New cyclometallated platinum(II) compounds with thiosemicarbazones:: crystal and molecular structure of [Pt{4-MeC6H3C(Me)=NN=C(S)NH2}(PPh3)]

Treatment of the thio semicarbazones 3-CH3(CH2)(5)OC6H4C(Me)=NN(H)C(=S)NH2 (a), 4-MeC6H4C(Me)=NN(H)=C(S)NH2 (b), C6H5C(Et)=NN(H)=C(S)NH2 (c), C6H5C{CH3(CH2)(10)}=NN(H)=C(S)NH2 (d) and 4-MeC6H4C(Me)=NN(H)=C(S)NHMe (e) with K-2[PtCl4] gives tetranuclear platinum(II) compounds 1a-1e with deprotonation of the -NH- group and with the ligand acting as a terdentate [C,N,S] moiety. Reaction of 1a-1e with PPh3 and of 1a with P(4-MeOC6H4)(3) yielded mononuclear species 2a-2e and 3a, respectively. Treatment of 1a with the diphosphines Ph2PCH2PPh2 (dppm), Ph2P(CH2)(2)PPh2 (dppe), Ph2P(CH2)(3)PPh2 (dppp), Ph2P(CH2)(4)PPh2 (dppb), Ph2P(CH2)(5)PPh2 (dpppe), Ph2P(CH2)(6)PPh2 (dpph), and 1,1'-ferrocenebis(diphenylphosphine) (dppf) gives dinuclear compounds 4a-10a. In all cases the Pd-S-chelating bond is strong enough to withstand reaction with the phosphorus ligands without bond cleavage. The molecular structure of 2b has been determined by X-ray crystallography. Mononuclear units are held together by hydrogen bonding, forming dimers in the solid state. (C) 2000 Elsevier Science S.A. All rights reserved.