The synthesis of mixed ligand complexes of platinum(II)

J. inorg,nucl.Chem.,197I, Vol.33, pp. 259 to 263. PergamonPress. Printedin Great Britain

THE

SYNTHESIS

OF MIXED LIGAND OF PLAT1NUM(ll)*

COMPLEXES

G E O R G E W. WATT and JOHN E. C U D D E B A C K Department of Chemistry, The University of Texas at Austin, Austin. Texas 78712 ( Received 8 July 1970) A b s t r a c t - T h e synthesis and characterization of certain mixed ligand complexes of platinum(l 1) and of ligands and intermediates required therefore are described. INTRODUCTION

FOR USE in studies to be described later, we have synthesized and characterized

numerous mixed ligand complexes of platinum(lI) involving both o-- and ~-bonding mono and bidentate ligands. In some cases it was necessary to prepare ligands and/or intermediates previously reported but not adequately characterized. EXPERIMENTAL Materials and methods. Unless otherwise indicated, reagent grade chemicals and standard analytical procedures were employed. Ligands and intermediates For each of the cases that follows, analytical data are assembled in Table I and X-ray diffraction data in Table 2; the latter are included only for those species for which such data have not been published. 1,2-Bis(diphenylarsine)ethane. Starting with phenyldichloroarsine prepared by the method of Bruker and Nikiforva[ I], EDA was prepared as described by Chatt and Mann[2]. The product was recrystallized twice from ethanol; m.p., 101 °. 1,2-Bis(phenylthio)ethane was prepared by the method of Brooks et a/.[3] and recrystallized twice from ethanol; m.p., 67-68 °. Dichloro(ethylenediamine)platinum(ll) was formed by the methods of Watt and Upchurch 14] and Drew [5] and recrystallized from water to which 10 drops of conc. HCI was added. Dibromo(ethylenediamine)platinum(ll). Approximately 1.3g of KzPtBr4 in 10 ml of water was formed by reducing K,.,PtBr6 with N2H4"HBr. This solution was made slightly basic with KOH solution, cooled in an ice bath and treated with 0.5 ml of 98% en; cooling and stirring was continued until crystals ceased to form. The product was filtered and recrystallized from water containing 5 drops of cont. HBr. *Abbreviations: 2,2'-Bip~,ridine, bipy; 1,2-bis(diphenylarsine)ethane, EDA; 1,2-bis(diphenylphosphine)ethane, EDP; ethylenediamine, en; N,N-dimethylethylenediamine, udmen; N,N'dimethylethylenediamine, sdmen; N,N,N'-trimethylethylenediamine, tmen; triphenylphosphine, Ph:~P; phenylsulfito ion, PhS; 1,2-bis(phenylthio)ethane, EPT: 1,2-dicyanoethylene- 1,2-dithiolato ion, MNT; 1,10-phenanthro ine, phen. I. A. B. Bruker and M. M. Nikiforva, Zh. obshch. Khim. 28, 2407 (1958). 2. J. Chatt and F. G. Mann, J. chem. Soc. 610 (1939). 3. R. Brooks, J. E. Cranham. W. A. Cummings, D. Greenwood. B. S. Jackson and H. A. Steveson, ,I. Sci. FoodAgr. 8, 31 (1957). 4. G. W. Watt and D. G. Upchurch, J. Am. chem. Soc. 90.914 (1968). 5. H. D. Drew, J. chem. Soc. 2329 (1932). 259

260

G. W. W A T T and J. E. C U D D E B A C K Table 1. Analytical and yield data

Compound (CrHs)2As (CH2)zAs (CrHs)2 (C8H5)S (CH2)2S (C6Hs) [Pt (en)C12] [Pt (en) Br2 ] [Pt(en) (NO2)2] [Pt(en) (SCN)2] [Pt(sdmen)(SCN)2] [Pt (udmen) (SCN)2] [Pt (tmen) (SCN)2] [Pt (phen)Cl2] [Pt(EDA)CI2] [Pt(EDA)Br2] [Pt(EDA)I2] [Pt(EDP)CI2] [Pt(EDP)Br2] [Pt(EDP)I2] [Pt (EPT)C12] [ P t ( M N T ) (en)] [Pt(bipy) (en)]I2 [Pt(phen) (en)]I2 [Pt (PhzP)2 (en) ] 12 [Pt(Ph3P) ( e n ) I ] I [Pt (EDA) (en) ]C12" t [ P t ( E D A ) (en)]Br2*~:§ [ P t ( E D P ) (en) ]Br2 [Pt (EDP) (en) ]C12~l [Pt2 (en)2 (PhS)z]CI2

Pt

Found (%) C

H

64.4 67.9

4.86 5.80

59.6 47.3 56.3 52-3

43.8 25.5 23.2 20.7 26.2

49.5 29.2 28.7 18.6 25.8 24.3 21.6 24.1 27.1 48.8

Pt

Calcd. (%) C

H

64.2 68.3

5.00 5.68

59.8 47.0 56.2 52.5 18-4 18-2 20.6

3.25 3.20 3.39

42-1 37.4 33.9 47.2 41.5 37.2 32.7 17.9

3.51 3.02 3"15 3.92 3.43 2.97 2.80 1.92

24-4 44.0 31-2

2.47 4.02 3.23

41.0 45.7 24-2

4.18 4.65 3.40

43.7 25-9 23.2 20.9 25-9

49.3 29.3 28.3 18.9 25-3 24.0 21.6 24.0 26.9 48.8

Yield (%)

(a) 45, (b) 65 82

18.1 18.1 20.3

3.01 3.01 3.39

41.5 37.1 33"4 47.0 41.5 36.9 32.8 18.2

3.22 2.88 2.59 3.64 3.21 2.86 2.74 2-02

24.4 44.2 31.1

2.34 3"70 3.00

41.3 46.5 24-0

3.96 4.48 3.25

63 92 88 99 60 94 99 94 70 65 82

(a) 80, (b) 92 85 99

*Carbon analyses were consistently low for all substituted arsine complexes containing en; hence these species were analyzed for N. ~N, Found 4.10; calcd. 3"45. :~N, Found 3.03; calcd. 3' 11. §Br, Found 17-7; calcd. 17.7. IIN, Found 3'87; calcd. 3.87. Dinitrito(ethylenediamine)platinum(ll). To 0-7g of K2Pt(NO2)4 in 15 ml of water was added 0-2 m of 98% en. After stirring for 10 min the solid was filtered, washed with water and ethanol, and dried in vacuo for 2 hr. Substantially the same procedure was employed for the preparation of the following intermediates: [Pt(en) (SCN)2], [Pt(sdmen) (SCN)2], [Pt(udmen) (SCN)2], and [Pt(tmen) (SCN)2] (see Tables 1 and 2). Dichloro(phenanthroline)platinum(li) was prepared by a modification of a procedure suggested by Hall and Plowman[6]. To a solution of 0-80g of K2PtCI4 in 40ml of water, 0.61g of 1,10phenanthroline was added and stirred for 5 min. Five drops of conc. HC1 was added and the solution was stirred for 45 min at 90 °, then cooled to 25 °. The bright yellow crystals were filtered, washed with water, ethanol, and ether, recrystallized from water containing a few drops of conc. HC1 and dried at 100° for 1 hr. Dichloro-l,2-bis(diphenylarsine)ethane platinum(ll). Westland's method[7] was modified as 6. J. R. Hall and R. A. Plowman, Austral. J. Chem. 9, 143 (1950). 7. A. D. Weestland, J. chem. Soc. 3060 (1965).

Mixed ligand complexes of Pt(li)

261

Table 2. X-ray diffraction data* d

(A)

d

1/1o

d

(A)

1/1,,

(A)

1/lo

[Pt(en) (NO2)z] 6.94 1.0 6-00 0.5 3-59 0-4 3-19 0.5 3-08 0-4 2-55 0.3

[Pt (en) (SCN)z] 7-13 1.0 6.19 0.4 4.35 0.8 3'80 0.2 3.29 0.2

[Pt(sdmen) (SCN)2] 7.37 1-0 6.02 0.3 4.74 0.6 4.52 1-0 4.22 0.4 3.00 0.3

[Pt (udmen) (SCN)2] 7-22 0.9 6-00 0.8 5-40 1-0 4-58 0.5 3-32 0.8 2.22 0.4

[Pt (tmen) (SCN)2] 8.30 0.8 7.37 1.0 5.79 0.3 4.78 0.8 4.39 0.6 4.58 0.5

[P1 (phen)CI2] 8.71 0-3 8.04 1-0 5.32 0.8 3.67 0.5 3.28 0.4

[Pt(EDA)Br2] 0.2

[Pt(EDA)I2] 10.3 0.2

[Pt(EDA)CI~] 0.8 8.62 1-0 6.88 0.5 6.65 0.5 5.73 0"3 4.11 0.3

11.6

[Pt(EDP)CI2] 0.8 8.66 1-0 6.86 0.6 6.62 0.4 6.21 0.9

11.3

11.6 10-8 8.34 7.28 5.42

0.3 1.0 0.7 0-2

[Pt(EDP)Brz]

11.2 8-54 6.68 6.39 6.15 5.71

0.9 1-0 0.6 0.5 0.3 0.3

8-30 7.25 6-83 3.35 3.55

1.0 0.9 0.2 0.3 0.2

[Pt(EDP)I~] 8.30 1.0 7-25 5.55 4.35 4.16

1-0 0.4 0.3 0-3

[Pt(MNT)(en)] 8.07 1.0 5.80 0-3 5.38 0-2 4.42 0.2 3.63 0-3 3.57 0.8

[Pt (EPT)CI2] 7.22 1.0 6-02 0-3 5'53 0.5 5'15 0.2 4.77 0.3 4.18 0.2

[Pt(phen) (en)]l,, 8.71 0.5 7.43 0-5 5-40 0-5 3"85 1-0 3-71 0.6 3.21 0-5

[Pt (PH3P)z (en) ]lz 11"8 0"6 9-25 0-9 8"62 1"0 5-20 0-2 4"16 0"4 3-89 0"2

[Pt(PhaP) (en) 1] I 8.75 0.4 7.82 0.2 7.46 0.8 6.80 0.2 4.50 0.3 4.36 1.0

[Pt(EDA) (en) ]CI2 11.0 0-8 9-35 0-9 7.25 1.0 6.88 1.0 4.33 0.6 4.23 0.6

262

G. W. WATT and J. E. C U D D E B A C K Table 2. (Contd.) d

(~,)

d

/~to

[Pt (EDA) (en) ] Br2 11.5 1.0 9.45 0.9 7-34 0.7 7.05 0.7 4-38 0.4 3.80 0.4

(h)

d

/~to

[Pt (EDP) (en)]Br2 11.3 1.0 9-40 0-6 7-25 0.8 6-96 0.8 4.34 0.7 3.76 0.8

(A)

t/to

[Pt (EDP) (en)]C12 11.4 1-0 9-35 0.3 8-62 0-2 7.28 0-2 4.36 0.4 3.77 0.5

[Pt2(en)2 (PhS)2]C12 9.25 0.6 6.83 1.0 6.19 0.8 3"66 0.4 2.45 0.4 *All powder patterns were obtained using CuK~ radiation filtered through a 0-70 mil Ni foil. The tube was operated at 35 kV and 15 ma; exposure times range from 6 to 14 hr. Relative intensities were estimated visually. tOnly the most intense lines are recorded here; for more complete data see: J. E. Cuddeback, Dissertation, The University of Texas at Austin (Jan. 1970). follows. 1,2-Bis(diphenylarsine)ethane (2.34g) in 40 ml of ethanol and 2.00g of finely powdered K2PtCI4 in 40 ml of conc. HCI were refluxed for 4 hr in a round bottom flask, cooled to 25 ° and filtered. The solid was washed with water to remove any unreacted starting materials. The crude product was heated at 80° in 25 ml of dimethylformamide until solution was complete. Decolorizing carbon was added, the solution was filtered and the filtrate was cooled to 25°. Slow addition of ether produced finely divided white crystals which were removed by filtration, washed with ether and dried in vacuo for 1 hr. Dibrorno-l,2-bis(diphenylarsine)ethane platinum(ll) was prepared as described by Westland[7] who did not report analytical, yield, or X-ray diffraction data (see Tables 1 and 2). Diiodo- 1,2-bis(diphenylarsine)ethane platinum(ll) was formed by heating 0.80g of [ Pt (EDA) Clz ] in 30 ml of I : 1 ethanol-conc. HI for 20 min. The bright yellow solid was filtered, washed with ethanol and ether and dried in vacuo for 30 min. Dichloro-l,2-bis(diphenylphosphine)ethane platinum(ll) was prepared by essentially the same procedure as that used for the analogous substituted arsine complex except that the reflux time was 8 hr. Dibromo-l,2-bis(diphenylphosphine)ethane platinum(ll). A solution of 0.90g of BaBr2 in I0 ml of dimethylformamide was added to 2.0g of [Pt(EDP)CI~] in 40 ml of hot dimethylformamide and stirred for 15 min. Ether (250 ml) was added and the precipitated solid was filtered and washed with water, ethanol and ether. The crude product was dissolved in 50 ml of hot dimethylformamide; decolorizing charcoal was added before the mixture was filtered. Slow addition of 300 ml of ether precipitated the desired product which was filtered, washed with ether, and dried for 1 hr at 110°. Diiodo-l,2-bis(diphenylphosphine)ethane platinum(ll) was prepared from [Pt(EDP)CI2] by the same method as that used for the corresponding arsine complex. Dichloro-l,2-bis(phenylthio)ethane platinum(ll) was synthesized by the method used by Pluscec and Westland [8] to form the analogous substituted propane complex. cis-l,2-Dicyanoethylene-l,2-dithiolato(ethylenediamine) platinum(ll). A 1.594g sample of [Pt(en)Cl~] was added to a solution of 1.661g of AgNO3 in 75 ml of water and heated on a steam bath for 3 hr. The mixture was cooled to 15° and filtered through decolorizing charcoal. The colorless 8. J. Pluscec and A. D. Westland, J. chem. Soc. 5371 (1965).

Mixed ligand c o m p l e x e s of Pt(ll)

263

filtrate was treated with 0.9 lg of sodium cis- 1,2-dicyanoethylene- 1,2-dithiolate [9] in 50 ml of ethanol to provide a yellow-green precipitate which was w a s h e d with ethanol and ether and dried in vacuo for 2 hr.

Complexes qf'the types [ Pt( L )( L' )])(2, [ Pt( L )I L' )2]Xz and [ Pt( L )( L' )( X ) ]X Bipyridyl(ethylenediamine)platinum(ll) iodide. T r e a t m e n t of 1.0g of [Pt (bipy)Cl2], prepared by the m e t h o d of Morgan and Bustall [10], with 10 ml of 95 % en in 50 ml of water at 90 ° was continued until solution was complete. Decolorizing carbon was added, the solution was filtered, cooled to 5 °, and treated with 2g of KI in 10 ml of water. T h e bright yellow precipitate was filtered, washed with water and ethanol and dried in vacuo for 2 hr. Ethylenediamine(phenanthroline)platinum(ll) iodide was prepared from 1.10g of [Pt (phen)CI,, ] by a procedure essentially the same as that described in the preceding paragraph. Bis(triphenylphosphine)(ethylenediamine)platinum(ll) iodide. Triphenylphosphine (1.96g) was dissolved in 30 ml of dimethylformamide and 1-22g of [Pt(en)Cl2] was added. T h e mixture was heated on a s t e a m bath with stirring for 45 rain. At 25 °, 2g of K! in 70 ml of water was added slowly and with stirring. After 30 min, the product was filtered, washed with water, ethanol, and ether and dried in vacuo for 2 hr. Iodo(triphenylphosphine)(ethylenediamine)platinum(ll) iodide was formed simply by stirring 1.0g of [Pt(Ph3P)(en)]lz for 1 hr in 75 ml of benzene. T h e white precipitate was filtered, washed with b e n z e n e and ether and dried in vactto for 2 hr. 1,2-Bis(diphenylarsine)ethane(ethylenediamine)platinum(ll) chloride. To a s u s p e n s i o n of 0.5g of [ P t ( E D A )CI~] in 50 ml of ethanol at 70 °. 95% en was added dropwise until all solids dissolved. T h e solution was evaporated to d r y n e s s and the residual solid was washed with ether and dried in t'acm~ for 4 hr. 1,2-Bis(diphenylarsine)ethane(ethylenediamine)platinum(ll) bromide was produced (a) from [Pt(EDA)CI2] by a procedure closely similar to that described in the preceding paragraph, and (b) by heating 1.0g of [Pt(EDA)Br2] in 20 ml of ethanol at 70 ° and adding en dropwise until solution was complete. Decolorizing carbon was added and the mixture was filtered. W h e n the filtrate was diluted slowly with 250 ml of ether a white solid formed; this was filtered and dried in vacuo for 2 hr. 1,2-Bis(diphenylphosphine)ethane(ethylenediamine)platinum(ll) bromide was prepared from 1-0g of [ P t ( E D P)Br2 ] by the procedure described in the preceding paragraph. 1,2-Bis(diphenylphosphine)ethane(ethylenediamine)platinum(ll) chloride. Dropwise addition of 9 5 % e n to 1.0g of [Pt(EDP)CI2] in 5 0 m l of ethanol was continued until the solid dissolved. T h e solution was evaporated to d r y n e s s and the residue baked in an oven at 110° for 4 hr. T h e crude product was dissolved in ethanol, filtered through decolorizing carbon and the filtrate was evaporated to d r y n e s s in a stream of air. T h e colorless crystals were washed with ether and dried in vacuo. Ethylenediamine-tx-diphenylsulfido(ethylenediamine)platinum~ll) chloride. This complex was obtained in an u n s u c c e s s f u l effort to synthesize [Pt(en)(PhS)~]. A suspension of 0.50g of [Pt(en)Cl..] and 0.40g of N a S P h in 60 ml of ethanol was refluxed for 5 hr, cooled to 20 ° and filtered. T h e yellow solid was w a s h e d with water, ethanol, and ether and dried in vaeuo for 1 hr. A c k n o w l e d g e m e n t - T h i s work was supported by the United States Atomic Energy C o m m i s s i o n and the Robert A. Welch Foundation. 9. A. D a v i s o n and R. H. Holm, Inorganic Syntheses Vol. 10. p. 1 I. McGraw-Hill. N e w York (1967). 10. G . T . Morgan and T. H. Burstall, J. chem. Soc. 965 (1934).