Oxime-substituted NCN-pincer palladium and platinum halide polymers through non-covalent hydrogen bonding (NCN = [C6H2(CH2NMe2)2-2,6]-)

Article abstract of DOI:10.1016/j.jorganchem.2008.03.020

The oxime-substituted NCN-pincer molecules HON{double bond, long}CH-1-C₆H₃(CH₂NMe₂)₂-3,5 (2a) and HON{double bond, long}CH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (2b) were accessible by treatment of the benzaldehydes H(O)C-4-C₆H₃(CH₂NMe₂)₂-3,5 (1a) and H(O)C-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (1b) with an excess of hydroxylamine. In the solid state both compounds are forming polymers with intermolecular O-H?N connectivities between the Me₂NCH₂ substituents and the oxime entity of further molecules of 2a and 2b, respectively. Characteristic for 2a and 2b is a helically arrangement involving a crystallographic 2₁ screw axis of the HON{double bond, long}CH-1-C₆H₃(CH₂NMe₂)₂-3,5 and HON{double bond, long}CH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 building blocks. The reaction of 2b with equimolar amounts of [Pd₂(dba)₃ · CHCl₃] (3) (dba = dibenzylidene acetone) or [Pt(tol)₂(SEt₂)]₂ (4) (tol = 4-tolyl) gave by an oxidative addition of the C-Br unit to M coordination polymers with a [(HON{double bond, long}CH-4-C₆H₂(CH₂NMe₂)₂-2,6)MBr] repeating unit (5: M = Pd, 6: M = Pt). Complexes 5 and 6 are in the solid state linear hydrogen-bridged polymers with O-H?Br contacts between the oxime entities and the metal-bonded bromide.

Full text of DOI:10.1016/j.jorganchem.2008.03.020

Journal of Organometallic Chemistry 693 (2008) 2244–2250
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Journal of Organometallic Chemistry
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Oxime-substituted NCN-pincer palladium and platinum halide polymers through
non-covalent hydrogen bonding (NCN = [C6H2(CH2NMe2)2-2,6]ꢀ)
Stefan Köcher a, Martin Lutz b, Anthony L. Spek b, Bernhard Walfort a, Tobias Rüffer a, Gerard P.M. van Klink c,
Gerard van Koten c, Heinrich Lang a,
*
a Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Chemie, Lehrstuhl für Anorganische Chemie, Straße der Nationen 62, 09111 Chemnitz, Germany
b Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
c Debye Institute, Organic Synthesis and Catalysis, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
a r t i c l e i n f o
a b s t r a c t
Article history:
The oxime-substituted NCN-pincer molecules HON@CH-1-C6H3(CH2NMe2)2-3,5 (2a) and HON@CH-4-
C6H2(CH2NMe2)2-2,6-Br-1 (2b) were accessible by treatment of the benzaldehydes H(O)C-4-
C6H3(CH2NMe2)2-3,5 (1a) and H(O)C-4-C6H2(CH2NMe2)2-2,6-Br-1 (1b) with an excess of hydroxylamine.
In the solid state both compounds are forming polymers with intermolecular O–Hꢁ ꢁ ꢁN connectivities
between the Me2NCH2 substituents and the oxime entity of further molecules of 2a and 2b, respectively.
Characteristic for 2a and 2b is a helically arrangement involving a crystallographic 21 screw axis of the
HON@CH-1-C6H3(CH2NMe2)2-3,5 and HON@CH-4-C6H2(CH2NMe2)2-2,6-Br-1 building blocks.
The reaction of 2b with equimolar amounts of [Pd2(dba)3 ꢁ CHCl3] (3) (dba = dibenzylidene acetone) or
[Pt(tol)2(SEt2)]2 (4) (tol = 4-tolyl) gave by an oxidative addition of the C–Br unit to M coordination poly-
mers with a [(HON@CH-4-C6H2(CH2NMe2)2-2,6)MBr] repeating unit (5: M = Pd, 6: M = Pt). Complexes 5
and 6 are in the solid state linear hydrogen-bridged polymers with O–Hꢁ ꢁ ꢁBr contacts between the oxime
entities and the metal-bonded bromide.
Received 17 December 2007
Received in revised form 26 February 2008
Accepted 20 March 2008
Available online 29 March 2008
Keywords:
Oxime
Palladium
Platinum
Coordination Polymer
Non-covalent hydrogen bonding
Molecular recognition
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
group) abbreviated as PCP-, SCS- or NCN-pincers [9,10]. In the cor-
responding PCP, SCS or NCN transition metal complexes stable
Since the pioneering work of Hantzch and Werner in the late
19th century and of Chugaev in 1905 on oximes and transition me-
tal complexes thereof this class of compounds has been intensively
studied [1,2]. Molecular recognition by the formation of intermo-
lecular hydrogen bonds in oximes, is widely used for the construc-
tion of supramolecular aggregates in the solid state [3]. Oximes
have an O–H group as hydrogen bond donor; the N and O atoms
are potential hydrogen bond acceptors, whereby in most cases
bonding to the N atom is preferred [4]. Most of all oximes form
hydrogen-bonded dimers in the solid state (graph set R22(6)), but
also trimers [5], tetramers [6] and linear chains [7] are relatively
common. Additional flexibility is achieved by the possible E/Z
isomerism of the oxime group. Furthermore, diverse coordination
modes including nitrogen- and/or oxygen-coordination to different
transition metal atoms are known for oximato-metal species [2–8].
Other versatile ligand systems for the stabilization of low-
valent transition metal centers are monoanionic, (potentially)
terdentate bisphosphino-, bissulfido- and bisaminoaryl anions of
general type [C6H3(CH2ERn)2-2,6]ꢀ (n = 1, 2; E = P, S, N; R = organic
carbon–metal r-bonds are present, due to the ortho-chelating ef-
fect of the pincer ligands.
A combination of both, the oxime and the pincer ligating groups
in a single molecule opens the possibility to prepare multimetallic
species with interesting coordination modes and properties. The
formation of larger molecules via self assembly should be possible.
We report here on the synthesis and reaction chemistry of
oxime-functionalized NCN-pincer molecules. Depending on the
nature of the 4-oxime-substituted NCN-pincer part different struc-
tural motifs are observed in the solid state.
2. Results and discussion
2.1. Synthesis and spectroscopy
Several methods for the preparation of oximes exist including
the reduction of nitro compounds [11], oxidation of amines [12],
addition of NOCl to alkenes [13] and addition of hydroxylamine
to aldehydes or ketones [14]. In the synthesis of the title com-
pounds the benzaldehydes H(O)C-1-C6H3(CH2NMe2)2-3,5 (1a)
and H(O)C-4-C6H2(CH2NMe2)2-2,6-Br-1 (1b) were heated to reflux
with an excess of hydroxylamine in ethanol solutions for 1 h
* Corresponding author. Tel.: +49 371 531 1673; fax: +49 371 531 1833.
E-mail address: heinrich.lang@chemie.tu-chemnitz.de (H. Lang).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.03.020

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 2244–2250
2245
(Eq. (1)). After appropriate work-up, HON@CH-1-C6H3(CH2NMe2)2-
3,5 (2a) and HON@CH-4-C6H2(CH2NMe2)2-2,6-Br-1 (2b) could be
isolated as colorless solids in 74% (2a) and 79% (2b) yield,
respectively.
weak intensity [17]. In addition, a broad intense vibration is ob-
served between 3150 and 3300 cmꢀ1 which is characteristic for
intra- or intermolecular hydrogen bond formations [17]. For 2a
and 2b this mOH absorption is found at 3165 and 3162 cmꢀ1
,
NMe2
NMe2
R
O
H
HO
N
H2NHO•HCl
C
C
R
EtOH/NaOH, 1 h reflux
ð1Þ
H
NMe2
NMe2
1a, R = H
1b, R = Br
2a, R = H
2b, R = Br
Single X-ray structure analysis shows the exclusive formation of
the E-isomer (see below).
respectively, when measured in Nujol. The existence of O–Hꢁ ꢁ ꢁN
bridges could be proven by single crystal X-ray structure analysis
(Figs. 1 and 2). For complexes 5 and 6 the mOH vibrations are found
at 3176 and 3174 cmꢀ1 (Nujol). The slight shift to higher wave-
numbers, when compared to 2a and 2b, indicates a somewhat
stronger O–H and thereof a weaker hydrogen acceptor bond in 5
and 6. This can be explained by the fact that the Me2NCH2 substit-
uents are datively-bonded to M (M = Pd, Pt) and hence, cannot
anymore act as hydrogen acceptors. As result thereof, a different
structural bonding motif with the weaker acceptor bromine (O–
Hꢁ ꢁ ꢁBr) is found which preserves in the solid state (5). Based on
the IR data of 5 and 6 it can be concluded that also for 6 a poly-
meric structure is a dominant structural feature in the solid state
(Section 4).
Carbon-halide oxidative addition to transition metals in low
oxidation states has been successfully used to prepare organome-
tallic C–M–X species (X = halide) [15]. Thus, 2b was reacted with
[Pd2(dba)3 ꢁ CHCl3] (3) (dba = dibenzylidene acetone) in benzene
at 25 °C (Eq. (2)). An irreversible chemo-selective oxidative addi-
tion of 2b to Pd took place and the insertion product [(HON@CH-
4-C6H2(CH2NMe2)2-2,6)PdBr] (5) was formed, which, after appro-
priate work-up, could be isolated as a pale yellow solid in 86%
yield. When instead of 3 the platinum(0) source [Pt(tol)2(SEt2)]2
(4) (tol = 4- tolyl) is used, then the iso-structural platinum pincer
complex [(HON@CH-4-C6H2(CH2NMe2)2-2,6)PtBr] (6) is formed.
Yellow 6 could be isolated in 98% yield (Eq. (2)).
NMe2
NMe2
HO
N
HO
N
.
[Pd2(dba)3 CHCl3] (3) or
C
Br
C
M Br
[Pt(tol-4)2(SEt2)]2 (4)
ð2Þ
H
H
NMe2
NMe2
2b
5, M = Pd
6, M = Pt
The 1H and 13C{1H} NMR spectra of 2a, 2b, 5 and 6 show reso-
2.2. Solid state structures of 2a, 2b and 5
nance signals typical for NCN-pincer complexes [10,15]. The
Me2N and CH2 protons for the non-metallated pincers 2a and 2b
appear as singlets at 2.22 and 3.43 ppm for 2a and at 2.33 and
3.60 ppm for 2b. A small downfield shift of these resonance signals
is noticed for 2b, when compared to 2a, explainable by the electron
withdrawing properties of the bromine atom. Upon coordination of
the Me2NCH2 ortho-substituents to palladium (5) or platinum (6) a
significant shift of these resonance signals to lower field is ob-
served (5: NMe2, 2.94; CH2, 4.10; 6: NMe2, 3.07; CH2, 4.10 ppm).
A similar tendency can be recognized in the 13C{1H} NMR spectra
for these building blocks (N(CH3)2: 44.9 (2a), 45.3 (2b), 53.7 (5),
and 55.2 (6); CH2: 63.7 (2a), 63.4 (2b), 74.2 (5), and 77.7 ppm
(6)). For 6 typical 195Pt satellites are found with coupling constants
of 38.5 Hz (3JPtH(Me)) and 45.6 Hz (3JPtH(CH2)), respectively.
Single crystals of 2a and 2b suitable for X-ray structure analysis
were obtained by slow evaporation of diethyl ether solutions con-
taining either 2a or 2b at ꢀ30 °C. The molecular structures of 2a
and 2b are shown in Figs. 1 and 2. Geometric details are listed in
Table 1 and the experimental crystal data are summarized in Table
3 (Section 4).
The main geometric features of 2a and 2b resemble to those
which are characteristic for aldoximes and non-metallated NCN-
pincer molecules in the solid state [2a,15,18]. The X-ray crystal
structure analyses clearly show that only the E-isomer of oximes
2a and 2b with torsion angles of 179.73(13) (C1–C7–N1–O1 for
2a) and 178.0(2) ° (C4–C13–N3–O1 for 2b) were formed (Figs. 1
and 2).
NMR spectroscopy also unequivocally allows to determine the
oxime moiety in 2a, 2b, 5 and 6. The N@CH methine proton can
be detected at ca. 8 ppm in the 1H NMR, while the sp2-hybridized
carbon atom of this unit is found at ca. 149 ppm in the 13C{1H}
NMR spectrum [16].
IR spectroscopy is also suitable to determine the oxime moiety
present in 2a, 2b, 5 and 6. The stretching vibration for the C@N
entity is found at 1655 (2a) or 1654 cmꢀ1 (2b, 5, 6) having both
The Me2NCH2 substituents point away from the C–R entity (2a:
R = H, 2b: R = Br) in ortho-position towards the amino-methyl sub-
stituents. For both compounds one Me2N group is located above
the benzene ring (2a: N2, C9 and C10, distance C6,plane–N2 =
1.3691(13) Å; 2b: N2, C11 and C12, d(C6,plane–N2) = 1.290(2) Å),
while the second Me2N entity is positioned below the aromatic
ring (2a: N3, C12 and C13, d(C6,plane–N3) = 0.9247(12) Å; 2b: N1,
C8 and C9, d(C6,plane–N1) = 0.357(2) Å).

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S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 2244–2250
Fig. 2. Displacement ellipsoid plot (50% probability level) of the molecular struct-
ure of 2b in the crystal and atom numbering scheme (top). Hydrogen-bonded one-
dimensional chain of 2b in the direction of the crystallographic b-axis. C–H
hydrogen atoms are omitted for clarity. Symmetry operations: (i) 1 ꢀ x, y + 0.5,
0.5 ꢀ z; (ii) 1 ꢀ x, y ꢀ 0.5, 0.5 ꢀ z (bottom).
Fig. 1. Displacement ellipsoid plot (50% probability level) of the molecular struct-
ure of 2a in the crystal and atom numbering scheme (top). Hydrogen-bonded one-
dimensional chain of 2a in the direction of the crystallographic b-axis. C–H
hydrogen atoms are omitted for clarity. Symmetry operations: (i) ꢀx, y + 0.5,
0.5 ꢀ z; (ii) ꢀx, y ꢀ 0.5, 0.5 ꢀ z (bottom).
17.94(5)° with respect to the screw axis, while in 2b this angle is
44.61(8)°. This leads to a longer repeating unit in 2a (length of
b-axis = 10.1344(1) Å) than in 2b (length of b-axis = 4.8213(1) Å).
Single crystals of 5 could be obtained by slow evaporation of a
dichloromethane–acetone solution (ratio 20:1) containing 5 at
ꢀ30 °C. The molecular structure of 5 is shown in Fig. 3. Selected
bond distances, angles, and torsion angles are listed in Table 1
and experimental crystal data are presented in Table 3 (Section 4).
The Pd1 atom adopts a distorted square-planar geometry, set-
up by C4, N1, N2 and Br1 (Fig. 3). The C4–Pd1–Br1 bond angle is
with 178.3(2)° linear, while the N1–Pd1–N2 angle is with
162.6(2)° deformed from linearity. The coordination plane around
Pd1 is with 11.1(3)° almost coplanar to the benzene ring C1–C6. As
for 2a and 2b, the oxime functionality in 5 has a E-configuration
(torsion angle (C1–C13–N3–O1) = ꢀ178.2(8)°) and is coplanar with
the plane build-up by the benzene ring (angle planeC1,C13,N3,O1–pla-
neC1–C6 = 4.8(12)°).
Oximes are known to form aggregates in the solid state, for
example, benzaldehyde oxim crystallizes as a tetramer by forming
intermolecular O–Hꢁ ꢁ ꢁN bonds with the nitrogen atom of the
oxime group as hydrogen acceptor [16]. In 2a and 2b four potential
hydrogen bond acceptors are present: the O and N atoms of the
oxime moiety and two tertiary Me2NCH2 amine groups. In both
cases one Me2NCH2 amine is chosen as hydrogen bond acceptor
(2a: N3; 2b: N2) (Figs. 1 and 2; Table 2). Whereas, the other three
potential acceptors do not participate in the hydrogen bonding. As
a consequence in 2a and 2b, one-dimensional hydrogen-bonded
chains are formed. In both cases these chains have a helical form
involving a crystallographic 21 screw axis. The major difference
between 2a and 2b is that in 2a the phenyl plane has an angle of

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 2244–2250
2247
Table 1
Selected bond lengths (Å), angles (°), and torsion angels (°) for 2a, 2b and 5a
Bond lengths
Bond angles
Torsion angles
Compound 2a
C7–N1
N1–O1
1.286(2)
1.3986(15)
C1–C7–N1
C7–N1–O1
120.62(14)
111.09(12)
C4–C3–C8–N2
C4–C5–C11–N3
C1–C7–N1–O1
95.95(16)
129.49(14)
179.73(13)
Compound 2b
C13–N3
N3–O1
1.260(3)
1.416(3)
1.923(2)
C4–C13–N3
C13–N3–O1
120.1(2)
111.7(2)
C1–C2–C7–N1
C1–C6–C10–N2
C4–C13–N3–O1
163.7(2)
108.4(2)
178.0(2)
C1–Br1
Complex 5
Pd1–Br1
Pd1–C4
Pd1–N1
Pd1–N2
C13–N3
N3–O1
2.5498(17)
1.923(8)
2.131(6)
2.152(7)
1.265(12)
1.425(10)
Br1–Pd1–C4
N1–Pd1–N2
Br1–Pd1–N1
Br1–Pd1–N2
C1–C13–N3
C13–N3–O1
178.3(2)
162.6(2)
97.41(17)
99.48(18)
122.4(8)
110.6(7)
C4–C3–C7–N1
C4–C5–C10–N2
Pd1–N1-C7–C3
Pd1–N2-C10–C5
C1–C13–N3–O1
ꢀ20.4(8)
ꢀ19.6(11)
28.4(7)
25.7(9)
ꢀ178.2(8)
a
Standard uncertainties are given in the last significant figure(s) in parenthesis.
Table 2
Hydrogen bonding interactions for 2a, 2b and 5a
[Pt(tol-4)2(SEt2)]2, respectively. In the solid state polymeric
structures are formed through non-covalent hydrogen bonding.
Compounds 2a and 2b form infinite, one-dimensional hydrogen-
bonded helical chains with only one Me2NCH2 amine as hydrogen
bond acceptor, while 5 forms linear polymeric chains build-up by
NO–Hꢁ ꢁ ꢁBr hydrogen bonds.
Compd.
D–Hꢁ ꢁ ꢁA
D–H (Å)
Hꢁ ꢁ ꢁA (Å)
Dꢁ ꢁ ꢁA (Å)
2.7315(16)
2.791(3)
3.266(9)
D–Hꢁ ꢁ ꢁA (°)
171.2
152(3)
154(12)
2a
2b
5
O1–H1Oꢁ ꢁ ꢁN3i
O1–H1ꢁ ꢁ ꢁN2ii
O1–H1ꢁ ꢁ ꢁBr1iii
1.02
0.88(3)
0.96(14)
1.72
1.98(3)
2.38(15)
Symmetry operations: (i) ꢀx, y + 0.5, 0.5 ꢀ z; (ii) 1 ꢀ x, y + 0.5, 0.5 ꢀ z; (iii) 1 + x, y,
z ꢀ 1.
4. Experimental
a
Standard uncertainties are given in the last significant figure(s) in parenthesis.
4.1. General methods
The two Me2NCH2 ortho-substituents are datively-bonded to
Pd1 (Pd1–N1 = 2.131(6), Pd1–N2 = 2.152(7) Å) and hence, cannot
act as hydrogen acceptor as in 2a and 2b, respectively. But in
contrast to 2b, where the C–Br group cannot be considered as
hydrogen bond acceptor, the metal-bound Br atom of 5 is a poten-
tial hydrogen bond acceptor like other metal-bound halides
[19,22]. Interestingly enough, as in 2a and in 2b, the oxime group
does not accept hydrogen bonds, but the Br atom does. The oxime
group is also not involved in metal coordination, which would cer-
tainly be possible [2–8]. The ‘‘donor–acceptor distance” of the
hydrogen bond is with 3.266(9) Å relatively long (sum of contact
radii: 3.37 Å [20]). Similar interactions were found in other transi-
tion metal complexes, i.e. [trans-FeBr4(H2O)2], (Ph3AsOH)2[CuBr4],
or [1-(5,6-dimethylbenzimidazolyl)-3-benzimidazolyl-2-thiapro-
pane]HgBr2 ꢁ MeOH [21]. Complex 5 forms in the solid state an al-
most linear polymeric chain through non-covalent hydrogen
bonding (Fig. 3), whereby the planes of the benzene rings are in
a perfect coplanar arrangement due to crystallographic symmetry.
Such structural arrangements have also been found for other para-
H-donor substituted NCN-pincer complexes, such as [PtCl(C6H2)-
(CH2NMe2)2-2,6-C„CH-4] and [PtCl(C6H2)(CH2NMe2)2-2,6-OH-4],
respectively [22]. In the case of the latter compound evidence
was provided that these polymers are also present in solution
[22].
All reactions were carried out under an atmosphere of purified
nitrogen using standard Schlenk techniques. Tetrahydrofuran,
diethyl ether, benzene and n-hexane were purified by distillation
from sodium/benzophenone ketyl. Infrared spectra (KBr) were re-
corded with a Perkin Elmer FT-IR 1000 spectrometer. NMR spectra
were recorded with a Bruker Avance 250 spectrometer (1H NMR at
250.12, 13C{1H} NMR at 62.86 MHz) or with a Varian Inova 300
spectrometer (1H NMR at 300.10, 13C{1H} NMR at 75.47 MHz) in
the Fourier transform mode. Chemical shifts are reported in d units
(parts
per
million)
downfield
from
tetramethylsilane
(d = 0.00 ppm) with the solvent as the reference signal (CDCl3:
1H NMR, d = 7.26; 13C{1H} NMR, d = 77.0; acetone-d6: 1H NMR,
d = 2.06; 13C{1H} NMR, d = 29.8). Melting points were determined
using sealed nitrogen purged capillaries with a Gallenkamp MFB
595 010 M melting point apparatus. Microanalyses were per-
formed by the Dornis und Kolbe, Mikroanalytisches Laboratorium,
Mülheim an der Ruhr and partly by the Department of Organic
Chemistry at Chemnitz, Technical University.
4.2. General remarks
H(O)C-1-C6H3(CH2NMe2)2-3,5
(1a)
[23],
H(O)C-4-C6H2-
(CH2NMe2)2-2,6-Br-1 (1b) [15], [Pd2(dba)3 ꢁ CHCl3] (3) [24] and
[Pt(4-tol)2(SEt2)]2 (4) [25] were prepared following published pro-
cedures. All other chemicals were purchased from commercial
sources and were used without any further purification.
3. Conclusion
The synthesis and characterization of oxime-substituted NCN-
pincer
molecules
HON@CH-1-C6H3(CH2NMe2)2-3,5
(2a),
5. Synthesis of HON@CH-1-C6H3(CH2NMe2)2-3,5 (2a)
HON@CH-4-C6H2(CH2NMe2)2-2,6-Br-1 (2b) and [(HON@CH-4-
C6H2(CH2NMe2)2-2,6)MBr] (M = Pd (5), Pt (6)) by applying different
synthesis methodologies is described. For the preparation of 2a
and 2b the appropriate benzaldehydes H(O)C-1-C6H3(CH2NMe2)2-
3,5 and H(O)C-4-C6H2(CH2NMe2)2-2,6-Br-1 were reacted with
hydroxylamine, while complexes 5 and 6 are accessible in a
straightforward manner upon treatment with [Pd2(dba)3] and
To 660 mg (3.00 mmol) of 1a and 1.0 g (14.4 mmol) of
H2NOH ꢁ HCl dissolved in 50 mL of ethanol were added 15 mL
(15.0 mmol) of 1 M NaOH. After the reaction mixture was heated
for 1 h to reflux, 100 mL of water were added and the reaction
solution was allowed to cool to 25 °C. The aqueous phase was ex-
tracted three times with 100 mL of diethyl ether and the combined

2248
S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 2244–2250
Fig. 3. Displacement ellipsoid plot (50% probability level) of the molecular structure of 5 in the crystal and atom numbering scheme (top). Hydrogen-bonded one-
ꢀ
dimensional chain of 5 in the direction of the crystallographic ½1; 0; 1ꢂ diagonal. C–H hydrogen atoms are omitted for clarity. Symmetry operations: (i) x ꢀ 1, y, z + 1; (ii) x + 1,
y, z ꢀ 1 (bottom).
organic phases were dried over MgSO4, filtered and evaporated in
oil-pump vacuum to gave a yellow oil. Upon addition of 3 mL of cold
diethyl ether a colorless solid precipitated which was collected and
dried in oil-pump vacuum to afford 520 mg (2.21 mmol, 74% based
on 1a) of 2a.
of H2NOH ꢁ HCl and 17 mL (17.0 mmol) of 1 M NaOH. Yield:
830 mg (2.64 mmol, 79% based on 1b).
M.p.: (°C) 94. IR (KBr): (cmꢀ1) 3166 (s) [mOH], 1654 (m) [mC@N];
(Nujol): (cmꢀ1) 3162 [mOH]. 1H NMR (CDCl3): [d] 2.33 (s, 12H,
NMe2), 3.60 (s, 4H, CH2N), 7.62 (s, 2H, C6H2), 8.09 (s, 1H, N@CH),
11.35 (br s, 1 H, OH). 13C{1H} NMR (CDCl3): [d] 45.3 (NCH3), 63.4
(NCH2), 127.9 (iCBr/C6H2), 128.2 (CH/C6H2), 132.2 (iC/C6H2), 138.4
(iC/C6H2), 148.2 (N@CH). Anal. Calc. for C13H20BrN3O (314.21): C,
49.69; H, 6.42; N, 13.27. Found: C, 49.84; H, 6.40; N, 13.39%.
M.p.: (°C) 112. IR (KBr): (cmꢀ1) 3169 (s) [mOH], 1655 (m) [mC@N];
(Nujol): (cmꢀ1) 3165 [mOH]. 1H NMR (CDCl3): [d] 2.22 (s, 12H,
NMe2), 3.43 (s, 4H, CH2N), 7.21 (s, 1H, C6H3), 7.58 (s, 2H, C6H3),
8.07 (s, 1H, N@CH), 10.75 (br s, 1 H, OH). 13C{1H} NMR (CDCl3):
[d] 44.9 (NCH3), 63.7 (NCH2), 126.1 (CH/C6H3), 131.4 (CH/C6H3),
133.3 (iC/C6H3), 138.3 (iC/C6H3), 148.9 (N@CH). EI-MS [m/z (rel.
int.)] 235 (10) [M+], 217 (5) [M+ꢀH2O], 192 (100) [M+ꢀNC2H5],
174 (70) [M+ꢀNMe2OH], 147 (80) [M+ꢀ2NMe2], 130 (45)
[M+ꢀ(NMe2)2OH], 103 (30) [C8H8]. Anal. Calc. for C13H21N3O
(235.32): C, 66.35; H, 8.99; N, 17.86. Found: C, 66.44; H, 9.11; N,
17.74%.
7. Synthesis of [(HON@CH-4-C6H2(CH2NMe2)2-2,6)PdBr] (5)
100 mg (0.32 mmol) of 2b and 160 mg (0.15 mmol) of 3 were
dissolved in 15 mL of benzene and the reaction mixture was stirred
for 18 h at 25 °C. Afterwards, 20 mL of tetrahydrofuran were added
and stirring was continued for 2 h. All volatiles were removed in
oil-pump vacuum and the residual greenish-black solid was dis-
solved in 20 mL of chloroform. The solution was filtered through
Celite and concentrated in oil-pump vacuum to 5 mL. n-Hexane
(50 mL) was added, whereby a yellow solid precipitated, which
was collected and washed twice with n-hexane (10 mL) and
6. Synthesis of HON@CH-4-C6H2(CH2NMe2)2-2,6-Br-1 (2b)
Compound 2b was prepared according to the procedure de-
scribed above by using 1.0 g (3.34 mmol) of 1b, 1.16 g (16.7 mmol)

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 2244–2250
2249
Table 3
Summary of crystallographic data for 2a, 2b and 5
Compd.
2a
2b
5
Formula
Fw
C
13H21N3O
C13H20BrN3O
314.23
C13H20BrN3OPd
420.63
235.33
Crystal color
Crystal size (mm3)
Temperature (K)
k (Å)
Colorless
0.36 ꢃ 0.36 ꢃ 0.15
150
Colorless
0.36 ꢃ 0.09 ꢃ 0.03
150
Colorless
0.4 ꢃ 0.3 ꢃ 0.1
298
0.71073
0.71073
0.71073
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Orthorhombic
Pbca (no. 61)
14.5429(1)
10.1344(1)
18.1260(2)
Monoclinic
P21/c (no. 14)
13.3626(3)
4.8213(1)
24.9384(5)
117.8142(11)
1421.03(5)
4
1.469
2.886
Multi-scan
0.83–0.92
21386/3262
0.65
Monoclinic
Cc (no. 9)
6.461(5)
24.635(18)
10.212(7)
99.476(12)
1603(2)
b (°)
V (Å3)
2671.47(4)
8
1.170
0.076
None
Z
4
Dx (g/cm3)
1.743
3.646
Multi-scan
0.34–1.00
10865/3179
0.63
l (mmꢀ1
)
Abs. Corr.
Abs. Corr. range
Refl. collected/unique
30740/2408
0.60
(sin h/k)max (Åꢀ1
)
Parameters/restraints
R1/wR2 [I > 2r(I)]
R1/wR2 [all refl.]
S
158/0
175/0
182/2
0.0402/0.1086
0.0557/0.1179
1.076
0.0309/0.0700
0.0537/0.0779
1.070
0.0466/0.1286
0.0502/0.1340
1.070
Flack ꢃ parameter [504]
0.10(2)
ꢀ0.83/0.68
qmin/max (e/Å3)
ꢀ0.20/0.29
ꢀ0.42/0.69
diethyl ether (10 mL) to gave 5 as a pale yellow solid (95 mg,
0.23 mmol, 68% based on 3).
ters. In 2a and 2b all hydrogen atoms were located in the difference
Fourier map. In 5 the O–H hydrogen atom was located in the differ-
ence Fourier map and all other hydrogen atoms were introduced in
geometrically optimized positions. All C–H hydrogen atoms were
refined with a riding model. The O–H hydrogen atom of 2a was
kept fixed in the located position. In 2b and 5 the O–H hydrogen
atoms were refined freely with isotropic displacement parameters.
Drawings, geometry calculations and checking for higher symme-
try was performed with the PLATON program [29]. Further crystallo-
graphic details are given in Table 3.
M.p.: (°C) 94. IR (KBr): (cmꢀ1) 3279 (vs) [mOH], 1654 (m) [mC@N];
(Nujol): (cmꢀ1) 3176 [mOH]. 1H NMR (acetone-d6): [d] 2.94 (s, 12H,
NMe2), 4.10 (s, 4H, CH2N), 7.05 (s, 2H, C6H2), 8.00 (s, 1H, N@CH),
10.21 (br s, 1H, OH). 13C{1H} NMR (CDCl3): [d] 53.7 (NCH3), 74.2
(NCH2), 118.4 (CH/C6H2), 128.9 (iC/C6H2), 145.5 (iC/C6H2), 150.5
(N@CH), 160.9 (iCPd/C6H2). Anal. Calc. for C13H20BrN3OPd
(420.64): C, 37.12; H, 4.79; N, 9.99. Found: C, 37.27; H, 4.87; N,
9.75%.
8. Synthesis of [(HON@CH-4-C6H2(CH2NMe2)2-2,6)PtBr] (6)
10. Supplementary material
165 mg (0.53 mmol) of 2b and 234 mg (0.25 mmol) of 4 were
dissolved in 20 mL of benzene and the reaction mixture was
refluxed for 5 min. The yellow solution was cooled to 25 °C and
concentrated in oil-pump vacuum to 5 mL. Upon addition of
20 mL of n-hexane a yellow precipitate formed which was col-
lected, washed twice with n-hexane (10 mL) and diethyl ether
(10 mL) and dried in oil-pump vacuum to afford 6 as a yellow solid
(125 mg, 0.25 mmol, 98% based on 4).
CCDC 604434, 604435 and 604436 contain the supplementary
crystallographic data for 2a, 2b and 5. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
We are grateful to the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie for financial support. This
work was partially supported (M.L., A.L.S.) by the Council for
Chemical Sciences of the Netherlands Organization for Scientific
Research (CW-NWO).
M.p.: (°C) 94. IR (KBr): (cmꢀ1) 3292 (vs) [mOH], 1654 (m) [mC@N];
(Nujol): (cmꢀ1) 3174 [mOH]. 1H NMR (acetone-d6): [d] 3.07 (s, 3JPtH
=
3
38.48 Hz, 12H, NMe2), 4.10 (s, JPtH = 45.62 Hz, 4 H, CH2N), 7.05 (s,
2H, C6H2), 7.97 (s, 1 H, N@CH), 9.92 (br s, 1 H, OH). 13C{1H} NMR
(acetone-d6): [d] 55.2 (NCH3), 77.7 (NCH2), 118.5 (CH/C6H2), 129.2
(iC/C6H2), 145.1 (iC/C6H2), 148.7 (N@CH), 150.7 (iCPt/C6H2). Anal.
Calc. for C13H20BrN3OPt ꢁ 1/3C6H6 (509.30): C, 33.65; H, 4.14; N,
7.95. Found: C, 33.16; H, 4.18; N, 7.95%.
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