Structurally diverse pyridyl or quinolyl enolato/enamido metal complexes of Li, Zr, Fe, Co, Ni, Cu and Zn

Article abstract of DOI:10.1016/j.ica.2013.02.040

Simple β-ketiminates and β-diketiminates are important monoanionic [N,O] and [N,N] chelating ligand systems with a rich coordination chemistry across the periodic table of elements. New structurally related ligands having one imine donor annelated by an heteroaromatic ring system were easily accessible by reacting α-picolyl/quinolyl-lithium with nitriles followed by sequential acidic hydrolysis and condensation with primary aromatic amines. The coordination chemistry of these [N,O] and [N,N] ligands was fully explored with metals ranging from group 1 to group 12 (M = Li-Zn) resulting in a large variety of coordination modes, including common k² and rare h⁵ motifs as well as novel oxido and non-oxido-bridged cluster assemblies, as shown by a total of 19 single crystal structure analyses.

Full text of DOI:10.1016/j.ica.2013.02.040

Inorganica Chimica Acta 401 (2013) 38–49
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Structurally diverse pyridyl or quinolyl enolato/enamido metal
complexes of Li, Zr, Fe, Co, Ni, Cu and Zn
Markus Graser a, Holger Kopacka a, Klaus Wurst a, Thomas Müller b, Benno Bildstein a,
⇑
a Institute of General, Inorganic and Theoretical Chemistry, Faculty of Chemistry and Pharmacy, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82,
6020 Innsbruck, Austria
b Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
a r t i c l e i n f o
a b s t r a c t
Article history:
Simple b-ketiminates and b-diketiminates are important monoanionic [N,O] and [N,N] chelating ligand
systems with a rich coordination chemistry across the periodic table of elements. New structurally
related ligands having one imine donor annelated by an heteroaromatic ring system were easily accessi-
Received 14 November 2012
Accepted 26 February 2013
Available online 26 March 2013
ble by reacting a-picolyl/quinolyl-lithium with nitriles followed by sequential acidic hydrolysis and con-
densation with primary aromatic amines. The coordination chemistry of these [N,O] and [N,N] ligands
was fully explored with metals ranging from group 1 to group 12 (M = Li–Zn) resulting in a large variety
of coordination modes, including common k2 and rare h5 motifs as well as novel oxido and non-oxido-
bridged cluster assemblies, as shown by a total of 19 single crystal structure analyses.
Ó 2013 Elsevier B.V. All rights reserved.
Keywords:
N,O ligand
N ligand
Transition metal complex
Oxido cluster
X-ray structure
1. Introduction
In this contribution, we report on the synthesis and structural
characterization of differently substituted pyridyl/chinolyl [N,O]
Chelating ligands with conjugated oxygen or nitrogen donor
sites represent some of the most important ligands in coordination
chemistry and their metal complexes are useful for various appli-
cations in homogenous catalysis, chemical vapour deposition,
supramolecular chemistry, redox sensing, photophysics, magnetic
materials, and so on. The most common generic structural types
are acetylacetonato (acac) [1] (A) and its [N,O] b-ketiminato [2]
(B) and [N,N] b-diketiminato (nacnac) [3] (C) derivatives, whose
electronic and steric properties can be tailored by appropriate sub-
stituents (Scheme 1). Whereas the chemistry of these ligand sys-
tems is extremely well explored, there are surprisingly few
examples D [4] and E [5] known where one of the imine donors
is part of a heteroaromatic ring system like pyridine or chinoline.
In comparison to simple b-(di)ketiminato ligands B and C, such
pyridyl/quinolyl-enolato D ligands and enamido E ligands have
an increased conjugation within the ligand backbone, a beneficial
feature for stronger ligand-to-metal bonding. Obviously, in the
case of pyridyl/quinolyl-enamido ligands E, variation of the N-sub-
stituent allows additional steric tuning, a beneficial feature for con-
trolling the reactivity at the coordinated metal. However, the very
few published examples of pyridylenamido ligands bear only N-si-
lyl or N-alkyl substituents, thereby limiting so far their scope in
coordination chemistry [5].
b-ketiminato and [N,N] b-diketiminato ligands containing N-aryl
substituents and we give a full account on the coordination chem-
istry of these ligand families with group 1 to group 12 metal cat-
ions. In total, single crystal structure analyses of 5 ligands and 14
homoleptic and heteroleptic complexes (M = Li, Zr, Fe, Co, Ni, Cu,
Zn) are reported and their structural properties are discussed in
comparison to related but simpler [N,O] and [N,N] coordination
compounds.
2. Results and discussion
2.1. Synthesis and properties of [N,O] and [N,N] ligands
In general, a-heterocyclic ketones should be easily available by
base-promoted condensation of an ortho-methylated heterocycle
and an appropriate synthon, e.g. an ester, a nitrile or a carboxylic
acid chloride. In practice [6], the best method proved to be the
procedure of Büchi and coworkers [4a] by reacting
a-picolyl/
quinolyl-lithium with acetonitrile or benzonitrile followed by
acidic hydrolysis (Scheme 2).
In this manner, pyridyl/quinolyl-enolates 1–4 were synthesized
as slightly air-sensitive or stable, yellow and crystalline oils or
solids in yields of 48–81%, depending on their substitution pattern.
Whereas the synthesis of pyridyl-[N,O]-ligands 1 and 2 was easily
accomplished in THF solution in analogy to the reported procedure
[4a], the preparation of their chinolyl relatives 3 and 4 was more
⇑
Corresponding author. Tel.: +43 512 507 57007; fax: +43 512 507 57099.
E-mail address: benno.bildstein@uibk.ac.at (B. Bildstein).
0020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.02.040

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
39
contrast, quinolyl-[N,O]-ligands 3 and 4 were observed only as
their enaminone tautomers (b). Due to this tautomerism the dipole
moment of the ketone functionality is reduced, thereby observa-
tion of the commonly diagnostic carbonyl stretching vibration in
the IR spectra of 1–4 is hampered. A single crystal structure anal-
yses is available for ligand 3 (Fig. 1). In the solid state this com-
pound exists in its enaminone (b) tautomer, in accordance with
its structure in solution.
[N,O]-Ligands 1–4 served as starting materials for the synthesis
of [N,N]-ligands (Scheme 2): In analogy to a published procedure
for simple aliphatic and unsubstituted aromatic amine substrates
[4a], condensation of 1–4 in refluxing p-xylene over a period of
10 days with 2,6-disubstituted anilines under azeotropic removal
of water by catalytic amounts of trifluoroacetic acid afforded com-
pounds 5–11 in 35–60% yield after work-up by column chromatog-
raphy. An alternative synthetic method that usually workes well
with ‘‘difficult’’ imine ligand systems, trimethylaluminum-pro-
moted condensation [9], proved ineffective in this case. Com-
pounds 5–11 are yellow, slightly air-sensitive solids (5–8,
containing a pyridine backbone) or air-stable (9–11, containing a
quinoline backbone). Structurally, these [N,N]-ligands may exist
either as an imine (a) or an enamine (b) tautomer (Scheme 2). As
anticipated, the enamine form (b) is the preferred isomer due to
the stabilizing intramolecular N–H–N hydrogen bridge. According
to NMR results, in a polar solvent like (D3C)2SO only the enamine
tautomer (b) was observed, whereas in apolar solvents like CDCl3
mixtures of both tautomers were present (vide infra, Section 4).
In the solid state, only the enamine structure was found, as shown
by 4 single-crystal structure analyses of [N,N]-ligands 6, 7, 9 and 11
(Fig. 2) as a representative example. The enamine moiety is clearly
evident from the alternating bond lengths in the ligand backbone
Scheme 1. Structural comparison of b-ketonato (A), b-ketiminato (B), b-diketim-
inato (C), b-pyridyl/chinolyl-enolato (D) and b-pyridyl/chinolyl-enamido (E) ligand
systems (R1–R6 = alkyl or aryl substituent).
demanding. Only at elevated temperatures and longer reaction
periods was an acceptable yield obtained. On the other hand, qui-
nolyl-[N,O]-ligands 3 and 4 have the advantage of higher stability,
they are air-stable in contrast to their oxygen-sensitive pyridyl
counterparts. Compounds 1–4 were characterized by NMR spec-
troscopy (1H, 13C), IR spectroscopy, mass spectrometry and sin-
gle-crystal structure analysis (vide infra, Section 4). Structurally,
three different tautomers, pyridyl/quinolyl-ketone (a), -enaminone
(b), -enol (c), are possible for this class of compounds (Scheme 2)
[8]. Depending on the polarity of the solvent, the equilibria be-
tween these forms may be shifted, e.g. [N,O]-ligand 2 exists in
CDCl3 solution as a mixture of 60% ketone (a) and 40% enol (b),
whereas in (D3C)2SO solution only enol form (b) is present. In
Scheme 2. Synthesis of [N,O]- and [N,N]-ligands 1–11.

40
M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
Fig. 1. Molecular structure of 3. Selected bond lengths [Å]: C(1)–N(1) 1.349(2),
C(1)–C(10) 1.395(2), C(10)–C(11) 1.395(3), C(11)–O(1) 1.270(2).
Scheme 3. Synthesis of Li-complexes 12–14.
Fig. 2. Molecular structure of 11. Selected bond distances: N(1)–C(2) 1.352(2),
C(2)–C(3) 1.365(2), C(3)–C(4) 1.432(2), C(4)–N(5) 1.336(2).
between the two nitrogen atoms. The bulky 2,6-diisopropylphenyl-
N-substituent is roughly orthogonal to the [N,N] ligand plane, as
expected and as intended in the design of these ligands, thereby
effecting steric protection in the axial positions of the coordination
plane.
2.2. Lithium complexes of [N,O]- and [N,N]-ligands
Deprotonation of [N,O]H and [N,N]H ligands by a suitable base
is the most common synthetic method to generate reactive, anionic
precursors for transmetalation reactions with transition metal ha-
lides. Therefore it was of interest to prove the validity of this ap-
proach on selected examples of ligands 1–11 (Scheme 3). In a
glove-box, reaction of pyridylacetophenone 2 in THF solution with
one equivalent of lithium diisopropylamide (LDA), followed by re-
moval of all volatile materials and crystallization from n-hexane,
afforded single crystals of complex 12 (Fig. 3). Overall, compound
12 is a tetrameric ([N,O]Li)4 cluster with a roughly cubic [Li4O4]
core. Due to steric constraints, the O–Li–O bond angles of 81.9°–
98.9° within the core deviate slightly from the ideal value of 90°
and the Li–O bond distances vary from 1.91–2.02 Å. The distorted
tetrahedral cordination sphere of the Li atoms is completed by
N–Li–O bond angles of 96.7°–98.9° and N–Li bond distances of
1.956–1.988 Å. The periphery of the heterocubane is composed of
the aromatic phenyl and pyridyl residues, resulting in an organic,
apolar shell that gave rise to its good solubility in organic solvents.
Deprotonation of [N,N]-ligand 7 by LDA in THF solution afforded
after work-up under inert conditions a yellow, air-sensitive oil that
Fig. 3. Molecular structure of 12. Selected bond lenghts [Å] and angles [°]: Li(1)–
O(1) 1.910, Li(1)–O(2) 1.954, Li(1)–O(4) 1.976, Li(2)–O(1) 1.977, Li(2)–O(2) 1.905,
Li(2)–O(3) 1.960, Li(3)–O(2) 2.016, Li(3)–O(3) 1.944, Li(3)–O(4) 1.916, Li(4)–1.996,
Li(4)–O(3) 1.910, Li(4)–O(4) 1.993, Li(1)–N(1) 1.956, Li(2)–N(2) 1.988, Li(3)–N(3)
1.986, Li(4)–N(4) 1.974; O(1)–Li(1)–O(2) 95.1, O(2)–Li(1)–O(4) 95.3, O(1)–Li(1)–
O(4) 95.6, O(1)–Li(2)–O(2) 94.5, O(1)–Li(2)–O(3) 96.2, O(2)–Li(2)–O(3) 96.8, O(2)–
Li(3)–O(3) 93.8, O(2)–Li(3)–O(4) 95.5, O(3)–Li(3)–O(4) 94.0, O(1)–Li(4)–O(3) 97.2,
O(1)–Li(4)–O(4) 92.2, O(3)–Li(4)–O(4) 92.7.

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
41
Fig. 4. Molecular structure of 14. Selected bond distances [Å] and angles [°]: Li(1A)–
N(1) 1.956(7), Li(1A)–N(2) 2.006(6), Li(1A)–O(1) 2.033(6), Li(1A)–O(2) 2.104(8);
N(1)–Li(1A)–N(2) 95.2(3), N(1)–Li(1A)–O(1) 116.0(3), O(1)–Li(1A)–N(2) 128.3(4),
N(2)–Li(1A)–O(2) 96.5(3), O(1)–Li(1A)–O(2) 102.7(3).
was characterized by NMR spectroscopy and mass spectrometry.
Significant findings included observation of the molecular ion of
([N,N]Li)2 (m/z = 612.25) in the FAB mass spectrum and coordina-
tion shifts of the three carbons of the N–C–C–C–N linkage in the
13C NMR spectrum as well as disappearance of the N–H signal in
the 1H NMR spectrum. Therefore this complex exists most likely
as a centrosymmetric ([N,N]Li)2 dimer with strongly twisted planes
Scheme 4. Synthesis of Zr-complexes 15 and 16.
of the two j
2-[N,N] ligand planes, similar to the structure of other
simple ketiminato–Li-complexes [10]. Due to the increased steric
bulk of ligand 7 in comparison to [N,O]-ligand 2, only a dimeric
structure is observed, no higher nuclearity cluster seems geometri-
cally possible.
Lithiation of the even bulkier [N,N]-ligand 11 in THF solution re-
sulted in a complex with a monomeric structure according to its
single-crystal structure analysis (Fig. 4). Besides the [N,N]-ligand
11 two or one THF coligands are coordinated to the lithium atom,
due to a 1:1 disorder of one of the THF molecules. In Fig. 4 only the
structure of the tetracoordinated molecule is shown. The bond an-
gles of 116° (O–Li–O) and 95.2° (N–Li–N) indicate a distorted tetra-
hedral coordination sphere, with roughly similar Li–O and Li–N
bond lengths (2.1004–1.967 Å).
X-ray quality single crystals of 15 were obtained only after
some months and their structure analysis revealed a partially
hydrolyzed, oxygen-bridged dimer (Fig. 5). We assume that hydro-
lysis took place on standing of the solution for crystallization.
Clearly evident is a distorted octahedral coordination environment
at zirconium with bond angles ranging from 76.4° to 106°, due to
steric constrains of the [N,O]Zr-chelate ring. The oxygen donor
atoms of the two [N,O]-ligands are trans to each other with shorter
bond lengths to zirconium in comparison to the nitrogen donors
2.3. Zirconium complexes of [N,O]- and [N,N]-ligands
The coordination chemistry of [N,O]- and [N,N]-ligands 1–11
with early transition metals was investigated on Zr(IV) metal cen-
ters with ligands 2 and 11 as representative examples, in part
motivated by the importance of such zirconium complexes as
non-metallocene olefin polymerization precatalysts [11]. In a di-
rect metalation reaction (Scheme 4), pyridylketone 2 and tetra-
kis(dimethylamido)zirconium(IV) were allowed to react in a
stoichiometric ratio of 2:1, resulting in an intermediate [N,O]2-
Zr(NMe2)2 complex that was subsequently chlorinated by trimeth-
ylchlorosilane to complex 15. The product was obtained in good
yield (71%) as a yellow, air-sensitive, crystalline compound that
was fully characterized by spectroscopic methods. 1H and 13C
NMR show slightly shifted signals of the three carbons between
the oxygen and nitrogen donor atoms in comparison to their sig-
Fig. 5. Molecular structure of 15’. Selected bond distances [Å] and angles [°]: Zr(1)–
O(1) 2.0074(12), Zr(1)–O(2) 2.0122(12), Zr(1)–O(3) 1.96(3), Zr(1)–N(1) 2.3687(16),
Zr(1)–N(2) 2.4161(15), Zr(1)–Cl(1) 2.4579(6); O(3)–Zr(1)–O(1) 99.6(8), O(3)–Zr(1)–
O(2) 97.1(8), O(3)–Zr(1)–N(1) 94.8(4), O(1)–Zr(1)–N(1) 77.97(5), O(2)–Zr(1)–N(1)
87.57(5), O(3)–Zr(1)–O(1) 99.6(8), O(1)–Zr(1)–N(2) 85.52(5), O(2)–Zr(1)–N(2)
76.42(5), N(1)–Zr(1)–N(2) 79.27(5), O(3)–Zr(1)–Cl(1) 96.0(4), N(2)–Zr(1)–Cl(1)
90.75(4).
nals in the free ligand 2 [C(O): 13C,
d = +9.1 ppm, 1H,
D
d = ꢀ3.8 ppm; C(H): 13C,
D
D
d = +0.13 ppm; C(N): 13C,
D
d = ꢀ3.7 ppm],
indicative of a regular chelating
depicted in Scheme 4.
j
2(O,N)-coordination mode as

42
M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
(dO(1)–Zr = 2.007 Å, dO(2)–Zr = 2.012 Å, dN(1)–Zr = 2.369 Å, dN(2)–Zr
=
2.759–2.796 Å), consistent with a g1g3-bonding motive. There
are very few b-diketiminato complexes reported in the literature
2.416 Å), suggesting stronger O–Zr bonding. Overall, the structure
shows the expected octahedral geometry with regular chelating
[N,O]-ligands, only one of the two chloride ligands of 15 is replaced
by a bridging oxido ligand.
Zirconium complex 16 was obtained in 74% yield by standard
transmetalation involving deprotonation of ligand 10 by LDA fol-
lowed by reaction with zirconium(IV) chloride (Scheme 4). In com-
parison to [N,O]2ZrCl2 15, [N,N]2ZrCl2 16 shows distinct differences
in its physical and chemical properties. The color of 16 is dark red,
[3a,12] with comparable g1g3- or g5
-p-bonding. p-Bonding of
b-diketiminato ligands is clearly favored for bulky ligands in
combination with metals having unfilled d orbitals of appropriate
symmetry. This unusual structure gives [g1g3-N,N]2ZrCl2 16 quite
some resemblance to [g
5-Cp]2ZrCl2, zirconocene dichloride, the
principal lead structure of metallocene olefin polymerization
catalysts.
indicative of extended conjugation and/or p-bonding. The sensitiv-
2.4. Late transition metal complexes of [N,O]- and [N,N]-ligands
ity towards hydrolysis is notably increased, suggesting a less
shielded metal center, although the [N,N]-ligand 10 is considerably
bulkier than [N,O] ligand 2. Overall, an unexpected coordination
mode seemed to be present. Therefore the structure of 16 in solu-
tion was fully explored by a range of two-dimensional NMR tech-
niques ([1H–13C]-HMQC/BIRD, [1H–1H]-COSY, [1H–13C]-HMBC)
resulting in a complete assignment for all 1H and 13C NMR signals.
Most significant, the coordination shifts of the three carbons be-
tween the two nitrogen donor atoms are quite different in compar-
ison to their signals in the free ligand 10 [C(Nimine): 13C,
The coordination chemistry ligands of 1–11 was further ex-
plored for all other 3d transition metals. Whereas attempts to syn-
thesize V(III), Cr(II), Cr(III) and Mn(II) complexes met so far with
failure, either due to undesired redox processes or due to non-opti-
mized experimental conditions, compounds of Fe(II), Co(II), Ni(II),
Cu(II) and Zn(II) were easily obtained in a straightforward manner
(Scheme 5). For Fe–Cu, transmetalation of lithiated ligands with
appropriate metal salts proved successful, whereas for Zn a direct
metalation of the free ligand by diethylzinc was most convenient
(see Section 4).
D
d = +4.9 ppm; C(H): 13C,
D
d = ꢀ12.5 ppm, 1H,
D
d = ꢀ0.25 ppm;
C(Nquinoline): 13C,
D
d = ꢀ2.9 ppm], consistent with an azaallyl
p-
The homoleptic [N,O]2M complexes of the d7–d9 cations of Co
(17), Ni (18) and Cu (19) are dark, paramagnetic solids, whereas
d10 Zn-complexes 20 and 21 are yellow, diamagnetic compounds,
as anticipated. Therefore Ni-complex 18 has either a tetrahedral
or a distorted square-planar structure, in contrast to earlier reports
based on magnetic measurements where a square-planar, diamag-
netic structure has been proposed [13]. By FAB mass spectrometry,
coordination mode as depicted in Scheme 4. Fortunately high qual-
ity single crystals could be obtained, allowing a decisive structural
description in the solid state (Fig. 6). Overall, a distorted tetrahe-
dral coordination at zirconium is observed with two
[N,N]-ligands and sterically shielding peripheral aryl substituents.
The bond distances within the -bonded [N,N]-ligand core are
p-bonded
p
shortest for the nitrogen atoms (dN–Zr = 2.267–2.297 Å) followed
by the enamine-carbon atoms in 2-position (dC(2)–Zr = 2.663 Å,
dC(32)–Zr = 2.652 Å) and those of the 1,3-carbon atoms (dC–Zr
=
Fig. 6. Molecular structure of 16. Selected bond distances [Å] and angles [°]: C(1)–
N(1) 1.317(5), C(1)–C(2) 1.414(6), C(2)–C(3) 1.436(6), C(3)–N(2) 1.338(5), C(31)–
N(3) 1.325(5), C(31)–C(32) 1.406(5), C(32)–C(33) 1.425(5), C(33)–N(4) 1.347(5),
Zr(1)–N(1) 2.275(3), Zr(1)–N(2) 2.278(3), Zr(1)–N(3) 2.267(3), Zr(1)–N(4) 2.297(3),
Zr(1)–C(1) 2.786(4), Zr(1)–C(2) 2.663(4), Zr(1)–C(3) 2.791(4), Zr(1)–C(31) 2.759(4),
Zr(1)–C(32) 2.652(4), Zr(1)–C(33) 2.796(4), Zr(1)–Cl(1) 2.4745(10), Zr(1)–Cl(2)
2.4769(11); Cl(1)–Zr(1)–Cl(2) 117.33(4), Cl(1)–Zr(1)–N(1) 84.34(8), Cl(1)–Zr(1)–
N(2) 138.85(9), Cl(2)–Zr(1)–N(3) 83.75(8), Cl(2)–Zr(1)–N(4) 140.07(8), N(1)–Zr(1)–
N(2) 73.80(11), N(3)–Zr(1)–N(4) 74.43(11).
Scheme 5. Overview of late transition metal complexes.

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
43
the molecular ions of all complexes were detectable, supporting
the [N,O]2M stoichiometry. Crystallization from dichlorometh-
ane-solvent mixtures afforded single crystals of all [N,O]2M com-
plexes 17–21, except for Ni-complex 18. Quite surprisingly, the
crystal structure analysis of Co-complex 17 revealed an unex-
pected result: Instead of the anticipated simple [N,O]2Co structural
motif, a heterometallic [N,O]6[O]Co3Li2 cluster 170 is present
(Fig. 7). Chemically, the formation of this complex in the course
of the crystallization may be rationalized by the assembly of three
equivalents of [N,O]2Co with one equivalent of Li2O that is gener-
ated most likely by twofold deprotonation of traces of water by
the excess of lithium diisopropylamide present. Such an assembly
process may be rationalized by the oxophilicity of Co(II) and by
entropic or crystal packing effects. Structurally, cluster 170 is com-
posed of a central oxygen surrounded by a trigonal ([N,O]Co)3
sphere with two lithium atoms positioned on the threefold rota-
tion axis. The cobalt atoms are in a trigonal–bipyramidal [N2O3]
coordination sphere formed by two chelating [N,O] ligands and
the central oxido ligand. Within this coordination sphere, the
central oxygen has the shortest bond to cobalt (dCo–O = 1.95 Å),
indicating strongest bonding, followed by longer bonds of the
Fig. 8. Molecular structure of 19. Selected bond distances [Å] and angles [°]: Cu(1)–
O(1) 1.8986(16), Cu(1)–O(2) 1.8811(16), Cu(1)–N(1) 2.0348(17), Cu(1)–N(2)
2.0283(18); O(1)–Cu(1)–N(1) 89.72(7), O(1)–Cu(1)–N(2) 90.47(7), N(1)–Cu(1)–
O(2) 89.13(7), O(2)–Cu(1)–N(2) 92.87(7).
nitrogen donors (dCo–N = 2.058 Å) and oxygen donors (dCo–O
=
2.09 Å) of the [N,O]-ligands. The lithium atoms are coordinated
to three oxygens of the [N,O]-ligands (dLi–O = 1.89 Å) and to the
central oxido ligand (dLi–O = 1.99 Å) in
a distorted trigonal–
pyramidal mode with roughly similar bond distances. Overall, this
structure is an unusual new Co(II) example of the quite common
[(l
3-oxido)M3]Ln structural unit in cluster chemistry; well known
representatives are [M3O(carboxylate)6] compounds that are of
general interest as models for protein active sites and as molecular
magnetic materials.
In contrast to 170 with its trimetallic cluster core, the molecular
structures of 19, 20 and 21 show the expected simple [N,O]2M
moieties with a slightly distorted square-planar coordination for
19 (M@Cu(II), Fig. 8) and a slightly distorted tetrahedral coordina-
tion for 20 and 21 (M = Zn(II), Fig. 9), due to the geometrical
restraints of the [N,O]-ligands. In each case the M–O bonds are
shorter (19: dCu–O = 1.88 Å; 21: dZn–O = 1.93 Å) than the M–N bonds
(19: dCu–N = 2.03 Å; 21: dZn–N = 2.00 Å). Interestingly, Zn-complexes
Fig. 9. Molecular structure of 21. Selected bond distances [Å] and angles [°]: Zn(1)–
O(1) 1.9256(11), Zn(1)–N(1) 2.0032(12); O(1)–Zn(1)–N(1) 98.85(5), O(1)–Zn(1)–
O(1A) 119.71(7), O(1)–Zn(1)–N(1A) 109.48(5).
Table 1
Pertinent structural properties of 22–27.
#
M
[N(1)–M–N(2)] vs.
[N(3)–M–N(4)]
N(1)–M–N(2)
N(3)–M–N(4)
N(1)–M
N(3)–M
N(2)–M
N(4)–M
22 Fe 74.76(4)°
23 Co 72.49(5)°
24 Ni 75.43(5)°
25 Ni 77.48(6)°
26 Cu 61.74(5)°
27 Zn 80.68(6)
95.36°
93.74°
95.09°
94.13°
95.03°
94.38°
95.95°
95.28°
94.32°
93.38°
98.05°
98.26°
1.982 Å
1.975 Å
1.960 Å
1.952 Å
1.942 Å
1.936 Å
1.990 Å
2.031 Å
1.959 Å
1.949 Å
1.975 Å
1.979 Å
2.056 Å
2.055 Å
1.996 Å
2.011 Å
1.989 Å
1.983 Å
1.959 Å
2.030 Å
1.979 Å
1.996 Å
2.044 Å
2.044 Å
20 and 21 show weak fluorescence in solution and, more pro-
nounced, in the solid state. In a forthcoming paper on such enam-
ido metal fluorophores, this property will be treated in full detail
[14].
The homoleptic [N,N]2M complexes of d6–d9 metal cations Fe2+
(22), Co2+ (23), Ni2+ (24, 25) and Cu2+ (26) are red (M = Fe, Co) or
black (M = Ni, Cu) paramagnetic solids, whereas d10 Zn-complex
27 is a yellow, diamagnetic compound. All complexes are air-
sensitive in solution, whereas as solids they can be handled in air
Fig. 7. Molecular structure of 170. Selected bond distances [Å] and angles [°]: Co(1)–
O(2) 1.9583(4), Li(1)–O(2) 1.985(7), Li(1)–O(1) 1.8867(16), Co(1)–O(1) 2.789(5),
Co(1)–N(1) 2.058(2); Co(1)–O(2)–Co(1B) 120.0, Co(1)–O(2)–Li(1) 90, Co(1)–O(1)–
Li(1) 88.9(2), O(2)–Co(1)–N(1) 121.56(6), O(1)–Li(1)–O(2) 92.2(2), O(1)–Li(1)–
O(1A) 119.86(3), O(1)–Co(1)–N(1) 87.65(7).

44
M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
Fig. 12. Molecular structure of 24. Selected bond distances [Å] and angles [°]:
Ni(1)–N(1) 1.9419(12), Ni(1)–N(2) 1.9890(13), Ni(1)–N(3) 1.9357(12), Ni(1)–N(4)
1.9827(12); N(1)–Ni(1)–N(2) 95.03(5), N(1)–Ni(1)–N(3) 128.16(5), N(1)–Ni(1)–N(4)
119.02(5), N(2)–Ni(1)–N(3) 124.09(5), N(2)–Ni(1)–N(4) 92.04(5), N(3)–Ni(1)–N(4)
94.38(5).
Fig. 10. Molecular structure of 22. Selected bond distances [Å] and angles [°]:
Fe(1)–N(1) 1.9822(10), Fe(1)–N(2) 1.20557(11), Fe(1)–N(3) 1.9752(10), Fe(1)–N(4)
2.0545(11); N(1)–Fe(1)–N(2) 95.36(4), N(1)–Fe(1)–N(3) 128.86(4), N(1)–Fe(1)–N(4)
119.53(4), N(2)–Fe(1)–N(3) 123.62(4), N(2)–Fe(1)–N(4) 91.07(4), N(3)–Fe(1)–N(4)
93.74(4).
with values of 73–81° (exception: M = Cu: 62°). The distortion of
the tetrahedral coordination is mainly caused by the small bite
angles [N–M–N] of 93–98° of the [N,N]-ligands and by their steric
bulk. Metal–ligand bonding is more or less similar for all N-donor
atoms, as evidenced by the close range of bond distances
(dM–N = 1.94–2.05 Å). Overall, all complexes 22–27 show simple
and quite similar structures in line with expectations.
for short periods without apparent degradation. Mass spectrome-
try showed the molecular ions of all compounds, thereby confirm-
ing their [N,N]2M identity. NMR spectrometry of Zn-complex 27
gave 1H/13C chemical shifts slightly shifted in comparison to the
free ligand 10, indicative of a coordinated, deprotonated ligand.
For all compounds 22–27 single crystal structure analyses are
available. For the sake of brevity and due to the similarity of the
structures, we discuss them jointly (Table 1) and present here
three representative examples (Fig. 10: 22, Fig. 11: 23, Fig. 12:
24). In general, all complexes 22–27 display distorted tetrahedral
structures, with the exception of 26, due to the preference of Cu(II)
for a square-planar coordination. The orientation of the two [N,N]-
ligand towards each other, defined by the angle between the coor-
dination planes [N(1)–M–N(2)] and [N(3)–M–N(4)], is quite similar
3. Conclusions
Starting from ortho-methylated pyridine or quinoline,
beta;-pyridyl/chinolyl-enolato ligands are easily accessible by lith-
iation followed by nucleophilic addition to a nitrile and acidic
hydrolysis. Depending on the substitution pattern and on the
polarity of the solvent, these [N,O]H ligands exist either in their
ketone, enol or enaminone tautomer, as shown by NMR analysis.
Condensation with various anilines afforded the corresponding
b-pyridyl/chinolyl-enamido ligands that have either an imine or
an enamine structure, as evidenced by NMR spectroscopy and by
single crystal structure analysis. The coordination chemistry of
11 [N,O]H or [N,N]H ligands was explored across the periodic table
of elements, resulting in 16 metal complexes with a rich structural
chemistry, ranging from simple
j
2-chelates to unusual
g
5-modes
as well as clustered species with or without l2
/l
3-oxido ligands.
The inclusion of a N-heterocycle in a b-enolato or -enamido ligand
systems offers therefore new and additional options in the coordi-
nation chemistry of [N,O]- and [N,N]-chelate complexes.
4. Experimental
4.1. General considerations
All reactions and manipulations of air- and/or moisture-sensi-
tive compounds were carried out under dry argon using standard
Schlenk techniques or in a dinitrogen filled MBraun glove-box. Sol-
vents were dried and saturated with argon by standard methods of
organometallic chemistry. The chemicals were commercially ob-
tained and used as received. The NMR spectra were recorded with
a Bruker Avance DPX 300 (300 MHz) spectrometer; the chemical
shifts are reported in ppm relative to Si(CH3)4 (1H, 13C). The IR
spectra were recorded with a THERMO Nicolet 5700 ATR-FTIR
spectrometer. The mass spectra were recorded with a Finnegan
Fig. 11. Molecular structure of 23. Selected bond distances [Å] and angles [°]:
Co(1)–N(1) 1.9600(14), Co(1)–N(2) 1.9957(16), Co(1)–N(3) 1.9522(15), Co(1)–N(4)
2.0114(15); N(1)–Co(1)–N(2) 95.09(6), N(1)–Co(1)–N(3) 138.06(6), N(1)–Co(1)–
N(4) 107.00(6), N(2)–Co(1)–N(3) 105.04(6), N(2)–Co(1)–N(4) 120.25(7), N(3)–
Co(1)–N(4) 94.13(6).

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
45
Table 2
Crystallographic data.
Compound
3
6
7
9
11
12
14
Formula
M
Crystal system
Space group
a (Å)
C
12H13NO2ꢁH2O C20H26N2
C21H20N2
300.39
monoclinic
P21/c
11.2144(4)
21.3255(9)
7.0455(2)
90
93.732(2)
90
4
1681.38(10)
233(2)
1.82–24.00
8430
C24H28N2
344.48
monoclinic
P21/n
9.002(3)
10.9823(4)
21.1272(7)
90
C29H30N2ꢁ0.5CH2Cl2 C52H40Li4N4O4ꢁ2CH2Cl2 C33H37LiN2O and C37H45LiN2O2
203.23
monoclinic
P21/n
4.5421(2)
12.4550(7)
18.8500(9)
90
90.625(3)
90
4
294.43
monoclinic
C2/c
449.01
monoclinic
P21/n
982.49
1041.28
triclinic
triclinic
P1
ꢀ
ꢀ
P1
24.1856(4)
11.2518(4)
26.7160(9)
90
93.795(2)
90
11.3408(5)
18.7613(8)
12.4890(3)
90
105.247(2)
90
11.0120(4)
15.9320(9))
17.0779(9)
107.968(2)
99.260(3)
109.543(3)
2
8.7890(3)
10.2331(2)
17.4981(5)
75.609(2)
88.980(2)
87.036(2)
1
b (Å)
c (Å))
a
(°)
b (°)
97.961(2)
90
4
c
(°)
Z
16
4
V (Å3)
1066.32(9)
233(2)
1.96–24.99
6168
7254.3(4)
233(2)
1.69–23.00
14815
5008
0.0508
0.0571
0.1329
408
2068.6(7)
233(2)
1.95–24.00
10714
3238
0.0224
0.0467
0.1207
241
2563.73(17)
233(2)
2.01–24.17
14067
2566.7(2)
233(2)
1.31–22.50
11643
1522.32(7)
233(2)
2.11–25.00
9157
T [K]
h Range (°)
Data
Unique data
Rint
R1
1880
2627
4070
6662
5306
0.0329
0.0450
0.1116
150
0.0277
0.0413
0.1082
215
0.0371
0.0495
0.1324
312
0.0327
0.0706
0.1886
658
0.0193
0.0551
0.1456
389
wR2
Parameters
Goodness-of-fit
1.045
1.022
1.047
1.042
1.048
1.055
1.054
Peak/hole (e/Å3) 0.164/ꢀ0.140
0.184/ꢀ0.128 0.183/ꢀ0.174 0.174/ꢀ0.155 0.192/ꢀ0.225
0.443/ꢀ0.474
0.294/ꢀ0.253
Compound
Formula
M
Crystal system
Space group
a (Å)
150
16
17’
19
20
21
C
52H40Cl2N4O5Zr2ꢁCH2Cl2
C50H42Cl2N4Zrꢁ2C4H8O
1005.20
monoclinic
P21/n
12.7194(2)
22.1936(6)
18.2873(6)
90
C78H60Co3Li2N6O7ꢁ3CH2Cl2
C26H20CuN2O2
455.98
monoclinic
P21/n
9.4444(3)
22.2615(8)
9.9361(2)
90
C26H20N2O2Zn
457.81
monoclinic
P21/n
11.2726(4)
16.1504(5)
11.7431(4)
90
C34H24N2O2Zn
557.92
monoclinic
C2/c
24.7460(3)
8.6601(3)
12.2225(4)
90
1139.15
monoclinic
P21/n
1638.77
trigonal
ꢀ
R3c
9.6242(1)
18.0723(3)
15.0107(3)
90
20.251(1)
20.251(1)
32.903(2)
90
b (Å)
c (Å)
a
(°)
b (°)
101.713(1)
90
97.899(2)
90
90
120
97.297(2)
90
90.669(2)
90
104.566(2)
90
c
(°)
Z
2
4
6
4
4
4
V (Å3)
2556.47(7)
233(2)
2.25–25.00
16001
5113.3(2)
296(2)
1.84–24.00
26420
7989
0.0623
0.0543
0.1219
606
1.047
11685.8(11)
233(2)
2.01–24.50
18141
2163
0.0545
0.0393
0.0902
169
2072.11(11)
233(2)
2.26–25.00
11017
2137.77(12)
233(2)
1.26–26.00
12739
4168
0.0305
0.0385
0.0916
281
1.058
2535.13(12)
233(2)
2.50–25.00
7822
T (K)
h Range (°)
Data
Unique data
Rint
R1
4499
3631
2228
0.0199
0.0239
0.0638
334
1.036
0.436/ꢀ0.475
0.0310
0.0324
0.0802
280
1.083
0.250/ꢀ0.501
0.0240
0.0238
0.0570
177
1.082
0.173/ꢀ0.260
wR2
Parameters
Goodness-of-fit
Peak/hole (e/Å3)
1.058
0.204/ꢀ0.259
0.517/ꢀ0.403
0.337/ꢀ0.363
Compound
Formula
M
Crystal system
Space group
a (Å)
22
23
24
25
26
27
C
42H38FeN4
C42H38CoN4
657.69
monoclinic
P21/n
20.9121(2)
8.2655(3)
21.6490(3)
90
113.229(2)
90
C42H38N4Ni
657.47
monoclinic
P21/c
10.2332(2)
16.3850(3)
20.2217(3)
90
91.977(2)
90
C48H54N4Ni
745.66
C42H38CuN4
C50H42N4ZnꢁCH2Cl2
654.61
monoclinic
P21/c
10.2774(1)
16.3353(2)
20.2966(3)
90
92.231(1)
90
4
3404.90(7)
233(2)
1.60–27.50
23765
7777
0.0199
0.0310
0.0793
428
662.30
monoclinic
P21/n
21.0026(2)
8.0519(1)
21.7477(3)
90
113.082(1)
90
4
849.17
triclinic
orthorhombic
Pbca
ꢀ
P1
10.7602(2)
11.3696(3)
18.8522(3)
83.913(1)
86.422(1)
65.770(1)
2
2090.87(8)
233(2)
2.08–26.00
12722
8065
0.0204
0.0393
0.0956
480
1.039
0.416/ꢀ0.360
10.2526(2)
22.0749(4)
38.2732(7)
90
90
90
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Z
4
4
8
V (Å3)
3438.66(14)
233(2)
1.74–25.00
16600
6049
0.0229
0.0347
0.0937
428
1.052
3388.57(10)
233(2)
1.60–25.94
21125
6574
0.0230
0.0302
0.0734
428
1.032
3383.35(7)
233(2)
2.73–27.00
24889
8662.2(3)
233(2)
2.13–25.00
36324
7578
0.0370
0.0386
0.0877
554
1.024
T (K)
h Range (°)
Data
Unique data
Rint
R1
7354
0.0245
0.0331
0.0922
428
1.059
0.321/ꢀ0.386
wR2
Parameters
Goodness-of-fit
Peak/hole [e/Å3]
1.037
0.286/ꢀ0.229
0.207/ꢀ0.300
0.233/ꢀ0.248
0.333/ꢀ0.367
MAT 95 mass spectrometer. The melting points were measured
with a Leica Galen III Kofler microscope. The single-crystal X-ray
measurements and structure determinations for 3, 6, 7, 9, 11, 12,
14, 150, 16, 170, 19, 20, 21, 22, 23, 24, 25, 26 and 27 (Table 2,
Figs. 1–12) were performed with a Nonius Kappa CCD diffractom-
eter by methods as recently published.[15]

46
M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
4.2. 2-(2-Pyridyl)acetone (1)
4.5.1. Enamine 5
Starting materials: 1 (1.87 g, 13.8 mmol), 2,6-dimethylaniline
(1.8 mL, 13.8 mmol). Experimental conditions: Azeotropic conden-
sation in toluene over 12 h with catalytic amounts of trifluoroace-
tic acid, chromatographic work-up. Yield: 2.5 g (75%) as a yellow,
slightly air-sensitive oil. 1H NMR (300 MHz, (CD3)2SO, 298 K):
d = 1.61 (s, 3H, CH3), 2.16 (s, 6H, CH3), 5.20 (s, 1H, olefinicH), 6.76
(d, 2H), 6.85 (m, IH), 6.97 (d, 2H), 7.51 (m, 1H), 8.32 (m, 1H),
10.92 (s, 1H, enamineH) ppm. 13C NMR (75 MHz, (CD3)2SO,
298 K): d = 18.1, 19.5, 93.8, 115.7, 116.5, 120.1, 126.4, 127.7,
This compound was synthesized as a yellow, slightly air-sensi-
tive oil (b.p. 67 °C at 0.5 mbar) in 61% yield by a published method
from the year 1962.[7] Because no spectral data have been re-
ported at that time, we include these here for future reference:
1H NMR (300 MHz, (CD3)2SO, 298 K): d = 2.13 (s, 3H, CH3), 3.91
(s, 2H, CH2), 7.28 (m, 2H, pyridylH), 7.74 (m, 1H, pyridylH), 8.47
(d, 1H, pyridylH) ppm. 13C NMR (75 MHz, (CD3)2SO, 298 K):
d = 30.0 (CH3), 52.3 (CH2); 121.9, 124.4, 136.6, 149.2, 155.4 (pyri-
dylC), 205.4 (C = O) ppm. IR (ATR):
m
= 1712 (
m
C@O), 1652 (
m
C@N),
127.9, 135.8, 136.5, 146.8, 149.6, 159.6 ppm. IR (ATR): m = 1619
1589 (mC
@
N
of pyridyl), 1473, 1434, 1355, 1156, 751 cmꢀ1
.
(mC@N), 1583 (mC
@
N
of pyridyl), 1543, 1471, 1411, 1262, 790,
760 cm–1. MS (FAB pos): m/z = 239.17 (M++H). Anal. Calc. for
C16H18N2 (238.33): C, 80.63; H, 7.61; N, 11.75. Found: C, 80.80;
H, 7.63; N, 11.63%.
4.3. 2-(2-Pyridyl)acetophenone (2)
A Schlenk tube was charged under an atmosphere of argon with
2-picoline (3 mL, 30.4 mmol), dry THF (15 mL) and a stirring bar.
After the solution has been cooled to ꢀ10 °C, a solution of n-butyl
lithium (60.8 mmol, 1.6 M in n-hexane) was slowly added under
efficient stirring. The external cooling bath was removed and the
mixture was allowed to warm to room temperature, resulting in
a deep red solution of lithiated 2-picoline. The mixture was again
cooled to ꢀ40 °C, dry benzonitrile (30.4 mmol, 3.1 mL) was added
in one portion, and after stirring has been continued for 2 d at
room temperature, the mixture was hydrolyzed without protection
from air with sulfuric acid (60% aqueous solution) under external
cooling in an ice bath until a pH of 1 was reached. After the result-
ing biphasic mixture has been stirred for 1 d to complete acidic
hydrolysis, saturated aqueous KOH solution was added to neutral-
ize the solution. During this procedure large amounts of potassium
sulfate precipitated. Sufficient water was added to dissolve this
precipitate and repeated extraction into dichloromethane, fol-
lowed by removal of volatiles on a rotary evaporator, resulted in
the crude product as a dark brown oil. Fractional vacuum distilla-
tion at 0.5 mbar pressure gave the pure product as a slightly air-
sensitive, yellow oil that slowly solidified on standing. Yield:
4.85 g (81%). B.p. 146 °C at 0.5 mbar. M.p. 39–44 °C. 1H NMR
(300 MHz, (CD3)2SO, 298 K): d = 4.5 (s, 1H), 6.3 (s, 1H), 7.1 (m,
1H), 7.2 (d, 1H), 7.7 (d ꢂ d, 1H), 7.80 (d, J = 7.53 Hz, 1H), 8.0 (d,
J = 7.94 Hz, 2H), 8.40 (d, J = 4.92 Hz, 1H), 8.48 (d, J = 4.79 Hz, 1H),
15.3 (s, 1H) ppm. 1H NMR (300 MHz, CD2Cl2, 298 K): d = 4.49 (s,
2H), 6.14 (s, 1H), 7.03 (m, 1H), 7.12 (d, J = 8.14 Hz, 1H), 7.19
(d ꢂ d, 1H), 7.31 (d, J = 7.83 Hz, 1H), 7.42 (m, 3H), 7.48 (m, 2H),
7.58 (m, 1H), 7.66 (m, 2H), 7.87 (m, 2H), 8.05 (d, J = 1.4 Hz, 1H),
8.07 (m, 1H), 8.34 (d, J = 4.97 Hz, 1H), 8.54 (d, J = 4.48 Hz, 1H),
15.36 (s, 1H) ppm. 13C NMR (75 MHz, (CD3)2SO, 298 K): d = 47.6,
93.7, 119.0, 121.8, 125.1, 128.4, 128.7, 129.4, 137.9, 144.2, 149.0,
196.9 (C@O) ppm. 13C NMR (75 MHz, CD2Cl2, 298 K): d = 48.8,
94.7, 119.3, 122.1, 122.3, 124.7, 125.8, 128.8, 129.1, 129.8, 133.7,
136.8, 137.7, 145.1, 149.9, 156.1, 159.1, 163.9, 197.3 (C@O) ppm.
4.5.2. Enamine 6
Starting materials: 1 (1.57 g, 11.6 mmol), 2,6-diisopropylaniline
(2.2 mL, 11.6 mmol). Experimental conditions: Azeotropic conden-
sation in toluene over 2d with catalytic amounts of trifluoroacetic
acid, chromatographic work-up. Yield: 1.23 g (35%) as a yellow,
slightly air-sensitive solid. M.p. 45 °C. 1H NMR (300 MHz, (CD3)2SO,
298 K): d = 1.15 (d ꢂ d, 14H, (CH(CH3)2), 1.60 (s, 3H, CH3), 5.11 (s,
1H, olefinicH), 6.54 (t, 1H), 6.96 (d, 1H), 7.16 (d, 1H), 7.24 (s, 1H),
7.52 (m, 1H), 8.28 (d, 1H), 11.05 (s, 1H, enamineH) ppm. 13C
NMR (75 MHz, (CD3)2SO, 298 K): d = 19.7, 22.2, 22.6, 24.6, 26.6,
27.9, 93.2, 116.5, 120.7, 122.1, 123.2, 127.4, 135.7, 146.6, 146.8,
149.9, 159.6 ppm. IR (ATR):
m = 2958, 2865, 1619 (mC@N), 1584
(mC@ .
of pyridyl), 1541, 1476, 1411, 1258, 1143, 793, 758 cm–1
N
MS (FAB pos): m/z = 295.22 (MꢀH)+. Anal. Calc. for C20H26N2
(294.43): C, 81.59; H, 8.90; N, 9.51. Found: C, 81.65; H, 8.93; N,
9.47%. Single crystal structure analysis of 6: Table 2.
4.5.3. Enamine 7
Starting materials: 2 (4.8 g, 24.3 mmol), 2,6-dimethylaniline
(2.5 mL, 24.3 mmol). Experimental conditions: Azeotropic conden-
sation in toluene over 2d with catalytic amounts of trifluoroacetic
acid, chromatographic work-up. Yield: 4.38 g (60%) as a yellow,
1
slightly air-sensitive solid. M.p. 112 °C. H NMR (300 MHz, (CD3)2-
SO, 298 K): d = 2.15 (s, 6H), 5.51 (s, 1H), 6.92 (d, J = 2.43 Hz, 3H),
6.99 (m, 1H), 7.22 (m, 3H), 7.62 (m, 2H), 7.65 (d ꢂ t, 1H), 8.46 (d,
J = 3.99 Hz, 1H), 11.19 (s, 1H, enamineH) ppm. 1H NMR
(300 MHz, CDCl3, 298 K): d = 2.08 (s, 6H), 2.25 (s, 6H), 4.10 (s,
2H), 5.47 (s, 1H), 6.81 (d, J = 7.84 Hz, 1H), 7.15 (m, 1H), 7.20 (m,
3H), 7.21 (m, 1H), 7.31 (d, J = 2.27 Hz, 1H), 7.33 (d, J = 1.75 Hz,
1H), 7.43 (m, 1H), 7.46 (d, J = 1.80 Hz, 1H), 7.54 (d ꢂ t, J = 1.85 Hz,
J = 7.7 Hz, 1H), 8.08 (d, J = 4.27 Hz, 1H), 8.11 (d, J = 2.13 Hz, 1H),
8.40 (d, J = 4.85 Hz, 1H), 8.45 (d, J = 4.78 Hz, 1H), 11.35 (s, 1H,
enamineH) ppm. 13C NMR (75 MHz, (CD3)2SO, 298 K): d = 18.6,
97.8, 117.7, 122.3, 125.1, 127.1, 127.7, 128.0, 128.1, 134.3, 136.0,
137.9, 139.0, 147.0, 151.9, 158.9 ppm. 13C NMR (75 MHz, CDCl3,
298 K): d = 18.1, 19.1, 39.9, 97.6, 117.2, 121.2, 122.1, 123.1, 123.4,
125.0, 126.1, 127.5, 127.6, 127.9, 128.0, 128.2, 128.3, 130.2,
135.1, 135.5, 136.2, 138.4, 139.6, 147.0, 149.3, 152.8, 156.9,
IR (ATR):
m
= 1676 (
m
C@O), 1596 (
m
C@N), 1545 (mC
@
N
of pyridyl),
1463, 1365, 1148, 803, 772, 736, 686 cmꢀ1. MS (FAB pos):
m/z = 198.10 (M++H).
4.4. 2-Chinolylacetone (3) and 2-chinolylacetophenone (4)
159.7, 165.5 ppm. IR (ATR):
m
= 2949, 2927, 1613 (
mC@N), 1584
(mC@
N
of pyridyl), 1542, 1466, 1147, 792, 769, 695 cm–1. MS (ESI
These compounds were prepared in a similar manner as for 2 in
analogy to published procedures [5f,7], spectral data and proper-
ties concur with literature values [5f]. Single crystal structure anal-
ysis of 3: Fig. 1 and Table 2.
pos): m/z = 301.10 (M+H)+, 323.10 (M+Na)+. Anal. Calc. for
C21H20N2 (300.40): C, 83.96; H, 6.71; N, 9.33. Found: C, 84.03; H,
6.68; N, 9.21%. Single crystal structure analysis of 7: Table 2.
4.5.4. Enamine 8
4.5. Enamines 5–11
Starting materials: 2 (1.5 g, 7.60 mmol), 2,6-diisopropylaniline
(1.5 mL, 7.60 mmol). Experimental conditions: Azeotropic conden-
sation in xylene (mixture of isomers) over 5d with catalytic
amounts of trifluoroacetic acid, chromatographic work-up. Yield:
1.6 g (59%) as a yellow solid. M.p. 77 °C. 1H NMR (300 MHz, CD2Cl2,
These materials were synthesized in analogy to a published
method [4a], scale, experimental details and spectral properties
are given in the following:

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
47
298 K): d = 2.15 (s, 6H), 5.51 (s, 1H), 6.92 (d, J = 2.43 Hz, 3H), 6.99
(m, 1H), 7.22 (m, 3H), 7.62 (m, 2H), 7.65 (d ꢂ t, 1H), 8.46 (d,
J = 3.99 Hz, 1H), 11.19 (s, 1H, enamineH) ppm. 1H NMR
(300 MHz, CD3Cl, 298 K): d = 0.87 (d, J = 6.91 Hz, 6H), 1.04 (d,
J = 6.85 Hz, 6H), 3.25 (sept, J = 6.89 Hz, 2H), 5.30 (s, 1H), 6.77
(d ꢂ d, J = 5.02 Hz, J = 7.3 Hz, 1H), 6.92 (d, J = 1.84 Hz, 1H), 6.95
(m, 2H), 6.99 (d, J = 3.12 Hz, 1H), 7.01 (s, 1H), 7.07 (d, J = 1.98 Hz,
2H), 7.11 (d, J = 3.01 Hz, 1H), 7.32 (m, 1H), 7.46 ((d ꢂ t, 1H), 8.29
(d, J = 4.19 Hz, 1H), 11.4 (s, 1H, enamineH) ppm. 13C NMR
(75 MHz, CD2Cl2, 298 K): d = 22.2, 25.7, 29.0, 97.1, 117.7, 122.5,
123.4, 123.6, 126.7, 128.1, 128.4, 128.8, 136.2, 136.7, 146.3,
ppm. 13C NMR (75 MHz, CD2Cl2, 298 K): d = 25.9, 29.2, 97.3,
123.3, 123.7, 124.5, 125.7, 127.1, 127.5, 127.9, 128.2, 128.7,
128.8, 129.8, 135.4, 136.4, 138.0, 146.4, 147.6, 155.8, 160.3 ppm.
IR (ATR):
m
= 2971, 1623 (
m
C@N), 1592 (mC
@
of quinolyl), 1572,
N
1537, 1492, 1413, 1321, 823, 741, 696 cm-1. MS (FAB pos): m/
z = 406.26 (M+), 407.27 (M+H)+. Anal. Calc. for C29H30N2 (406.56):
C, 85.67; H, 7.44; N, 6.89. Found: C, 85.60; H, 7.42; N, 6.81%. Single
crystal structure analysis of 11: Fig. 2, Table 2.
4.6. Lithium complexes 12–14
147.6, 153.5, 160.4 ppm. IR (ATR):
m
= 2958, 2865, 1610 (
m
C@N),
Representative procedure for 13: A Schlenk tube was charged
with freshly distilled diisopropylamine (5 mmol, 700 lL), dry THF
1579 (mC
@
of pyridyl), 1534, 1468, 1325, 1147, 790, 693 cmꢀ1
.
N
MS (FAB pos): m/z = 357.23 (M+H)+. Anal. Calc. for C25H28N2
(356.51): C, 84.23; H, 7.92; N, 7.86. Found: C, 84.31; H, 7.93; N,
7.82%.
(15 mL) and a stirring bar. After the mixture was cooled to –
50 °C, n-butyl lithium (5 mmol, 3.15 mL of a 1.6 M solution in hex-
ane) was added by syringe. After the temperature of the solution
has reached 0 °C, 7 (350 mg, 1.14 mmol) was added in one portion
and the mixture was stirred for 1 h. On a vacuum line, the solution
was reduced in volume until appr. 5 mL. In a glove-box, the con-
centrated solution was allowed to stand until the product crystal-
lized as yellow needles.
4.5.5. Enamine 9
Starting materials: 3 (1.45 g, 7.85 mmol), 2,6-diisopropylaniline
(1.5 mL, 7.85 mmol). Experimental conditions: Azeotropic conden-
sation in xylene (mixture of isomers) over 10d with catalytic
amounts of trifluoroacetic acid, chromatographic work-up, crystal-
lization from ethanol. Yield: 1.4 g (53%) as a yellow solid. M.p.
85 °C. 1H NMR (300 MHz, (CD3)2SO, 298 K): d = 1.09 (d,
J = 6.82 Hz, 6H), 1.22 (d, J = 6.95 Hz, 6H), 1.69 (s, 3H), 3.11 (sept,
J = 6.8 Hz, 2H), 5.35 (s, 1H), 7.14 (d, J = 8.71 Hz, 1H), 7.23 (s, 1H),
7.28 (d, J = 8.20 Hz, 1H), 7.33 (d, J = 6.83 Hz, 1H), 7.52 (t,
J = 6.87 Hz, 1H), 7.61 (d, J = 7.98 Hz, 1H), 7.74 (d, J = 7.25 Hz, 1H),
8.02 (d, J = 8.72 Hz, 1H), 12.21 (s, 1H, enamineH) ppm. 13C NMR
(75 MHz, (CD3)2SO, 298 K): d = 19.5, 21.9, 24.7, 28.1, 93.4, 121.9,
123.2, 123.5, 124.4, 126.0, 127.4, 127.5, 129.3, 134.8, 146.3,
4.6.1. Lithium complex 12
Yield: <2% (Comment: The low yield is due to the very high sol-
ubility of 12 in hexane. No NMR data are available due to the lim-
ited amount of material available). Single crystal structure analysis
of 12: Fig. 3 and Table 2.
4.6.2. Lithium complex 13
Yield: 350 mg (90%). M.p. 168–172 °C. 1H NMR (300 MHz,
C4D8O (THF-d8), 298 K): d = 2.05 (s, 6H), 4.75 (s, 1H), 6.19 (d,
J = 5.9 Hz, 1H), 6.39 (d, J = 7.33 Hz, 1H), 6.60 (m, 3H), 6.90 (m,
4H), 7.20 (m, 2H), 7.80 (d, J = 3.4 Hz) ppm. 1H NMR (300 MHz, CD2-
Cl2, 298 K): d = 2.12 (s, 6H), 4.82 (s, 1H), 6.32 (d ꢂ d, J = 5.9 Hz, 1H),
6.55 (d ꢂ d, J = 7.35 Hz, 1H), 6.73 (s, 1H), 6.76 (m, 4H), 6.94 (d,
J = 4.37 Hz, 2H), 6.97 (d, J = 5.33 Hz, 2H), 7.08 (m, 4H), 7.17 (m,
2H), 7.29 (m, 2H), 7.88 (d, J = 4.45 Hz, 1H) ppm. 13C NMR
(75 MHz, C4D8O (THF-d8), 298 K): d = 26.3, 93.9, 110.8, 120.0,
122.0, 126.8, 127.1, 128.0, 129.1, 131.2, 134.4, 146.9, 147.0,
155.1, 161.0, 163.5 ppm. 13C NMR (75 MHz, CD2Cl2, 298 K):
d = 19.7, 93.1, 111.0, 120.2, 121.8, 126.8, 127.2, 127.8, 128.7,
146.4, 153.0, 159.5 ppm. IR (ATR):
m = 3047, 2950, 1629 (mC@N),
1581 (mC
@
N
of quinolyl), 1542, 1416, 1319, 831 cmꢀ1. Anal. Calc.
for C24H28N2 (344.49): C, 83.68; H, 8.19; N, 8.13. Found: C, 83.74;
H, 8.22 N, 8.05%. Single crystal structure analysis of 9: Table 2.
4.5.6. Enamine 10
Starting materials: 4 (2.0 g, 8.1 mmol), 2,6-dimethylaniline
(1.05 mL, 8.1 mmol). Experimental conditions: Azeotropic conden-
sation in xylene (mixture of isomers) over 10d with catalytic
amounts of trifluoroacetic acid, chromatographic work-up, crystal-
lization from ethanol. Yield: 1.5 g (53%) as a yellow solid. M.p.
127 °C. 1H NMR (300 MHz, (CD2Cl2, 298 K): d = 2.15 (s, 6H), 5.48
(s, 1H), 6.86 (m, 3H), 7.09 (d, J = 4.10 Hz, 1H), 7.11 (d, J = 2.49 Hz,
2H), 7.22 (d, J = 1.48 Hz, 1H), 7.24 (m, 1H), 7.50 (t, J = 6.95 Hz,
1H), 7.59 (d, J = 8.01 Hz, 1H), 7.72 (d, J = 8.39 Hz, 1H), 7.84 (d,
J = 8.67 Hz, 1H), 12.30 (s, 1H, enamineH) ppm. 13C NMR (75 MHz,
CD2Cl2, 298 K): d = 19.4, 98.2, 123.2, 124.6, 125.8, 127.8, 127.9,
128.3, 128.6, 128.8, 129.7, 135.4, 135.5, 138.8, 139.9, 147.6,
131.2, 134.7, 146.9, 157.8, 160.4, 163.2 ppm. IR (ATR):
m = 1608,
1541, 1479, 1447, 1364, 1283, 1080, 892, 815, 770, 679, 650 cm–
1. MS (FAB pos): m/z = 612.24 (M+), 613.25 (M+H)+. Single crystal
structure analysis of 13: Fig. 4 and Table 2.
4.6.3. Lithium complex 14
1
Yield: 22 mg (20%). H NMR (300 MHz, CD2Cl2, 298 K): d = 0.95
(d, J = 6.87 Hz, 12H), 3.28 (sept, J = 6.85 Hz, 2H), 4.94 (s), 6.82 (m),
6.93 (d, J = 2.0 Hz), 7.08 (d, J = 1.8 Hz), 7.10 (d, J = 2.15 Hz), 7.21
(m), 7.28 (m), 7.39 (m) ppm. 13C NMR (75 MHz, CD2Cl2, 298 K):
d = 21.8, 23.3, 25.2, 28.3, 95.3, 120.6, 122.5, 123.3, 123.4, 124.3,
126.3, 127.1, 127.4, 127.7, 128.0, 128.9, 133.0, 141.2, 144.3,
149.7, 150.0, 158.7, 164.5 ppm. Single crystal structure analysis
of 14: Fig. 5 and Table 2.
155.3, 160.1 ppm. IR (ATR):
m
= 3050, 2917, 1624 (
mC@N), 1585 (mC-
@
N
of quinolyl), 1541, 1493, 1359, 1190, 828, 772, 693 cmꢀ1. MS
(FAB pos): m/z = 350.19 (M+), 351.19 (M+H)+. Anal. Calc. for
C25H22N2 (350.46): C, 85.68; H, 6.33; N, 7.99. Found: C, 85.75; H,
6.34; N, 8.08%.
4.5.7. Enamine 11
Starting materials: 4 (1.74 g, 7.0 mmol), 2,6-diisopropylaniline
(1.3 mL, 7.0 mmol). Experimental conditions: Azeotropic conden-
sation in toluene over 9 d with catalytic amounts of trifluoroacetic
acid, chromatographic work-up, crystallization from ethanol.
Yield: 1.75 g (61%) as a yellow solid. M.p. 120 °C. 1H NMR
(300 MHz, CD2Cl2, 298 K): d = 1.01 (d, J = 6.89 Hz, 6H), 1.20 (d,
J = 6.81 Hz, 6H), 3.41 (sept, J = 6.81 Hz, 2H), 5.57 (s, 1H), 7.10 (d,
J = 6.85 Hz, 2H), 7.23 (m, 5H), 7.28 (m, 2H), 7.36 (d, J = 7.05 Hz,
1H), 7.58 (t, J = 7.69 Hz, 1H), 7.70 (d, J = 8.00 Hz, 1H), 7.78 (d,
J = 8.49 Hz, 1H), 7.94 (d, J = 8.68 Hz, 1H), 12.52 (s, 1H, enamineH)
4.7. Zirconium complex 15
A Schlenk vessel was charged with tetrakis(dimethylamido)zir-
conium(IV) (135 mg, 0.507 mmol), dry THF (30 mL) and a stirring
bar. Under protection from air, 2 (200 mg, 1.01 mmol) was added.
After the solution was stirred at room temperature for 2 h, all vol-
atile materials were removed on a vacuum line. To the solid resi-
due, an excess of trimethylchlorosilane (5 mL) was added to
effect exchange of amido ligands versus chloro ligands. After the
mixture was stirred at room temperature for 3 h, volatile materials

48
M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
were removed on a vacuum line. The solid residue was triturated
with dry n-hexane, filtered off, and dissolved in a small amount
of dry dichloromethane. Crystallization afforded the product in
the form of yellow needles. Yield: 200 mg (71%). M.p. 255–
259 °C. 1H NMR (300 MHz, CD2Cl2, 298 K): d = 6.27 (s, 1H), 6.82
(d ꢂ d, J = 6.30 Hz, J = 6.44 Hz, 1H), 7.13 (d, J = 8.03 Hz, 1H), 7.50
(m, 3H), 7.59 (d ꢂ d, J = 7.0 Hz, 1H), 7.95 (d, J = 5.71 Hz, 2H), 8.48
(d, J = 5.39 Hz, 1H) ppm. 13C NMR (75 MHz, CD2Cl2, 298 K):
d = 104.0, 120.4, 126.2, 126.4, 129.4, 130.6, 136.0, 139.9, 149.2,
4.9.2. [N,O]-Ni-complex 18
Yield: 95 mg g (21%) as brown powder. M.p. 202–204 °C. 1H/13
C
NMR: broad signals due to paramagnetism. IR (ATR):
m = 3028,
2962, 1586, 1570, 1520, 1475, 1450, 1393, 1153, 1090, 887, 771,
694 cm–1. MS (FAB pos): m/z = 451.10 (M+). Anal. Calc. for C26H20-
N2NiO2 (451.15): C, 69.22; H, 4.47; N, 6.21. Found: C, 69.13; H,
4.43; N, 6.15%.
4.9.3. [N,O]-Cu-complex 19
155.4, 160.2 ppm. IR (ATR):
m
= 1608, 1541, 1479, 1447, 1364,
Yield: 280 mg g (60%) as black crystals. M.p. 197 °C. 1H/13
C
1283, 1080, 892, 815, 770, 679, 650 cm–1. MS (FAB pos): m/
z = 532.29 (MꢀCl+O)+. Single crystal structure analysis of 150:
Fig. 5 and Table 2.
NMR: broad signals due to paramagnetism. IR (ATR): m = 2983,
2888, 1588, 1529, 1476, 1448, 1391, 1270, 1234, 1177, 1049,
886, 772, 694, 641 cm–1. MS (FAB pos): m/z = 456.00 (M+). Anal.
Calc. for C26H20CuN2O2 (456.00): C, 68.48; H, 4.42; N, 6.14. Found:
C, 68.40; H, 4.38; N, 6.07%. Single crystal structure analysis of 19:
Fig. 8 and Table 2.
4.8. Zirconium complex 16
A Schlenk tube was charged with freshly distilled diisopropyl-
amine (2.54 mmol, 400
lL), dry THF (15 mL) and a stirring bar.
4.10. [N,O]-complexes 20 and 21
After the mixture was cooled to ꢀ50 °C, n-butyl lithium
(2.56 mmol, 1.8 mL of a 1.6 M solution in hexane) was added by
syringe. The cooling bath was removed and the mixture was al-
lowed to warm to room temperature. 10 (460 mg, 1.31 mmol)
was added in one portion and stirring was continued for 1 h. After
zirconiumtetrachloride (155 mg, 0.66 mmol) was added under pro-
tection from air, the mixture was stirred for further 2 h. On a vac-
uum line, all volatile materials were removed, the solid residue
was repeatedly triturated with dry n-hexane, resulting in a red
crude product that was recrystallized from a mixture of dry dichlo-
romethane/n-hexane/THF, affording the pure product as yellow,
slightly air-sensitive needles. Yield: 420 mg (74%). 1H NMR
(300 MHz, CD2Cl2, 298 K): d = 1.28 (s, 3H), 1.30 (s, 3H), 5.23 (s,
1H), 6.06 (d, J = 7.21, 1H), 6.56 (d, J = 7.21 Hz, 1H), 6.79 (d ꢂ d,
J = 7.47 Hz, 1H), 7.04 (d, J = 7.26 Hz, 1H), 7.28 (d, J = 7.57 Hz, 2H),
7.34 (m, 1H), 7.41 (m, 2H), 7.52 (m, 2H), 7.56 (d, J = 6.90 Hz, 1H),
7.62 (m, 1H), 9.03 (d, J = 8.45 Hz, 1H) ppm. 13C NMR (75 MHz, CD2-
Cl2, 298 K): d = 26.5, 85.7, 121.5, 124.9, 125.3, 125.6, 126.5, 127.3,
127.9, 128.4, 128.6, 129.9, 130.7, 130.9, 133.5, 134.8, 138.0,
Representative procedure for 20: A Schlenk tube was charged
with 2 (140 mg, 0.7 mmol), dry toluene (10 mL) and a stirring
bar. Under protection from air, diethyl zinc (0.35 mmol, 320 lL of
a 1.0 M solution in toluene) was added and the mixture was stirred
at room temperature until all gas evolution has ceased, followed by
a reflux period of 15 min. On cooling to room temperature, the
product began to precipitate. After all volatile materials were re-
moved on a vacuum line, the Schlenk vessel was transferred to
the glove-box and the brown solid residue was dissolved in a small
volume of dry dichloromethane for crystallization, resulting in
large single crystals of the product.
4.10.1. [N,O]-Zn-complex 20
Yield: 120 mg (74%) as yellow crystals. M.p. 231 °C. 1H NMR
(300 MHz, CD2Cl2, 298 K): d = 5.88 (s, 1H), 6.68 (m, 1H), 6.97 (d,
J = 8.42 Hz, 1H), 7.26 (m, 3H), 7.46 (m, 1H), 7.76 (d, J = 5.28 Hz,
1H), 7.82 (d, J = 1.61 Hz, 1H), 7.84 (d, J = 2.16 Hz, 1H) ppm. 13C
NMR (75 MHz, CD2Cl2, 298 K): d = 93.2, 117.4, 124.1, 126.9, 128.5,
138.4, 145.3, 149.3, 152.4, 165.0 ppm. IR (ATR):
m
= 2967, 2841,
129.4, 139.0, 142.4, 146.6, 160.4, 172.6 ppm. IR (ATR): m = 3050,
1596, 1498, 1441, 1394, 1372, 1185, 1144, 1061, 1020, 831,
756 cmꢀ1. MS (FAB pos): m/z = 823.34 (MꢀCl)+, 858.30 (M)+,
859.30 (M+H)+. Single crystal structure analysis of 16: Fig. 6 and
Table 2.
3009, 1605, 1585, 1570, 1516, 1475, 1449, 1393, 1160, 873, 799,
735, 686, 656 cmꢀ1. MS (FAB pos): m/z = 456.04, 457.08, 458.08,
459.08, 460.08, 461.08 (M+). Anal. Calc. for C26H20N2O2Zn
(457.84): C, 68.21; H, 4.40; N, 6.12. Found: C, 68.11; H, 4.36; N,
6.15%. Single crystal structure analysis of 20: Table 2.
4.9. [N,O]-complexes 17–19
4.10.2. [N,O]-Zn-complex 21
Representative procedure for 17: A Schlenk tube was charged
with 2 (400 mg, 2.03 mmol), dry THF (10 mL), anhydrous cobalt(II)
chloride and a stirring bar. In a separate Schlenk tube, a solution of
lithium diisopropylamide (LDA) was prepared in THF (25 mL) from
Starting material: 4 (400 mg, 1.62 mmol) Yield: 440 mg (98%) as
yellow crystals. Solubility: only slightly soluble in organic solvents.
M.p. 330 °C. 1H NMR (300 MHz, CDCl3, 298 K): d = 6.21 (s, 1H), 7.19
(d ꢂ d, J = 3.41 Hz, J = 2.72 Hz, 1H), 7.26 (m, 3H), 7.37 (m, 2H), 7.55
((d ꢂ d, 2H), 7.89 (d, J = 8.85, 1H), 7.96 (d, J = 2.31, 1H), 7.99 (m, 1H)
ppm. 13C NMR (75 MHz, CD2Cl2, 298 K): no data due to insufficient
diisopropylamine (700 lL, 5.0 mmol) and n-butyl lithium (3.15 mL
of a 1.6 M solution in hexane, 5.0 mmol). The LDA-solution was
added under protection from air to the solution of 2 and CoCl2.
After the mixture has been stirred overnight, all volatile materials
were removed on a vacuum line. The Schlenk vessel was trans-
ferred into the glove-box and the dark colored solid residue was
dissolved in a small volume of dry dichloromethane. Layering the
solution with dry n-hexane afforded brown single crystals of the
product.
solubility. IR (ATR):
m = 1620, 1610, 1570, 1524, 1474, 1452, 855,
827, 733, 677 cm–1. MS (ESI pos): m/z = 557.13 (M+). Anal. Calc.
for C34H24N2O2Zn (557.96): C, 73.19; H, 4.34; N, 5.02. Found: C,
73.07; H, 4.29; N, 4.94%. Single crystal structure analysis of 21:
Fig. 9 and Table 2.
4.11. [N,N]-complexes 22–27
4.9.1. [N,O]-Co-complex 17
These compounds were synthesized in analogy to [N,O]-com-
plexes 17–21; scale, experimental details and properties are given
in the following:
Yield: 210 mg (46%) as brown crystals. M.p. 207–209 °C. 1H/13
C
NMR: broad signals due to paramagnetism. IR (ATR):
m = 2955,
2920, 2863, 1589, 1524, 1477, 1450, 1397, 1154, 1097, 1008,
772, 695 cmꢀ1. Anal. Calc. for C26H20CoN2O2 (451.39): C, 69.18; H,
4.47; N, 6.21. Found: C, 69.06; H, 4.42; N, 6.11%. Single crystal
structure analysis of 170: Fig. 7 and Table 2.
4.11.1. [N,N]-Fe-complex 22
Starting materials: 7 (250 mg, 0.83 mmol), anhydrous FeCl2
(60 mg, 0.42 mmol), LDA (1.25 mmol). Yield: 260 mg (95%) as red

M. Graser et al. / Inorganica Chimica Acta 401 (2013) 38–49
49
crystals. M.p. > 150 °C, dec. 1H/13C NMR: broad signals due to para-
763.37, 764.30, 765.31, 766.38, 767.32 (M+). Anal. Calc. for
50H42N4Zn (764.29): C, 78.58; H, 5.54; N, 7.33. Found: C, 78.51;
H, 5.51; N, 7.30%. Single crystal structure analysis of 27: Table 2.
magnetism. IR (ATR):
m
= 1603, 1554, 1498, 1483, 1442, 1380,
C
1188, 1153, 997, 769, 697 cm–1. MS (FAB pos): m/z = 654.21 (M+).
Anal. Calc. for C42H38FeN4 (654.64): C, 77.06; H, 5.85; N, 8.56.
Found: C, 76.95; H, 5.80; N, 8.48%. Single crystal structure analysis
of 22: Fig. 10 and Table 2.
Acknowledgement
We thank Basell Polyolefine GmbH, Frankfurt, Germany for par-
tial funding. M.G. thanks the University of Innsbruck for a Ph.D.
stipend.
4.11.2. [N,N]-Co-complex 23
Starting materials: 7 (250 mg, 0.83 mmol), anhydrous CoCl2
(54 mg, 0.42 mmol), LDA (1.25 mmol). Yield: 170 mg (62%) as red
crystals. M.p. 182–185 °C, dec. 1H/13C NMR: broad signals due to
Appendix A. Supplementary material
paramagnetism. IR (ATR):
m = 2917, 2847, 1604, 1558, 1502,
1444, 1382, 1252, 1192, 1147, 1004, 755, 695 cm–1. MS (FAB
pos): m/z = 657.29, 658.38, 659.30 (M+). Anal. Calc. for C42H38CoN4
(657.72): C, 76.70; H, 5.82; N, 8.52. Found: C, 76.62; H, 5.77; N,
8.45%. Single crystal structure analysis of 23: Fig. 11 and Table 2.
CCDC 899162–899180 contains the supplementary crystallo-
graphic data for 3, 6, 7, 9, 11, 12, 14, 150, 16, 170, 19, 20, 21, 22,
23, 24, 25, 26, 27. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.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.2013.02.040.
4.11.3. [N,N]-Ni-complex 24
Starting materials: 7 (250 mg, 0.83 mmol), anhydrous Ni(CH3-
CO2)2 (75 mg, 0.42 mmol), LDA (1.25 mmol). Yield: 90 mg (29%)
as black crystals. M.p. 240 °C, dec. H/13C NMR: broad signals due
1
References
to paramagnetism. IR (ATR):
m = 2914, 2844, 1605, 1557, 1505,
1442, 1417, 1383, 1193, 1153, 1000, 783, 767, 698 cmꢀ1. MS
(FAB pos): m/z = 656.26, 657.30, 658.27, 659.32 (M+). Anal. Calc.
for C42H38N4Ni (657.48): C, 76.73; H, 5.83; N, 8.52. Found: C,
76.70; H, 5.80; N, 8.50%. Single crystal structure analysis of 24:
Fig. 12 and Table 2.
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Comprehensive Coordination Chemistry II, vol. 1, Elsevier, Oxford, 2004, p. 97
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(c) M. Westerhausen, Angew. Chem., Int. Ed. 47 (2008) 2185.
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(c) M.F. Elshazly, T. Salem, A. Eldissouky, A.M. Hindaway, Inorg. Chim. Acta 25
(1977) 55.
4.11.4. [N,N]-Ni-complex 25
Starting materials: 9 (250 mg, 0.73 mmol), anhydrous Ni(CH3-
CO2)2 (65 mg, 0.36 mmol), LDA (1.25 mmol). Yield: 175 mg (65%)
as black crystals. M.p. 186 °C, dec. H/13C NMR: broad signals due
1
[5] (a) B.J. Deelman, P.B. Hitchcock, M.F. Lappert, W.P. Leung, H.K. Lee, T.C.W. Mak,
Organometallics 18 (1999) 1444;
to paramagnetism. IR (ATR):
m = 3047, 2952, 2917, 2860, 1622,
(b) B.J. Deelman, M.F. Lappert, H.K. Lee, T.C.W. Mak, W.P. Leung, P.R. Wei,
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(g) M. Graser, H. Kopacka, K. Wurst, B. Bildstein, Z. Kristallogr. -New Cryst.
Struct. 225 (2010) 673.
1562, 1524, 1479, 1403, 1378, 1315, 1282, 1253, 1178, 1144,
1098, 1021, 823, 795, 756, 737 cmꢀ1. MS (FAB pos): m/z = 744.44,
745.45, 746.46 (M+). Anal. Calc. for C48H54N4Ni (745.67): C, 77.32;
H, 7.30; N, 7.51. Found: C, 77.21; H, 7.26; N, 7.47%. Single crystal
structure analysis of 25: Table 2.
4.11.5. [N,N]-Cu-complex 26
[6] M. Graser, Design und Synthese neuer Enamido-Olefin-Polymer-
isationskatalysatoren, Diploma Thesis, University of Innsbruck, 2008.
[7] J. Büchi, F. Kracher, G. Schmidt, Helv. Chim. Acta 45 (1962) 729.
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(b) A.R.E. Carey, S. Eustace, R.A. More O’Ferral, B.A. Murray, J. Chem. Soc., Perkin
Trans. 2 (1993) 2285.
Starting materials: 7 (250 mg, 0.83 mmol), anhydrous Cu(CF3-
SO3)2 (150 mg, 0.42 mmol), LDA (1.25 mmol). Yield: 90 mg (29%)
1
as black crystals. M.p. 206 °C, dec. H/13C NMR: broad signals due
to paramagnetism. IR (ATR):
m = 3025, 2908, 1604, 1561, 1503,
1443, 1384, 1251, 1150, 1006, 770, 754, 731, 695, 676 cmꢀ1. MS
(FAB pos): m/z = 661.28, 663.31 (M+). Anal. Calc. for C42H38CuN4
(662.34): C, 76.16; H, 5.78; N, 8.46. Found: C, 76.04; H, 5.74; N,
8.40%. Single crystal structure analysis of 26: Table 2.
[9] (a) B. Bildstein, P. Denifl, Synthesis (1994) 158;
(b) G.A. Luinstra, J. Queisser, B. Bildstein, H.-H. Görtz, C. Amort, M. Malaun, A.
Krajete, G. Werne, M.O. Kristen, N. Huber, C. Gernert, in: B. Rieger, L.S. Baugh, S.
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Organometallics 16 (1997) 1247;
4.11.6. [N,N]-Zn-complex 27
(b) X. Chen, L.L. Guan, M.S. Eisen, H.F. Li, H.B. Tong, L.P. Zhang, D.S. Liu, Eur. J.
Inorg. Chem. (2009) 3488.
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1945;
(b) B.-J. Deelman, P.B. Hitchcock, M.F. Lappert, W.-P. Leung, H.-K. Lee, T.C.W.
Mak, Organometallics 18 (1999) 1444.
[13] (a) M.F. El-Shazly, T. Salem, A. El-Dissouky, A.M. Hindaway, Inorg. Chim. Acta
25 (1977) 55;
(b) A. El-Dissouky, A.Z. Elsonbati, Polyhedron 9 (1990) 2443.
[14] M. Graser, H. Kopacka, K. Wurst, M. Ruetz, C. Kreutz, T. Müller, G, Knör, C.
Hirtenlehner, B. Bildstein, Inorg. Chim. Acta 2013, submitted.
[15] D. Eisenstecken, B. Enk, H. Kopacka, K. Wurst, T. Müller, F. Pevny, R.F. Winter, B.
Bildstein, Eur. J. Inorg. Chem. (2011) 2958.
Starting materials: 10 (250 mg, 0.72 mmol), diethylzinc (350 lL
of a 1.0 M solution in toluene, 0.35 mmol). Yield: 200 mg (74%) as
yellow crystals. M.p. 174–178 °C. 1H NMR (300 MHz, CDCl3, 298 K):
d = 1.82 (s, 6H), 5.30 (s, 1H), 6.13 (m, 1H), 6.38 (m, 1H), 6.74 (s, 1H),
6.87 (d, J = 8.91 Hz, 1H), 6.98 (m, 5H), 7.18 (m, 3H), 7.30 (d,
J = 6.55 Hz, 1H), 7.48 (d, J = 8.98 Hz, 1H), 7.78 (d, J = 9.55 Hz, 1H)
ppm. 13C NMR (75 MHz, CD2Cl2, 298 K): 19.8, 97.7, 123.2, 123.6,
124.7, 125.2, 125.8, 127.5, 127.9, 128.2, 128.4, 128.6, 129.9,
132.9, 135.7, 143.5, 145.9, 149.3, 158.8, 167.7 ppm. IR (ATR):
m
= 3050, 2958, 2914, 2848, 1613, 1517, 1466, 1409, 1375, 1258,
1194, 1144, 827, 757, 732, 688 cmꢀ1. MS (FAB pos): m/z = 762.37,