Larry F. Mehne

Synthesis and complexation studies of mesocyclic and macrocyclic polythioethers XIV. Crown thioether complexes of palladium(II) and platinum(II)

Abstract This paper describes the synthesis and characterization of several crown thioether complexes of Pt(II) and Pd(II). We wish to report the syntheses and X-ray crystal structures of both the Pd(II) and Pt(II) complexes with the macrocyclic thioether complex, 1,4,7,11,14,17-hexathiacycloeicosane (20S6). Crystal data for [Pd(20S6)](PF6)2: C14H28F12P2PdS6; monoclinic, space group P2 1 c ; a = 12.910(3) A , b = 9.810(20) A , c = 22.103(6) A , β = 102.170(20)°, V = 2700.39 A 3 ; Z = 4; R = 0.055; D = 1.931 g cm −3 ; 6346 reflections measured. Crystal data for [Pt(20S6)](PF6)2·CH3NO2: C15H31F12NO2P2PtS6; monoclinic, space group Cc; a = 12.321(5) A , b = 14.608(7) A , c = 17.032(5) A ; β = 98.15(3)°, V= 3034.55 A 3 ; Z= 4; R = 0.036; D = 2.045 g cm −3 ; 2777 reflections measured. Neither complex exhibits any significant electrochemistry or any visible absorption bands. Both complexes crystallize in the same linkage isomer where the metal ion is surrounded by a distorted square planar arrangement of four sulfur atoms. Two sulfur atoms that are adjacent to each other in the macrocyclic ring remain uncoordinated. 13C NMR spectroscopy reveals the presence of additional isomers in solution. We also wish to report the synthesis and X-ray crystal structure of the crown thioether complex, bis(1,4,7-trithiacyclodecane)platinum(II) hexafluorophosphate, [Pt(10S3)2](PF6)2. The two 10S3 ligands are arranged around the platinum in pseudooctahedral fashion to yield the meso stereoisomer. Four of the six sulfur atoms from the 10S3 ligands form a square planar arrangement around the platinum (mean Pt-Sequatorial bond distance = 2.30 A). The remaining two sulfurs are coordinated axially at a much greater distance from the Pt (Pt-Saxial = 3.21 A). Crystal data for [Pt(10S3)2](PF6)2·2CH3NO2: C16H34PdS6P2F12N2O4; monoclinic, space group C2 c ; a = 22.473(9) A , b = 12.071(4) A , c = 11.186(3) A ; β = 94.14(3)°, V= 3026.53 A 3 ; Z = 4; R = 0.046; D = 1.991 g cm −3 ; 2836 reflections measured. Cyclic voltammetry measured in acetonitrile showed a single, reversible oxidation wave at +0.324 V versus F c F c + . Variable temperature 13C NMR spectroscopy shows no solvent-complex interactions, in contrast to the Pd(II) analog. The palladium(II) complex, [Pd(ttn)2](PF6)2, which contains the acyclic thioether 2,5,8-trithianonane (ttn) was also prepared.

The synthesis and structure of bis(1,4,7-trithiacyclodecane)-ruthenium (II) perchlorate: the meso diastereoisomer☆

The synthesis of the Ru(II) crown thioether complex, bis(1,4,7-trithiacyclodecane) ruthenium (II) perchlorate, [Ru(10S3)2](ClO4)2, and a study of its properties utilizing single crystal X-ray diffraction, electronic spectroscopy, 13C NMR spectroscopy and cyclic voltammetry is reported. The crystal structure shows the two 10S3 ligands are arranged in a trans or anti fashion around the ruthenium (II) center in nearly octahedral fashion to yield the meso stereoisomer. 13C NMR spectroscopy demonstrates that this stereoisomer is also the predominant one observed in solution, in contrast to the Co(III) and Fe(II) complexes. The electronic absorption spectrum is similar to other previously observed hexakis (thioether) ruthenium (II) complexes with d-d transitions at 346 and 297 nm. The electrochemical behavior is also similar to related Ru(II) complexes and shows a single quasi-reversible oxidation wave at + 1.37 V versus Fc/Fc+. Crystal data for [Ru(10S3)2](ClO4)2: C14H28Cl2O8RuS6; monoclinic, space group P21/c; a = 7.391(2), b = 9.480(2), c = 17.351(3) A; β = 97.10(2)0, V = 1206.4(5) A3; Z = 2; R = 0.0521; D = 1.896 g cm−3; 3211 reflections measured. The properties of the complex are compared with the congeneric Fe complex.

Transition metal complexes with macrocyclic oxathiaethers

Abstract Complexation studies with Ni(II), Co(III), Co(II), Cd(II), and Cu(II) for the two mixed oxathia crown ligands 1-oxa-4,7-dithiacyclononane (9S2O) and 1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane (18S4O2) are reported. These ten complexes have been characterized by a variety of means including electronic spectroscopy, cyclic voltammetry, and nuclear magnetic resonance spectroscopy. Furthermore, the complexes [Ni(18S4O2](BF4)2, [Cu(9S2O)2](BF4)2 and [Ni(9S2O)2](ClO4)2, have been characterized by single crystal X-ray diffraction. For the complex [Ni(18S4O2](BF4)2 the diastereoisomer obtained is the one which contains the two oxygen atoms trans to each other and a meridional positioning of the diethylene SOS moiety. Selectivity for this particular stereoisomer is also supported by NMR data for the Cd(II) and Co(III) complexes, and this selectivity arises from the conformational preferences of the individual CO and CS bonds in the macrocycle. Both the nickelsulfur and nickeloxygen bonds in the complex are highly compressed due to the rigid macrocyclic structure and are among the shortest of these types of bonds found in any crown Ni(II) complex. The copper(II) complex, [Cu(9S2O)2](BF4)2, shows an interesting Jahn–Teller distortion from an octahedral geometry resulting in coordinate bonds which are all remarkably similar in length (CuS(4) 2.3293(6); CuS(7) 2.3336(6); and CuO(1) 2.355(2) A). The oxygen atoms are found in a trans position around the copper(II) center, and the axial CuO bonds are elongated due to the Jahn–Teller distortion. In all of these complexes, the two oxathiaether ligands function as much weaker field ligands than do their crown thioether analogs. Also, cyclic voltammetric experiments reveal that the oxathia crowns do not have the ability to stabilize less common metal oxidation states, a common property of many crown thioether ligands.

Synthesis and X-ray crystal structures of mixed sandwich Group 8 cyclopentadienyl complexes containing crown trithioether ligands

The syntheses and characterization of three new mixed sandwich complexes involving crown thioether ligands and Group 8 metal ions are reported. These complexes are: [Ru(C 5 H 5 )(9S3)]PF 6 ( 1 ), [Ru(C 5 H 5 )(10S3)]PF 6 ( 2 ) and [Fe(C 5 H 5 )(10S3)]PF 6 ( 3 ), where 9S3=1,4,7-trithiacyclononane and 10S3=1,4,7-trithiacyclodecane. All three complexes have been characterized by single-crystal X-ray crystallography, and all structures show an octahedral metal center with facially coordinated carbocyclic and macrocyclic ligands. The average MS bond lengths in 1 , 2 and 3 are 2.289(2), 2.331(2) and 2.1823(7) A, respectively, and these are shorter than the MS bond lengths in the corresponding bis 9S3 and 10S3 complexes. We propose that this distance decrease is caused by enhanced metal–thioether π bonding due to the strong σ-donating ability of the Cp ligand. All structures are confirmed in solution via 1 H- and 13 C-NMR spectroscopy. Cyclic voltammetric studies on the three heteroleptic complexes show E 1/2 values that are intermediate between those of the corresponding homoleptic hexakis(thioether) complexes and metallocenes. This electrochemical behavior is also consistent with the relative σ-donating and π-accepting abilities of the Cp and trithioether ligands.