SYNTHESIS AND COMPLEXATION STUDIES OF MESOCYCLIC AND MACROCYCLIC POLYTHIOETHERS .14. CROWN THIOETHER COMPLEXES OF PALLADIUM(II) AND PLATINUM(II)

This paper describes the synthesis and characterization of several cro wn thioether complexes of Pt(II) and Pd(II). We wish to report the syn theses and X-ray crystal structures of both the Pd(II) and Pt(II) comp lexes with the macrocyclic thioether complex, 1,4,7,11,14,17-hexathiac ycloeicosane (20S6). Crystal data for [Pd(20S6)](PF6)2: C14H28F12P2PdS 6; monoclinic, space group P2(1)/c; a = 12.910(3) Angstrom, b = 9.810( 20) Angstrom, c = 22.103(6) Angstrom; beta = 102.170(20)degrees, V = 2 700.39 Angstrom(3): Z = 4; R = 0.055; D = 1.931 g cm(-3); 6346 reflect ions measured. Crystal data for [Pt(20S6)](PF6)(2) . CH3NO2: C15H31F12 NO2P2PtS6; monoclinic, space group Cc; a = 12.321(5) Angstrom, b = 14. 608(7) Angstrom, c = 17.032(5) Angstrom; beta = 98.15(3)degrees, V = 3 034.55 Angstrom(3); Z = 4; R = 0.036; D = 2.045 g cm(-3); 2777 reflect ions measured. Neither complex exhibits any significant electrochemist ry or any visible absorption bands. Both complexes crystallize in the same linkage isomer where the metal ion is surrounded by a distorted s quare planar arrangement of four sulfur atoms. Two sulfur atoms that a re adjacent to each other in the macrocyclic ring remain uncoordinated . C-13 NMR spectroscopy reveals the presence of additional isomers in solution. We also wish to report the synthesis and X-ray crystal struc ture of the crown thioether complex, bis(1,4,7-trithiacyclodecane)plat inum(II) hexafluorophosphate, [Pt(10S3)(2)](PF6)(2). The two 10S3 liga nds are arranged around the platinum in pseudo-octahedral fashion to y ield the meso stereoisomer. Four of the six sulfur atoms from the 10S3 ligands form a square planar arrangement around the platinum (mean Pt -S-equatorial bond distance = 2.30 Angstrom). The remaining two sulfur s are coordinated axially at a much greater distance from the Pt (Pt-S -axial = 3.21 Angstrom). Crystal data for [Pt(10S3)(2)](PF6)(2) . 2CH( 3)NO(2): C16H34PdS6P2F12N2O4; monoclinic, space group C2/c; a = 22.473 (9) Angstrom, b = 12.071(4) Angstrom, c = 11.186(3) Angstrom; beta = 9 4.14(3)degrees, V = 3026.53 Angstrom(3); Z = 4; R = 0.046; D = 1.991 g cm(-3); 2836 reflections measured. Cyclic voltammetry measured in ace tonitrile showed a single, reversible oxidation wave at +0.324 V versu s F-c/F-c(+). Variable temperature C-13 NMR spectroscopy shows no solv ent-complex interactions, in contrast to the Pd(II) analog. The pallad ium(II) complex, [Pd(ttn)(2)](PF6)(2), which contains the acyclic thio ether 2,5,8-trithianonane (ttn) was also prepared.