Palladium(II) and Platinum(II) Complexes of 1,4,7,10,13,16‐Hexathiacyclooctadecane

Anion and Solvent Effects upon the Structures of Platinum(II) Complexes with Thiacrown Ligands: The Crystal Structures of [Pt(9S3)2](PF6)2·2 CH3NO2, [Pt(9S3)2](BF4)2·2 CH3NO2, [Pt(9S3)2](OTf)2·2 CH3NO2, and [Pt(18S6)](BF4)2

“…The simple NMR spectrum is not consistent with the [S 4 ϩ S 1 ] binding mode in the crystal structure, but rather the symmetrical [S 4 ϩ S 2 ] structure shown by the tetraphenylborate salt. [9] Our NMR spectroscopic data suggest that the ligand, in solution, forms an S-shaped elongated octahedral structure, and that packing effects during crystallization result in the [S 4 ϩ S 1 ] structure seen in our X-ray data. Another important result from the NMR study is the lack of fluxionality for the 18S6 ligand.…”

“…Previous 18S6 structures with Pd II and Pt II reported exclusively staggered or eclipsed conformers, so our structure represents an interesting intermediate case. [1,9] SϪPtϪS chelate bite angles in the 18S6 structure are even smaller than the for the three 9S3 structures at slightly less than 89°. The four sulfur atoms in the equatorial plane (S1, S2, S4, and S5) are co-planar to within 0.126 Å .…”

“…The structure crystallizes in a triclinic cell with space group, P1 ( [9] As seen in the 9S3 structures, the coordination mode of the 18S6 can be switched between [S 4 ϩ S 2 ] and [S 4 ϩ S 1 ] depending upon crystal packing forces that arise from the counterion or crystallization solvent. Although the preferred conformation of the ligand is generally important in determining how it will bind to a metal ion, there appears to be some limited flexibility in coordination modes towards d 8 [10] The all-sulfur exodentate conformation of the12S3 ligand precludes its forming two PtϪS axial interactions, but it, too, has limited flexibility in its ability to coordinate these ions.…”

“…The tetraphenylborate salt of [Pd(18S6] 2ϩ is yellow-brown while the hexafluorophosphate salt is green. [1,9] In addition, the PdϪS bond lengths and conformations of ethylene linkages also differ, illustrating how counterion effects can alter structures. As the spectroscopic and electrochemical properties of [Pt(18S6] 2ϩ have not been reported, those data are included here, along with our X-ray structure of the tetrafluoroborate salt.…”

“…As the spectroscopic and electrochemical properties of [Pt(18S6] 2ϩ have not been reported, those data are included here, along with our X-ray structure of the tetrafluoroborate salt. [9] Control of complex cation structure by solvent and counterion could have important impli-cations in crystal engineering applications. Both Pd II and Pt II complexes of thiacrowns have been used by the Schröder and Lippolis groups as templates for control and the self-assembly of three-dimensional structures.…”