Ligand substitution reactions on aquapentachloro- and hexachloroplatinic acid - Synthesis and characterization of tetrachloroplatinum(IV) complexes with heterocyclic N,N donors

Article abstract of DOI:10.1002/zaac.200390119

Reactions of aquapentachloroplatinic acid, (H₃O)[PtCl₅(H₂O)] ·2(18C6)·6H₂O (1) (18C6 = 18-crown-6), and H₂[PtCl₆]·6H₂O (2) with heterocyclic N,N donors (2,2′-bipyridine, bpy; 4,4

Full text of DOI:10.1002/zaac.200390119

Ligand Substitution Reactions on Aquapentachloro- and Hexachloroplatinic
Acid ؊ Synthesis and Characterization of Tetrachloroplatinum(IV) Complexes
with Heterocyclic N,N Donors
Akmal Gaballa, Christoph Wagner, Harry Schmidt, and Dirk Steinborn*
Halle, Institut für Anorganische Chemie der Martin-Luther-Universität
Received November 25th, 2002.
ˇ
Dedicated to Professor Jaroslav Holecek on the Occasion of his 70th Birthday
Abstract.
Reactions
of
aquapentachloroplatinic
acid,
bpym, 9). Identities of all complexes were established by microana-
lysis as well as by NMR (1H, 13C, 195Pt) and IR spectroscopic in-
vestigations. Molecular structures of [PtCl4(bpym)]·MeOH (7) and
[PtCl2(Ph2phen)] (6) were determined by X-ray diffraction analyses.
Differences in reactivity of bpy/bpym and phen ligands are dis-
cussed in terms of calculated structures of complexes
[PtCl5(N២N)]Ϫ with monodentately bound N,N ligands (N២N ϭ
bpy, 10a; phen, 10b; bpym, 10c).
(H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) (18C6 ϭ 18-crown-6), and
H2[PtCl6]·6H2O (2) with heterocyclic N,N donors (2,2Ј-bipyridine,
bpy; 4,4Ј-di-tert-butyl-2,2Ј-bipyridine, tBu2bpy; 1,10-phenanthro-
line, phen; 4,7-diphenyl-1,10-phenanthroline, Ph2phen; 2,2Ј-bipy-
rimidine, bpym) afforded with ligand substitution platinum(IV)
complexes [PtCl4(N២N)] (N២N ϭ bpy, 3a; tBu2bpy, 3b; Ph2phen,
5; bpym, 7) and/or with protonation of N,N donor yielding
(R2phenH)2[PtCl6] (R ϭ H, 4a; Ph, 4b) and (bpymH)ϩ (8). With
UV irradiation Ph2phen and bpym reacted with reduction yielding
platinum(II) complexes [PtCl2(N២N)] (N២N ϭ Ph2phen, 6;
Keywords: Platinum; Chelate ligands; Ligand substitution reac-
tions; Ab initio calculations.
Ligandsubstitutionsreaktionen an Aquapentachloro- und Hexachloroplatinsäure ؊
Synthese und Charakterisierung von Tetrachloroplatin(IV)-Komplexen mit
heterocyclischen N,N-Donatoren
Inhaltsübersicht. Reaktionen der Aquapentachloroplatinsäure,
(H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) (18C6 ϭ 18-Krone-6), und
von H2[PtCl6]·6H2O (2) mit heterocyclischen N,N-Donatoren
(2,2Ј-Bipyridin, bpy; 4,4Ј-Di-tert-butyl-2,2Ј-bipyridin, tBu2bpy;
bpym unter Reduktion zu Platin(II)-Komplexen [PtCl2(N២N)]
(N២N ϭ Ph2phen, 6; bpym, 9). Die Identität aller Komplexe
wurde durch Elementaranalyse sowie NMR- (1H, 13C, 195Pt) und
IR-spektroskopisch bewiesen. Die Molekülstrukturen von
[PtCl4(bpym)]·MeOH (7) und [PtCl2(Ph2phen)] (6) wurden durch
Einkristallröntgenstrukturanalysen erhalten. Unterschiede in der
Reaktivität von bpy-/bpym- und phen-Liganden werden auf Basis
der berechneten Strukturen der Komplexe [PtCl5(N២N)]Ϫ mit ein-
zähnig gebundenen N,N-Liganden (N២N ϭ bpy, 10a; phen, 10b;
bpym, 10c) diskutiert.
1,10-Phenanthrolin,
phen;
4,7-Diphenyl-1,10-phenanthrolin,
Ph2phen; 2,2Ј-Bipyrimidin, bpym) führten unter Ligandsubstitu-
tion zu Platin(IV)-komplexen [PtCl4(N២N)] (N២N ϭ bpy, 3a;
tBu2bpy, 3b; Ph2phen, 5; bpym, 7) und/oder Protonierung des
N,N-Donors zu (R2phenH)2[PtCl6] (R ϭ H, 4a; Ph, 4b) und
(bpymH)ϩ (8). Unter UV-Bestrahlung reagierten Ph2phen und
Introduction
simple complexes as aquapentachloroplatinates(IV) can be
principially formed by oxidation of [PtCl4]2Ϫ with chlorine
in aqueous solution [2] or by photoinduced chloride ex-
change of hexachlorplatinates(IV) [1]. To isolate them as
solids in pure state was only recently by the reaction of
hexachloroplatinic acid with crown ether 18-crown-6 (18C6)
yielding (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) [3]. Sub-
sequent neutralization resulted in formation of
[K(18C6)][PtCl5(H2O)] and [N(nBu)4][PtCl5(H2O)]·1/2-
(18C6)·H2O [4]. The aquapentachloroplatinic acid 1 proved
to be more prone to ligand substitution reactions than
hexachloroplatinic acid H2[PtCl6]·6H2O (2).
Platinum(IV) forms a plethora of octahedral complexes that
are thermodynamically stable and kinetically inert due to
the low-spin d6 electron configuration of PtIV. Most of them
were prepared by oxidation of requisite platinum(II) com-
plexes because ligand substitution reactions on PtIV are
hampered. They may be accelerated photochemically or by
PtII. Thus, it has been known for a long time that such
* Prof. Dr. Dirk Steinborn
Soon after the discovery of the carcinostatic effect of cis-
[PtCl2(NH3)2] by Rosenberg et al. [5], platinum(IV) com-
plexes were also tested as antitumor agents. The ongoing
interest of platinum(IV) complexes in chemotherapy [6] led
Institut für Anorganische Chemie
Martin-Luther-Universität Halle-Wittenberg
Kurt-Mothes-Straße 2, D-06120 Halle
E-mail: steinborn@chemie.uni-halle.de
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 0044Ϫ2313/03/629/703Ϫ710 $ 20.00ϩ.50/0
703

A. Gaballa, C. Wagner, H. Schmidt, D. Steinborn
to a revival of coordination chemistry of PtIV, especially of
those with bioligands. Most of them were prepared by oxi-
dation of preformed platinum(II) complexes, but synthesis
may fail due to oxidative degradation of bioligands. We are
interested in synthesis of platinum(IV) complexes with bio-
ligands via ligand substitution reactions and succeeded to
synthesize those with amino acid ligands [7] and carbo-
hydrate ligands [8]. Nowadays our interest is focused on
platinum(IV) complexes with nucleobase ligands [9]. To
provide background for this, we investigated first reactions
of aquapentachloro- (1) and hexachloroplatinic acid (2)
with bipyridines (R2bpy), phenanthrolines (R2phen) and
2,2Ј-bipyrimidine (bpym) being of similar basicity and
nucleophilicity as nucleobases. As we report here, these re-
actions proceeded either with protonation of the N,N ligand
only or with ligand substitution forming complexes of the
type [PtCl4(N២N)] (N២N ϭ bpy, phen, bpym). Synthesis
of complexes of these types were described earlier by oxi-
dation of the preformed platinum(II) complexes
[PtCl2(N២N)] with chlorine or H2O2/HCl [10].
soluble in dimethylformamide and dimethylsulfoxide. Com-
plex 4a did not undergo any reaction at stirring in meth-
anol/water (9/1) at 60 °C for 30 hours. On the other hand,
stirring a suspension of complex 4b in methanol for few
minutes at 60 °C resulted in formation of [PtCl4(Ph2phen)]
(5) to a small extent (ca. 10 %). There was no substantial
increase of the quantity of complex 5 at longer reaction
times.
Reaction of aquapentachloroplatinic acid 1 with Ph2phen
in more diluted methanolic solution did not proceed in pre-
cipitation of complex 4b. Instead of that, within 3 hours at
room temperature precipitation of a yellow microcrystalline
substance was observed that proved to be complex 5 (19 %
Scheme 3
yield) (Scheme 3). With UV irradiation at 40 °C not only a
ligand substitution reaction took place but also a reduction
forming the platinum(II) complex [PtCl2(Ph2phen)] (6). As
for bipyridine platinum(IV) complexes 3, [PtCl4(Ph2phen)]
(5) underwent reduction in dmf solution yielding
[PtCl2(Ph2phen)] (6) within several hours at room tempera-
ture.
Results and Discussion
Both aquapentachloroplatinic acid 1 and hexachloropla-
tinic acid 2 underwent with 2,2Ј-bipyridine and 4,4Ј-di-tert-
butyl-2,2Ј-bipyridine in alcoholic solutions ligand substi-
tution reactions yielding (bipyridine)tetrachloroplatinum(IV)
complexes [PtCl4(R2bpy)] (R ϭ H, 3a; R ϭ tBu, 3b)
Reactions
of
aquapentachloroplatinic
(1)
and
hexachloroplatinic acid (2) with 2,2Ј-bipyrimidine (bpym)
in methanol at room temperature resulted in immediate for-
1
mation of a yellowish precipitate. H NMR spectroscopic
measurements made clear that about 1:3 mixture of
[PtCl4(bpym)] and a bipyrimidinium salt (8) was formed.
Subsequent heating at 60 °C for several hours resulted in
formation of [PtCl4(bpym)]·MeOH (7) as main product that
Scheme 1
(Scheme 1). Reactions proceeded within few minutes at
room temperature (3a) and at 40 °C (3b), respectively. Com-
plexes 3 were isolated as yellow microcrystals in yields of
about 95 % (3a) and 81 % (3b). Whereas complex 3b is
freely soluble in common organic solvents, complex 3a is
only soluble in dimethylformamide and dimethylsulfoxide.
Solutions of 3a and 3b in dmso were stable. In dmf within
several days a reduction took place yielding the correspond-
ing platinum(II) complexes [PtCl2(R2bpy)] (R ϭ H, 3c; R ϭ
tBu, 3d).
Scheme 4
was isolated as reddish microcrystals (Scheme 4). But under
these reaction conditions PtIV was partially reduced and the
products contained < 10 % of [PtCl2(bpym)] (9). Starting
from 2, the product contained about 13 % of a bipyrimidi-
num salt (8, probably as chloride or hexachloroplatinate),
too. Performing the reaction of 1 with bpym under UV light
(MeOH, 60 °C, 5 h) resulted in complete reduction of PtIV
forming [PtCl2(bpym)] (9) in nearly quantitative yield.
Corresponding reactions with 1,10-phenanthroline and
4,7-diphenyl-1,10-phenanthroline in methanol at room tem-
perature resulted in protonation of phenanthrolines only
yielding
phenanthrolinium
hexachloroplatinates
Spectroscopic characterization
All complexes were fully characterized by microanalysis, IR
and NMR (1H, 13C, 195Pt) spectroscopies. If necessary, as-
signments were verified by two-dimenisonal NMR experi-
ments. Formation of bipyridine complexes 3 was unambig-
Scheme 2
(R2phenH)2[PtCl6] (R ϭ H, 4a; R ϭ Ph, 4b) (Scheme 2).
Complexes 4 were isolated as yellowish powders that are
1
ously shown in H NMR spectra by platinumϪhydrogen
704
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710

Ligand Substitution Reactions on Aquapentachloro- and Hexachloroplatinic Acid
3
Table 2 Chemical shifts δ(1H) of free Ph2phen and bpym and co-
ordinated in their platinum(II) and platinum(IV) complexes in
[D6]-dmso.
couplings JPt,H6/3JPt,H6Ј (26.2 Hz, 3a; 25.8 Hz, 3b) and by
3
platinumϪcarbon couplings JPt,C3/3JPt,C3Ј (19.8 Hz, 3a;
3
20.4 Hz, 3b), JPt,C5/3JPt,C5Ј (25.9 Hz, 3a; 26.3 Hz, 3b), and
2JPt,C6/2JPt,C6Ј (16.3 Hz, 3a; 14.7 Hz, 3b). Comparison with
free ligands revealed coordination induced lowfield shifts
for proton resonances up to 0.98 and 0.87 ppm (H6/H6Ј) in
complex 3a and 3b, respectively. Coordination of bipyri-
dines to the PtCl4 unit resulted in substantial lowfield shifts
for C3ϪC5 in 3a (5.8Ϫ6.9 ppm) and for C2, C3 and C5
in 3b (5.6Ϫ7.5 ppm). Only carbon atom C6 in complex 3b
underwent a remarkable highfield shift by 9.2 ppm.
Selected NMR spectroscopic data of phenanthrolinium
hexachlorplatinates 4 are shown in Table 1 along with that
of simple phenanthrolinium salts (R2phenH)Cl (R ϭ H,
Ph) and of the non-protonated compounds R2phen. There
are no significant differences in hydrogen and carbon reson-
ances of phenanthrolinium cations with hexachloroplatinate
(complexes 4) and chloride as counter anion, respectively.
On the other hand, comparison with non-protonated
R2phen reveals that protonation gives rise to lowfield shifts
(up to 0.59 ppm) of all aromatic hydrogen atoms. In 13C
NMR spectra protonation of phen resulted in remarkable
lowfield shift of C4/C7 and highfield shift of C10a/C10b,
whereas that of Ph2phen gave shifts into the opposite direc-
tion.
CH (2/9)
CH (3/8)
CH (5/6)
Ph2phen
[PtCl2(Ph2phen)] (6)
[PtCl4(Ph2phen)] (5)
9.13
9.37
9.80
7.68
8.15
8.44
7.82
8.11
8.32
CH (6/6Ј)
CH (5/5Ј)
CH (4/4Ј)
bpym
[PtCl2(bpym)] (9)
[PtCl4(bpym)] (7)
9.00
9.69
9.79
7.64
7.99
8.36
9.00
9.34
9.56
num(IV) complexes 3a/b, 4a/b, 5 and 7 were between 3687
and 4208 ppm.
Single-crystal X-ray diffraction analyses
Single crystals of [PtCl4(bpym)]·MeOH (7) were obtained
from methanolic solutions. X-ray diffraction analysis re-
vealed that crystals consist of separated molecules of
[PtCl4(bpym)] without unusual short contacts to neigh-
bored molecules. The molecular structure is shown in Fig-
ure 1, selected bond lengths and angles are summarized in
Table 3. The complex exhibits C2ν symmetry in good
approximation. The platinum atom is octahedrally coordi-
nated (PtCl4N2). The only noticeable distortion from ideal
octahedron is caused by the restricted bite of the bipyrimi-
Most characteristic for coordination of Ph2phen and
bpym to both PtIV and PtII are remarkable low field shifts
(up to 0.79 ppm) of all hydrogen atoms (Table 2). These
are more pronounced in platinum(IV) than in platinum(II)
complexes as expected from the electrophilicity PtIV > PtII.
For platinum(IV) complexes couplings to platinum
˚
Table 3 Selected bond lengths (in A) and bond angles (in °) for
[PtCl4(bpym)]·MeOH (7).
2
(3JPt,H ϭ 27.4 Hz, 5; 25.7 Hz, 7; JPt,C ϭ 19.2 Hz, 5;
16.8 Hz, 7) were observed. Likely, due to dominant chemi-
cal shift anisotropy relaxation [11] such couplings were not
observed in the platinum(II) complexes 6 and 9.
Platinum resonances show the oxidation state of platinum
[12]: δ(195Pt) (referred to aqueous solution of Na2[PtCl6]
δ ϭ ϩ4520) in platinum(II) complexes 3c, 6 and 9 were
found between 2135 and 2194 ppm whereas those in plati-
PtϪCl1
PtϪCl2
PtϪCl3
Cl1ϪPtϪCl2
Cl1ϪPtϪN1
Cl1ϪPtϪN3
Cl2ϪPtϪN1
Cl1···H8
2.301(2)
2.302(2)
2.335(2)
90.18(7)
174.7(2)
94.8(2)
94.7(2)
2.71
PtϪCl4
PtϪN1
PtϪN3
N1ϪPt1ϪN3
Cl2ϪPtϪN3
Cl3ϪPtϪCl4
2.322(2)
2.051(6)
2.042(6)
80.3(3)
174.9(2)
177.66(8)
C8ϪH8···Cl1
C1ϪH1···Cl2
120.3
120.1
Cl2···H1
2.70
Table 1 Selected chemical shifts δ(13C) and δ(1H) (in parantheses)
for phenanthrolines (phen, Ph2phen) and phenanthrolinium com-
pounds in [D6]-dmso.
group
number
CH
2/9
CH
3/8
CH/Ca) CH
4/7 5/6
C
C
10a/10b 4a/6a
phen
149.9 123.2 136.1 126.6 145.5 128.4
(9.09) (7.75) (8.47) (7.97)
(phenH)Cl
147.8 125.5 141.4 127.4 137.9 129.4
(9.28) (8.19) (9.05) (8.33)
(phenH)2[PtCl6] (4a)
Ph2phen
147.7 125.6 141.8 127.5 137.6 129.5
(9.28) (8.21) (9.06) (8.34)
150.0 124.0 146.7 124.3 147.9 137.7
(9.13) (7.68)
148.4 125.8 140.2 126.3 153.5 136.7
(9.55) (8.23) (8.20)
(Ph2phenH)2[PtCl6] (4b) 147.2 125.0 138.6 125.6 152.6 135.3
(9.36) (8.20) (8.16)
(7.82)
(Ph2phenH)Clb)
Figure 1 Structure of [PtCl4(bpym)]·MeOH (7) in crystal (displace-
ment ellipsoids at 30 % probability). Solvent molecule is not shown.
CϪH···Cl hydrogen bonds are drawn by dashed lines.
a) CH for phen and C for Ph2phen. b) In CD3OD/[D7]-dmf (1/1).
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710
705

A. Gaballa, C. Wagner, H. Schmidt, D. Steinborn
˚
Table 4 Selected bond lengths (in A) and angles (in °) for
[PtCl2(Ph2phen)] (6) crystallizing in the space group P21/n with two
symmetry independent molecules a and b, respectively.
molecule a
2.296(2)
molecule b
Pt1ϪCl1
Pt1ϪCl2
Pt1ϪN1
Pt1ϪN2
N1ϪC1
N2ϪC10
Pt2ϪCl3
Pt2ϪCl4
Pt2ϪN3
Pt2ϪN4
N3ϪC25
N4ϪC34
2.295(1)
2.306(1)
2.020(4)
2.022(5)
1.316(7)
1.339(7)
81.1(2)
89.65(5)
175.1(1)
175.4(1)
2.73
2.307(2)
2.016(4)
2.029(5)
1.323(7)
1.323(7)
81.3(2)
90.50(6)
175.7(1)
174.0(1)
2.71
N1ϪPt1ϪN2
Cl1ϪPt1ϪCl2
N1ϪPt1ϪCl1
N2ϪPt1ϪCl2
Cl1···H10
N3ϪPt2ϪN4
Cl3ϪPt2ϪCl4
N3ϪPt2ϪCl3
N4ϪPt2ϪCl4
Cl3···H34
Cl2···H1
2.70
120.1
120.0
2.83
Cl4···H25
2.72
119.9
120.0
2.67
C10ϪH10···Cl1
C1ϪH1···Cl2
Cl2···H44a)
C34ϪH34···Cl3
C25ϪH25···Cl4
Cl3···H42Јb)
C44ϪH44···Cl2a) 147.8
C42ЈϪH42Ј···Cl3b) 157.9
a) Intermolecular CϪH···Cl bridge between molecule a and b. b) Intermole-
cular CϪH···Cl bridge between molecule b and bЈ (symmetry code: 1Ϫx,
Ϫy, Ϫz).
dine ligand (N1ϪPtϪN3 80.3(3)°; N1ϪPtϪCl2 94.7(2)°;
N3ϪPtϪCl1 94.8(2)°). The skeleton of the bipyrimidine li-
gand (N1ϪN4, C1ϪC8) and the unit Pt,Cl1,Cl2,N1,N3 de-
fine planes in very good approximation (greatest deviations
˚
from the least-square mean-planes: 0.027(9) A for C1 and
˚
0.021(6) A for N1) that are nearly coplanar (interplanar
angle 3.8(2)°).
Figure 2 Structure of the two symmetry independent molecules
(a/b) in crystals of [PtCl2(Ph2phen)] (6) (displacement ellipsoids at
30 % probability). CϪH···Cl hydrogen bonds are drawn by dashed
lines. Symmetry codes for equivalent atoms (Ј): 1Ϫx, Ϫy, Ϫz.
The (CϪ)H8···Cl1 and (CϪ)H1···Cl1 distances amount
˚
˚
to 2.71 A and 2.70 A and the angles C8ϪH8···Cl1 and
C1ϪH1···Cl2 to 120.3° and 120.1°, respectively. All these
values are within the geometrical cutoffs for the H···Cl dis-
1)
˚
tance (2.95 A ) and for the CϪH···Cl angle (> 90°) to
identify CϪH···Cl hydrogen bonds [13]. The PtϪCl bonds
trans to N atoms are shorter than those to mutually trans
The chloro ligands are in close contact to aromatic hy-
drogen atoms indicating CϪH···Cl hydrogen bonds:
˚
˚
˚
Cl atoms (2.301(2)/2.302(2) versus 2.335(2)/2.322(2) A).
(CϪ)H1···Cl2
2.70 A,
(CϪ)H10···Cl1
2.71 A,
˚
˚
This points to a (structural) trans influence Cl > bpym.
Analogously, X-ray diffraction analysis of [PtCl4(bpy)] re-
vealed a greater trans influence of Cl than bpy [14].
(CϪ)H34···Cl3 2.73 A, (CϪ)H25···Cl4 2.72 A. Besides these
“intramolecular” hydrogen bonds the molecules are connec-
ted via intermolecular CϪH···Cl hydrogen bonds, shown as
dashed lines in Figure 2. Closest of these contacts are
From solutions of the diphenylphenanthroline plati-
num(II) complex 6 in [D7]dmf well shaped single-crystals
suitable for X-ray diffraction analysis were obtained. The
unit cell contains two symmetry-independent molecules
whose structures are shown in Figure 2. Selected bond
lengths and angles are given in Table 4. The platinum atoms
are square planar coordinated (PtCl2N2). The two mole-
cules are not strictly planar: The PtCl2N2 planes include
with the planes of the phenanthroline ligands (without con-
sideration the phenyl substituents) angles of 9.2(1)° (mole-
cule a) and 7.7(1)° (molecule b), respectively. With respect
to the phenanthroline plane the phenyl substituents are ro-
tated in both molecules “disrotatory” by 41.0(2)/48.3(2)°
˚
˚
(CϪ)H42Ј···Cl3 (2.67 A) and (CϪ)H44···Cl2 (2.83 A).
Quantum chemical calculations
Investigations exhibited that ligand substitution reactions
on octahedral coordinated platinum(IV) center ([PtCl6]2Ϫ
,
[PtCl5(H2O)]Ϫ) with 2,2Ј-bipyridine and 2,2Ј-bipyrimidine
proceeded more readily than with 1,10-phenanthroline. On
the other hand, bipyrimidine is considerably less basic
(pKb ϭ 13.4) than bipyridine (pKb ϭ 10.4) and phenanthro-
line (pKb ϭ 9.5) [15]2). Thus, reactivity of [PtCl6]2Ϫ and
(PhC13/PhC19, molecule a) and by 55.3(2)/66.0(2)° (PhC43
PhC37, molecule b).
/
2) Alkyl substitution of bipyridine on 4,4Ј position does not
strongly affect the basicity (cf. Me2bpy: pKb ϭ 9.6). Phenyl subsitu-
tion of phenanthroline in 4,7 position results in a decrease of pKb
value by 0.2 only [15].
1) This value corresponds to the sum of the van der Waals radii of
H and Cl. The distance criterion given in lit. [13] is even weaker.
706
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710

Ligand Substitution Reactions on Aquapentachloro- and Hexachloroplatinic Acid
Table 5 Calculated structural parameters of complexes
[PtCl5(N២N)]Ϫ (10) (bond lengths in A, angles in °). In paranthe-
˚
ses bond orders in electron pairs are given.
N២N
bpy (10a)
phen (10b)
bpym (10c)
PtϪN
PtϪCltrans
PtϪClcis
2.263 (0.268)
2.335 (0.627)
2.382Ϫ2.413
(0.450Ϫ0.487)
174.6
2.313 (0.244)
2.330 (0.646)
2.389Ϫ2.418
(0.443Ϫ0.492)
171.9
14.0
52.9
2.234 (0.263)
2.332 (0.630)
2.379Ϫ2.411
(0.445Ϫ0.490)
174.8
Ϫ120.8
75.2
NϪPtϪCltrans
NϪCϪCϪNЈ
Ϫ142.9
PtCl4/heterocyclea) 68.2
a) Interplanar angle between PtCl4 unit and coordinated NC5 and N2C4
ring, respectively.
Figure 4 Conformational energy diagram for 2,2Ј-bipyridine (bpy),
1,10-phenanthroline (phen) and 2,2Ј-bipyrimidine (bpym).
plexes 10a and 10c monodentate coordination resulted in
twisting the heterocyclic rings (NϪCϪCϪNЈ Ϫ142.9°, 10a;
Ϫ120.8°, 10c). Dependence of energy on torsional angle
NϪCϪCϪNЈ in the non-coordinated ligands is shown in
Figure 4. To twist bipyridine from the energetically most
favored trans conformation (NϪCϪCϪNЈ 180°) into that
of the complex requires 2.5 kcal/mol and to twist non-coor-
dinated bipyrimidine (NϪCϪCϪNЈ Ϫ151.6°) to the con-
formation in complex 10c requires 0.9 kcal/mol only. As
shown in Figure 4 distortion of phenanthroline is energeti-
cally much more unfavored. Thus, in phen complex 10b the
NϪCϪCϪNЈ angle amounts to 14.0° (corresponding to an
expense of energy of 1.0 kcal/mol). But, due to steric hin-
drance phen ligand is far away to be bound perpendicular
onto the equatorial PtCl4 complex plane (interplanar angle
PtCl4/NcoordC5: 52.9°). Thus, PtϪN bond in 10b is much
˚
longer than those in 10a/10c (2.313 vs. 2.263/2.234 A) and
exhibits a lower bond order (0.244 vs. 0.268/0.263). This
reduced donor capability for monodentate coordination of
phenanthroline may be the reason for its lower reactivity in
substitution reactions of octahedral complexes.
Figure 3 Calculated structures of complexes [PtCl5(N២N)]Ϫ with
monodentately bound N,N ligands (N២N ϭ bpy, 10a; phen, 10b;
bpym, 10c).
Experimental
NMR spectra were recorded on Varian Unity 500, VXR 400 and
Gemini 200 spectrometers operating at 499.88, 399.96 and
199.97 MHz for 1H, respectively. Solvent signals (1H, 13C) were
used as internal references and Na2[PtCl6] (δ(195Pt) ϭ ϩ4520 corre-
sponding to Ξ(195Pt) ϭ 21.4 MHz) as an external reference. When
[PtCl5(H2O)]Ϫ in ligand substitution reactions with chelate
N,N donors cannot be understood in terms of their basici-
ties. Substitution reactions of chelate ligands can be viewed
as two step processes [16]. Thus, complexes of the type
[PtCl5(N២N)]Ϫ (10) with monodentately bound bpy (10a),
phen (10b) and bpym (10c) have to be considered as inter-
mediates in reactions of [PtCl6]2Ϫ with N,N donors.
To get insight into the course of reactions, complexes
10aϪc were calculated on the DFT level of theory. Calcu-
lated structures are shown in Figure 3, selected bond
lengths and angles are given in Table 5. In the case of com-
necessary, assignments were revealed by H-1H and H-13C COSY
NMR experiments. IR spectra were recorded on a Galaxy FT-IR
spectrometer (Mattson 5000) using CsBr pellets. Microanalyses (C,
H, N) were performed by the University of Halle microanalytical
laboratory using CHNS-932 (LECO) and vario-EL (elementar
Analysensysteme) elemental analyzers. Chlorine was determined by
burning the substance in oxygen with platinum contact and sub-
sequent titration with mercury nitrate towards diphenylcarbazide.
1
1
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710
707

A. Gaballa, C. Wagner, H. Schmidt, D. Steinborn
[D7]-dmf): δ 30.0 (s, CH3), 36.0 (s, CMe3), 121.7 (s, C3/C3Ј), 124.4 (s, C5/
C5Ј), 148.1 (s, C6/C6Ј), 156.9 (s, C4/C4Ј), 165.0 (s, C2/C2Ј). Spectra are
identical with those of an authentical sample (prepared in analogy to lit.
[19]) measured in the same solvent.
(H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) was prepared as described
previously [3]. 4,4Ј-Di-tert-butyl-2,2Ј-bipyridine (tBu2bpy) was ob-
tained according to a modified [17] procedure described in lit. [18].
Authentic samples of complexes [PtCl2(bpy)] (3c), [PtCl2(tBu2bpy)]
(3d), and [PtCl2(Ph2phen)] (6) were prepared as described in lit.
[19, 20] and in analogy to it, respectively. Phenanthrolinium salts
(phenH)Cl (m.p. 195 °C) and (Ph2phenH)Cl (m.p. 101 °C) were ob-
tained by adding requisite amount of HCl to phenanthrolines in
MeOH. Other chemicals were commercially available.
Synthesis of (phenH)2[PtCl6] (4a)
To a solution of 1,10-phenanthroline (72.0 mg, 0.40 mmol) in
methanol (5 ml), a solution of of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O
(1) and H2[PtCl6]·6H2O (2) (0.20 mmol), resepctively, in methanol
(4 ml) was added. Mixing the clear solutions with stirring produced
immediately faint yellow precipitates, which were filtered off,
washed with methanol (3 ϫ 1 ml) and dried in vacuo. Yield: 130/
146 mg (84/95 %).
Synthesis of [PtCl4(bpy)] (3a)
To
a solution of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) and
H2[PtCl6]·6H2O (2) (0.13 mmol), respectively, in methanol (3 ml), a
solution of 2,2Ј-bipyridine (20.3 mg, 0.13 mmol) in methanol (3 ml)
was added. Mixing the clear solutions resulted in formation of yel-
low precipitates, which were filtered off, washed with methanol
(3 ϫ 1 ml) and dried in vacuo. Yield: 62.0/60.0 mg (97/94 %).
Anal. found: C, 24.53; H, 1.94; N, 5.43; Cl 28.66 %. Anal. calcd.
for C10H8Cl4N2Pt (493.09): C, 24.36; H, 1.64; N, 5.68; Cl, 28.76 %.
3
Anal. found: C, 37.36; H, 2.48; N, 7.28; Cl 27.50 %. Anal. calcd.
for C24H18Cl6N4Pt (770.25): C, 37.43; H, 2.36; N, 7.27; Cl, 27.62 %.
3
3
1H NMR (400 MHz, [D6]-dmso): δ 8.21 (dd, JH3,H2 ϭ 4.98 Hz, JH3,H4
ϭ
3
8.30 Hz, 4H, H3/H8), 8.34 (s, 4H, H5/H6), 9.06 (dd, JH4,H3 ϭ 8.30 Hz,
4JH4,H2 ϭ 1.45 Hz, 4H, H4/H7), 9.28 (dd, JH2,H3 ϭ 4.98 Hz, JH2,H4
ϭ
3
4
1.45 Hz, 4H, H2/H9). 13C NMR (126 MHz, [D6]-dmso): δ 125.6 (s, C3/C8),
127.5 (s, C5/C6), 129.5 (s, C4a/C6a), 137.6 (s, C10a/C10b), 141.8 (s, C4/C7),
147.7 (s, C2/C9). 195Pt NMR (107 MHz, [D6]-dmso): δ 3688 (s). IR (CsBr):
3050 (s), 1594 (s), 1538 (vs), 1465 (s), 845 (vs), 715 (s), 326 (vs) cmϪ1
.
1H NMR (400 MHz, [D7]-dmf): δ 8.30 (dt, JH5,H4
ϭ
3JH5,H6 ϭ 7.89 Hz3),
3
4JH5,H3 ϭ 1.66 Hz, 2H, H5/H5Ј ), 8.72 (dt, JH4,H5
ϭ
3JH4,H3 ϭ 7.89 Hz,
3
4
4JH4,H6 ϭ 1.25 Hz, 2H, H4/H4Ј), 9.12 (dd, JH3,H4 ϭ 7.89 Hz, JH3,H5
ϭ
Synthesis of (Ph2phenH)2[PtCl6] (4b)
3
4
1.66 Hz, 2H, H3/H3Ј), 9.69 (ddϩdd, JH6,H5 ϭ 5.81 Hz, JH6,H4 ϭ 1.25 Hz,
To
0.20 mmol) in methanol (5 ml) and few drops of methylene chlo-
ride, solution of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) and
a solution of 4,7-diphenyl-1,10-phenanthroline (66.5 mg,
3JPt,H6 ϭ 26.15 Hz, 2H, H6/H6Ј). 13C NMR (101 MHz, [D7]-dmf): δ 127.4
3
3
(sϩd, JPt,C3 ϭ 19.8 Hz, C3/C3Ј), 130.5 (sϩd, JPt,C5 ϭ 25.9 Hz, C5/C5Ј),
2
144.6 (s, C4/C4Ј), 148.5 (sϩd, JPt,C6 ϭ 16.3 Hz, C6/C6Ј), 155.4 (s, C2/C2Ј).
a
195Pt NMR (107 MHz, [D7]-dmf): δ 4206 (s). IR (CsBr): 3085 (s), 1600 (s),
H2[PtCl6]·6H2O (2) (0.10 mmol), respectively, in methanol (4 ml)
was added. Mixing the clear solutions with stirring produced im-
mediately faint orange precipitates, which were filtered off, washed
with methanol (3 ϫ 1 ml) and dried in vacuo. Yield: 58/98 mg
(54/91 %).
Anal. found: C, 53.23; H, 3.50; N, 5.34; Cl 19.88 %. Anal. calcd. for
C48H34Cl6N4Pt (1074.64): C, 53.65; H, 3.15; N, 5.21; Cl, 19.79 %.
1H NMR (400 MHz, [D6]-dmso): δ 7.66-7.70 (m, 20H, 4 ϫ C6H5), 8.16 (s,
1449 (s), 1310 (s), 1245 (s), 769 (vs), 345 (vs) cmϪ1
.
Synthesis of [PtCl4(tBu2bpy)] (3b)
To
a solution of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) and
H2[PtCl6]·6H2O (2) (0.10 mmol), resepctively, in ethanol (5 ml), a
solution of 4,4Ј-di-tert-butyl-2,2Ј-bipyridine (26.8 mg, 0.10 mmol)
in ethanol (5 ml) was added. Mixing the clear solutions produced
immediately faint yellowish precipitates. The reaction mixtures
were stirred for few minutes at 40 °C, then the precipitates were
filtered off, washed with ethanol (3 ϫ 1 ml) and dried in vacuo.
Yield: 50.0/48.5 mg (83/80 %).
3
3
4H, H5/H6), 8.20 (d, JH3,H2 ϭ 4.98 Hz, 4H, H3/H8), 9.36 (d, JH2,H3
ϭ
4.98 Hz, 4H, H2/H9). 13C NMR (101 MHz, [D6]-dmso): δ 125.0 (s, C3/C8),
125.6 (s, C5/C6), 135.3 (s, C4a/C6a), 138.6 (s, C4/C7), 147.2 (s, C2/C9), 152.6
(s, C10a/C10b), 126.7 (s, i-C), 129.0 (s, p-C), 129.6 (s, o-C), 129.7 (s, m-C).
195Pt NMR (107 MHz): δ 3687 (s), [D6]-dmso; 4135 (s), [D7]-dmf. IR (CsBr):
3595 (vs), 3126 (vs), 3096 (vs), 1590 (vs), 1461 (s), 1442 (s), 1404 (s), 855
Anal. found: C, 35.69; H, 4.18; N, 4.70; Cl 22.66 %. Anal. calcd.
for C18H24Cl4N2Pt (605.31): C, 35.72; H, 4.00; N, 4.63; Cl, 23.43 %.
3
(vs), 765 (s), 703 (vs), 325 (vs) cmϪ1
.
1H NMR (400 MHz, CD3CN): δ 1.48 (s, 18H, CH3), 7.97 (dd, JH5,H6
ϭ
4
4
Synthesis of [PtCl4(Ph2phen)] (5)
To solution of 4,7-diphenyl-1,10-phenanthroline (33.2 mg,
6.40 Hz, JH5,H3 ϭ 2.34 Hz, 2H, H5/H5Ј), 8.51 (d, JH3,H5 ϭ 2.00 Hz, 2H,
3
3
H3/H3Ј), 9.42 (dϩdd, JH6,H5 ϭ 6.40 Hz, JPt,H6 ϭ 25.80 Hz, 2H, H6/H6Ј).
a
13C NMR (101 MHz, CD3CN): δ 30.3 (s, CH3), 37.1 (s, CMe3), 124.9 (sϩd,
0.10 mmol) in methanol (10 ml) (it may be necessary to add few
drops of methylene chloride to get a clear solution), a solution
of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1) (104.6 mg, 0.10 mmol) in
methanol (15 ml) was added. Stirring the resulting clear solution
for ca. 3 hours produced a yellow precipitate, which was filtered
off, washed with methanol (3 ϫ 1 ml) and dried in vacuo. Yield:
13.0 mg (19 %).
3JPt,C3 ϭ 20.4 Hz, C3/C3Ј), 127.5 (sϩd, JPt,C5 ϭ 26.3 Hz, C5/C5Ј), 147.9
3
(sϩd, JPt,C6 ϭ 14.7 Hz, C6/C6Ј), 155.1 (s, C4/C4Ј), 169.5 (s, C2/C2Ј). 195Pt
2
NMR (107 MHz): δ 4208 (s), [D6]-dmso; 4151 (s), CD3CN; 4097 (s), CD2Cl2.
IR (CsBr): 2967 (vs), 1617 (vs), 1421 (vs), 1252 (s), 856 (s), 345 cmϪ1
.
[PtCl2(bpy)] (3c) from decomposition of complex 3a
3
1H NMR (400 MHz, [D7]-dmf): δ 7.91 (dt, JH5,H4
ϭ
ϭ
3JH5,H6 ϭ 7.47 Hz,
3
4JH5,H3 ϭ 1.66 Hz, 2H, H5/H5Ј), 8.49 (dt, JH4,H5
3JH4,H3 ϭ 7.47 Hz,
Anal. found: C, 42.76; H, 2.63; N, 4.18; Cl 20.97 %. Anal. calcd.
for C24H16Cl4N2Pt (669.31): C, 43.07; H, 2.41; N, 4.19; Cl, 21.19 %.
3
4
4JH4,H6 ϭ 1.25 Hz, 2H, H4/H4Ј), 8.68 (dd, JH3,H4 ϭ 7.47 Hz, JH3,H5
ϭ
3
3
1.66 Hz, 2H, H3/H3Ј), 9.67 (dd, JH6,H5 ϭ 4.98 Hz, JH6,H4 ϭ 1.25 Hz, 2H,
H6/H6Ј). 13C NMR (101 MHz, [D7]-dmf): δ 124.8 (s, C3/C3Ј), 128.3 (s, C5/
C5Ј), 141.1 (s, C4/C4Ј), 149.3 (s, C6/C6Ј), 157.9 (s, C2/C2Ј). 195Pt NMR
(107 MHz, [D7]-dmf): δ 2194 (s). Spectra are identical with those of an auth-
entical sample (prepared according to lit. [19]) measured in the same solvent.
1H NMR (200 MHz, CD2Cl2): δ 7.63-7.67 (m, 10H, 2 ϫ C6H5), 8.04 (d,
3JH3,H2
ϭ
3JH8,H9 ϭ 4.98 Hz, 2H, H3/H8), 8.13 (s, 2H, H5/H6), 9.88 (d,
3JH2,H3 ϭ 3JH9,H8 ϭ 5.19 Hz, 2H, H2/H9). 1H NMR (200 MHz, [D6]-dmso):
δ 7.69-7.74, 7.82-7.84 (m, 10H, 2 ϫ C6H5), 8.32 (s, 2H, H5/H6), 8.44 (d,
3JH3,H2 ϭ 5.81 Hz, 2H, H3/H8), 9.80 (dϩd, JH2,H3 ϭ 5.81 Hz, JPt,H2
ϭ
3
3
27.39 Hz, 2H, H2/H9). 13C NMR (101 MHz, [D6]-dmso): δ 127.3/127.9 (s/s,
[PtCl2(tBu2bpy)] (3d) from decomposition of complex 3b
2
C3/C8, C5/C6), 134.2 (s, C4a/C6a), 145.1 (s, C4/C7), 148.1 (sϩd, JPt,C2
ϭ
1H NMR (400 MHz, [D7]-dmf): δ 1.45 (s, 18H, CH3), 7.90 (dd, JH5,H6
ϭ
3
19.2 Hz, C2/C9), 153.9 (s, C10a/C10b), 129.4 (s, i-C), 129.8 (s, p-C), 130.3 (s,
4
4
6.23 Hz, JH5,H3 ϭ 2.08 Hz, 2H, H5/H5Ј), 8.70 (d, JH3,H5 ϭ 2.08 Hz, 2H,
o-C), 130.5 (s, m-C). 195Pt NMR (107 MHz): δ 4188 (s), [D6]-dmso; 4146 (s),
H3/H3Ј), 9.51 (d, JH6,H5 ϭ 6.23 Hz, 2H, H6/H6Ј). 13C NMR (101 MHz,
3
[D7]-dmf. IR (CsBr): 1561 (s), 1421 (vs), 1403 (s), 765 (vs), 702 (vs) cmϪ1
.
Synthesis of [PtCl2(Ph2phen)] (6)
3) All complexes prepared in this work exhibit in solution C2ν sym-
metry. Thus couplings that are identical for symmetry reasons are
given only once.
To
a solution of 4,7-diphenyl-1,10-phenanthroline (99.7 mg,
0.30 mmol) in methanol (5 ml), a solution of (H3O)[PtCl5(H2O)] ·
708
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710

Ligand Substitution Reactions on Aquapentachloro- and Hexachloroplatinic Acid
2(18C6)·6H2O (1) (313.8 mg, 0.30 mmol) in methanol (5 ml) was
added. Mixing the clear solutions produced immediately a faint
orange precipitate. After addition of water (2 ml) the reaction mix-
ture was stirred at 40 °C for 10Ϫ30 hours with UV irradiation (Hg
medium-pressure lamp, Heraeus TQ150). The resulting yellow pre-
cipitate was filtered off, washed with methanol (3 ϫ 1 ml) and dried
in vacuo. Yield: 160.0 mg (89 %).
Table 6 Crystal data and details on the structure determination of
complexes [PtCl2(Ph2phen)] (6) and [PtCl4(bpym)]·MeOH (7).
6
7
Empirical formula
Mr
C24H16Cl2N2Pt
598.38
monoclinic
P21/n
15.332(3), 17.502(4),
15.574(3)
90, 104.18(2), 90
4052(1)
C9H6Cl4N4OPt
523.07
orthorhombic
Pcab
18.294(3), 11.921(1),
13.270(2)
90, 90, 90
2893.9(7)
8
Crystal system
Space group
Anal. found: C, 48.17; H, 2.87; N, 4.66; Cl 11.88 %. Anal. calcd.
for C24H16Cl2N2Pt (598.41): C, 48.17; H, 2.70; N, 4.68; Cl, 11.85 %.
˚
˚
˚
a/A, b/A, c/A
1H NMR (200 MHz, CD2Cl2): δ 7.63 (s, 10H, 2 ϫ C6H5), 7.88 (d, 3JH3,H2 ϭ
α/°, β/°, γ/°
3
˚
3
V/A
5.61 Hz, 2H, H3/H8), 8.07 (s, 2H, H5/H6), 9.96 (d, JH2,H3 ϭ 5.60 Hz, 2H,
H2/H9). 1H NMR (400 MHz, [D7]-dmf): δ 7.71-7.72, 7.83-7.86 (m, 10H, 2
ϫ C6H5), 8.21 (s, 2H, H5/H6), 8.22 (d, 3JH3,H2 ϭ 5.67 Hz, 2H, H3/H8), 9.89
(d, 3JH2,H3 ϭ 5.66 Hz, 2H, H2/H9). 13C NMR (126 MHz, [D7]-dmf): δ 126.7/
127.0 (s/s, C3/C8, C5/C6), 136.5 (s, C4a/C6a), 149.0 (s, C4/C7), 149.3 (s, C2/
C9), 151.9 (s, C10a/C10b), 129.6 (s, i-C), 129.9 (s, p-C), 130.5 (s, o-C), 130.6
(s, m-C). 195Pt NMR (107 MHz, [D7]-dmf): δ 2179 (s). IR (CsBr): 3450 (s),
Z
8
Dber./g cmϪ3
1.962
7.203
2.401
10.430
µ/mmϪ1
F(000)
θ range/°
Refl. collected
Refl. observed [I > 2σ(I)]
Refl. independent
2288
2.04Ϫ25.97
31086
1936
2.23Ϫ25.83
12179
3413 (s), 1621 (s), 1557 (s), 1418 (s), 763 (s), 699 (vs), 231 (s) cmϪ1
.
6281
2043
7806 (Rint ϭ 0.0825) 2774 (Rint ϭ 0.0749)
Data/restraints/parameters 7806/0/523
2774/0/183
0.986
0.0321, 0.0727
0.0521, 0.0779
1.157/Ϫ0.999
Goodness-of-fit on F2
R1, wR2 [I>2σ(I)]
R1, wR2 (all data)
1.014
NMR data of [PtCl2(Ph2phen)] (6) prepared according to lit. [10d]:
1H NMR (400 MHz, CD2Cl2): δ 7.63 (s, 10H, 2 ϫ C6H5), 7.88 (d, 3JH3,H2 ϭ
0.0309, 0.0709
0.0437, 0.0744
3
Largest diff. peak/hole /eAϪ3 0.928/Ϫ1.562
5.81 Hz, 2H, H3/H8), 8.07 (s, 2H, H5/H6), 9.96 (d, JH2,H3 ϭ 5.81 Hz, 2H,
H2/H9). 1H NMR (400 MHz, [D6]-dmso): δ 7.66-7.72 (m, 10H, 2 ϫ C6H5),
3
8.11 (s, 2H, H5/H6), 8.15 (d, JH3,H2 ϭ 5.40 Hz, 2H, H3/H8), 9.37 (d,
3JH2,H3 ϭ 5.40 Hz, 2H, H2/H9). 13C NMR (101 MHz, [D6]-dmso): δ 126.4/
126.6 (s/s, C3/C8, C5/C6), 135.7 (s, C4a/C6a), 148.3 (s, C4/C7), 149.0 (s, C2/
C9), 151.0 (s, C10a/C10b), 128.8 (s, i-C), 129.6 (s, p-C), 130.0 (s, o-C), 130.3
(s, m-C). 195Pt NMR (107 MHz, [D6]-dmso): δ 2179 (s).
Crystallographic studies
Single crystals of complexes 6 and 7 suitable for X-ray diffraction
analysis were grown from [D7]-dmf and methanol solutions, respec-
tively. The X-ray measurements were performed at 220(2) K on a
Synthesis of [PtCl4(bpym)]·MeOH (7)
˚
STOE IPDS image plate system using MoKα radiation (0.71073 A,
With stirring, to a solution of (H3O)[PtCl5(H2O)]·2(18C6)·6H2O
(1) and H2[PtCl6]·6H2O (2) (0.10 mmol), respectively, in methanol
(10 ml) a solution of 2,2Ј-bipyrimidine (15.8 mg, 0.10 mmol) in
methanol (10 ml) was added resulting in formation of yellowish
precipitates. Heating at 60 °C for 6 h resulted in formation of red-
orange precipitates (7) that were filtered off, washed with methanol
(3 ϫ 1 ml) and dried in vacuo. Yield: 30.0/40.0 mg (57/76 %).
graphite monochromator). Absorption corrections were carried out
numerically (Tmin/Tmax 0.288/0.597, 6; 0.198/0.722, 7). A summary
of crystallographic data, data collection parameters, and refine-
ment parameters is given in Table 6. The structures were solved by
direct methods with SHELXS-97 and refined using full-matrix
least-squares routines against F2 with SHELXL-97 [20]. Non-hy-
drogen atoms were refined with anisotropic displacement param-
eters. Hydrogen atoms were included in calculated positions and
refined with isotropic displacement parameters according to the
riding model. The oxygen atom of solvate molecule in 7 (MeOH)
is disordered over two positions with 60/40 % probability; hydrogen
atoms of MeOH were not found and not included into the model.
Crystallographic data (excluding structure factors) have been de-
posited at the Cambridge Crystallographic Data Center as sup-
plementary publication nos. CCDC-203726 (6) and CCDC-203725
(7). Copies of the data can be obtained free of charge on appli-
cation to CCDC, 12 Union Road, Cambridge, CB2, 1EZ, UK [Fax:
(internat.) ϩ44(0)1223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
3
3
1H NMR (400 MHz, [D6]-dmso): δ 8.36 (dd, JH5,H6 ϭ 5.81 Hz, JH5,H4
ϭ
3
4
4.98 Hz, 2H, H5/H5Ј), 9.56 (dd, JH4,H5 ϭ 4.98 Hz, JH4,H6 ϭ 1.66 Hz, 2H,
H4/H4Ј), 9.79 (ddϩdd, JH6,H5 ϭ 5.81 Hz,4JH6,H4 ϭ 1.66 Hz,3JPt,H6
ϭ
3
25.73 Hz, 2H, H6/H6Ј). 13C NMR (101 MHz, [D6]-dmso): δ 127.2 (sϩd,
3JPt,C5 ϭ 21.2 Hz, C5/C5Ј), 154.7 (s, C6/C6Ј), 158.1 (sϩd, 2JPt,C2 ϭ 16.8 Hz,
C2/C2Ј), 163.7 (s, C4/C4Ј). 195Pt NMR (107 MHz, [D6]-dmso): δ 4088 (s).
IR (CsBr): 3063 (m), 1578 (vs), 1451 (m), 1407 (vs), 1029 (m), 818 (m), 739
(m), 672 (m), 350 (s) cmϪ1
.
1H NMR spectra revealed that the product prepared from 1 con-
tained about 8 % [PtCl2(bpym)] (9) and from 2 about 9 %
[PtCl2(bpym)] (9) and 13 % (bpymH)ϩ (8, probably as chloride or
as hexachloroplatinate).
Quantum chemical calculations
Synthesis of [PtCl2(bpym)] (9)
All DFT calculations were carried out by the Gaussian98 [21] pro-
gram package using the hybrid functional B3LYP [22]. For the
main group atoms the basis set 6-31G* [23] was employed. The
valence shell of platinum has been approximated by a split valence
basis set too, for its core orbitals an effective core potential in com-
bination with consideration of relativistic effects has been used [24].
All systems have been fully optimized without any symmetry re-
strictions. The resulting geometries were characterized as equilib-
rium structures by the analysis of the force constants of the normal
vibrations. Bond orders were obtained by the natural bond orbital
(NBO) analysis of Reed et al. [25] as implemented in Gaussian98.
Final coordinates and energies of all calculated structures are given
in Supplemental Material available on request from the authors.
Analogous reaction as described above between 2,2Ј-bipyrimidine
(15.8 mg, 0.10 mmol) and (H3O)[PtCl5(H2O)]·2(18C6)·6H2O (1)
(104.6 mg, 0.10 mmol) in methanol (8 ml) but with UV light (Hg
medium-pressure lamp, Heraeus TQ150) resulted in a brick-reddish
precipitate of 9. Yield: 40.0 mg (94 %).
Anal. found: C, 21.50; H, 1.50; N, 12.95; Cl 17.05 %. Anal. calcd.
for C8H6Cl2N4Pt (424.16): C, 22.65; H, 1.43; N, 13.21; Cl, 16.72 %.
3
3
1H NMR (400 MHz, [D6]-dmso): δ 7.99 (dd, JH5,H6 ϭ 5.81 Hz, JH5,H4
ϭ
4.77, 2H, H5/H5Ј), 9.34 (dd, 3JH4,H5 ϭ 4.77 Hz, 4JH4,H6 ϭ 1.87 Hz, 2H, H4/
H4Ј), 9.69 (dd, JH6,H5 ϭ 5.92 Hz, JH6,H4 ϭ 1.97 Hz, 2H, H6/H6Ј). 13C
NMR (101 MHz, [D6]-dmso): δ 125.4 (s, C5/C5Ј), 155.6 (s, C6/C6Ј), 160.6 (s,
C4/C4Ј), 162.8 (s, C2/C2Ј). 195Pt NMR (107 MHz, [D6]-dmso): δ 2135 (s).
3
4
IR (CsBr): 1581 (vs), 1552 (m), 1405 (vs), 739 (s), 675 (m), 340 (m) cmϪ1
.
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710
709

A. Gaballa, C. Wagner, H. Schmidt, D. Steinborn
[14] T. W. Hambley, Acta Crystallogr. 1986, C42, 49.
Acknowledgment. We thank the Deutsche Forschungsgemeinschaft
for financial support as well as Merck (Darmstadt) and Degussa
(Hanau) for gifts of chemicals. A. G. is thankful for a graduate
fellowship provided by the Egyptian government (Channel pro-
gramme).
[15] P. Ferreira, W.-M. Xue, E. Bencze, E. Herdtweck, F. E. Kühn,
Inorg. Chem. 2001, 40, 5834 and literature cited therein.
[16] (a) R. G. Wilkins, Kinetics and Mechanism of Reactions of
Transition Metal Complexes, VCH Verlagsgesellschaft,
Weinheim 1991. (b) J. D. Atwood, Inorganic and Organometal-
lic Reaction Mechanisms, VCH Publishers, New York 1997.
[17] A. Vjaters, PhD Thesis, Univ. Halle-Wittenberg, 2001.
[18] C. K. McGill, US Patent 4177349 (1979) [Chem. Abstr.
92:110871].
[19] G. T. Morgan, F. H. Burstall, J. Chem. Soc. 1934, 965.
[20] G. M. Sheldrick, SHELXS-97, SHELXL-97. Programs for the
Solution and Refinement of Crystal Structures, University of
Göttingen, Germany 1997.
˚
References
[1] (a) L. I. Elding, L. Gustafson, Inorg. Chim. Acta 1976, 19, 31.
(b) L. Drougge, L. I. Elding, Inorg. Chim. Acta 1986, 121, 175.
[2] L. E. Cox, D. G. Peters, E. L. Wehry, J. Inorg. Nucl. Chem.
1972, 34, 297.
[3] D. Steinborn, O. Gravenhorst, H. Hartung, U. Baumeister,
Inorg. Chem. 1997, 36, 2195.
[21] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M.
A. Robb, J. R. Cheeseman, V. G. Zakrzewski, J. A. Montgom-
ery, Jr., R. E. Stratmann, J. C. Burant, S. Dapprich, J. M.
Millam, A. D. Daniels, K. N. Kudin, M. C. Strain, O. Farkas,
J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Mennucci, C.
Pomelli, C. Adamo, S. Clifford, J. Ochterski, G. A. Petersson,
P. Y. Ayala, Q. Cui, K. Morokuma, D. K. Malick, A. D.
Rabuck, K. Raghavachari, J. B. Foresman, J. Cioslowski, J. V.
Ortiz, A. G. Baboul, B. B. Stefanov, G. Liu, A. Liashenko, P.
Piskorz, I. Komaromi, R. Gomperts, R. L. Martin, D. J. Fox,
T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M.
Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W.
Wong, J. L. Andres, C. Gonzalez, M. Head-Gordon, E. S.
Replogle, J. A. Pople, Gaussian 98, Revision A.9, Gaussian
Inc., Pittsburgh PA 1998.
ˇ
[4] D. Steinborn, O. Gravenhorst, C. Bruhn, D. Miklos, M. Du-
ˇ
naj-Jurco, A. Kolbe, Z. Anorg. Allg. Chem. 1997, 623, 1954.
[5] B. Rosenberg, L. Van Camp, J. E. Trosko, V. H. Mansour,
Nature 1969, 222, 385.
[6] (a) B. K. Keppler (ed.), Metal Complexes in Cancer Chemo-
therapy, VCH, Weinheim 1993. (b) B. Lippert (ed.), Cisplatin:
Chemistry and Biochemistry of a Leading Anticancer Drug,
WILEY-VCH, Weinheim 1999.
[7] (a) D. Steinborn, O. Gravenhorst, H. Junicke, F. W. Heine-
mann, Z. Naturforsch. 1998, 53b, 581. (b) O. Gravenhorst, C.
Bruhn, R. Herzog, D. Steinborn, Z. Anorg. Allg. Chem. 1999,
625, 1349.
[8] D. Steinborn, H. Junicke, Chem. Rev. 2000, 100, 4283.
[9] X. Zhu, E. Rusanov, R. Kluge, H. Schmidt, D. Steinborn,
Inorg. Chem. 2002, 41, 2667.
[22] (a) R. Krishnan, J. R. Binkley, R. Seeger, J. A. Pople, J. Chem.
Phys. 1980, 72, 650. (b) A. D. Becke, J. Chem. Phys. 1986, 84,
4525. (c) C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37,
785. (d) A. D. Becke, J. Chem. Phys. 1993, 98, 5648.
[23] I. N. Levine, Quantum Chemistry, Prentice-Hall International,
London 1991, 463.
[10] Selected references: (a) K. D. Hodges, J. V. Rund, Inorg. Chem.
1975, 14, 525. (b) A. Peloso, J. Chem. Soc., Dalton Trans. 1976,
984. (c) A. Vogler, H. Kunkely, Angew. Chem. 1982, 94, 217.
(d) F. P. Fanizzi, G. Natile, M. Lanfranchi, A. Tiripicchio, F.
Laschi, P. Zanello, Inorg. Chem. 1996, 35, 3173.
´
[11] J.-Y. Lallemand, J. Soulie, J.-C. Chottard, J. Chem. Soc.,
[24] D. Andrae, U. Häußermann, M. Dolg, H. Stoll, H. Preuß,
Theor. Chim. Acta 1990, 77, 123.
Chem. Commun. 1980, 436.
[12] R. G. Kidd, Annual Reports NMR Spectroscopy 1991, 23, 85.
´
´
[13] C. B. Aakeröy, T. A. Evans, K. R. Seddon, I. Palinko, New. J.
[25] A. E. Reed, R. B. Weinstock, F. J. Weinhold, J. Chem. Phys.
1985, 83, 735.
Chem. 1999, 23, 145.
710
Z. Anorg. Allg. Chem. 2003, 629, 703Ϫ710