Inorganica Chimica Acta 256 (1997) 87–92

0020-1693/97/$17.00 q 1997 Elsevier Science S.A. All rights reserved

PII S0020-1693(96)05422 -9

Journal: ICA (Inorganica Chimica Acta) Article: 5422

The crown ether influence on ligand exchange reactions of Na

2

PtCl

6

with

glycine and D-(q)-alanine; synthesis and characterization of

platinum(IV) amino acid complexes

1

Dirk Steinborn

U, Henrik Junicke, Frank W. Heinemann

Institut fur Anorganische Chemie der Martin-Luther-Universitat Halle-Wittenberg, Kurt-Mothes-Strasse 2, D-06120 Halle, Germany

Received 28 March 1996

Abstract

The reaction of Na

2

PtCl

6

with glycine in water yields cis-[PtCl2

(gly)

2

] (1). [Na(18-cr-6)]2

[PtCl

6

]P3H2

O reacts with glycine and

D-(q)-alanine in water to give [Na(18-cr-6)(H

2

O)

2

][PtCl

4

(gly)]P(18-cr-6) (2) and [Na(18-cr-6)][PtCl4

(ala)] (3), respectively.Cis-[PtCl

4

(glyH)

2

]P2(18-cr-6) (4) and cis-[PtCl4

(alaH)

2

]P(18-cr-6) (5), respectively, are formed when the reaction mixture is irradiated

with light from a halogen lamp. All complexes were characterized by microanalysis as well as by NMR, IR and Raman spectroscopy revealing

that in complexes 1–3 the glycinato and alaninato ligands act as N,O-chelate ligands whereas in complexes 4 and 5 the amino acids act as N-

donor ligands. The molecular structure of 1 (orthorhombic, Pbca, as10.163(2), bs11.028(2), cs16.310(4) A

˚

, Zs8, R1

s0.0413,

wR2

s0.0953) exhibits a distorted octahedral coordinated Pt atom with a cis-PtCl2

unit and two N,O-coordinated glycinato ligands (OC-6-32). The complex is stabilized by intramolecular hydrogen bonds between the amino group and the C–O group as well as the chloro ligand.

The crystal structure of 2 (orthorhombic, Pnma, as23.262(9), bs11.149(4), cs15.834(5) A

˚

, Zs4, R1

s0.067, wR2

s0.1644) shows a

[PtCl

4

(gly)]

yunit and an [Na(18-cr-6)(H

2

O)

2

]

qunit linked via hydrogen bridges with a further crown ether molecule.

Keywords: Crystal structures; Platinum complexes; Amino acid complexes; Crown ether complexes

1. Introduction

There has been increasing interest in complexes of plati-

num(IV) with biologically important ligands because of

the recent development of new anti-cancer drugs of plati-

num(IV) [1,2] and the evidence that they may react with

DNA without being reduced to platinum(II) [3]. Compared

to the numerous complexes of platinum(II)with amino acids

as ligands, there are much fewer examples of such plati-

num(IV) complexes [4]. These were prepared by oxidation

of platinum(II) amino acid complexes [5] or in the case of

trimethylplatinum(IV) derivatives by ligand substitution

reactions starting with [PtMe

3

(H

2

O)

3

]

q[6]. [PtCl

6

]

2yas

startingmaterial is described to be unsuitable due to its kinetic

inertness and/or a partial reduction to give platinum(II)

[4,5].

We report here on the synthesis of novel platinum(IV)

amino acid complexes by simple ligand exchange reactions

Abbreviations: glyHsglycine; alaHsD-(q)-alanine; 18-cr-6s18-crown-6.

UCorresponding author.

1

Dedicated to Professor Rudolf Taube on the occasion of his 65th

birthday.

with Na

2

[PtCl

6

] and its crown ether adduct, [Na(18-cr-

6)]

2

[PtCl

6

]P3H2

O, as starting materials.

2. Results and discussion

Sodium hexachloroplatinate reacts with an excess of gly-

cine in aqueous solution to give the glycinato platinum(IV)

complex cis-[PtCl2

(gly)

2

] (1) as well-shaped yellow crys-

tals. The reaction proceeds at room temperature within 1–2

weeks. The homologous amino acidD-(q)-alanine does not

react in the same way.

Glycine and D-(q)-alanine react with [Na(18-cr-

6)]

2

[PtCl

6

]P3H2

O according to Eq. (1).

D. Steinborn et al. / Inorganica Chimica Acta 256 (1997) 87–9288

Journal: ICA (Inorganica Chimica Acta) Article: 5422

Table 1

Selected IR and Raman oscillations of platinum(IV) amino acid complexes 1–5

Complex IR (cm

y1

) Raman

a

(cm

y1

)

n(C_O) n(C–Oy) n(Pt–N) n(Pt–Cl) n(Pt–Cl)

1 1678vs 1596s 408m 365s, 350s

2 1704vs 1645s 399m 355m, 336s, 328sh, 321sh 344m, 328s, 322sh

3 1698vs 1645m 407w 354s, 338vs, 325sh, 318sh 350m, 336vs, 296w

4 1702vs 399m 350sh, 340s, 328sh 351vs, 340m, 325vs

5 1703vs 407m 358m, 341s, 329sh 352m, 337sh, 328vs

a

Weaker bands at 360–400 cm

y1

were not assigned.

Table 2

Selected bond lengths (A

˚

) and angles (8) of cis-[PtCl2

(gly)

2

] (1)

Pt1–Cl1 2.288(2) N1–C1 1.48(1)

Pt1–Cl2 2.311(2) N2–C3 1.49(1)

Pt1–N1 2.034(6) C2–O1 1.21(1)

Pt1–N2 2.040(6) C4–O3 1.21(1)

Pt1–O2 2.010(6) C2–O2 1.32(1)

Pt1–O4 2.019(5) C4–O4 1.31(1)

Cl1–Pt1–Cl2 92.49(7) Cl1–Pt1–O4 175.3(2)

Cl1–Pt1–O2 175.3(2) Cl1–Pt1–N2 89.8(2)

Cl2–Pt1–N2 174.0(2) N1–C1–C2 112.6(9)

Cl2–Pt1–O4 90.8(2) N2–C3–C4 111.9(7)

N1–Pt1–O4 175.4(3) C1–C2–O1 121.9(7)

N2–Pt1–O4 83.5(3) C3–C4–O3 120.9(7)

N1–Pt1–N2 96.6(3) O1–C2–O2 120.8(8)

N1–Pt1–O2 84.4(2) O3–C4–O4 122.8(8)

Hydrogen bonds

N2–H3∆Cl1 3.059(7) N2–H3∆O1

b

2.784(10)

N2–H4∆O2 2.775(10) N1–H2∆O1

c

2.872(9)

N1–H1∆O3

a

2.971(9) N2–H4∆O4

d

2.950(9)

a x, 1/2yy, y1/2qz.b

1/2yx, 1/2qy, z.c

1/2yx, 1/2qy, z.d

1/2qx, y, 1/2yz.Fig. 1. Molecular structure of cis-[PtCl2

(gly)

2

] (1).

The reaction is influenced by light. Without irradiation

anionic platinate(IV) complexes (2, 3) are formed with a

chelating N,O-coordinated glycinato and alaninato ligand,

respectively. When the reaction mixture is irradiated with

halogen lamps (200 W) neutral complexes of platinum(IV)

(4, 5) with two monodentate N-coordinated glycine and ala-

nine ligands are yielded.

The N,O-coordination of amino acid ligands in 1–3 and

the N-coordination in 4 and 5 were revealed by vibrational

spectroscopy (IR, Raman) analyzing n(Pt–N) andn(C–O),

see Table 1. Because of the chelate formation, 2 and 3 have

to be in cis configuration (OC-6-11). The n(Pt–Cl) in 2–5are very similar and in accordance with a localC

2v symmetry

of the PtCl

4

unit [7]. Thus, the cis configuration (OC-6-11)of 4 and 5 was established. In all complexes the

1

H NMR

signals are shifted downfield in comparison with the non-

coordinated amino acids. A coupling

3J(195Pt,1H) could notbe observed.

The molecular structure of 1 is shown in Fig. 1. Selected

bond lengths and angles are listed in Table 2. The Pt atom

exhibits a distorted octahedral coordination with a cis-PtCl2

unit and two N,O-coordinated glycinato ligands forming the

configuration OC-6-32. In accordance with the higher transinfluence of the amino group compared to the carboxylate

group, the Pt–Cl2 bond (2.311(2) A

˚

) is longer than the

Pt–C11 bond (2.288(2) A

˚

). Both chelate rings (ring 1: Pt1,

N1, C1, C2, O2; ring 2: Pt1, N2, C3, C4, O4) are almost

planar. The maximum deviations from the corresponding

least-squares planes amount to 0.157(8) A

˚

(atom C1 of ring

1) and 0.205(9) A

˚

(atom C3 of ring 2), respectively. The

remarkable difference of the exo- and endocyclic C–O bond

lengths (ring 1: 1.21(1) versus 1.32(1) A

˚

; ring 2: 1.21(1)

versus 1.31(1) A

˚

) indicates a distinguished double bond

character of both exocyclic C–O bonds. This is in contrast to

the observations made for the closely related complex cis-[PtMe

2

(gly)

2

] [8], in which both C–O bonds are of com-

parable length (1.244 versus 1.268 A

˚

).

The formation of complex 1 with its configuration OC-6-32 (there are another four configurational isomers) could be

related to the stabilizing effect of the intramolecularhydrogen

bonds (N2–H4∆O2, N2–H3∆Cl1) between the amino

group and the carboxylate group as well as the chloro ligand,

see Table 2. Furthermore, there are intermolecular hydrogen

bonds between the exocyclic C_O group and the NH

2

group

(N1–H1∆O3) in the crystalline state.

The first molecular structure of a complex with a PtCl

4

unit

and an N,O-coordinated amino acid (2) is shown in Fig. 2.

D. Steinborn et al. / Inorganica Chimica Acta 256 (1997) 87–92 89

Journal: ICA (Inorganica Chimica Acta) Article: 5422

Fig. 2. Molecular structure of [Na(18-cr-6)(H

2

O)

2

][PtCl

4

(gly)]P

(18-cr-6) (2).

Table 3

Selected bond lengths (A

˚

) and angles (8) of [Na(18-cr-6)(H

2

O)

2

]-

[PtCl

4

(gly)]P(18-cr-6) (2)

Pt1–Cl1 2.307(6) C1–C2 1.52(4)

Pt1–Cl2 2.318(4) C2–N1 1.35(2)

Pt1–Cl3 2.302(6) Na1–O7 2.68(2)

Pt1–N1 2.11(2) Na1–O8 2.83(2)

Pt1–O1 2.07(2) Na1–O9 2.67(2)

C1–O1 1.29(3) Na1–O10 2.33(2)

C1–O2 1.25(3) Na1–O11 2.29(2)

N1–Pt1–O1 84.7(6) O1–Pt1–Cl1 89.2(5)

N1–Pt1–Cl29 92.4(5) Cl1–Pt1–Cl3 93.7(3)

N1–Pt1–Cl1 173.9(5) N1–Pt1–Cl2 87.5(1)

O1–Pt1–Cl2 88.9(1) O11–Na1–O10 178.9(7)

Cl3–Pt1–Cl2 90.9(1) O10–Na1–O9 87.8(6)

Cl2–Pt1–Cl29 174.8(2) O7–Na1–O9 118.0(7)

O1–Pt1–Cl3 177.2(5) O9–Na1–O99 62.6(9)

Hydrogen bonds

N1–H1∆O5 3.02(2) O11–H∆O6

a

2.96(2)

C2–H2∆O4 3.30(2) C9–H9A∆O2

b

3.34(3)

O11–H∆O3

a

2.95(2) C10–H10A∆O2

c

3.13(3)

a

Hydrogen not localized.

b

1/2yx, yy, 1/2qz.c

1/2yx, yy, 1/2qz.

Selected bond lengths and angles are listed in Table 3. The

complex is characterized by a crystallographically imposed

Cs symmetry. The Pt atom exhibits a distorted octahedral

coordination with an N,O-coordinated glycinato ligand. The

chelate ring (Pt, O1, C1, O2, C2, N1) is exactly planar due

to the crystallographic Cs symmetry. Different from complex

1, the two C–O bond lengths of the carboxylate group in 2are equal within the 3s criterion (1.25(3) versus 1.29(3)

A

˚

) indicating a delocalization of p electrons.

The sodium ion exhibits the coordination number 8 form-

ing an [Na(18-cr-6)(H

2

O)

2

]

qunit. Four O atoms of the

crown ether (O7, O79, O9, O99) lie exactly in a plane from

which Na

qis only slightly deviated (0.041(9) A

˚

). Such a

‘boat’ conformation is quite common for 18-crown-6 com-

plexed to Na

q[9,10]. The additional coordination of water

to Na

qseems to stabilize the significantly smaller Na

qin the

crown ether ring.

The [Na(18-cr-6)(H

2

O)

2

]

qand the [PtCl

4

(gly)]

yunits

are linkedwithin the crystal by a further crown ethermolecule

via hydrogen bonds, see Table 3. This crown ether molecule

has the same conformation as the one in the [Na(18-cr-

6)(H

2

O)

2

]

qunit. The four oxygen atoms lying in the plane

(O4, O5, O49, O59) form hydrogen bonds to the amino and

methylene group of the glycinato ligand. The other two O

atoms (O3, O6) form hydrogen bonds with one water mol-

ecule (O11) of the cation [Na(18-cr-6)(H

2

O)

2

]

q. At least,

an intermolecular hydrogen bond between amethylenegroup

of the Na containing crown ether and the C_O group of the

glycinato ligand has to be mentioned (C10–H10A∆O2 ;

U

d(C10–O2 )s3.13(3) A

˚

).

U

The loss of one crown ether molecule in the analogous

alanine complex 3 could be a consequence of preventing

strong hydrogen bonds between the alaninato ligand and the

crown ether due to the steric demand of the methyl group of

alanine.

It has been known for a long time that sunlight produces a

profound acceleration of substitution reactions with hexa-

chloroplatinates [11]. Thus, it can be understood thatwithout

irradiation complexes of platinum(IV) are yielded with one

N,O-coordinated amino acid ligand in its anionic form in the

reaction described. With irradiation, a further substitution

reaction takes place to give complexes of platinum(IV)with

two N-coordinated amino acid ligands in cis position. Inves-tigations on the role and the influence of the crown ether on

these reactions are in progress.

3. Experimental

3.1. General

Spectra were recorded on the following instruments:

1

H

NMR: Varian NMR spectrometers Unity 500 and Gemini

200 using solvent signals as internal references

(d(CHCl3

)s7.24 ppm, d(H2

O)s4.8, d(DMSO)s2.58);

195

Pt NMR: Bruker AC80 using Na

2

PtCl

6

(dsq4520 ppm)

for external reference (J(

195

Pt)s21.4 MHz); IR/Raman:

Unicam IR spectrometer Galaxy using CsBr and Bruker IR/

Raman spectrometer IFS66/FRA 106. Microanalyses were

performed by the Microanalytical Laboratory of the Phar-

maceuticalDepartment of theUniversity.H

2

PtCl

6

P6H2

Owas

commercially available (DEGUSSA GmbH).

[Na(18-cr-6)]2[PtCl6]P3H2O. An aqueous solution of

Na

2

PtCl

6

(3.67 mmol), prepared by combining solutions of

H

2

PtCl

6

P6H2

O (1.79 g, 3.67 mmol) in water (3 ml) and

Na

2

CO

3

(389 mg, 3.67 mmol) in water (3 ml), was finally

added to a solution of 18-cr-6 (3.83 g, 14.50 mmol) in water

(6 ml). The solvent was evaporated to half of its volume.

After 2 days, cubic orange crystals of [Na(18-cr-6)]

2

-

[PtCl

6

]P3H2

O were separated, washed with a small amount

of water and dried (yield 2.3 g, 60%).

Anal. Calc. for C24

H

54

Cl

6

Na

2

O

15

Pt (1036.45): C, 27.81;

H, 5.25; Cl, 20.52; Pt, 18.82. Found: C, 28.12; H, 5.21; Cl,

D. Steinborn et al. / Inorganica Chimica Acta 256 (1997) 87–9290

Journal: ICA (Inorganica Chimica Acta) Article: 5422

Table 4

Crystallographic and data collection parameters for compounds 1 and 2

1 2

Formula C

4

H

8

Cl

2

N

2

O

4

Pt C

26

H

56

Cl

4

NNaO

16

Pt

Formula weight 414.11 998.59

Temperature (K) 200(2) 293(2)

Crystal size (mm) 0.53=0.34=0.23 0.61=0.38=0.23

Crystal system orthorhombic orthorhombic

Space group Pbca PnmaUnit cell dimensions

a (A

˚

)/a (8) 10.163(2)/90 23.262(9)/90

b (A

˚

)/b (8) 11.028(2)/90 11.149(4)/90

c (A˚ )/g (8) 16.310(4)/90 15.834(5)/90

V (A

˚

3

) 1828.0(7) 4107(3)

Density (calc.) (Mg m

y3

) 3.009 1.609

Z 8 4

m(Mo Ka) (nmy1

) 15.92 3.75

F(000) 1520 2000

u Range for data collection (8) 2.50–29.99 1.56–21.50

Reflections collected 2655 2632

Independent reflections 2655 (Rint

s0.0000) 2507 (Rint

s0.0360)

Transmission: max., min. 0.0680, 0.0223 0.090, 0.052

Data/restraints/parameters 2655/0/151 2481/6/241

Goodness-of-fit on F2

1.262 1.365

Final indices R1

/wR2

(I)2s(I)) 0.0413/0.0953 0.0671/0.1483

R1

/wR2

(all data) 0.0413/0.0953 0.1022/0.1644

Largest difference peak and hole (e A

˚

y3

) 2.300 and y1.399

a

2.787 and y0.805

a

a

The highest peaks are localized close to the Pt atom.

20.45; Pt, 18.33%.

1

HNMR: d (ppm, CDCl

3

) 3.60 (s, CH2

).

195

Pt NMR: d (ppm, D

2

O) 4535 (s). IR: 326vs (Pt–Cl)

cm

y1

.

3.2. Syntheses

3.2.1. Cis-[PtCl2(gly)2] (1)To a solution of Na

2

PtCl

6

(200 mg, 0.40 mmol) in water

(4 ml) a solution of glycine (179 mg, 2.38 mmol) in water

(1 ml) was added. After one week the orange color of the

solution had been changed to yellow and after a further week

the yellow precipitation of 1 was separated, washed with a

small amount of water and dried (yield 42 mg, 26%).

1

H NMR: d (ppm, DMSO-d

6

) 3.28 (s, CH2

), 7.56 (s,

NH2

, broad).

3.2.2. [Na(18-cr-6)(H2O)2][PtCl4(gly)]P(18-cr-6) (2)To a solution of [Na(18-cr-6)]

2

[PtCl

6

]P3H2

O (800 mg,

0.77 mmol) in water (4 ml) a solution of glycine (348 mg,

4.64 mmol) in water (4 ml) was added. After one week the

orange color of the solution had changed to yellowandyellow

crystals of 2 were separated, washed with a small amount of

water and dried (yield 207 mg, 27%).

Anal. Calc. for C26

H

56

Cl

4

NNaO

16

Pt (998.59): C, 31.27;

H, 5.65; N, 1.40; Cl, 14.20. Found: C, 31.16; H, 5.50; N,

1.41; Cl, 14.42%.

1

H NMR: d (ppm, DMSO-d

6

) 3.36 (s,

CH2

, 2H), 3.51 (s, CH2

, 48H), 7.34 (s, NH2

, broad).

195

Pt

NMR: d (ppm, D

2

O) 4817.

3.2.3. [Na(18-cr-6)][PtCl4(ala)] (3)To a solution of [Na(18-cr-6)]

2

[PtCl

6

]P3H2

O (600 mg,

0.58 mmol) in water (6 ml) a solution of D-(q)-alanine

(153 mg, 1.70 mmol) in water (2 ml) was added. Within 30

days, 3 crystallized in well-shaped yellow needles, which

were separated and dried (yield 244 mg, 59%).

Anal. Calc. for C15

H

30

Cl

4

NNaO

8

Pt (712.28): C, 25.29; H,

4.25; N, 1.97; Cl, 19.90. Found: C, 25.19; H, 4.53; N, 2.04;

Cl, 19.18%.

1

H NMR: d (ppm, D

2

O) 1.51 (d, CH3

, 3H),

3.62 (s, CH2

, 24H), 4.11 (q, CH, 1H).

195

Pt NMR: d (ppm,

D

2

O) 4817.

3.2.4. Cis-[PtCl4(glyH)2]P2(18-cr-6) (4)To a solution of [Na(18-cr-6)]

2

[PtCl

6

]P3H2

O (600 mg,

0.58 mmol) in water (6 ml) a solution of glycine (260 mg,

3.46 mmol) in water (2 ml) was added. The solution was

irradiated with halogen lamps (200 W) and stirred for 12 h

at room temperature. The yellow solution was evaporated in

vacuo to 2 ml where upon complex 4 precipitated as a yellowpowder. 4 was filtered off, washed with a small amount of

water and dried (yield 178 mg, 30%).

Anal. Calc. for C28

H

58

Cl

4

N

2

O

16

Pt (1015,65): C, 33.11; H,

5.76;Cl, 13.96; Pt, 19.22. Found:C, 32.66;H, 5.48;Cl, 14.33;

Pt, 19.16%.

1

H NMR: d (ppm, DMSO-d

6

) 3.51 (s, CH2

,

4H), 3.68 (s, CH2

, 48H), 8.0 (s, NH2

, broad).

3.2.5. Cis-[PtCl4(alaH)P18-cr-6 (5)To a solution of [Na(18-cr-6)]

2

[PtCl

6

]P3H2

O (400 mg,

0.38 mmol) in water (4 ml) a solution of D-(q)-alanine

(204 mg, 2.28 mmol) in water (2 ml) was added. Complex

D. Steinborn et al. / Inorganica Chimica Acta 256 (1997) 87–92 91

Journal: ICA (Inorganica Chimica Acta) Article: 5422

Table 5

Atomic coordinates and equivalent isotropic displacement parameters (A

˚

2

)

for 1 (e.s.d.s in parentheses)

Atom x y z Ueq

Pt1 0.01165(3) 0.23406(2) 0.15691(2) 0.01565(8)

Cl1 y0.0866(2) 0.4196(2) 0.1431(1) 0.0264(5)

Cl2 y0.1571(2) 0.1368(2) 0.0884(1) 0.0254(5)

O1 0.2531(7) y0.0389(6) 0.1041(4) 0.033(2)

O2 0.1123(6) 0.0782(5) 0.1686(3) 0.023(2)

O3 y0.0557(8) 0.2383(7) 0.3985(4) 0.037(2)

O4 y0.0790(5) 0.2060(6) 0.2654(3) 0.023(1)

N1 0.1095(7) 0.2489(6) 0.0486(4) 0.019(2)

N2 0.1541(6) 0.3107(7) 0.2283(4) 0.023(2)

C1 0.1723(8) 0.1314(7) 0.0297(5) 0.024(2)

C2 0.1852(8) 0.0508(7) 0.1043(5) 0.023(2)

C3 0.0967(9) 0.3358(9) 0.3104(5) 0.030(2)

C4 y0.0187(8) 0.2535(8) 0.3290(5) 0.025(2)

Ueq

s .

1U UU a a a aij i j i j883 i j

Table 6

Atomic coordinates and equivalent isotropic displacement parameters (A

˚

2

)

for 2 (e.s.d.s in parentheses)

Atom x y z Ueq

Pt 0.12883(3) 0.25000(0) 0.17703(5) 0.0700(3)

Cl1 0.1422(3) 0.25000(0) 0.3214(4) 0.122(3)

Cl2 0.1301(2) 0.0423(3) 0.1706(3) 0.093(2)

Cl3 0.0301(2) 0.25000(0) 0.1874(4) 0.097(3)

Na1 0.0880(4) 0.25000(0) 0.6239(6) 0.109(4)

O1 0.2171(8) 0.25000(0) 0.161(1) 0.108(8)

O2 0.2764(8) 0.25000(0) 0.057(1) 0.14(1)

O3 0.2427(6) 0.25000(0) 0.8113(10) 0.096(7)

O4 0.1991(5) 0.027(1) 0.8777(7) 0.104(5)

O5 0.0840(5) 0.034(1) 0.9466(7) 0.104(5)

O6 0.0327(6) 0.25000(0) 0.8953(10) 0.094(7)

O7 0.1825(7) 0.127(2) 0.580(1) 0.175(10)

O8 0.4204(9) y0.003(1) 0.084(1) 0.155(8)

O9 y0.0065(7) 0.125(2) 0.663(1) 0.166(9)

O10 0.0568(9) 0.25000(0) 0.484(1) 0.138(10)

O11 0.1206(5) 0.25000(0) 0.7606(8) 0.083(6)

N1 0.1262(7) 0.25000(0) 0.0439(9) 0.067(6)

C1 0.225(1) 0.25000(0) 0.080(2) 0.11(1)

C2 0.180(1) 0.25000(0) 0.012(2) 0.10(1)

C3 0.2755(7) 0.144(2) 0.823(1) 0.104(8)

C4 0.2371(8) 0.036(2) 0.809(1) 0.111(9)

C5 0.1590(10) y0.067(2) 0.862(1) 0.13(1)

C6 0.1185(9) y0.071(2) 0.937(1) 0.14(1)

C7 0.0370(10) 0.039(2) 0.889(1) 0.121(10)

C8 0.0030(8) 0.147(2) 0.914(1) 0.125(10)

C9 0.325(1) y0.031(2) 0.037(2) 0.18(2)

C10 0.369(1) 0.049(3) 0.078(2) 0.17(1)

C11 y0.040(1) 0.047(3) 0.368(1) 0.17(1)

C12 y0.014(1) 0.015(3) 0.638(2) 0.15(1)

C13 0.272(1) y0.198(3) 1.060(2) 0.25(3)

C14 0.4454(10) 0.192(2) 0.841(2) 0.21(2)

Ueq

s .

1U UU a a a aij i j i j883 i j

5 was isolated as described above (see Section 3.2.4) after

irradiation for 24 h (yield 46 mg, 15%).

Anal. Calc. for C18

H

38

Cl

4

N

2

O

10

Pt (779.39): C, 27.74; H,

4.91;Cl, 18.19; Pt, 25.03. Found:C, 27.98;H, 5.19;Cl, 18.44;

Pt, 24.65%.

1

H NMR: d (ppm, DMSO-d

6

) 1.46 (d, CH3

,

6H), 3.61 (s, CH2

, 24H), 3.91 (q, CH, 2H).

3.3. X-ray structure determinations

Single crystals of 1 (yellow) and 2 (yellow) were formed

by slow concentration of the aqueous solutions. Compounds

were measured at 200 K on a STOE STADI 4 diffractometer

(for 1) and at room temperature on a STOE IPDS (for 2)using graphite monochromatized Mo Ka radiation

(ls0.71073 A

˚

). Structures were solved by the heavy-atom

method using SHELXS-86 [12]. Full-matrix least-squares

refinement was carried out on F2

values using SHELXL-93

[13]. All non-hydrogen atoms of 1 and 2 were refined with

anisotropic displacement parameters. The positions of all H

atoms of 1were located in a difference Fourier and the hydro-gen atoms were refined isotropically. For 2 the H atoms were

located in positions calculated for geometrical reasons. Crys-

tal parameters, data collection details and results of the refine-

ments are summarized in Table 4. The final atomic

coordinates are listed in Tables 5 and 6.

4. Supplementary material

Further details of the crystal structure analyses can be

obtained from the Fachinformationszentrum Karlsruhe,

Gesellschaft fur wissenschaftlich-technische Information

mbH, Postfach 2465, D-76012 Karlsruhe, citing the deposi-

tion nos. CSD-404873 (1) and CSD-404874 (2), the authorsand the reference.

Acknowledgements

We gratefully acknowledge support by the Deutsche For-

schungsgemeinschaft and the Fonds der Chemischen Indus-

trie. We also thank the companies Merck (Darmstadt) and

Degussa (Hanau) for gifts of chemicals as well as Dr Karla

Schenzel (Halle) for Raman spectroscopic investigations.

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