Copper(i) thiolates [CuSC n H 2n1 ] (n 4, 6,8,10,12, 16,18) have been prepared, and their liquid crystal behavior has been studied. Contrary to previous reports the compounds possess a lamellar structure in the solid state, which has been characterized by X-ray diffraction analysis of polycrystalline samples. Melting leads to a columnar mesophase which is stable within a range of 50 ± 60 8C for most of the derivatives, and has been characterized for [CuSC 10 H 21 ]: the X-ray diffraction pattern is consistent with a hexagonal columnar mesophase (a 2.15 nm) composed of [Cu 4 (m 2 -SC 10 H 21 ) 4 ] aggregates, and suggests that additional S´´´Cu interactions between the disklike tetramers induce a fairly ordered intracolumnar arrangement of these aggregates.

Reactions of trans,trans-(C6F5)(p-tol3P)2Pt(CC)4Pt(Pp-tol3)2(C6F5) and diphosphines Ar2P(CH2)mPAr2 yield trans,trans-(C6F5)(Ar2P(CH2)mPAr2)Pt(CC)4Pt(Ar2P(CH2)mPAr2)(C6F5), in which the platinum atoms are spanned via an sp and two sp3 carbon chains (Ar/m = 3, Ph/14, 87%; 4, p-tol/14, 91%; 5, p-C6H4-t-Bu/14, 77%; 7, Ph/10, 80%; 8, Ph/11, 80%; 9, Ph/12, 36%; only oligomers form for m > 14). Crystal structures of 3-5 show that the sp3 chains adopt chiral double-helical conformations that shield the sp chain at approximately the van der Waals distance, with both enantiomers in the unit cell. The platinum square planes define angles of 196.6 degrees -189.9 degrees or more than a half twist. Crystal structures of 7-9, which have shorter sp3 chains, exhibit nonhelical conformations. Reaction of the corresponding Pt(CC)6Pt complex and Ph2P(CH2)18PPh2 gives an analogous adduct (27%). The crystal structure shows two independent molecules, one helical and the other not. Low-temperature NMR data suggest that the enantiomeric helical conformations of 3-5 rapidly interconvert in solution. Cyclic voltammograms of 3-5 show more reversible oxidations than model compounds lacking bridging sp3 chains. These are the only double-helical molecules that do not feature bonding interactions between the helix strands, or covalent bonds to templates dispersed throughout the strands, or any type of encoding. The driving force for helix formation is analyzed.

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The air-stable complexes trans- [Ni(C 6 Cl 2 F 3 ) 2 L 2 ] (L = SbPh 3 , 1; AsPh 3 , 2; AsCyPh 2 , 3; AsMePh 2 , 4; PPh 3 , 5) have been synthesized by arylation of [NiBr 2 (dme)] (dme = 1,2-dimethoxyethane) in the presence of the corresponding ligand L (for compounds 1-4) or by ligand substitution starting from 1 (for compound 5). The structures of 1, 2, and 5 have been determined by X-ray diffraction and show an almost perfect square-planar geometry in all cases. Their catalytic activity in insertion polymerization of norbornene have been tested