexes bearing monoaza-trithia-macrocyclic ligands (LXR),
[Mo(CO)3(LXR)] (X = 12 or 14, R = H), and [Mo(CO)3(L14Py)Mo(CO)4] have been synthesized to gain an
understanding of the unique properties of macrocyclic ligands. X-ray structure analysis of [Mo(CO)3
(L14H)] has revealed that intra- and intermolecular hydrogen bonds existed and these interaction
regulated CO bond lengths. In addition, vibrational spectroscopy indicates that a specific hydrogen
bonding interaction affects the strength of the binding of carbon monoxide molecules to the metal. In
case of using L14Py, it is expected that dinuclear molybdenum complex was generated.
Ó 2013 Elsevier B.V. All rights reserved.
Article history:
Received 16 August 2012
Received in revised form 1 March 2013
Accepted 17 March 2013
Available online 27 March 2013
Keywords:
Molybdenum
Macrocycle
Hydrogen bond
Carbon monoxide
Crystal structure
1. Introduction
Interestingly, we found that the coordination structures of these
molybdenum complexes and the coordinated carbonyl molecules
Sulfur-containing macrocyclic compounds such as thia-, oxa-
thia-, and azathiacrown ethers show high affinity to transition
metals with various oxidation states (especially group 6 metals)
forming stable complexes with them [1–5]. Therefore, a lot of stud-
ies were performed to develop various reagent and catalyst using a
metal complex bearing macrocyclic ligand [6–8]. And, it is known
that metal–carbonyl complexes are very useful tool for investigat-
ing the property of metal complex such as a structure and elec-
tronic state. Carbon monoxide can bind strongly to low oxidation
state transition metals. And, it shows distinctive peaks that can
be an indicator of property of metal complexes in vibration spec-
troscopy [9–11]. And, conversion of CO molecule is very important
process in C1 chemistry. Especially, molybdenum–carbonyl com-
plexes are getting a lot more attention lately. Because it has been
reported that vanadium/molybdenum nitrogenases catalyze
reductive catenation of carbon monoxide to ethylene, ethane, pro-
pylene, propane and so on [12–14].
Thus, we synthesized two types of macrocyclic ligands, 1,4,7-
trithia-10-azacyclododecane [15] and 1,4,7-trithia-11-azacyclote-
tradecane [16,17] to provide coordination sphere which can
coordinate to low oxidation state molybdenum ion, and prepared
molybdenum carbonyl complexes with these ligands. In addition,
we investigated the properties of these molybdenum complexes
using X-ray diffraction analysis and vibration spectroscopic studies.
are affected by the hydrogen bonds formed in the crystal.
2. Experimental
2.1. Material and methods
All manipulations were carried out under atmospheric condi-
tions of purified argon or dinitrogen gas in an mBRAUN MB
150B-G glovebox or by standard Schlenk techniques. 1H NMR
(300 MHz: Varian, 600 MHz: Bruker) and 13C{1H} NMR (75 MHz:
Varian, 150 MHz: Bruker) spectra were measured on a Varian Mer-
cury 300 spectrometer or a Bruker Avance 600 spectrometer, and
lH and 13C{1H} chemical shifts were estimated relative to an inter-
nal standard of tetramethylsilane (TMS) or residual protons in the
deuterated solvent. Fourier transform infrared (FT-IR) spectra of
solid compounds were obtained from KBr pellets using a JASCO
FT/IR-410 spectrophotometer. Electrospray ionization time-of-
flight mass spectra ESI-TOF/MS were obtained with a Micromass
LCT spectrometer. Elemental analyses were obtained with a Perkin
Elmer CHN-900 elemental analyzer. Energy dispersive X-ray fluo-
rescence analyses (EDX) were performed by EDX-800, Shimadzu
Co. Ltd. The reagents and solvents employed were commercially
available. All anhydrous solvents were purchased from Wako Ltd
or Sigma–Aldrich, and were degassed with argon or dinitrogen.
Molecular mechanics calculations were performed by Fujitsu CACHE
program.
⇑
Corresponding author. Tel.: +81 52 735 5228; fax: +81 52 735 5209.
E-mail address: masuda.hideki@nitech.ac.jp (H. Masuda).
0020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.03.027

102
T. Ogawa et al. / Inorganica Chimica Acta 401 (2013) 101–106
2.2. X-ray crystallography
NCH2-pyridine), 7.18, 7.50, 7.68, 8.53 (m, 4H, pyridine). 13C{1H}
NMR (d/ppm vs TMS in CDCl3, 150 MHz): d 26.0 (SCH2CH2N),
28.0, 28.8 (SCH2CH2S), 52.0 (SCH2CH2N), 60.8 (NCH2-pyridine),
122.3, 122.9, 136.5, 149.1, 159.0 (pyridine).
Single crystals of 1Py and 2H suitable for X-ray diffraction anal-
yses were obtained from CH2Cl2/Et2O solutions after standing for
a few days under a N2 atmosphere. A crystal was mounted on a
glass fiber, and diffraction data were collected on a Rigaku/MSC
FT-IR (KBr, cmꢀ1) 3049, 3006, 2961, 2933, 2841, 1588, 1569,
1472, 1453, 1426, 1260, 800.
Mercury CCD using graphite monochromated Mo K
a
radiation
ESI-TOF-MS (pos.) m/z = 315.0 [M+H]+.
at 173 K. The structures were solved by a combination of direct
methods (SIR 92 or SHELX97) and Fourier techniques. All non-
hydrogen atoms except for some of the solvent molecules were
refined anisotropically. Hydrogen atoms were refined using the
riding model. A Sheldrick weighting scheme was employed. Plots
Anal. Calc. for C14H22N2S3: C, 53.46; H, 7.05; N, 8.91. Found: C,
52.94; H, 7.26; N, 8.62%.
2.3.2. N-(2-pyridylmethyl)-1,4,7-trithia-11-azacyclotetradecane
(L14Py
)
of
R
w(|F0| ꢀ |Fc|)2 versus |F0|, reflection order in data collection,
This compound was prepared by a modification of a literature
procedure [6,15–17]. The treatment of 1,4,7-trithia-11-azacyclote-
tradecane (0.350 g, 1.57 mmol) and 2-(chloromethyl)pyridine
hydrochloride (0.257 g, 1.58 mmol) afforded the objective product
(0.320 g, 1.02 mmol) with a 64.9% yield as a solid after chromatog-
raphy on silica gel (CH2Cl2/AcOEt 10: 1 eluent) and drying under
reduced pressure.
sin h/k, and various classes of indices showed no unusual tenden-
cies. Neutral atomic scattering factors were obtained from the
International Tables for X-ray Crystallography Vol. IV [18]. Anom-
alous dispersion terms were included in Fcalc, [19] and the values
for
D D
f0 and f00 were taken from International Tables for X-ray
Crystallography Vol. C [20]. The values for the mass attenuation
coefficients were obtained from International Tables for X-ray
Crystallography Vol. C [21]. All calculations were performed using
the crystallographic software package CRYSTALSTRUCTURE [22,23]. A
summary of crystallographic data is provided in the supporting
information (Table 1).
1H NMR (d/ppm from TMS in CDCl3, 300 MHz): d 1.79 (q, 4H,
NCH2CH2CH2N), 2.59 (m, 8H, NCH2CH2CH2N), 2.78 (m, 8H, SCH2-
CH2S), 3.72 (s, 2H, NCH2-pyridine), 7.17, 7.42, 7.70, 8.53 (s m, 4H,
pyridine). 13C{1H} NMR (d/ppm from TMS in CDCl3, 150 MHz): d
27.9 (SCH2CH2CH2N), 29.5 (SCH2CH2CH2N), 31.0, 31.4 (SCH2CH2S),
53.0 (SCH2CH2CH2N), 61.9 (NCH2-pyridine), 122.0, 123.0, 136.3,
149.0, 159.8 (pyridine).
2.3. Synthesis
FT-IR (KBr, cmꢀ1) 3046, 3010, 2946, 2931, 2798, 1587, 1570,
1469, 1431, 1274, 761.
2.3.1. N-(2-pyridylmethyl)-1,4,7-trithia-10-azacyclododecane (L12Py
)
ESI-TOF-MS (pos.) m/z = 343.06 [M+H]+.
Under an argon atmosphere, a solution of 1,4,7-trithia-10-aza-
cyclododecane (0.350 g, 1.57 mmol), 2-(chloromethyl)pyridine
hydrochloride (0.257 g, 1.58 mmol), and triethylamine (0.406 g,
4.02 mmol) in ethanol (50 mL) was refluxed at 75 °C for 30 h. The
solvent was removed in vacuo, and then the residue was dissolved
in CHCl3 (200 mL) and washed liberally with water. The organic
fraction was dried by MgSO4, and the solvent was removed to ob-
tain a yellow solid. The residue was purified by column chromatog-
raphy on silica gel using a mixture of CH2Cl2/AcOEt (7:3 v/v ratio)
as eluent. Yield 0.320 g, 1.02 mmol (yield 65.0%).
2.3.3. [Mo(CO)3(L12H)] (1H)
A suspension of L12H (1.03 ꢁ 10ꢀ1 g, 3.26 ꢁ 10ꢀ4 mol) and
molybdenum
hexacarbonyl
[Mo(CO)6]
(1.12 ꢁ 10ꢀ1 g,
4.24 ꢁ 10ꢀ4 mol) in toluene (5 mL) was refluxed overnight. The
reaction mixture was concentrated in vacuo. The resulting brown
solid was dissolved in CH2Cl2 (5 mL) and was filtered through a
Celite pad. Crystallization from CH2Cl2/Et2O yielded brown crystals
of 1H.
1H NMR (d/ppm from TMS in CDCl3, 600 MHz): d 2.68 (t, 4H,
NCH2CH2), 2.83 (m, 12H, NCH2CH2SCH2CH2S), 3.81 (s, 2H,
1H NMR (d/ppm from TMS in CD3CN, 300 MHz): d 2.15 (s, 2H),
2.64 (t, 2H), 2.73 (br, 3H), 2.83 (m, 5H), 2.98 (br, 2H), 3.10 (br, 3H).
FT-IR (KBr, cmꢀ1) d 3258 (NꢀH), 1913, 1781, 1754 (C„O), 517,
473 (MoꢀC).
Table 1
Summary of crystallographic data.
ESI-TOF-MS (pos.) m/z = 377.9 [MꢀCO]+.
Complex
1Py
2H
Anal. Calc. for C11H17MoNO3S3: C, 32.75; H, 4.25; N, 3.47. Found:
C, 32.56; H, 4.48; N, 3.29%.
Formula
C17H22MoN2O3S3 C26H42Mo2N2O6S6
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
494.49
862.87
orthorhombic
Pna21 (#33)
29.541(4)
8.9741(11)
12.783(2)
90
90
90
3388.8(8)
4
1.691
11.496
19.38
25693
7676 (0.0339)
12126
0.0337
0.0665
1.098
0.84, ꢀ0.72
monoclinic
P21/c (#14)
19.1121(8)
8.2591(3)
12.8459(5)
90
104.630(3)
90
1962.0(2)
4
1.674
10.063
19.12
14850
4494 (0.0161)
4494
0.0239
0.0551
1.090
2.3.4. fac-[Mo(CO)3(L12py)] (1py
)
According to a procedure similar to the procedure used for
preparation of 1H,
a
suspension of L12Py (1.23 ꢁ 10ꢀ1 g,
3.91 ꢁ 10ꢀ4 mol) and molybdenum hexacarbonyl [Mo(CO)6]
(1.23 ꢁ 10ꢀ1 g, (4.66 ꢁ 10ꢀ4 mol) in toluene (5 mL) was refluxed
for 8 h. The reaction mixture was concentrated in vacuo, and then
the resulting brown solid was dissolved in CH2Cl2 (5 mL) and fil-
tered through a Celite pad. Crystallization from CH2Cl2/n-pentane
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g cmꢀ3
)
yielded yellow crystals of 1Py
.
l
(Mo K
a
) (cmꢀ1
)
Reflection/parameter ratio
Reflection collected
1H NMR (d/ppm from TMS in CDCl3, 300 MHz): d 2.6–3.2 (m,
16H, macrocycle), 4.04 (s, 2H, NCH2Py), 7.37 (d, 1H, pyridine-3H),
7.71, 7.80 (t, 1H, pyridine-4,5H), 8.91 (d, 1H, pyridine-6H).
13C{1H} NMR (d/ppm from CDCl3 in CDCl3, 75 MHz) d 24.09,
27.75, 28.90, 57.04, 65.21, 123.09, 123.92, 138.04, 153.32, 217.55,
221.95, 231.34.
Independent reflections (Rint
)
Observed reflectionsa
a
R1
a
wR2
Goodness-of-fit (GOF)
FT-IR (KBr, cmꢀ1) d 1901, 1763 (C„O), 515, 462 (MoꢀC).
Anal. Calc. for C17H22MoN2O3S3: C, 41.29; H, 4.48; N, 5.66.
Found: C, 41.74; H, 4.85; N, 5.66%.
Largest difference in peak and hole
0.67, ꢀ0.41
(e Åꢀ3
)
a
All reflections.

T. Ogawa et al. / Inorganica Chimica Acta 401 (2013) 101–106
103
2.3.5. fac-[Mo(CO)3(L14H)] (2H)
and fac-[(L14H)Mo(CO)3] (2H), a single crystal suitable for X-ray
structure analysis was obtained. Molecular structures of 1Py and
2H are shown in Figs. 1 and 2, respectively. The selected inter-
atomic distances and angles for 1Py and 2H are listed in Tables 2
and 3, respectively. The crystal structure of 2H revealed that it con-
tains two slightly different independent molecules in the unit cell.
For both 1Py and 2H, each molybdenum center is octahedrally coor-
dinated with three carbon monoxide molecules coordinated to the
metal center in a facial fashion. For 1Py, the remaining three sites
are coordinated by one pyridine nitrogen atom, one sulfur atom,
and one alkyl amine nitrogen atom of the macrocyclic ligand
L12py. In contrast, for 2H, the metal ion is coordinated by three sul-
fur atoms of ligand L14H, and not coordinated by any of the alkyl
amine nitrogen atoms. The different coordination arrangements
provided by the two ligands can be explained by the chelate effect.
According to a procedure similar to the procedure used for
preparation of 1H,
a
suspension of L14H (1.39 ꢁ 10ꢀ1 g,
5.54 ꢁ 10ꢀ4 mol) and molybdenum hexacarbonyl [Mo(CO)6]
(1.50 ꢁ 10ꢀ1 g, 5.69 ꢁ 10ꢀ4 mol) in toluene (5 mL) was refluxed
for 8 h. The reaction mixture was concentrated in vacuo, and then
the resulting brown solid was dissolved in CH2Cl2 (5 mL) and fil-
tered through a Celite pad. Crystallization from CH2Cl2/n-hexane
yielded yellow crystals of 2H.
1H NMR (d/ppm from TMS in CDCl3, 600 MHz) d 1.90 (br, 2H),
2.18 (m, 2H), 2.34 (m, 2H), 2.60 (m, 2H), 2.70 (m, 4H), 2.81 (s,
1H), 2.90 (m, 2H), 3.19 (br, 4H), 3.25 (m, 2H).
13C{1H} NMR (d/ppm from CDCl3 in CDCl3, 150 MHz) d 27.70,
34.66, 35.07, 38.36, 47.12, 221.12 (CO), 223.78 (CO).
FT-IR (KBr, cmꢀ1) d 3347 (NꢀH), 1910, 1790 (C„O), 517, 471
(MoꢀC).
For 1Py, the pyridine nitrogen, which is a strong
p-acceptor ligand,
Anal. Calc. for C13H21MoNO3S3: C, 36.19; H, 4.91; N, 3.25. Found:
C, 35.99; H, 4.88; N, 3.20%.
coordinates to molybdenum to form a five-membered chelate ring
with an alkyl amine nitrogen. In the case of 2H, the five-membered
chelate ring formed with three sulfur atoms for molybdenum is
more stable than the six-membered chelate ring with two sulfur
atoms instead of one alkyl amine nitrogen. Interestingly, an
intramolecular hydrogen bond was identified in crystal 2H;
N(1)ꢂ ꢂ ꢂS(1) = 3.037 Å) and N(2)ꢂ ꢂ ꢂS(6) = 3.041 Å [24]. These hydro-
gen bonds may inhibit the coordination of an alkyl amine nitrogen
atom to the molybdenum center. The Mo–CO bonds for 1Py are
1.9410(17) Å for Mo(1)ꢀC(1), 1.9390(19) Å for Mo(1)ꢀC(2), and
1.9381(17) Å for Mo(1)ꢀC(3), respectively. The MoꢀS length is
2.5935(5) Å for Mo(1)ꢀS(1), and the Mo(1)ꢀNalkyl(1) and
2.3.6. [Mo(CO)3(L14Py)Mo(CO)4] (2Py
)
According to a procedure similar to the procedure used for
preparation of 1H,
a
suspension of L14Py (1.60 ꢁ 10ꢀ1 g,
4.67 ꢁ 10ꢀ4 mol) and molybdenum hexacarbonyl [Mo(CO)6]
(1.23 ꢁ 10ꢀ1 g, 4.66 ꢁ 10ꢀ4 mol) in toluene (5 mL) was refluxed
for 8 h. The reaction mixture was concentrated in vacuo, and then
the resulting brown solid was washed with THF and CH2Cl2. Dinu-
clear molybdenum complex [Mo(CO)3(L14Py)Mo(CO)4] was yielded
as pale yellow powder.
FT-IR (KBr, cmꢀ1) d 2007, 1917, 1871, 1820, 1786 (C„O), 457
(MoꢀC).
Anal. Calc. for C13H21MoNO3S3: C, 37.81; H, 3.59; N, 3.83. Found:
C, 38.20; H, 3.64; N, 3.80%.
O2
O1
O3
C2
C3
C1
3. Results and discussion
Mo1
Monoaza-trithia-macrocyclic ligands were synthesized accord-
ing to literature procedures with slight modifications [15–17]. Reac-
tions of 3-thia-1,5-pentanedithiol with bis(2-chloroethyl)amine
and bis(2-chloropropyl)amine in the presence of cesium carbonate
in DMF gave 1,4,7-trithia-10-monoazacyclododecane (L12H) and
1,4,7-trithia-11-monoazacyclotetradecane (L14H), respectively.
The reactions of LXH (X = 12 and 14) with 2-(chloromethyl)pyridine
in the presence of triethylamine in ethanol gave N-substituted
N2
N1
S3
S1
S2
ligands,
N-(2-pyridylmethyl)-1,4,7-trithia-10-azacyclododecane
(L12Py) and N-(2-pyridylmethyl)-1,4,7-trithia-11-azacyclotetrade-
cane (L14Py), respectively (Scheme 1). The structures of these
ligands were confirmed by several techniques (NMR, FT-IR, and
elemental analysis).
Fig. 1. Molecular structure of fac-[(L12Py)Mo(CO)3] (1Py) with 50% thermal ellip-
soids. Hydrogen atoms are omitted for clarity.
Molybdenum tricarbonyl complexes have been synthesized
from molybdenum hexacarbonyl and the corresponding macrocy-
O5
cle ligands. Fortunately, in each case of fac-[(L12py)Mo(CO)3] (1py
)
C15
S5
S4
O3
Mo2
O4
C16
O1
C3
S6
C14
O2
C2
Mo1
O6
C1
N2
S3
S1
S2
N1
Fig. 2. Molecular structure of fac-[(L14H)Mo(CO)3] (2H) with 50% thermal ellipsoids.
Hydrogen atoms are omitted for clarity.
Scheme 1. Synthesis of L12Py and L14Py
.

104
T. Ogawa et al. / Inorganica Chimica Acta 401 (2013) 101–106
Table 2
1.972(4) Å for Mo(1)ꢀC(3), 1.928(4) Å for Mo(2)ꢀC(14), 1.939(4) Å
for Mo(2)ꢀC(15), and 1.946(4) Å for Mo(2)ꢀC(16), respectively.
The MoꢀS bond lengths of 2H are 2.5804(10) Å for Mo(1)ꢀS(1),
2.5556(12) Å for Mo(1)ꢀS(2), 2.5597(9) Å for Mo(1)ꢀS(3),
2.5830(11) Å for Mo(2)ꢀS(4), 2.5581(9) Å for Mo(2)ꢀS(5), and
2.6148(10) Å for Mo(2)ꢀS(6), respectively. Although these sulfur
atoms are provided by the same alkylthioether, the Mo(1)ꢀS(1)
and Mo(2)ꢀS(6) bond lengths are longer than other MoꢀS bonds.
This may be explained as the result of the S(1) and S(6) atoms
operating as hydrogen bond acceptors with N(1) and N(2), respec-
tively. The C„O bond lengths of 2H are 1.156(5) Å for C(1)ꢀO(1),
1.170(4) Å for C(2)ꢀO(2), 1.150(6) Å for C(3)ꢀO(3), 1.179(5) Å for
C(14)ꢀO(4), 1.169(5) Å for C(15)ꢀO(5), and 1.159(6) Å for
C(16)ꢀO(6), respectively. Unlike the case of 1Py, the C(2)ꢀO(2)
and C(14)ꢀO(4) bond lengths for 2H are slightly longer than the
C(3)ꢀO(3) and C(15)ꢀO(5) bond lengths. This may be dependent
upon the presence or absence of a weak interaction because the
former two groups form an intermolecular hydrogen bonding
interaction and the latter ones do not have such an interaction;
O2ꢂ ꢂ ꢂN2 = 3.330 Å and O4ꢂ ꢂ ꢂN1 = 3.308 Å. The C(3)ꢀO(3) and
C(15)ꢀO(5) bonds that are located at the trans positions of S(1)
and S(6) are not elongated, although S(1) and S(6) have the hydro-
gen bond and Mo(1)ꢀS(1) and Mo(2)ꢀS(6) bond lengths are elon-
gated. These findings indicate that intra- and intermolecular
hydrogen bonds play an important role in controlling the reactivity
of the molybdenum center and carbon monoxide molecules.
Comparisons of crystal structures of 1Py and 2H with those of
several tricarbonyl molybdenum complexes reported previously
shows that C„O bond lengths of fac-[Mo(CO)3(TACN)]
(TACN = 1,4,7-trisisopropyl-1,4,7-triazacyclononane) [26] which
contain three coordinated alkylamine nitrogen atoms, are longer
than those of fac-[Mo(CO)3(TTCN)] (TTCN = 1,4,7-trithiacyclonon-
ane) [27] which contain three coordinated sulfur atoms (Table 4).
Selected interatomic distances and angles of fac-[Mo(CO)3(L12Py)] (1Py).
Atom distances (Å)
C(1)ꢀO(1)
1.172(2)
1.164(3)
1.9390(19)
2.5935(5)
2.2689(13)
4.8002(5)
C(2)ꢀO(2)
1.165(3)
C(3)ꢀO(3)
Mo(1)ꢀC(1)
Mo(1)ꢀC(3)
Mo(1)ꢀN(1)
1.9410(17)
1.9381(17)
2.3752(13)
Mo(1)ꢀC(2)
Mo(1)ꢀS(1)
Mo(1)ꢀN(2)
Mo(1)ꢂ ꢂ ꢂS(2)
Mo(1)ꢂ ꢂ ꢂS(3)
5.2129(4)
Bond angles (Å)
Mo(1)ꢀC(1)ꢀO(1)
Mo(1)ꢀC(3)ꢀO(3)
C(2)ꢀMo(1)ꢀS(1)
N(1)ꢀMo(1)ꢀN(2)
S(1)ꢀMo(1)ꢀN(2)
175.94(16)
174.44(18)
173.38(6)
73.26(5)
Mo(1)ꢀC(2)ꢀO(2)
C(1)ꢀMo1ꢀN(2)
C(3)ꢀMo(1)ꢀN(1)
N(1)ꢀMo(1)ꢀS(1)
174.71(16)
177.81(7)
166.61(6)
79.76(4)
75.30(4)
Table 3
Selected interatomic distances and angles of fac-[Mo(CO)3(L14H)] (2H).
Atom distances (Å)
AC(1)ꢀO(1)
1.156(5)
1.170(4)
1.150(6)
1.948(4)
1.933(4)
1.972(4)
2.5804(10)
2.5556(12)
2.5597(9)
4.397(5)
C(14)ꢀO(4)
C(15)ꢀO(5)
C(16)ꢀO(6)
Mo(2)ꢀC(14)
Mo(2)ꢀC(15)
Mo(2)ꢀC(16)
Mo(2)ꢀS(4)
Mo(2)ꢀS(5)
Mo(2)ꢀS(6)
Mo(2)ꢂ ꢂ ꢂN(2)
1.179(5)
1.169(5)
1.159(6)
1.928(4)
1.939(4)
1.946(4)
2.5830(11)
2.5581(9)
2.6148(10)
4.217(5)
C(2)ꢀO(2)
C(3)ꢀO(3)
Mo(1)ꢀC(1)
Mo(1)ꢀC(2)
Mo(1)ꢀC(3)
Mo(1)ꢀS(1)
Mo(1)ꢀS(2)
Mo(1)ꢀS(3)
Mo(1)ꢂ ꢂ ꢂN(1)
Bond angles (°)
Mo(1)ꢀC(1)ꢀO(1)
Mo(1)ꢀC(2)ꢀO(2)
Mo(1)ꢀC(3)ꢀO(3)
C(1)ꢀMo1ꢀS(2)
C(2)ꢀMo(1)ꢀS(3)
C(3)ꢀMo(1)ꢀS(1)
S1ꢀMo(1)ꢀS(2)
S(2)ꢀMo(1)ꢀS(3)
S(1)ꢀMo(1)ꢀS(3)
175.6(4)
177.3(3)
177.3(4)
178.38(11)
177.05(13)
172.72(12)
77.15(4)
83.24(4)
90.30(4)
Mo(2)ꢀC(14)ꢀO(4)
Mo(2)ꢀC(15)ꢀO(5)
Mo(3)ꢀC(16)ꢀO(6)
C(14)ꢀMo(2)ꢀS(5)
C(15)ꢀMo(2)ꢀS(6)
C(16)ꢀMo(2)ꢀS(4)
S(4)ꢀMo(2)ꢀS(5)
S(5)ꢀMo(2)ꢀS(6)
S(4)ꢀMo(2)ꢀS(6)
173.8(4)
175.5(4)
176.2(4)
177.54(14)
171.69(11)
176.96(12)
82.01(4)
This result indicates that
sulfur atoms reduces the
p
p
-back donation from molybdenum to
-back donation from molybdenum to
75.28(3)
90.79(4)
the carbonyl molecule. For 1Py with various coordinated atoms
(alkylamine, alkylthioether, and pyridine nitrogen), the C„O bond
lengths are between those of fac-[Mo(CO)3(TACN)] and fac-
[Mo(CO)3(TTCN)]. The shorter MoꢀNpyridine bond relative to the
MoꢀS or MoꢀNalkyl bond lengths in 1Py is similar to the MoꢀNpyri-
dine bond of fac-[Mo(CO)3(TPA)] (TPA = tris(2-pyridylmethyl)amine)
[28]. The MoꢀS and CꢀO bond lengths of 2H are similar to those of
fac-[Mo(CO)3(TTCN)] except for the Mo complexes with hydrogen
bonds.
Mo(1)ꢀNpyridine(2) bond lengths are 2.3752(13) Å and
2.2689(13) Å, respectively. The MoꢀNpyridine bond length is shorter
than that of MoꢀNalkyl. This can be explained by the strong
p-
acceptor binding ability of pyridine ligand. For 1Py, the CꢀO lengths
of carbonyl groups are 1.172(2) Å for C(1)ꢀO(1), 1.165(3) Å for
C(2)ꢀO(2), and 1.164(3) Å for C(3)ꢀO(3), respectively. These
C„O bond lengths are slightly longer than that of the free carbon
monoxide molecule (1.128 Å) [25]. In case of 2H, the MoꢀCO bond
lengths are 1.948(4) Å for Mo(1)ꢀC(1), 1.933(4) Å for Mo(1)ꢀC(2),
In order to clarify the contribution of hydrogen bonds, we mea-
sured FT-IR spectra of molybdenum tricarbonyl complexes with
macrocyclic ligands (Fig. 3). The
m
(NꢀH) values of 1H and 2H are
Table 4
Comparison of selected bond lengths for triscarbonyl–molybdenum complexes.a
[Mo(CO)3L]
L
L12Py
L14H (I)
L14H (II)
TACNb
TTCNc
TPAd
MoꢀS or N (Å)
2.5935(5) (S)
2.3752(13) (N)
2.2689(13) (Py)
2.5804(10) (S)
2.5556(12) (S)
2.5597(9) (S)
2.5830(11) (S)
2.5581(9) (S)
2.6148(10) (S)
2.360(2) (N)
2.371(2) (N)
2.377(2) (N)
2.512(6) (S)
2.504(6) (S)
2.534(7) (S)
2.333(5) (N)
2.253(5) (Py)
2.255(5) (py)
MoꢀC (Å)
CꢀO (Å)
1.9410(17)
1.9390(19)
1.9381(17)
1.948(4)
1.933(4)
1.972(4)
1.928(4)
1.939(4)
1.946(4)
1.914(3)
1.921(3)
1.920(3)
1.94(2)
1.97(2)
1.93(2)
1.915(8)
1.930(7)
1.950(7)
1.172(2)
1.165(3)
1.164(3)
1.156(5)
1.170(4)
1.150(6)
1.179(5)
1.169(5)
1.159(6)
1.190(4)
1.178(3)
1.173(4)
1.15(2)
1.15(2)
1.18(2)
–
–
–
a
b
c
S = thioether, N = alkylamine, Py = pyridine nitrogen, italic characters = with hydrogen bond.
TACN = 1,4,7-tris-isopropyl-1,4,7-triazacyclononane, Ref. [26].
TTCN = 1,4,7-trithiacyclononane, Ref. [27].
d
TPA = tris(2-pyridylmethyl)amine, Ref. [28].

T. Ogawa et al. / Inorganica Chimica Acta 401 (2013) 101–106
105
Fig. 3. FT-IR spectra of molybdenum–carbonyl complexes (KBr method).
Fig. 4. Possible structure of [Mo(CO)3(L14Py)Mo(CO)4] (2Py) calculated by MM2
calculations.
Table 5
Solid state IR spectral data of [Mo(CO)3L] complexes.
(TACN)]. The
(C„O) (A1 mode) values of 1H and fac-[Mo(CO)3(TTCN)]. This re-
sult suggests that the intra- and intermolecular hydrogen bonds
have an effect on the activation of carbon monoxide molecules
through the bonds.
m
(C„O) (A1 mode) [30] value of 2H is between the
[Mo(CO)3L]
m )
(C„O) (cmꢀ1
m
1H (L12H)
1913(A1), 1781, 1754(E)
1901(A1), 1763(E)
1910(A1), 1790(E)
1Py (L12Py
2H (L14H)
2Py (L14Py
)
)
2007, 1917(A1), 1871, 1820, 1786(E)
[Mo(CO)3(TACN)]a
[Mo(CO)3(TTCN)]b
[Mo(CO)3(TPA)]c
[Mo(CO)4(dimine)]d
[Mo(CO)6]e
1892(A1), 1741, 1720(E)
1900(A1), 1759(E)
1915(A1), 1783(E)
2010, 1890, 1870, 1820.
2155(A1), 1983(E)
4. Conclusion
We have prepared four novel molybdenum tricarbonyl com-
plexes with monoaza-trithia-macrocyclic ligands and character-
ized these complexes by X-ray structural and FT-IR analyses. It
has been found that the intra- and intermolecular hydrogen bonds
control the structural conformation around metal center, and that
a
b
c
TACN = 1,4,7-tris-isopropyl-1,4,7-triazacyclononane, Ref. [26].
TTCN = 1,4,7-trithiacyclononane, Ref. [27].
TPA = tris(2-pyridylmethyl)amine, Ref. [28].
dimine = CH3(C6H5)C = N(CH2)2N = C(C6H5)CH3, Ref. [29].
Ref. [31].
d
e
these hydrogen bonds contribute to regulating the m(CO) value of
carbon monoxide molecules coordinated to the metal. This may
indicate that hydrogen bond networks play an important role in
the control of electronic and structural properties of metal center.
3258 and 3347 cmꢀ1, respectively. This large difference suggests
that an intramolecular hydrogen bond exists in 2H, but not in 1H.
This is explained by the effect of the chain length of the ethyl group
in 1H, which is too short to form the intramolecular hydrogen bond.
Acknowledgments
Next, the
listed in Table 5 together with those of several tricarbonyl molyb-
denum complexes reported previously. Here, the (C„O) values
with E mode are not completely assigned because of their overlap
with other peaks. The
(C„O) values of 1R and 2R (R = H, Py) are
1913, 1781 and 1754 cmꢀ1 for 1H; 1901 and 1763 cmꢀ1 for 1Py
1910 and 1790 cmꢀ1 for 2H; and 2007, 1917, 1871, 1820, and
1786 cmꢀ1 for 2Py. The (C„O) values for 2Py are quite different
m
(C„O) (A1 mode) values of 1R and 2R (R = H, Py) are
We gratefully acknowledge support for this work from a Grant-
in-Aid for Scientific Research from the Ministry of Education, Cul-
ture, Sports, Science and Technology and the Knowledge Cluster
Project.
m
m
;
Appendix A. Supplementary material
m
CCDC 896087 and 896088 contain the supplementary crystallo-
graphic data for compounds 1Py and 2H, respectively. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via http://www.ccdc.cam.ac.uk/data_request/
cif. Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.ica.2013.03.
027.
from those of the other three complexes. This suggests that the
structure of 2Py is different from the structures of 1H, 1Py and 2H.
To further discuss, we tried additional characterizations, but solu-
bility for 2Py is extremely low for several solvents. It is difficult to
characterize it in solution state. However, based on FT-IR and ele-
mental analysis, we assigned 2Py as a dinuclear metal complex
which has tricarbonyl molybdenum and tetracarbonyl molybde-
num unit. The formation was also confirmed by EDX study. Possi-
ble structure of 2Py estimated by MM2 calculation has been shown
in Fig. 4. This complex has two different environment carbonyl
units. Therefore, FT-IR spectrum of 2Py is completely different from
those of 1H, 1Py, and 2H. (A sharp peak at 2007 cmꢀ1 for 2Py is typ-
ical peak that can be assigned to tetracarbonyl complex which has
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