Spectrochimica Acta Part A 60 (2004) 3087–3092 Triphenyl phosphine adducts of platinum(IV) and palladium(II) dithiocarbamates complexes: a spectral and in vitro study N. Manav, A.K. Mishra, N.K. Kaushik ∗ Department of Chemistry, University of Delhi, Delhi 110007, India Received 15 December 2003; accepted 27 January 2004 Abstract Triphenyl phosphine adducts of dithiocarbamate complexes of platinum(IV) and palladium(II) of the type [Pt(L) 2 PPh 3 Cl 2 ] and [Pd(L) 2 PPh 3 ] [L: morpholine dithiocarbamate (L 1 ), aniline dithiocarbamate (L 2 ) and N-(methyl, cyclohexyl) dithiocarbamate (L 3 )] were prepared and characterized by elemental analysis, electronic, IR, 1 H NMR and 13 C NMR spectral studies. Thermal studies of the complexes were carried out. In vitro antitumor activity has been screened towards human adenocarcinoma cell lines and showed significant inhibition even at very low concentration. © 2004 Elsevier B.V. All rights reserved. Keywords: Dithiocarbamate complexes; Spectral, thermal and in vitro study; Triphenyl phosphine 1. Introduction Platinum(IV) and palladium(II) complexes with tertiary phosphines have been poorly characterized [1–3]. The re- action of all M(S–S) compounds (M = Pt, Pd; (S–S) - = - S 2 CNR 2 (R = Me, Et), - S 2 COR (R = Et · PhCH 2 ), - S 2 P(OEt) 2 and - S 2 PR 2 (R = Me, Et, Ph)] with tertiary phosphines occurs by stepwise cleavage of metal–sulphur bonds to generate four-coordinate compounds of for- mulae [M(S–S) 2 PR 3 ′ ] and [M(S–S)(PR 3 ′ ) 2 ] (S–S) with unidentate/bidentate and ionic/bidentate coordination re- spectively [4–7]. All the ionic compounds readily revert to the [M(S–S) 2 PR 3 ′ ] complexes in the presence of non-polar solvents via nucleophilic attack by (S–S) - on the metal. The investigation of platinum and palladium complexes is important for the treatment of human cancer [8–10]. Even at very low concentration these have been found to be active as revealed by in vitro studies. The general consensus is that they derived their activity through different adducts that they formed with DNA [11]. The synthesis of triphenyl phosphine adducts was planned after considering that square planar [M(S–S) 2 ] complexes ∗ Corresponding author. Tel.: +91-11-27667725x1391; fax: +91-11-7256605. E-mail addresses: navneet92@rediffmail.com (N. Manav), ajaykmishra1@yahoo.com (A.K. Mishra). [M = Pd or Pt; (S–S) - = R 2 NCS 2 - , ROCS 2 - ,(RO) 2 PS 2 - and R 2 PS 2 - ] easily form adducts with various tertiary phos- phines [12–16]. 2. Experimental 2.1. Dithiocarbamates L (L: L 1 ,L 2 ,L 3 and L 4 ) The dithiocarbamates were prepared by the method de- scribed by Gilman and Blatt [17] with some modifications. 0.4 mol of corresponding amine was dissolved in methanol and chilled. To this a chilled solution of 2.24 g (0.04 mol) potassium hydroxide in aqueous methanol was mixed with constant stirring. The mixed solution was treated with an ice cold solution of 2.5 cm 3 (0.04 mol) car- bon disulphide (density 1.27) in 4 cm 3 methanol keeping the temperature of the reaction mixture below 10 ◦ C. Dur- ing the process, desired crystalline precipitates separated. It was filtered and washed with ice cold aqueous methanol and recrystallized. 2.2. Mixed ligand complexes 2.2.1. [Pt(L) 2 (PPh 3 )Cl 2 ], [Pd(L) 2 (PPh 3 )] (where L = L 1 ,L 2 and L 3 ) The complexes were prepared by taking [Pt(L) 2 Cl 2 ] and [Pd(L) 2 ] as starting materials. [Pt(L) 2 Cl 2 ] and [Pd(L) 2 ] was 1386-1425/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2004.01.031