Photochemical synthesis, structure and spectroscopic properties of [W(CO)4(C5H10N)2CH2]

Article abstract of DOI:10.1016/j.inoche.2014.04.023

Dipiperidylmethane (CH₂dipip) coordinates to photochemically created W(CO)₄ species to give a tungsten(0) complex [W(CO) ₄(CH₂dipip)]. The structure of the new bidentate amine complex of tungsten(0) was established by spectroscopic methods (NMR, IR, UVVis) in solution and by single-crystal X-ray diffraction studies. A preliminary experiment indicates that the tungsten complex emits light at λ_max. 556 nm, when it is excited by λ_max. 523 nm in the solid state at room temperature.

Full text of DOI:10.1016/j.inoche.2014.04.023

Inorganic Chemistry Communications 45 (2014) 105–107
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Photochemical synthesis, structure and spectroscopic properties
of [W(CO) (C H N) CH ]
4
5
10
2
2
Paulina Kocięcka, Andrzej Kochel, Teresa Szymańska-Buzar ⁎
Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Dipiperidylmethane (CH dipip) coordinates to photochemically created W(CO) species to give a tungsten(0)
2
4
Received 20 January 2014
Accepted 18 April 2014
Available online 26 April 2014
4 2
complex [W(CO) (CH dipip)]. The structure of the new bidentate amine complex of tungsten(0) was established
by spectroscopic methods (NMR, IR, UVVis) in solution and by single-crystal X-ray diffraction studies. A
preliminary experiment indicates that the tungsten complex emits light at λmax. 556 nm, when it is excited by
λmax. 523 nm in the solid state at room temperature.
Keywords:
©
2014 Elsevier B.V. All rights reserved.
Tungsten
Chelating amine
Photolysis
NMR method
X-ray structure
Transition metal complexes containing very labile amine ligands
have attracted considerable attention in the field of homogenous
catalysis due to its applicability to the exchange of the amine ligands
on the organic substrate and their activation. Among the examples are
tungsten and molybdenum complexes containing two piperidine (pip)
4 2
When the reaction of cis-[W(CO) (pip) ] in the presence of piperi-
dine in dichloromethane solution was monitored by IR and UVvis spec-
troscopy, we could not detect any changes of the spectroscopic
characteristics of the tungsten complex; however, the evaporation of
3
the solvent and the NMR spectroscopy of the residue in CDCl revealed
ligands of the type cis-[M(CO)
that the reaction of cis-[M(CO)
GeCl leads to the formation of anionic seven-coordinate tungsten(II)
and molybdenum(II) complexes containing the piperidinium cation as
the counter ion. The latter complexes appeared as very attractive cata-
lysts in the metathesis of norbornene [4–6]. The catalytic activity of
the molybdenum complex has been observed in the cyclotrimerization
4
(pip)
2
] [1–3]. Recently, we have shown
the full transformation of piperidine to dipiperidylmethane 1 [8–11]
and the salt containing the piperidinium cation ([Hpip]Cl) [12] in the
molar ratio of ca. 1:2, as well as the substitution of piperidine by 1 in
the piperidine complex of tungsten and the formation of 2 [13].
The diamine 1 is a known compound and different methods of its
preparation have been described, including one exploiting the high
pressure reaction of piperidine and dichloromethane [9] and, recently,
the catalytic activity of 1 in carbon–carbon bond formation has been
discovered [10]. However, the coordination properties of the diamine
1 are unknown.
4
(pip)
2
] (M = W, Mo) with SnCl and
4
4
of alkynes and alkynols [7]. Continuing our studies of the catalytic activ-
1
ity of cis-[W(CO)
4
(pip)
2
], we observed by H NMR spectroscopy that,
in dichloromethane solution containing piperidine, the latter amine
+
very easily transformed to the piperidinium cation (Hpip ) and to
To isolate the tungsten complex 2, the photochemical reaction of
2 5 2 2
dipiperidylmethane (1) (CH dipip, (C H10N) CH ) (Scheme 1).
6
W(CO) and the diamine 1 was carried out in n-hexane [13] (Scheme 2).
Consequently, we decided to carefully investigate diamine 1 forma-
tion in dichloromethane solution and the coordination of 1 to tung-
After this reaction, a yellow solid was separated and washed with
n-hexane. The IR spectrum of this solid in KBr pellets revealed four
−
1
sten(0) to give complex [W(CO)
Herein we report on an attempt to obtain evidence that the reaction
of cis-[W(CO) (pip) ] in dichloromethane solution can lead to the
4 2
(CH bipip)] (2).
v(C`O) bands between 2005 and 1806 cm typical of tungsten(0)
carbonyl compounds with a C2v local symmetry [1], very close to
4
2
4 2
those observed for cis-[W(CO) (pip) ] in dichloromethane solution
formation of 1 and its coordination to tungsten to give complex 2,
which possesses very similar IR and UVVis characteristics to the starting
piperidine complex but a different reactivity.
[14]. It should be noted that in the solid state the supramolecular hydro-
gen bonding between the piperidine NH hydrogen atom and the
oxygen atom of the carbonyl ligand trans to the piperidine ligand of
4 2
the cis-[W(CO) (pip) ] complex leads to the substantial lowering of
−
1
the v(C`O) frequency, up to 1768 cm [15].
1
The H NMR spectrum of 2 exhibited seven resonances for the meth-
⁎
Corresponding author. Tel.: +48 71 375 7221; fax: +48 71 328 23 48.
E-mail address: teresa.szymanska-buzar@chem.uni.wroc.pl (T. Szymańska-Buzar).
ylene groups of the dipiperidylmethane ligand 1 in the intensity ratio of
http://dx.doi.org/10.1016/j.inoche.2014.04.023
387-7003/© 2014 Elsevier B.V. All rights reserved.
1

106
P. Kocięcka et al. / Inorganic Chemistry Communications 45 (2014) 105–107
C(21)
C(11)
O(2) N(2)
C(12)
C(13)
N(1)
C(20)
C(19)
C(2)
C(16)
C(14)
C(17)
C(18)
W(1)
C(15)
4 2
Scheme 1. Conversion of piperidine in the presence of cis-[W(CO) (pip) ] in dichloro-
methane solution.
C(3)
C(1)
C(4)
O(4)
O(3)
1
:2:2:2:1:2:1 [13] (see supplementary data Fig. 2Sa). Two protons of the
O(1)
methylene bridge resonate at 4.43 ppm, which is a 1.61 ppm downfield
shift compared with the resonance of the free ligand 1 (δ 2.82). Six mul-
tiplet signals of piperidinyl rings of the diamine ligand in 2 were
1
1
1
13
Fig. 1. ORTEP diagram of the complex 2 [22]. Selected bond lengths (Å) and angles (°):
W(1)\C(1) 1.955(3), W(1)\C(2) 2.032(3), W(1)\C(3) 1.949(3), W(1)\C(4)
assigned after an analysis of two-dimensional H H COSY and H
C
HMQC NMR spectra (see supplementary data Fig. 2S). From this analy-
sis, it is clear that after the coordination of 1 to the tungsten atom the
methylene protons of piperidinyl rings become diastereotopic and
their signals are observed as three pairs of doublets or more complicat-
ed multiplets (δ 3.312.78, 1.991.66, 1.731.16 ppm), which correlate to
2
.032(3), W(1)\N(1) 2.329(2), W(1)\N(2) 2.331(2), C(1)\W(1)\C(2) 86.32(12),
C(1)\W(1)\C(3) 88.76(13), C(1)\W(1)\C(4) 86.16(12), C(2)\W(1)\C(3)
84.25(11), C(2)\W(1)\C(4) 168.69(11), C(3)\W(1)\C(4) 87.15(12), C(1)\W(1)\
N(1) 103.38(11), C(2)\W(1)\N(1) 95.45(10), C(3)\W(1)\N(1) 167.83(10), C(4)\
W(1)\N(1) 94.50(10), C(1)\W(1)\N(2) 165.52(11), C(2)\W(1)\N(2) 94.12(10),
C(3)\W(1)\N(2) 105.70(10), C(4)\W(1)\N(2) 95.27(10), N(1)\W(1)\N(2)
2
each other with JHH of 10.5, 14.3, and 13.0 Hz, respectively. In a two-
62.15(8), N(1)\C(11)\N(2) 108.4(2).
1
13
dimensional H C HMQC NMR spectrum, each pair of the proton sig-
nals correlates with one carbon signal at δ 66.3, 25.2, and 22.5 ppm, re-
spectively. The coordination of 1 to the tungsten atom resulted in a
and the C\W\N angle of 166.6° (av.) in 2 are close to those found for
recently studied [W(CO) (bpy)] and [W(CO) (phen)], where the
C\W\C angles of 171.4(5) and 166.2(11) and the C\W\N angles
of 168.9° (av.) and 169.6° (av.) were detected, respectively [20]. How-
1
3
downfield shift of C resonances. The biggest coordination shift
Δδ 13.2 ppm) was observed for the resonance of the αCH group of
the piperidyl ring, while for αCH of the methylene bridge the Δδ at
.9 ppm is smaller.
The 1 C{ H} NMR spectrum of 2 in a CDCl
ature exhibited two equal intensity carbonyl carbon resonances at δ
4
4
o
o
(
2
2
o
7
ever, the mean N(1)\W(1)\N(2) angle of 62.15(8) in 2 is close to
3
1
the mean N\W\P angle of 62.84(5)o of the chelating ligand in
[W(CO) {Ph PC(NCy)(NHCy)}] [16] and to the mean C\W\C angles
3
solution at room temper-
C
=
4
2
1
3 183
2
13.5 and δ
C
= 205.0, which were considerably different by the
C
of 59.9° (av.) in [W(CO) (nbd)] [17], where two coordinating atoms
of the bidentate ligand are at a short distance. When two nitrogen
atoms were separated by two carbon atoms as in the bipyridine ligand
of the [W(CO) (bpy)] complex, the N\W\N angle of 71.4(3) was
4
1
1
W coupling constants ( JCW = 171 Hz and JCW = 136 Hz, respectively)
1
3
183
1
[13]. The unusually high value of the
C
W coupling constant ( JCW
=
o
171 Hz) indicates a very strong interaction of the tungsten atom and the
4
carbonyl groups trans to the nitrogen atoms of 2, while the interactions of
the tungsten atom with the two mutually trans carbonyl groups are small-
er ( JCW = 136 Hz). This assumption is in agreement with the X-ray dif-
detected [20]. Two terminal nitrogen ligands in cis-[W(CO) (pip) ] are
4
2
o
coordinated with the N\W\N angle of 85.90(15) [14] and with the
1
o
N\W\N angle of 83.33(11) in cis-[W(CO) (py) ] [21].
4
2
fraction analysis, which shows two longer (2.032 (3) Å) and two
shorter (av. 1.952 Å) W\CO distances (Fig. 1). Similar differences
between the axial and equatorial W\CO distances were detected in
The W\N distances of 2.330 Å (av.) in 2 are almost identical
with those observed for other compounds of tungsten(0) containing
two mutually cis N-donor ligands, such as cis-[W(CO) (pip) ] with a
4
2
other X-ray investigated complexes of the type [W(CO)
4
2
L ] with a C2v
W\N distance of 2.323 Å (av.) [15], slightly longer than in complexes
local symmetry [15–21].
containing an aromatic amine (2.266 Å (av.) in [W(CO) (bpy)] [20]
4
A molecule of 2 can be seen as being formed by the W(CO)
4
frag-
and 2.272(2) Å in [W(CO) (py) ] [21]).
4
2
ment and two nitrogen atoms of the chelating ligand 1, such that the
tungsten atom shows a distorted octahedral geometry, in some re-
spects very similar to that found in other structurally characterized
six-coordinate tungsten(0) complexes containing a chelating ligand,
As was expected, the complex 2 is much more stable than cis-
[W(CO) (pip) ] in dichloromethane or chloroform solution, and, as
4
2
1
was observed by H NMR investigations during two weeks, about 20%
of complex decays with the formation, the most probable was the
cationic form of ligand 1, which was detected due to three proton
signals at the intensity ratio 2:2:1 at δH = 3.12, 1.89, and 1.69 ppm, re-
e.g. [W(CO)
norbornadiene) [17], [W(CO)
W(CO) (bpy)] [19,20], and [W(CO)
4
{Ph
2
PC(NCy)(NHCy)}] [16], [W(CO)
(cod)] (cod = 1,5-cyclooctadiene) [18],
(phen)] [20]. The most significant
4
(nbd)] (nbd =
4
1
13
[
4
4
spectively. These resonances correlate in the H C HMQC spectrum
with carbon resonances at δC 44.5, 22.6, and 22.4 ppm, respectively.
These NMR data are very close to those observed for HpipCl [12]. This
feature of these compounds is the bending of axial and equatorial
carbonyl ligands. The mean C(2)\W(1)\C(4) angle of 168.69(11)o
4 2
time, repeated trials to obtain the NMR spectra of cis-[W(CO) (pip) ]
in dichloromethane or chloroform solution were unsuccessful. Only
the decomposition product HpipCl was identified.
A preliminary experiment indicates, that complex 2, similar to
other six-coordinate tungsten(0) complexes containing a chelating
ligand, e.g. [W(CO)
ethylenediamine) [19,23] emits light (λemiss. 556 nm), when excited
exc. 523 nm) in the solid state at room temperature. Investigations of
4 4 4
(bpy)], [W(CO) (phen)], and [W(CO) (en)] (en =
(
λ
the optical properties and the reactivity of compound 2 are in progress.
In summary, in this study the evidence was obtained that diamine 1
is a good chelating ligand and, in the photochemical substitution of two
6
carbonyl ligands in W(CO) by 1, a new tungsten(0) complex 2 was iso-
4 2
Scheme 2. Synthesis of the tungsten complex [W(CO) (CH dipip)] (2).
lated. The molecular structure of the new compound of tungsten(0) was

P. Kocięcka et al. / Inorganic Chemistry Communications 45 (2014) 105–107
107
9
5, N 11.51; found: C 49.01, H 9.88, N 11.24. IR (KBr, cm−1): 2950 vs, 2841 s,
2739 s, 2633 m, 2602 w, 2582 w, 2626 m, 2427 m, 1592 m, 1462 s, 1436 w,
388 w, 1317 vw, 1276 vw, 1163 w, 1080 w, 1058 vw, 1032 m, 947 w, 862 w,
established by spectroscopic methods in solution and by single-crystal
X-ray diffraction analysis. H NMR spectroscopy reveals that after coor-
1
1
1
dination of 1 to the tungsten atom the methylene protons of piperidinyl
rings become diastereotopic. Complex 2 is the first example of coordina-
tion of a diamine ligand with neighboring nitrogen atoms at short dis-
556 m, 439 m, 398 vw. H NMR (500.13 MHz, CDCl ): δ 9.38 (s, 2H, NH ), 3.11
3
H
2
3
3
), 1.62 (tt, 3
(
6
(
t,
J
H–H =5.6 Hz, 4H, α-CH
2
), 1.87 (tt,
). C{ H} NMR (125.76 MHz, CDCl
), 22.6 (1C, γ-CH ).
J
HH = 5.6 Hz, 4H, β-CH
2
JHH = 5.
1
3
1
Hz, 2H, γ-CH
2C, β-CH
2
3
): δ 47.7 (2C, α-CH
C
2
), 22.9
2
2
3
2
tances (N\CH \N).
[13] A solution of W(CO)6 (0.1 g, 0.28 mmol) and 1 (ca. 0.3 mmol) in n-hexane (50 cm )
was irradiated through quartz at 293 K under an atmosphere of nitrogen using an
HBO 200 W medium-pressure Hg lamp. The colour of the solution changed from
pale to dark yellow and a pale yellow solid precipitated during the course of the
reaction (ca. 2 h). The volatile materials were then stripped from the reaction
mixture under reduced pressure at room temperature. The residue was washed
with hexane, dried in vacuum, and analyzed by elemental analysis, UVVis, IR, and
NMR spectroscopy. The yellow single crystals of 2 were grown during prolonged
cooling of the concentrated post-reaction n-hexane solution. Elemental analysis
Acknowledgements
This work was financed by the Polish Ministry of Science and Higher
Education under Grant No. 4478/E-344/M/2013. The authors thank
Dr. J. Skonieczny for the measurements of the NMR spectra, M. Hojniak
for the GS-MS analyses and Dr. M. Karbowiak for the measurements of
emission spectra.
calcd (%) for C15
8
4
H
22
N
2
O
4
W (M
1, H 4.93, N 5.58; UV–Vis (CH
00 (0.3), 445 (0.1). IR (KBr pellet, ν, cm ): 2942 w, 2860 vw, 2005 m (CO), 1882
w
= 478.19): C 37.68, H 4.64, N 5.86; found: C 36.
4
−1
−1
2
Cl
2
solution, λmax/nm (ε/10
M
cm ): 295 (1.4),
−
1
sh,s (CO), 1855 vs (CO), 1806 vs (CO), 1469 vw, 1453 w, 1350 vw, 1268 vw, 1228
Appendix A. Supplementary data
vw, 1154 vw, 1097 vw, 1081 vw,1038 vw, 987 w, 862 vw, 813vw, 638 vw, 579 vw,
−
1
1
1
3
80 w cm
.
H NMR (500.13 MHz, CDCl
HH
HH = 10.5 Hz, 4H, α-CH ), 2.78 (ddd, JHH = 10.5 Hz, J J =
HH = 12.0 Hz, 3
3
3
): δ 4.43 (s, JHC = 145 Hz, 2H, μ-CH ), 3.
H
2
2
2
3
3
2
1 (d,
J
2
CCDC980971 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge via www.ccdc.
cam.ac.uk/conts/retrieving.html (or from the CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK; Tel: +44 1223 336408; fax: +44 1223
2
HH = 14.3 Hz, 3JHH = 12.0 Hz,
2
.2 Hz, 4H, α-CH ), 1.99 (dtt, J JHH = 3.6 Hz, 4H, β-
2 3 2
CH ), 1.73 (dt, JHH = 13.0 Hz, JHH = 3.6 Hz, 2H, γ-CH ), 1.66 (d, JHH = 14.3 Hz,
2
2
2
3
3
13
4
{
H, β-CH
2
), 1.16 (dtt,
H} NMR (125.76 MHz, CDCl
0.6 (1C, μ-CH ), 66.3 (4C, α-CH
J
HH = 13.0 Hz,
): δ 213.6 ( JCW = 171 Hz), 205.0 ( JCW = 136 Hz),
), 25.2 (4C, β-CH ), 22.5 (2C, γ-CH ). Corrected
J
HH = 12.0 Hz,
J
HH = 4.2 Hz, 2H, γ-CH
2
).
C
1
1
1
3
C
9
2
2
2
2
3
36033; E-mail: deposit@ccdc.cam.ac.uk). Supplementary NMR data
to this article can be found in the online version at http://dx.doi.org/
0.1016/j.inoche.2014.04.023.
emission and excitation spectra have been recorded on an Edinburgh Instruments
FLSP-920 spectrofluorimeter, equipped with a 450 W xenon lamp and a red-
sensitive photomultiplier (Hamamatsu R-928): λexc. 523 nm, λemiss. 556 nm, in the
solid state at room temperature.
1
[
14] M. Ardon, G. Hogarth, D.T.W. Oscroft, J. Organomet. Chem. 689 (2004) 2429.
References
[15] P. Braunstein, J.-P. Taquet, O. Siri, R. Welter, Angew. Chem. Int. Ed. 43 (2004) 5922.
16] J. Grundy, M.P. Coles, P.B. Hitchcock, Dalton Trans. (2003) 2573.
[
[
[
[
1] D.J. Darensbourg, R.L. Kump, Inorg. Chem. 17 (1978) 2680.
[17] F.-W. Grevels, J. Jacke, P. Betz, C. Krüger, Y.-H. Tsay, Organometallics 8 (1989) 293.
[18] M. Górski, A. Kochel, I. Czeluśniak, T. Szymańska-Buzar, Inorg. Chem. Commun. 8
(2005) 202.
[19] Q. Ye, Q. Wu, H. Zhao, Y.-M. Song, X. Xue, R.-G. Xiong, S.-M. Pang, G.-H. Lee, J.
Organomet. Chem. 690 (2005) 286.
[20] C. Makedonas, C.A. Mitsopoulou, Eur. J. Inorg. Chem. (2007) 110.
[21] J. Holzbock, W. Sawodny, E. Grosse, M. Haseidl, L. Waltz, Acta Crystallogr. C52
(1996) 3039.
2] I.-H. Wang, G.R. Dobson, J. Organomet. Chem. 356 (1988) 77.
3] R.S. Herrick, J. Dupont, I. Wrona, J. Pilloni, M. Beaver, M. Benotti, F. Powers, C.J.
Ziegler, J. Organomet. Chem. 692 (2007) 1226.
[
4] A. Malinowska, M. Górski, A. Kochel, T. Szymańska-Buzar, Inorg. Chem. Commun. 10
(2007) 1233.
[5] A. Malinowska, A. Kochel, T. Szymańska-Buzar, J. Organomet. Chem. 692 (2007) 3994.
[6] M. Zyder, A. Kochel, T. Szymańska-Buzar, J. Organomet. Chem. 694 (2009) 4196–4203.
[7] I. Czeluśniak, P. Kocięcka, T. Szymańska-Buzar, J. Organomet. Chem. 716 (2012) 70–78.
[8] NMR characterisation of dipiperidylmethane (1) (See supplementary data Fig. 1S).
[22] Crystal data for 2: monoclinic, space group P2 /c, a = 17.407(3), b = 7.626(4), c =
1
o
3
−3
12.661(5) Å, β = 100.10(4) , V = 1654.6(11) Å , Z = 4, ρcalcd = 1.179 g cm
F(000) = 527; crystal dimension: 0.15 × 0.15 × 0.11 mm ; diffractometer: crystal
dimension 0.15 × 0.14 × 0.11 mm ; diffractometer: Xcalibur with a Ruby CCD
;
1
2.82 (s, 1
1
3
H NMR (500.13 MHz, CDCl
3
): δ
H
J
H-C = 138 Hz, 2H, μ-CH
2
), 2.38 (s,
HH = 5.7 Hz, 8H, β-CH
). C{ H} NMR (125.76 MHz, CDCl ): δ 82.7 (1C,
), 25.9 (4C, β-CH ), 24.9 (2C,γ-CH ).
J
HC
=
1
3
3
1
(
μ-CH
34 Hz, 8H, α-CH ), 1.52 (tt,
2
J
HC = 124 Hz,
J
2
), 1.40
3
13
1
tt,
J
HH = 5.7 Hz, 4H, γ-CH
2
3
C
detector, MoK
(CrysAlisPro, Agilent Technologies, Version 1.171.35.19, 2011), 7496 unique (Rint
0.0444); refinement: 7496 reflections, 199 parameters, R [I N 2σ(I)] = 0.0300,
(all data) = 0.0740, GOF on F = 1.097; max./min. residual electron density:
α
radiation, λ = 0.71073 Å, T = 100(2) K; 28559 reflections collected
), 53.1 (4C, α-CH
2
2
2
=
2
[9] K. Matsumoto, S. Hashimoto, Y. Ikemi, S. Otani, Heterocycles 22 (1984) 1417.
1
2
[
[
[
10] M.J. Climent, A. Corma, I. Domnguez, S. Iborra, M.J. Sabater, G. Sastre, J. Catal. 246
2007) 136.
11] M.G. Shabakova, I.G. Titova, G.A. Makhmudiyarov, A.G. Ibragimov, U.M. Dzhemilev,
Russ. J. Org. Chem. 46 (2010) 43.
12] Piperidinium chloride (HpipCl). A white solid separated from reaction of piperidine
in dichloromethane was washed several times with n-hexane and dried under
wR
2
−
3
(
1.904/−1.822 e Å ; min/max absorption coefficients 0.346/0.567. The crystal
structure was solved by direct methods in SHELXS and refined in SHELXL software
(G. M. Sheldrick, SHELXTL 5.1, Bruker AXS Inc., 6300 Enterprise Lane, Madison, WI
53719-1173, USA 1997).
[23] G.L. Geoffroy, M.S. Wrighton, Organometallic Photochemistry, Academic Press,
1979.
5 w
vacuum. Elemental analysis calcd (%) for C H12NCl (M = 121.61): C 49.38, H 9.