Crown ether adducts of olefin complexes of Zeise's salt type - [K(18-crown-6)][PtCl3(olefin)]

[K(18-cr-6)]2[Pt2Cl6] reacts with olefins in CH2Cl2 to give crown ether adducts of olefin complexes of Zeise's salt type [K(18-cr- 6)][PtCl3(olefin)] (2) [olefin: EtCH=CH2 (2a), cis-MeCH=CHMe (2b), trans-MeCH=CHMe (2c), nPrCH=CH2 (2d), cis-EtCH=CHMe (2e), trans-EtCH=CHMe (2f), nBuCH=CH2 (2g), cis-nPrCH=CH-Me (2h), cis-EtCH=CHEt (2i), trans-EtCH=CHEt (2j), cyclohexene (2k), PhCH=CH2 (2l)]. The complexes were characterized by microanalysis, n.m.r. (1H, 13C) and i.r. spectroscopy. The crystal structures of the cis-but-2-ene (2b) and cis-pent-2-ene complexes (2e) were determined by single-crystal X-ray analyses. The Pt atom is square-planar, coordinated by three chloro ligands and the olefin ligand [interplanar angle PtCl3/Pt(C=C) 89.6° (2b), 86.6° (2e)]. The C=C bond length is 1.38(1)Å (2b) and 1.32(2)Å (2e), respectively. The substituents (Me, Et) on the double bond are bent back away from Pt [torsion angles C-C=C-Pt 109(2)-110.7(8)°]. There are close contacts of the [K(18- cr-6)]+ cations both to the trans and one of the cis chloro ligands [K···Cl 3.208(2)/3.230(2)Å (2b); 3.220(5)/3.370(5)Å (2e)].[PUBLICATION ABSTRACT]