Hydrazone-diacetyl platinum(II) complexes: Substituent effect on intramolecular N-H?O hydrogen-bond strength

Article abstract of DOI:10.1016/j.jorganchem.2014.03.030

Bis(benzylamine)diacetylplatinum(II) (3) reacted with 2-pyridyl- functionalized hydrazones and with diacetyl dihydrazone to yield diacetyl platinum(II) complexes [Pt(COMe)₂(2-pyCRNNH₂)] (R = H, 4a; Me, 4b; Ph, 4c) and [Pt(COMe)₂(H₂NNCMe-CMeNNH ₂)] (5). These complexes showed weak intramolecular N-H?O hydrogen bonds where the hydrazone and the acetyl ligand act as H donor and H acceptor, respectively. Using hydrazones 2-pyCRNNHR′ substituted with electron-withdrawing groups R′ resulted in complexes [Pt(COMe) ₂(2-pyCRNNHR′)] (R/R′ = H/C₆H₄-p-F, 6d; Me/C₆H₄-p-F, 6e; H/COMe, 7a; Me/COMe, 7b; H/COPh, 7c; Me/COPh, 7d; H/CO(C₆H₄-p-F), 7e; Me/CO(C ₆H₄-p-F), 7f) with stronger intramolecular N-H?O hydrogen bonds. The isolation of the analogous phenylhydrazone complexes (R′ = Ph) failed on this way, but reactions of the 1D coordination polymer [{Pt(COMe)₂}_n] (2) with phenylhydrazones resulted in the formation of the desired complexes [Pt(COMe)₂(2-pyCRNNHR′)] (R/R′ = H/Ph, 6a; Me/Ph, 6b; Ph/Ph, 6c; H/C₆F₅, 6f). The constitution of all complexes was unambiguously confirmed analytically, spectroscopically and, in part, by single-crystal X-ray diffraction analyses. Structural and NMR parameters gave evidence that the strength of the N-H?O hydrogen bond is increased in the order 5 a‰? 4a-c < 6a-e < 6f a‰? 7a-f. This goes parallel with an activation of the acetyl ligand, but in no case the reaction with amines resulted in the formation of iminoacetyl platinum(II) complexes as it was found in analogous oxime-diacetyl complexes [Pt(COMe)₂(2-pyCRNOH)] which have stronger (even than in type 6f/7a-f complexes) intramolecular O-H?O hydrogen bonds.

Full text of DOI:10.1016/j.jorganchem.2014.03.030

Journal of Organometallic Chemistry 762 (2014) 48e57
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Hydrazoneediacetyl platinum(II) complexes: Substituent effect
on intramolecular NeH/O hydrogen-bond strength
,
,
Tim Kluge a, Eileen Bette a b, Martin Bette a, Jürgen Schmidt b, Dirk Steinborn a
*
a Institute of ChemistryeInorganic Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle, Germany
b Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Bis(benzylamine)diacetylplatinum(II) (3) reacted with 2-pyridyl-functionalized hydrazones and with
diacetyl dihydrazone to yield diacetyl platinum(II) complexes [Pt(COMe)2(2-pyCR]NNH2)] (R ¼ H, 4a;
Me, 4b; Ph, 4c) and [Pt(COMe)2(H2NN]CMeeCMe]NNH2)] (5). These complexes showed weak intra-
molecular NeH/O hydrogen bonds where the hydrazone and the acetyl ligand act as H donor and H
acceptor, respectively. Using hydrazones 2-pyCR]NNHR0 substituted with electron-withdrawing groups
R0 resulted in complexes [Pt(COMe)2(2-pyCR]NNHR0)] (R/R0 ¼ H/C6H4-p-F, 6d; Me/C6H4-p-F, 6e; H/
COMe, 7a; Me/COMe, 7b; H/COPh, 7c; Me/COPh, 7d; H/CO(C6H4-p-F), 7e; Me/CO(C6H4-p-F), 7f) with
stronger intramolecular NeH/O hydrogen bonds. The isolation of the analogous phenylhydrazone
complexes (R0 ¼ Ph) failed on this way, but reactions of the 1D coordination polymer [{Pt(COMe)2}n] (2)
with phenylhydrazones resulted in the formation of the desired complexes [Pt(COMe)2(2-pyCR]
NNHR0)] (R/R0 ¼ H/Ph, 6a; Me/Ph, 6b; Ph/Ph, 6c; H/C6F5, 6f). The constitution of all complexes was
unambiguously confirmed analytically, spectroscopically and, in part, by single-crystal X-ray diffraction
analyses. Structural and NMR parameters gave evidence that the strength of the NeH/O hydrogen bond
is increased in the order 5 z 4aec < 6aee < 6f z 7aef. This goes parallel with an activation of the acetyl
ligand, but in no case the reaction with amines resulted in the formation of iminoacetyl platinum(II)
complexes as it was found in analogous oximeediacetyl complexes [Pt(COMe)2(2-pyCR]NOH)] which
have stronger (even than in type 6f/7aef complexes) intramolecular OeH/O hydrogen bonds.
Ó 2014 Elsevier B.V. All rights reserved.
Received 10 December 2013
Received in revised form
3 February 2014
Accepted 28 March 2014
Keywords:
Organoplatinum complexes
Acetyl ligands
Hydrazone ligands
Hydrogen-bond strength
Introduction
aminocarbene ligands, and deprotonated oxime ligands are pre-
sent [1].
In diacetyl platinum(II) complexes bearing 2-pyridyl ket-/
aldoxime ligands (I) or dioxime ligands (II) the oxime ligands act
as H donor and the O acetyl atoms as H acceptor, thus forming
relatively strong intramolecular OeH/O hydrogen bonds both in
the solid state and in solution (Scheme 1) [1]. This gives rise to an
activation of the acetyl ligands, and complexes I and II were
found to react with primary amines in a Schiff-base type reaction
under formation of iminoacetyl complexes III and IV, respec-
tively. The characteristic structural features of these complexes
are also intramolecular hydrogen bonds in which the iminoacetyl
and oxime ligands act as H donor and H acceptor, respectively.
Thus, in these complexes protonated iminoacetyl ligands, i.e.
Type I and II complexes were synthesized from reactions of the
dinuclear platina- -diketone (1), an acetylehydroxycarbene com-
plex which is stabilized by intramolecular OeH/O hydrogen bonds
[2], with 2-pyridyl-functionalized monoximes or with dioximes in
the presence of bases such as NaOMe (Scheme 1) [1]. Alternatively,
as shown with the reaction of dimethylglyoxime as example, the 1D
b
coordination polymer [{Pt(COMe)2}n] (2), in which kC:kO bridging
acetyl ligands are present, can be used as precursor complex [3].
Furthermore, in bis(amine)ediacetyl platinum(II) complexes such
as 3 the weakly coordinated amine ligands were found to be prone
of ligand substitution reactions [4,5]. Due to the amine cleaved off
in these reactions, complexes 3 reacted with oximes directly
yielding type III/IV complexes (Scheme 1) [1].
The activation of acetyl ligands for reactions I / III and II / IV
(Scheme 1) were found to be strongly dependent on the strength of
the intramolecular hydrogen bond and on the nucleophilicity of the
amine [1]. Structurally related to oximes are hydrazones which can
* Corresponding author. Tel.: þ49 345 55 25620; fax: þ49 345 55 27028.
E-mail address: dirk.steinborn@chemie.uni-halle.de (D. Steinborn).
http://dx.doi.org/10.1016/j.jorganchem.2014.03.030
0022-328X/Ó 2014 Elsevier B.V. All rights reserved.

T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
49
Scheme 1.
also act as H donor in hydrogen bonds. Thus, it is of interest to
investigate whether diacetyl platinum(II) complexes with hydra-
zone co-ligands can be prepared and whether NeH/O hydrogen
bonds were formed which are strong enough to activate the acetyl
ligands for Schiff-base type reactions.
red (4a), orange colored (4b/c), and yellow (5) microcrystals. The
constitution of all complexes was unambiguously prooved by high-
resolution ESI mass spectrometry, by NMR (1H, 13C, 195Pt) and IR
spectroscopy, and by single-crystal X-ray diffraction analyses
(4b/c, 5).
As for the respective oxime complexes I that exhibit intra-
molecular OeH/O hydrogen bonds (Scheme 1), the hydrazone
complexes described here form intramolecular NeH/O hydrogen
bonds. To strengthen these hydrogen bonds the terminal N atom of
the hydrazone was substituted by electron-withdrawing groups
(R0). Thus, phenylhydrazones 2-pyCR]NNHR0 (R0 ¼ Ph, C6H4-p-F,
C6F5) and acyl substituted hydrazones 2-pyCR]NNH(COR00)
(R00 ¼ Me, Ph, C6H4-p-F), i.e. acid hydrazides, were reacted with
bis(benzylamine)diacetylplatinum(II) (3) (Scheme 2, B/C). In all
cases the reaction mixtures became immediately red and diacetyl
platinum(II) complexes bearing fluorophenyl (6d/e) and acyl
Results and discussion
Syntheses
Bis(benzylamine)diacetylplatinum(II) (3) was found to react
with 2-pyridyl-functionalized hydrazones 2-pyCR]NNH2 (R ¼ H,
Me, Ph) and with diacetyl dihydrazone under ligand substitution
yielding diacetyl platinum(II) complexes bearing the respective
hydrazone (4aec) and dihydrazone ligand (5) (Scheme 2, reaction
path A). The complexes were isolated in good yields (54e95%) as
Scheme 2.

50
T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
substituted (7aef) 2-pyridyl-functionalized hydrazone ligands
could be isolated in good yields (65e83%). In the case of the phenyl
and pentafluorophenyl substituted hydrazones 2-pyCR]NNHPh
and 2-pyCR]NNH(C6F5), respectively, the reaction mixtures
became also immediately red, thus indicating the formation of
complexes 6aec and 6f, but their isolation failed. Instead, only the
starting complex 3 could be re-formed. To obtain these complexes,
the 1D coordination polymeric diacetyl bridged platinum(II) com-
plex 2 was reacted with 2-pyCR]NNHR0 (R0 ¼ Ph, C6F5, Scheme 2,
D). On this way 6aec and 6f could be isolated in a pure state in 71e
83% yields. Using this method for the synthesis of complexes 6d/e,
the isolated products contained unidentified side products,
whereas complexes 7aef were obtained in a pure state (Scheme 2,
E). All complexes were fully characterized by microanalyses or
high-resolution ESI mass spectrometry, by NMR (1H, 13C, (19F), 195Pt)
and IR spectroscopy, as well as by single-crystal X-ray diffraction
analyses (6a, 7a, 7c$CH2Cl2, 7e).
Fig. 2. Molecular structure of [Pt(COMe)2(2-pyCH]NNHPh)] (6a, displacement ellip-
soids of non-hydrogen atoms at 30% probability). The broken line indicates an intra-
molecular NeH/O hydrogen bond.
Structural characterization
From single-crystal X-ray diffraction analyses of [Pt(COMe)2(2-
pyCR]NNHR0)] (R/R0 ¼ Me/H, 4b; Ph/H, 4c; H/Ph, 6a; H/COMe,
7a; H/COPh, 7c$CH2Cl2; H/CO(C6H4-p-F), 7e) molecular structures
of the complexes were obtained. They are shown in Figs. 1e3;
selected structural parameters are given in Table 1. The asymmetric
units of crystals of complexes 4c and 7a contain two symmetry-
independent molecules with very similar structures. In all com-
plexes the platinum atoms are coordinated in a square-planar
fashion (sum of angles between neighbored ligands: 360.0e
360.3ꢀ) by two acetyl ligands and a k2N,N0 coordinated pyridyl-
functionalized hydrazone ligand. Due to this bidentate coordina-
tion the N1ePteN2 angles are considerably smaller (75.6(2)e
76.5(8)ꢀ) than 90ꢀ. Notably, these angles are even smaller than
those in platinum(II) complexes with bidentately coordinated 2-
pyCR]NR0 (R/R0 ¼ H, alkyl, aryl) ligands (median 79.8ꢀ; lower/
upper quartile 78.5/80.1ꢀ; n ¼ 29, n ¼ number of observations [6]).
In all these complexes the NeH group and an O atom of an acetyl
ligand act as H donor and H acceptor, respectively, thus forming
intramolecular NeH/O hydrogen bonds (graph set [7]: S(6)). The
at the terminal N atom of the hydrazone ligand with electron-
withdrawing groups R0 gives rise to stronger hydrogen bonds:
0
R0 ¼ H (2.740(7)e2.855(6) A, 4b/c) < R ¼ Ph (2.701(3) A,
ꢀ
ꢀ
0
00
ꢀ
6a) < R ¼ COR (2.653(7)e2.684(4) A, 7a/c/e). Additionally, in type
7 complexes the O3 atoms of the acyl substituents act as H acceptor
in weak intramolecular C3eH/O3 hyꢀdrogen bonds (C3/O3
ꢀ
2.758(5)e2.809(5) A, C3eH/O3 118e123 ).
Except for complex 4b, due to the intramolecular NeH/O
hydrogen bonds the acetyl ligands which are involved in these
hydrogen bonds lie nearly in the complex planes (3.8(5)e29.6(4)ꢀ)
whereas the other ones, as usual [3,5,9], are nearly perpendicularly
arranged (72.1(5)e85.1(4)ꢀ). In complex 4b the two acetyl ligands
form angles with the complex plane of 46.0(2) and 48.7(1)ꢀ. This
might be reasoned by0 weak intermolecular N3eHꢀ/O10 hydrogen
0
ꢀ
bonds (Fig. 1; N3/O1 3.019(5) A, N3eH/O1 155 , graph set [7]:
C(6)) which give rise to a 1D network of hydrogen bonds in crystals
of 4b. Analogously, intermolecular hydrogen bonds link the two
symmetry-independent molecules in complex 4c (N3/O4/N6/O2
ꢀ
ꢀ
2.986(8)/2.812(9) A, N3eH/O4/N6eH/O2 124/112 , graph set:
R22ð12Þ, Fig. 1) so that dinuclear entities are formed in crystals of 4c.
The molecular structure of the diacetyl platinum complex 5
bearing a dihydrazone ligand is shown in Fig. 4 and structural
ꢀ
N/O distances (2.653(7)e2.855(6) A) and the NeH/O angles
(141e159ꢀ) indicate moderately strong hydrogen bonds [8]. On the
basis of the distance criterion it will be obvious that a substitution
Fig. 1. Structures of [Pt(COMe)2(2-pyCR]NNH2)] in crystals of 4b (R ¼ Me, left) and 4c (R ¼ Ph, right; all displacement ellipsoids of non-hydrogen atoms at 30% probability, on the
right H atoms are not shown except hydrogen bonded ones). The broken lines indicate intra- and intermolecular NeH/O hydrogen bonds.

T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
51
Fig. 3. Structures of [Pt(COMe)2(2-pyCH]NNHR0)] in crystals of 7a (R0 ¼ COMe, left; one of the two symmetry-independent molecules is shown), 7c∙CH2Cl2 (R0 ¼ COMe, middle),
and 7e (R0 ¼ CO(C6H4-p-F), right; all displacement ellipsoids of non-hydrogen atoms at 30% probability). The broken lines indicate intramolecular NeH/O and CeH/O hydrogen
bonds.
parameters are given in the Figure caption. The platinum atom is
square-planar coordinated (sum of angles: 360.0ꢀ) by two acetyl
ligands and the bidentately k2N,N0 coordinated dihydrazone ligand.
The dihydrazone ligand gives rise to the formation of two intra-
molecular NeH/O hydrogen bonds. As for the complexes with 2-
pyCR]NNHR0 ligands, the N/O distances (N4/O1/N3/O2
H/Pt0 hydrogen bonds, in which the doubly occupied 6dz2 orbital
of Pt acts as H acceptor [10], are formed (graph set [7]: C(4)) such
that the crystal is threaded by a 2D network of hydrogen bonds.
Altogether, the N4H2 group acts both as H donor and as H acceptor
whereas the N3H2 group functions only as H donor. According to
the concept of the
s-bond cooperativity [8], this could be the
ꢀ
2.800(5)/2.982(5) A) and the NeH/O angles (N4eH/O1/N3e
reason for the stronger intramolecular N4eH/O1 bond compared
with the N3eH/O2 one. In accordance with this, DFT calculations
(details see Supplemental material) of complex 5, representing the
structure of an isolated molecule in the gas phase, gave proof of a
nearly C2 symmetric molecule having two hydrogen ꢀbonds of the
H/O2 146/148ꢀ) give evidence for moderately strong hydrogen
bonds [8]. The two acetyl ligands are twisted out of the complex
plane by 30.5(2)ꢀ and 50.7(3)ꢀ, respectively, whereas the smaller
interplanar angle belongs to the shorter N/O distance and hence
stronger hydrogen bond (N4eH/O1).
ꢀ
same strength (N/O 2.796/2.796 A, NeH/O 153/153 ), see Fig. S1.
ꢀ
The large difference of 0.182 A between the two N/O distances
can be traced back to intermolecular hydrogen bonds found in
Spectroscopic characterization
crystals of 5 (Fig. 5). On the one side, intermolecular N3eH/N40
0
0
ꢀ
ꢀ
hydrogen bonds (N3/N4 3.126(5) A, N3eH/N4 144 ) are formed
(graph set [7]: C(6)). On the other side, non-conventional N4e
NMR spectroscopic data proved to be fully consistent with the
constitution of the complexes given in Scheme 2. Characteristic 1H,
Table 1
Selected distances (in A) and angles (in ꢀ) of complexes [Pt(COMe)2(2-pyCR]NNHR0)] (4b/c, 6a, 7a, 7c∙CH2Cl2, 7e).
ꢀ
4b
4ca
6a
7aa
7c∙CH2Cl2
7e
R/R0
PteC1
PteC2
PteN1
Me/H
Ph/H
H/Ph
H/COMe
H/COPh
1.982(4)
1.984(5)
2.130(4)
2.144(3)
1.218(5)
1.234(5)
1.372(4)
91.0(2)
96.1(2)
75.9(1)
97.0(2)
73.9(2)
28.4(3)
2.668(5)
158
H/CO(C6H4-p-F)
1.978(4)
1.980(4)
2.122(4)
2.169(3)
1.222(5)
1.246(5)
1.363(5)
90.9(2)
98.0(2)
75.9(1)
95.2(2)
82.4(6)
1.988(5)
2.004(5)
2.126(4)
2.132(4)
1.228(6)
1.220(6)
1.370(5)
89.7(2)
96.3(2)
75.6(2)
98.7(2)
48.7(1)
46.0(2)
2.855(6)
151
1.973(5)/1.985(5)
1.976(6)/1.983(6)
2.116(4)/2.111(5)
2.139(4)/2.152(4)
1.217(6)/1.210(7)
1.243(7)/1.232(7)
1.357(6)/1.342(6)
90.5(2)/90.6(3)
97.6(2)/97.4(2)
76.0(2)/75.7(2)
95.9(2)/96.4(2)
72.1(5)/72.1(5)
29.6(4)/29.6(4)
2.790(6)/2.740(7)
147/141
1.985(3)
1.994(3)
2.119(2)
2.160(2)
1.208(4)
1.234(3)
1.347(3)
91.3(1)
97.7(1)
76.5(8)
94.5(1)
83.0(2)
12.5(1)
2.701(3)
156
1.978(7)/1.976(6)
1.979(7)/1.982(7)
2.133(5)/2.130(5)
2.169(5)/2.167(5)
1.230(9)/1.234(9)
1.245(8)/1.258(8)
1.374(8)/1.367(7)
91.6(3)/91.4(3)
97.5(2)/97.7(2)
76.3(2)/76.2(2)
94.6(2)/94.8(2)
85.1(4)/85.1(4)
3.8(5)/3.8(5)
PteN2
C1¼O1
C2¼O2
N2eN3
C1ePteC2
C2ePteN2
N1ePteN2
N1ePteC1
g
(c.p./MeC1]O1)b
g
(c.p./MeC2]O2)b
19.3(6)
2.684(4)
154
2.758(5)
118
N3/O2
2.669(8)/2.653(7)
155/159
2.784(8)/2.786(8)
123/119
N3eH/O2c
C3/O3
2.809(5)
118
C3eH/O3d
a
The values of the two symmetry-independent molecules are given separated by a slash.
c.p. ¼ coordination plane.
b
c
H atoms found in the electron density maps.
d
H atoms placed on calculated positions.

52
T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
found: R0 ¼ acyl (12.40e14.35 ppm; 7aef) z C6F5 (12.43 ppm;
6f) > Ph, C6H4-p-F (9.97e11.63 ppm; 6aee) > H (6.61e8.08 ppm;
4aec/5). Furthermore, as shown by low-field shifts of the NH
signals by 0.4e1.7 ppm in complexes bearing 2-pyCH]NNHR0 li-
gands compared to those bearing 2-pyCR]NNHR0 (R ¼ Me, Ph)
ligands, the former ones tend to form stronger NeH/O hydrogen
bonds. At room temperature (4aec/5) and at ꢁ85 ꢀC (4b), for the
complexes bearing non-substituted hydrazone ligands, only one
signal for the two NH2 protons were found. Furthermore, for all
3
complexes, except for complexes 4, characteristic JPt,H coupling
constants of 15e20 Hz were observed.
The stronger the intramolecular NeH/O hydrogen bond the
more the acetyl ligand involved in this hydrogen bond is activated
for a nucleophilic attack. When type I oximeediacetyl platinum(II)
complexes are obtained analogously as the hydrazoneediacetyl
complexes described here (Scheme 2, AeC), the OeH/O hydrogen
bonds formed were strong enough to activate the acetyl ligands
such that with the benzylamine cleaved off type III iminoacetyl
platinum(II) complexes were obtained in a Schiff-base type reac-
tion, cf. Scheme 1 [1]. Here, in no case, not even in type 6f/7aef
complexes with the strongest NeH/O hydrogen bonds, a forma-
tion of iminoacetyl platinum(II) complexes was observed. There-
fore, complexes 4aec, 6d/f, and 7c were reacted with a 10- and 100-
fold excess of benzylamine (pKa ¼ 9.3; here and in the following the
pKa values of the corresponding RNH3þ cations are given [11]) and
complex 7e with 5-fold excess of the more basic 2-
phenylethylamine (pKa ¼ 9.8) and ethylamine (pKa ¼ 10.6), but
NMR spectra of reaction solutions or isolated solids indicated in no
case the formation of iminoacetyl complexes. Even in the presence
of a water scavenger (molecular sieve 4A) an iminoacetyl complex
formation did not take place.
Fig. 4. Molecular structure of [Pt(COMe)2(NH2N¼CMeeCMe]NNH2)] (5, displace-
ment ellipsoids of non-hydrogen atoms at 30% probability). The broken lines indicate
intramolecular NeH/O hydrogen bonds. Selected distances (in A) and angles (in ꢀ):
ꢀ
PteC1 1.999(4), PteC2 1.993(4), PteN1 2.131(3), PteN2 2.128(3), C1eO1 1.226(5), C2e
O2 1.221(5), N1eN3 1.365(4), N2eN4 1.377(4), C1ePteN2 97.6(1), C1ePteC2 91.5(2),
C2ePteN1 96.1(1), N1ePteN2 74.8(1),
g(c.p./MeC1]O1) 30.5(2), g(c.p./MeC2]O2)
50.7(3) (c.p. ¼ coordination plane), N3/O2 2.982(5), N4/O1 2.800(5), N3eH/O2 148,
N4eH/O1 146.
13C, and 195Pt NMR spectroscopic parameters of complexes 4e7 are
compiled in Table 2. Due to the different ligands in trans position
(except for complex 5), two sets of signals with typical platinum
coupling constants were found for the two acetyl ligands. HSQC
measurements allowed to assign the methyl protons of the acetyl
ligands to the corresponding C atoms. With complex 7e as example,
the respective carbonyl C atom was identified via HMBC measure-
ments. Furthermore, a NOESY experiment (coupling between
COCH3 at 2.59 ppm and H6(py) at 8.52 ppm) exhibited which acetyl
ligand is trans to the hydrazone N atom and which one trans to the
pyridine N atom. On this basis the acetyl ligands of the other
complexes were assigned (Table 2). This assignment is consistent
with that of the pyridyl-functionalized oxime complexes (type I,
Scheme 1) [1]. The platinum chemical shifts were found in the
expected range (ꢁ3364 to ꢁ3444 ppm) and did not show a char-
acteristic dependence on the substitution pattern of the hydrazone
ligand [1,3,5].
Conclusions
The investigations presented in this work exhibited that in
diacetyl platinum(II) complexes bearing 2-pyridyl-functionalized
hydrazone (4, 6, 7) and dihydrazone (5) ligands intramolecular Ne
H/O hydrogen bonds are present both in the solid state and in
In an NeH/O hydrogen bond the NH shift can be regarded as a
measure for the hydrogen-bond strength [8]. On this basis, the
following dependence of the NeH/O hydrogen-bond strength on
the substitution pattern of the hydrazone group ]NNHR0 was
solution. The chemical shifts of the hydrogen bonded protons d(NH)
and the N/O distances can be regarded as a measure of the
hydrogen-bond strength [8]. As expected, it increases with
increasing electron-withdrawing character of the substituents R0 at
the terminal N atoms (Fig. 6). But in all cases, these hydrogen bonds
were proven to be weaker than the OeH/O hydrogen bonds in the
respective oxime complexes. As experimentally shown here, the
expected activation of the acetyl ligands by the hydrogen bonds e
in contrast to that in oxime complexes [1] e is not strong enough to
form iminoacetyl complexes with amines in Schiff-base type re-
actions. In line with all experimental results, DFT calculations show
an NeH/O connectivity of intramolecular hydrogen bonds (see
global minima in Fig. 7). Relaxed potential energy surface scans
with N/H distances as scan coordinate result with fixed N/O
distances (to avoid break of the hydrogen bonds, cf. Supplemental
Material) in typical double-well potentials of hydrogen bonds
(Fig. 7). The transfer from the energetically favored into the unfa-
vored well (NeH/O / N/HeO) costs for 4b*/7b* (starred
numbers indicate calculated complexes) 15.9/15.9 kcal/mol. The
energy demand for the proton transfer within an OeH/O
hydrogen bond of an analogous oxime complex (cf. I* in Fig. 7) is
much smaller (6.9 kcal/mol). Because this proton transfer is the
crucial step for the activation of the acetyl ligands, in full accord
with the experimental results, oximeediacetyl platinum(II) com-
plexes are prone to Schiff-base type reactions but not the respective
hydrazone complexes.
Fig. 5. Wire model of [Pt(COMe)2(H2NN]CMeeCMe]NNH2)] in crystals of 5 showing
the inter- and intramolecular hydrogen bonds (broken lines). Hydrogen atoms are
omitted for clarity, except those which are involved in hydrogen bonds. Selected dis-
tances (in A) and angles (in ꢀ): N3/O2 2.982(5), N3eH/O2 148, N4/O1 2.800(5),
ꢀ
N4eH/O1 146, N3/N40 3.126(5), N3eH/N40 144, N4/Pt0 3.413(4), N4eH/Pt0 135.

T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
53
Table 2
Selected NMR spectroscopic parameters (
NNH2)] (5).
d
in ppm, J in Hz, in CDCl3) of complexes [Pt(COMe)2(2-pyCR]NNHR0)] (4aec, 6aef, 7aef)a and [Pt(COMe)2(H2NN¼CMeeCMe]
R/R0
dH (3JPt,H) NH
dH (3JPt,H) COCH3
dC (2JPt,C) COCH3
dC (1JPt,C) COCH3
dPt Pt
4a
4b
4c
5
6a
6b
6c
6d
6e
6f
7a
7b
7c
7d
7e
7f
H/H
Me/H
Ph/H
e
8.08
7.53
7.67
2.25 (28.6)/2.47 (22.1)
2.21 (28.9)/2.42 (23.4)
2.26 (29.4)/2.47 (24.4)
2.30 (26.4)
43.0 (381)/45.0 (349)
43.2 (374)/45.1 (348)
43.1 (375)/45.0 (355)
44.2 (361)
230.8/227.0
ꢁ3384
ꢁ3397
ꢁ3389
ꢁ3444
ꢁ3395
ꢁ3404
ꢁ3364
ꢁ3397
ꢁ3408
ꢁ3415
ꢁ3411
ꢁ3392
ꢁ3413
ꢁ3396
ꢁ3412
ꢁ3395
231.6 (1292)/228.7 (1292)
230.2 (1298)/228.9 (1295)
232.1
229.0/228.7
232.5/228.3
229.7/228.7
229.1/228.7
232.3/228.3
227.9/227.7
228.5/227.9
230.4/228.7
229.1/227.7
230.4/229.0
229.4/227.8
230.4/229.2
6.61 (22)
11.63 (18)
10.65 (16)
9.97 (19)
11.37 (18)
10.60 (17)
12.43 (18)
13.50 (18)
12.40 (15)
14.25 (18)
13.34 (17)
14.35 (20)
13.40 (16)
H/Ph
Me/Ph
Ph/Ph
2.27 (31.2)/2.52 (23.8)
2.15 (29.7)/2.45 (23.3)
2.00 (27.9)/2.39 (23.5)
2.08 (33.5)/2.34 (23.7)
2.14 (29.6)/2.44 (23.3)
2.27 (32.8)/2.55 (23.3)
2.26 (32.5)/2.52 (23.4)
2.23 (30.5)/2.45 (23.1)
2.28 (32.4)/2.54 (23.5)
2.21 (30.9)/2.48 (22.9)
2.33 (32.8)/2.59 (23.4)
2.20 (31.5)/2.48 (28.5)
42.7 (375)/44.9 (347)
42.9 (371)/45.0 (342)
42.8 (367)/44.4 (361)
42.7 (370)/44.9 (347)
42.8 (375)/45.0 (347)
42.3 (371)/44.7 (345)
42.5 (374)/44.7 (340)
42.7 (370)/44.0 (339)
42.4 (370)/44.7 (346)
42.6 (370)/44.9 (340)
42.4 (374)/44.7 (347)
42.7 (372)/44.9 (335)
H/C6H4-p-F
Me/C6H4-p-F
H/C6F5
H/COMe
Me/COMe
H/COPh
Me/COPh
H/CO(C6H4-p-F)
Me/CO(C6H4-p-F)
a
The NMR parameters of the acetyl ligands trans to the Npy and the Nhydrazone atoms are given separated by a slash.
Experimental section
120 m
L hꢁ1. The platinum(II) precursor complexes [{Pt(COMe)2}n]
(2) [3] and [Pt(COMe)2(NH2Bn)2] (3) [4] as well as the hydrazones/
dihydrazones [12e15] (NMR data cf. Supplemental material) were
prepared according to literature methods.
General comments
All reactions were performed in an argon atmosphere using the
standard Schlenk techniques. Solvents were dried (diethyl ether
and n-pentane over Na/benzophenone; CHCl3/CH2Cl2 over CaH2)
and distilled prior to use. NMR spectra were recorded at 27 ꢀC with
Varian Gemini 200, VXR 400, and Unity 500 spectrometers.
Chemical shifts are relative to the solvent signals of CDCl3 (dH 7.24,
Syntheses of complexes 4 and 5 with hydrazone ligands of the type
2-pyCR]NNH2 and H2NN]CMeeCMe]NNH2
At room temperature, [Pt(COMe)2(NH2Bn)2] (3) (80 mg,
0.16 mmol) and 2-pyCR]NNH2 (R ¼ H, Me, Ph; 0.16 mmol) or
H2NN]CMeeCMe]NNH2 (0.16 mmol) were dissolved in methy-
lene chloride (5 mL) and the reaction mixture was stirred for one
hour. The volume of the resulting orange colored (4) or dark yellow
(5) solution was reduced to ca. 1 mL in vacuo. After the addition of
diethyl ether (1 mL) and n-pentane (2 mL) a precipitate was ob-
tained, which was filtered off, washed with diethyl ether (3 ꢂ 5 mL),
and dried in vacuo.
dC 77.0) as internal references;
d(
195Pt) is referenced to Na2[PtCl6];
d(
19F) is relative to external CCl3F. If necessary, 2D NMR techniques
(COSY, HSQC, HMBC and NOESY) were used to assign the signals in
1H and 13C NMR spectra. IR spectra were recorded by a Bruker
Tensor 28 spectrometer with a Platinum ATR unit. Microanalyses
were performed by the University of Halle microanalytical labora-
tory using Vario EL (Elementar Analysensysteme) elemental
analyzer. The high-resolution ESI mass spectra were obtained from
a Bruker Apex III Fourier transform ion cyclotron resonance (FT-
ICR) mass spectrometer (Bruker Daltonics) equipped with an in-
finity cell, a 7.0 T superconducting magnet (Bruker), an rf-only
hexapole ion guide, and an external APOLLO electrospray ion
source (Agilent, off-axis spray). The sample solutions were intro-
duced continuously via a syringe pump with a flow rate of
[Pt(COMe)2(2-pyCH]NNH2)] (4a). Yield: 35 mg (54%). HRMS
(ESI): m/z calcd for [C10H13N3O2PtNa]þ 425.05477, found for
[M þ Na]þ 425.05506. 1H NMR (CDCl3, 500 MHz):
d
2.25 (s þ d,
3JPt,H ¼ 28.6 Hz, 3H, COCH3), 2.47 (s þ d, 3JPt,H ¼ 22.1 Hz, 3H, COCH3),
7.26 (m, 1H, H5 py), 7.39 (m, 1H, H3 py), 7.83 (m, 1H, H4 py), 8.08 (s,
2H, NH2), 8.20 (s, 1H, CH]NNH2), 8.28 (m, 1H, H6 py). 13C NMR
(CDCl3, 125 MHz):
d
43.0 (s þ d, 2JPt,C ¼ 381 Hz, COCH3), 45.0 (s þ d,
Fig. 6. Chemical shifts of the hydrogen-bonded protons (top) and N/O distances (bottom) as parameters for the strength of the intramolecular NeH/O hydrogen bonds in
hydrazoneediacetyl platinum(II) complexes. For comparison, the corresponding values of OeH/O hydrogen bonds in oximeediacetyl platinum(II) complexes of types I and II (cf.
Scheme 1) are given [1]. a) 3 entries.

54
T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
2-pyCH]NNH(C6F5) (49 mg, 0.17 mmol) was added dropwise. After
stirring for 30 min at this temperature, the orange colored reaction
mixture was warmed up to room temperature and stirred for
further 8 h. The solvent of the red solution was reduced to ca. 1 mL
and diethyl ether (3 mL) was added. The red (6aec) and orange
colored (6f) precipitate obtained was filtered off, washed with
diethyl ether (3 ꢂ 3 mL), and dried in vacuo.
[Pt(COMe)2(2-pyCH]NNHPh)] (6a). Yield: 53 mg (78%). Anal.
found (calc.): C16H17N3O2Pt (478.41 g/mol), C 39.91 (40.17), H 3.36
(3.58), N 8.84 (8.78). 1H NMR (CDCl3, 200 MHz):
d
2.27 (s þ d,
3JPt,H ¼ 31.2 Hz, 3H, COCH3), 2.52 (s þ d, 3JPt,H ¼ 23.8 Hz, 3H, COCH3),
7.20e7.32 (m, 5H, H5 py þ H3 py þ p-H Ph þ o-H Ph), 7.43 (m, 2H, m-
3
Fig. 7. Relaxed potential energy surface scans with N/H distances as scan coordinate
with fixed N/O distances of hydrazoneediacetyl platinum(II) complexes 4b* (-) and
7b* (C). Additionally, the structures representing the global minima were character-
ized as equilibrium structures which is not the case for the local minima (see
Supplemental material). The oximeediacetyl platinum(II) complex I* (>, see for-
mula sketch and Ref. [1]) is given for comparison (O/H distance as scan coordinate
with fixed O/O distance).
H Ph), 7.80 (m, 1H, H4 py), 8.06 (s þ d, JPt,H ¼ 24.4 Hz, 1H,
3
CH¼NNHPh), 8.36 (m, 1H, H6 py), 11.63 (s þ d, JPt,H ¼ 18 Hz, 1H,
2
NH). 13C NMR (CDCl3, 100 MHz):
d
42.7 (s þ d, JPt,C ¼ 375 Hz,
COCH3), 44.9 (s þ d, 2JPt,C ¼ 347 Hz, COCH3), 122.6e127.3 (4 ꢂ s, C3
py þ C5 py þ p-C Ph þ o-C Ph), 129.9 (s, m-C Ph), 131.1 (s,
CH¼NNHPh), 137.9 (s, i-C Ph), 139.2 (s, C4 py), 150.5 (s þ d,
2JPt,C ¼ 43 Hz, C6 py), 156.6 (s, C2 py), 228.7 (s, COCH3), 229.0 (s,
COCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3395 (s). IR 2854(w),
2JPt,C ¼ 349 Hz, COCH3),122.9 (s, C3 py),124.3 (s, C5 py),138.7 (s, CH]
NNH2), 139.2 (s, C4 py), 150.3 (s þ d, 2JPt,C ¼ 47 Hz, C6 py), 155.4 (s, C2
py), 227.0 (s, COCH3), 230.8 (s, COCH3). 195Pt NMR (CDCl3, 107 MHz):
1614(s), 1526(s) cmꢁ1
.
[Pt(COMe)2(2-pyCMe]NNHPh)] (6b). Yield: 58 mg (83%). Anal.
found (calc.): C17H19N3O2Pt (492.44 g/mol): C 40.58 (41.46), H 3.79
d
ꢁ3384 (s). IR 3257(w), 3130(w), 1610(m), 1545(m) cmꢁ1
.
(3.89), N 8.57 (8.53). 1H NMR (CDCl3, 200 MHz):
d
2.15 (s þ d,
3JPt,H ¼ 29.7 Hz, 3H, COCH3), 2.17 (s, 3H, C(CH3)]NNHPh), 2.45
[Pt(COMe)2(2-pyCMe]NNH2)] (4b). Yield: 57 mg (84%). HRMS
(ESI): m/z calcd for [C11H15N3O2PtNa]þ 439.07042, found for
3
(s þ d, JPt,H ¼ 23.3 Hz, 3H, COCH3), 6.74 (m, 2H, o-H Ph), 6.96 (m,
[M þ Na]þ 439.07039. 1H NMR (CDCl3, 200 MHz):
d
2.21 (s þ d,
1H, p-H Ph), 7.23 (m, 2H, m-H Ph), 7.52 (m, 1H, H5 py), 7.70 (m, 1H,
H3 py), 8.02 (m, 1H, H4 py), 8.61 (m, 1H, H6 py), 10.65 (s þ d,
3JPt,H ¼ 28.9 Hz, 6H, COCH3 þ C(CH3)]NNH2), 2.42 (s þ d,
3JPt,H ¼ 23.4 Hz, 3H, COCH3), 7.31 (m, 1H, H5 py), 7.53 (m, 3H, H3
3JPt,H ¼ 16 Hz, 1H, NH). 13C NMR (CDCl3, 100 MHz):
d 17.4 (s,
py þ NH2), 7.90 (m, 1H, H4 py), 8.37 (m, 1H, H6 py). 13C NMR (CDCl3,
2
C(CH3)]NNHPh), 42.9 (s þ d, JPt,C ¼ 371 Hz, COCH3), 45.0 (s þ d,
2JPt,C ¼ 342 Hz, COCH3),117.4 (s, o-C Ph),122.9 (s, p-C Ph),123.9 (s, C3
py), 126.7 (s, C5 py), 129.2 (s, m-C Ph), 139.4 (s, C4 py), 144.1 (s, i-C
2
50 MHz):
d
12.6 (s, C(CH3)]NNH2), 43.2 (s þ d, JPt,C ¼ 373.7 Hz,
COCH3), 45.1 (s þ d, 2JPt,C ¼ 347.8 Hz, COCH3), 121.9 (s, C3 py), 124.7
(s þ d, JPt,C ¼ 20 Hz, C5 py), 139.0 (s, C4 py), 146.5 (s, C(CH3)]
3
2
Ph), 151.1 (s þ d, JPt,C ¼ 42 Hz, C6 py), 155.6 (s, C2 py), 163.0 (s,
NNH2), 150.4 (s þ d, JPt,C ¼ 44 Hz, C6 py), 156.1 (s, C2 py), 228.7
2
C(CH3)]NNHPh), 228.3 (s, COCH3), 232.5 (s, COCH3). 195Pt NMR
1
1
(s þ d, JPt,C ¼ 1292 Hz, COCH3), 231.6 (s þ d, JPt,C ¼ 1292 Hz,
(CDCl3, 86 MHz):
d
ꢁ3404 (s). IR 2968(w), 2891(w), 1610(m),
COCH3). 195Pt NMR (CDCl3, 107 MHz):
3151(m), 1583(m), 1564 (m) cmꢁ1
d
ꢁ3397 (s). IR 3294(m),
1594(m), 1568(s), 1559(s), cmꢁ1
.
.
[Pt(COMe)2(2-pyCPh]NNHPh)] (6c). Yield: 56 mg (71%). HRMS
(ESI): m/z calcd for [C22H21N3O2PtNa]þ 577.11737, found for
[Pt(COMe)2(2-pyCPh]NNH2)] (4c). Yield: 62 mg (80%). HRMS
(ESI): m/z calcd for [C16H17N3O2PtNa]þ 501.08607, found for
[M þ Na]þ 577.11731. 1H NMR (CDCl3, 400 MHz):
d
2.00 (s þ d,
[M þ Na]þ 501.08649. 1H NMR (CDCl3, 200 MHz):
d
2.26 (s þ d,
3JPt,H ¼ 27.9 Hz, 3H, COCH3), 2.39 (s þ d, 3JPt,H ¼ 23.5 Hz, 3H, COCH3),
6.77 (m, 2H, o-H NePh), 6.84 (m, 1H, p-H NePh), 6.99 (m, 2H, m-H
NePh), 7.06 (m,1H, H3 py), 7.10 (m, 2H, o-H/m-H CePh), 7.26 (m, 3H,
p-H þ o-H/m-H CePh), 7.38 (m, 1H, H5 py), 7.74 (m, 1H, H4 py), 8.62
3JPt,H ¼ 29.4 Hz, 3H, COCH3), 2.47 (s þ d, 3JPt,H ¼ 24.4 Hz, 3H, COCH3),
6.93 (m, 1H, H3 py), 7.23e7.37 (m, 3H, H5 py þ H Ph), 7.54e7.64 (m,
3H, H Ph), 7.67 (s, 2H, NH2), 7.74 (m, 1H, H4 py), 8.52 (m, 1H, H6 py).
2
13C NMR (CDCl3, 50 MHz):
d
43.1 (s þ d, JPt,C ¼ 375.4 Hz, COCH3),
(m, 1H, H6 py), 9.97 (s þ d, 3JPt,H ¼ 19 Hz, 1H, NH). 13C NMR (CDCl3,
45.0 (s þ d, 2JPt,C ¼ 355.3 Hz, COCH3), 123.2 (s, C3 py), 124.4 (s þ d,
3JPt,C ¼ 19 Hz, C5 py), 128.4 (s, o-C/m-C Ph), 129.1 (s, i-C), 130.3 (s, o-
C/m-C Ph), 130.8 (s, p-C Ph), 138.8 (s, C4 py), 146.8 (s, CPh]NNH2),
2
100 MHz):
d
42.8 (s þ d, JPt,C ¼ 367 Hz, COCH3), 44.4 (s þ d,
2JPt,C ¼ 361 Hz, COCH3), 122.1 (s, o-C NePh), 124.7 (s, p-C NePh),
125.0 (s, C3 py), 125.5 (s, C5 py), 128.5 þ 128.5 (2 ꢂ s, m-C NePh þ o-
C/m-C CePh), 129.1 (s, o-C/m-C CePh), 130.0 (s, p-C CePh), 131.5 (s,
i-C CePh), 138.6 (s, C4 py), 143.2 (s, i-C NePh), 150.8 (s þ d,
2JPt,C ¼ 40 Hz, C6 py), 155.4 (s, C2 py), 156.4 (s, CPh]NNHPh), 228.7
150.6 (s þ d, JPt,C ¼ 45 Hz, C6 py), 156.6 (s, C2 py), 228.9 (s þ d,
2
1JPt,C ¼ 1295 Hz, COCH3), 230.2 (s þ d, 1JPt,C ¼ 1298 Hz, COCH3). 195Pt
NMR (CDCl3, 86 MHz):
d
ꢁ3389 (s). IR 3371(m), 3115(m), 1612(m),
1562(m) cmꢁ1
.
1
1
(s þ d, JPt,C ¼ 1294 Hz, COCH3), 229.7 (s þ d, JPt,C ¼ 1294 Hz,
COCH3). 195Pt NMR (CDCl3, 86 MHz):
3049(w), 1634(w), 1591(s), 1528(m) cmꢁ1
d
ꢁ3364 (s). IR 3155(w),
[Pt(COMe)2(H2NN]CMeeCMe]NNH2)] (5). Yield: 61 mg (95%).
HRMS (ESI): m/z calcd for [C8H16N4O2PtNa]þ 418.08132, found for
.
[M þ Na]þ 418.08177. 1H NMR (CDCl3, 200 MHz):
d 2.01 (s, 6H,
[Pt(COMe)2{2-pyCH]NNH(C6F5)}] (6f). Yield: 65 mg (79%).
H2NN]CCH3), 2.30 (s þ d, 3JPt,H ¼ 26.4 Hz, 6H, COCH3), 6.61 (s þ d,
HRMS (ESI): m/z calcd for [C16H12F5N3O2PtNa]þ 591.03896, found
3JPt,H ¼ 21.5 Hz, 4H, NH2). 13C NMR (CDCl3, 125 MHz):
d 13.8 (s,
for [M þ Na]þ 591.03847. 1H NMR (CDCl3, 200 MHz):
d
2.27 (s þ d,
H2NN]CCH3), 44.2 (s þ d, 2JPt,C ¼ 361.1 Hz, COCH3),150.3 (s, H2NN]
3JPt,H ¼ 32.8 Hz, 3H, COCH3), 2.55 (s þ d, 3JPt,H ¼ 23.3 Hz, 3H, COCH3),
7.33e7.44 (m, 2H, H5 þ H3 py), 7.60 (s þ d, 3JPt,H ¼ 22 Hz, 1H, CH]
NNH), 7.91 (m, 1H, H4 py), 8.40 (m, 1H, H6 py), 12.43 (s þ d,
CCH3), 232.1 (s, COCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3444 (s). IR
3346(m), 3234(m), 3198(w), 3107(m), 1549 (m) cmꢁ1
.
3JPt,H ¼ 18 Hz, 1H, NH). 13C NMR (CDCl3, 100 MHz):
d
42.3 (s þ d,
2
Syntheses of complexes 6aec and 6f with phenylhydrazone ligands
2JPt,C ¼ 371 Hz, COCH3), 44.7 (s þ d, JPt,C ¼ 345 Hz, COCH3),
123.9 þ 125.1 (2 ꢂ s, C3 py þ C5 py), 135.2 (s, CH]NNH), 136.9 (m,
C6F5), 139.6 (s, C4 py), 141.4 þ 142.3 þ 144.0 (3 ꢂ m, C6F5), 150.9
(s þ d, 2JPt,C ¼ 42 Hz, C6 py), 155.0 (s, C2 py), 227.7 (s, COCH3), 227.9
At ꢁ78 ꢀC, to a suspension of [{Pt(COMe)2}n] (2) (40 mg,
0.14 mmol) in methylene chloride (15 mL) an equimolar amount of
2-pyCR]NNHPh (R ¼ H, Me, Ph; 0.14 mmol) or an excess of 20% of
(s, COCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3415 (s). 19F NMR (CDCl3,

T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
55
376 MHz):
d
ꢁ159.90 (m, 2F, m-F), e153.14 (m, 1F, p-F), e142.13 (m,
[Pt(COMe)2{2-pyCMe]NNH(COMe)}] (7b). Yield: 49 mg (76%).
HRMS (ESI): m/z calcd for [C13H17N3O3PtNa]þ 481.08099, found for
2F, o-F). IR 2819(w), 1633(m), 1604(m), 1569(w) cmꢁ1
.
[M þ Na]þ 481.08091. 1H NMR (CDCl3, 200 MHz):
d 2.22 (s, 3H, Ne
3
COCH3); 2.23 (s þ d, JPt,H ¼ 30.5 Hz, 3H, PteCOCH3), 2.27 (s, 3H,
Syntheses of complexes 6d/c with p-fluorophenylhydrazone ligands
3
C(CH3)]NNH), 2.45 (s þ d, JPt,H ¼ 23.1 Hz, 3H, PteCOCH3), 7.54
(m, 1H, H5 py), 7.81 (m, 1H, H3 py), 8.04 (m, 1H, H4 py), 8.53 (m, 1H,
At room temperature, to a solution of [Pt(COMe)2(NH2Bn)2] (3)
(80 mg, 0.16 mmol) in methylene chloride (15 mL) 2-pyCR]
NNH(C6H4-p-F) (R ¼ H, Me) with an excess of 20% (0.19 mmol) was
added. The reaction mixture was stirred for 24 h resulting in an
orange colored suspension. After filtration, the volume of the so-
lution was reduced to 1 mL and diethyl ether (3 mL) was added. The
orange precipitate obtained was filtered off, washed with diethyl
ether (3 ꢂ 3 mL), and dried in vacuo.
H6 py), 12.40 (s þ d, JPt,H ¼ 15 Hz, 1H, NH). 13C NMR (CDCl3,
3
100 MHz):
d
18.4 (s, C(CH3)]NNH), 22.3 (s, NeCOCH3), 42.7 (s þ d,
2JPt,C ¼ 370 Hz, PteCOCH3), 44.0 (s þ d, 2JPt,C ¼ 339 Hz, PteCOCH3),
125.2 (s, C3 py), 127.5 (s, C5 py), 139.6 (s, C4 py), 151.0 (s, C6 py),
155.2 (s, C2 py), 166.7 (s, C(CH3)]NNH), 167.1 (s, NeCOCH3), 228.7
(s, PteCOCH3), 230.4 (s, PteCOCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3392 (s). IR 3132(w) 3047(w), 1716(m) 1618(m), 1596(w),
1560(m) cmꢁ1
.
[Pt(COMe)2{2-pyCH]NNH(C6H4-p-F)}] (6d). Yield: 55 mg (69%).
HRMS (ESI): m/z calcd for [C16H16FN3O2PtNa]þ 519.07665, found for
[Pt(COMe)2{2-pyCH]NNH(COPh)}] (7c). Yield: 56 mg (78%).
Anal. found (Calc.): C17H17N3O3Pt (506.42 g/mol), C 39.57 (40.32), H
[M þ Na]þ 519.07685. 1H NMR (CDCl3, 500 MHz):
d
2.08 (s þ d,
3.11 (3.38), N 8.07 (8.30). 1H NMR (CDCl3, 400 MHz):
d
2.28 (s þ d,
3JPt,H ¼ 33.5 Hz, 3H, COCH3), 2.34 (s þ d, 3JPt,H ¼ 23.7 Hz, 3H, COCH3),
6.98 (m, 2H, m-H C6H4F), 7.04e7.09 (m, 4H, H5 py þ H3 py þ o-H
C6H4F), 7.62 (m,1H, H4 py), 7.69 (s þ d, 3JPt,H ¼ 24 Hz,1H, CH]NNH),
3JPt,H ¼ 32.4 Hz, 3H, COCH3), 2.54 (s þ d, 3JPt,H ¼ 23.5 Hz, 3H, COCH3),
7.47 (m, 1H, H5 py), 7.55 (m, 3H, m-H þ p-H Ph), 7.69 (m, 1H, H3 py),
8.00 (m, 1H, H4 py), 8.16 (m, 2H, o-H Ph), 8.48 (m, 1H, H6 py), 10.60
8.19 (m, 1H, H6 py), 11.37 (s þ d, JPt,H ¼ 18 Hz, 1H, NH). 13C NMR
3
3
(s þ d, JPt,H ¼ 26.2 Hz, 1H, CH]NNH), 14.25 (s þ d, 3JPt,H ¼ 18 Hz,
(CDCl3, 125 MHz):
d
42.7 (s þ d, 2JPt,C ¼ 370 Hz, COCH3), 44.9 (s þ d,
2
1H, NH). 13C NMR (CDCl3, 100 MHz):
d
42.4 (s þ d, JPt,C ¼ 370 Hz,
2JPt,C ¼ 347 Hz, COCH3), 117.1 (d, JF,C ¼ 22.7 Hz, m-C C6H4F),
2
COCH3), 44.7 (s þ d, 2JPt,C ¼ 346 Hz, COCH3), 126.3 (s, C3 py), 126.7 (s,
C5 py),127.7 (s, o-C Ph),129.1 (s, m-C Ph),132.1 (s, i-C Ph),132.9 (s, p-
C Ph),139.9 (s, C4 py),150.8 (s, CH]NNH),151.1 (s, C6 py),155.7 (s, C2
py), 165.9 (s, COPh), 227.7 (s, COCH3), 229.1 (s, COCH3). 195Pt NMR
122.7 þ 123.9 (2 ꢂ s, C3 py þ C5 py), 127.6 (d, JF,C ¼ 8.6 Hz, o-C
3
C6H4F), 131.5 (s, CH]NNH), 133.8 (d, 4JF,C ¼ 3.2 Hz, i-C C6H4F), 139.3
(s, C4 py), 150.6 (s þ d, 2JPt,C ¼ 38 Hz, C6 py), 156.4 (s, C2 py), 161.6 (d,
1JF,C ¼ 248.6 Hz, CeF), 228.7 (s, COCH3), 229.1 (s, COCH3). 195Pt NMR
(CDCl3, 86 MHz):
d
ꢁ3413 (s). IR 3057(w), 2966(w) 1674(w),
(CDCl3, 86 MHz):
d
ꢁ3397 (s). 19F NMR (CDCl3, 376 MHz):
d
ꢁ112.71
1615(m), 1579(w) cmꢁ1
.
(m). IR 3058(w), 2947(w), 1616(m), 1602(m), 1527(s) cmꢁ1
.
[Pt(COMe)2{2-pyCMe]NNH(COPh)}] (7d). Yield: 61 mg (83%).
[Pt(COMe)2{2-pyCMe]NNH(C6H4-p-F)}] (6e). Yield: 54 mg
HRMS (ESI): m/z calcd for [C18H19N3O3PtNa]þ 543.09664, found for
(65%). HRMS (ESI): m/z calcd for [C17H18FN3O2PtNa]þ 533.09230,
[M þ Na]þ 543.09631. 1H NMR (CDCl3, 400 MHz):
d
2.21 (s þ d,
found for [M þ Na]þ 533.09254. 1H NMR (CDCl3, 200 MHz):
d 2.13
3JPt,H ¼ 30.9 Hz, 3H, COCH3), 2.35 (s, 3H, C(CH3)]NNH), 2.48 (s þ d,
3JPt,H ¼ 22.9 Hz, 3H, COCH3), 7.50e7.60 (m, 4H, H5 py þ m-H Ph þ p-
H Ph), 7.85 (m, 1H, H3 py), 8.06 (m, 1H, H4 py), 8.13 (m, 2H, o-H Ph),
(s, 3H, C(CH3)]NNH), 2.14 (s þ d, 3JPt,H ¼ 29.6 Hz, 3H, COCH3), 2.44
(s þ d, 3JPt,H ¼ 23.3 Hz, 3H, COCH3), 6.74 (m, 2H, o-H C6H4F), 6.93 (m,
2H, m-H C6H4F), 7.52 (m, 1H, H5 py), 7.68 (m, 1H, H3 py), 8.00 (m, 1H,
3
8.58 (m, 1H, H6 py), 13.34 (s þ d, JPt,H ¼ 17 Hz, 1H, NH). 13C NMR
H4 py), 8.60 (m, 1H, H6 py), 10.60 (s þ d, 3JPt,H ¼ 17 Hz, 1H, NH). 13
C
(CDCl3, 100 MHz):
d
18.7 (s, pyC(CH3)]NNH(COPh)), 42.6 (s þ d,
NMR (CDCl3, 100 MHz):
d
17.2 (s, C(CH3)]NNH), 42.8 (s þ d,
2JPt,C ¼ 370 Hz, COCH3), 44.9 (s þ d, 2JPt,C ¼ 340 Hz, COCH3), 125.2 (s,
C3 py),127.5 (s, C5 py),128.2 (s, o-C Ph),129.0 (s, m-C Ph),131.6 (s, i-C
Ph), 132.8 (s, p-C Ph), 139.7 (s, C4 py), 151.1 (s þ d, 2JPt,C ¼ 40 Hz, C6
py), 155.4 (s, C2 py), 163.2 (s, pyC(CH3)]NNH(COPh)), 166.9 (s,
COPh), 229.0 (s, COCH3), 230.4 (s, COCH3). 195Pt NMR (CDCl3,
2JPt,C ¼ 375 Hz, COCH3), 45.0 (s þ d, 2JPt,C ¼ 347 Hz, COCH3), 115.9 (d,
2JF,C ¼ 22.8 Hz, m-C C6H4F), 119.5 (d, 3JF,C ¼ 8.0 Hz, o-C C6H4F), 123.9
(s, C3 py), 126.8 (s, C5 py), 139.4 (s, C4 py), 140.6 (d, 4JF,C ¼ 2.7 Hz, i-C
C6H4F), 151.1 (s þ d, 2JPt,C ¼ 40 Hz, C6 py), 155.5 (s, C2 py), 158.8 (d,
1JF,C ¼ 242.4 Hz, CeF), 162.8 (s, C(CH3)]NNH), 228.3 (s, COCH3),
86 MHz):
d
ꢁ3396 (s). IR 3134(w), 3051(w), 1688(m), 1622(m),
232.3 (s, COCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3408 (s). 19F NMR
1599(w), 1551(m) cmꢁ1
.
(CDCl3, 376 MHz):
d
ꢁ119.76 (m). IR 3076(w), 2949(w), 1617(s),
[Pt(COMe)2{2-pyCH]NNH{CO(C6H4-p-F)}}] (7e). Yield: 63 mg
1597(m), 1559(s) cmꢁ1
.
(84%). HRMS (ESI): m/z calcd for [C17H17FN3O3Pt]þ 525.08962,
found for [M þ H]þ 525.09025. 1H NMR (CDCl3, 500 MHz):
d 2.33
Syntheses of complexes 7 bearing acyl substituted hydrazone
ligands
(s þ d, 3JPt,H ¼ 32.8 Hz, 3H, COCH3), 2.59 (s þ d, 3JPt,H ¼ 23.4 Hz, 3H,
COCH3), 7.27 (m, 2H, m-H C6H4F), 7.52 (m,1H, H5 py), 7.75 (m,1H, H3
py), 8.05 (m,1H, H4 py), 8.25 (m, 2H, o-H C6H4F), 8.52 (m,1H, H6 py),
3
The procedure is analogous to that described for the syntheses
of complexes 6aec (see above), but with a shortened reaction time
of 6 h.
10.60 (s þ d, JPt,H ¼ 25.2 Hz, 1H, CH]NNH), 14.35 (s þ d,
3JPt,H ¼ 20 Hz, 1H, NH). 13C NMR (CDCl3, 125 MHz):
d
42.4 (s þ d,
2JPt,C ¼ 374 Hz, COCH3), 44.7 (s þ d, 2JPt,C ¼ 347 Hz, COCH3), 116.3 (d,
2JF,C ¼ 22.1 Hz, m-C C6H4F), 126.4 (s, C3 py), 126.8 (s, C5 py), 128.3 (d,
4JF,C ¼ 3.0 Hz, i-C C6H4F), 130.3 (d, 3JF,C ¼ 9.3 Hz, o-C C6H4F), 139.9 (s,
C4 py), 150.9 (s, CH]NNH), 151.2 (s, C6 py), 155.6 (s, C2 py), 164.7 (s,
[Pt(COMe)2{2-pyCH]NNH(COMe)}] (7a). Yield: 52 mg (83%).
HRMS (ESI): m/z calcd for [C12H16N3O3Pt]þ 445.08339, found for
[M þ H]þ 445.08339. 1H NMR (CDCl3, 200 MHz):
d
2.26 (s þ d,
3JPt,H ¼ 32.5 Hz, 3H, PteCOCH3), 2.28 (s, 3H, NeCOCH3), 2.52 (s þ d,
3JPt,H ¼ 23.4 Hz, 3H, PteCOCH3), 7.48 (m, 1H, H5 py), 7.64 (m, 1H, H3
py), 7.99 (m, 1H, H4 py), 8.48 (m, 1H, H6 py), 10.33 (s þ d,
3JPt,H ¼ 26.0 Hz, 1H, CH]NNH), 13.50 (s þ d, 3JPt,H ¼ 18 Hz, 1H, NH).
CO(C6H4F)), 165.6 (d, JF,C ¼ 254.6 Hz, CeF), 227.8 (s þ d,
1
1JPt,C ¼ 1310 Hz, COCH3), 229.4 (s þ d, 1JPt,C ¼ 1340 Hz, COCH3). 195Pt
NMR (CDCl3, 86 MHz):
d
ꢁ3412 (s). 19F NMR (CDCl3, 376 MHz):
d
ꢁ105.39 (m). IR 3407(w), 1658(w), 1633(m), 1579(w), 1596(m),
13C NMR (CDCl3, 100 MHz):
d
23.6 (s, NeCOCH3), 42.5 (s þ d,
1550(w) cmꢁ1
.
2JPt,C ¼ 374 Hz, PteCOCH3), 44.7 (s þ d, 2JPt,C ¼ 340 Hz, PteCOCH3),
126.2 (s, C3 py), 126.7 (s, C5 py), 139.9 (s, C4 py), 150.4 (s, CH]NNH),
151.2 (s, C6 py), 155.6 (s, C2 py), 169.0 (s, NeCOCH3), 227.9 (s, Pte
[Pt(COMe)2{2-pyCMe]NNH{CO(C6H4-p-F)}}] (7f). Yield: 52 mg
(68%). HRMS (ESI): m/z calcd for [C18H18FN3O3PtNa]þ 561.08721,
found for [M þ Na]þ 561.08702. 1H NMR (CDCl3, 500 MHz):
d 2.20
COCH3), 228.5 (s, PteCOCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3411
(s þ d, 3JPt,H ¼ 31.5 Hz, 3H, COCH3), 2.34 (s, 3H, C(CH3)]NNH), 2.48
(s). IR 3053(w), 2960(w), 1682(w), 1621(m), 1552(w) cmꢁ1
.
(s þ d, JPt,H ¼ 28.5 Hz, 3H, COCH3), 7.20 (m, 2H, m-H C6H4F), 7.57
3

56
T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
(m, 1H, H5 py), 7.85 (m, 1H, H3 py), 8.07 (m, 1H, H4 py), 8.15 (m, 2H,
o-H C6H4F), 8.57 (m, 1H, H6 py), 13.40 (s þ d, 3JPt,H ¼ 16 Hz, 1H, NH).
relativistic effects was used [22]. The appropriateness of the func-
tional in combination with the basis sets and effective core po-
tential used for reliable interpretation of structural and energetic
aspects of related platinum complexes has been demonstrated [23].
Molecules 4b*, 5*, and 7b* were fully optimized without any re-
strictions. The resulting geometries were characterized as equilib-
rium structures by analysis of the force constants of the normal
vibrations.
13C NMR (CDCl3, 125 MHz):
d
18.8 (s, C(CH3)]NNH), 42.7 (s þ d,
2JPt,C ¼ 372 Hz, COCH3), 44.9 (s þ d, 2JPt,C ¼ 335 Hz, COCH3), 116.1 (d,
2JF,C ¼ 22.0 Hz, m-C C6H4F), 125.2 (s, C3 py), 127.5 (s, C5 py), 127.9 (d,
4JF,C ¼ 3.1 Hz, i-C C6H4F), 130.7 (d, 3JF,C ¼ 9.3 Hz, o-C C6H4F), 139.7 (s,
C4 py), 151.1 (s, C6 py), 155.3 (s, C2 py), 162.3 (s, C(CH3)]NNH), 165.5
1
(d, JF,C ¼ 253.9 Hz, CeF), 167.0 (s, CO(C6H4F)), 229.2 (s, COCH3),
230.4 (s, COCH3). 195Pt NMR (CDCl3, 86 MHz):
d
ꢁ3395 (s). 19F NMR
(CDCl3, 376 MHz):
d
ꢁ105.73 (s (br)). IR 3151(w), 3053(w),1686 (m),
Appendix A. Supplementary material
1625(m), 1601(m), 1549(m) cmꢁ1
.
CCDC 958319, 958320, 958321, 958322, 958323, 958324, and
958325 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Investigations on the reactivity of diacetyl platinum(II) complexes
with amines
A solution of complex 4aec, 6d/f, and 7c (0.05 mmol) in CH2Cl2
(2 mL) was reacted with benzylamine (0.50 mmol and 5 mmol) at
room temperature. After 2 h stirring, the solvent of the solution was
reduced to about 0.5 mL, diethyl ether/n-pentane (2 mL, 1:1) was
added and the precipitate was filtered off. NMR spectroscopic an-
alyses showed the existence of the starting complexes 4aec, 6d/f,
and 7c. Furthermore, complex 7e (10 mg, 0.02 mmol) was treated
with NH2CH2CH2Ph (0.05 mmol) in CD2Cl2, but NMR spectroscop-
ically no reaction was observed within 1 day. The reaction of
Appendix B. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2014.03.030.
References
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data, the data collection parameters, and the refinement param-
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platinum were approximated by a split valence basis set, too; for
their core orbitals an effective core potential with consideration of

T. Kluge et al. / Journal of Organometallic Chemistry 762 (2014) 48e57
57
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