Carbon-carbon bond formation in cationic aryl-olefin-platinum (II) complexes
- Universita del Molise, Campobasso (Italy)
- Universita di Napoli (Italy)
Cationic five-coordinate [Pt(3-R{sup 1}-4-R{sup 2}-C{sub 6}H{sub 3})(MeCN) (6-Me-py-2-CH=NPh)(C{sub 2}H{sub 4})]{sup +} complexes (R{sup 1}, R{sup 2} = H, Me, OMe) undergo an unexpected rearrangement at 0{degrees}C in chloroform solution, affording, after treatment with aqueous LiCl, the neutral four-coordinate species [Pt(2-Et-4-R{sup 1}-5-R{sup 2}-C{sub 6}H{sub 2})Cl(6-Me-py-1-CH=NPh)]. Pt-C{sub aryl} bond breaking and making is involved in the whole process, resulting in a 1,2-shift of the platinum atom to an adjacent position of the benzene ring. The same compound is obtained, together with products deriving from a typical insertion, when an equimolar amount of ethylene is added to a chloroform solution of [Pt(3-R{sub 1}-4-R{sup 2}-C{sub 6}H{sub 3})(MeCN)(6-Me-py-2-CH=NPh)]{sup +} at 0{degrees}C. When higher ethylene/Pt ratios are used, only five-coordinate [Pt(3-R{sup 1}-4-R{sup 2}-C{sub 6}H{sub 3}CH{sub 2}CH{sub 2})Cl(6-Me-py-2-CH{double_bond}NPh)(C{sub 2}H{sub 4})] complex is isolated. As the experimental data rule out the possibility of a (2-arylethyl)platinum to (2-ethylaryl)platinum rearrangement, different reaction paths are suggested for the two processes. When the two reactions are combined in a {open_quotes}one-pot{close_quotes} sequence, a regiocontrolled double alkylation of the aryl system can be obtained. The behavior substrates containing bidenate nitrogen ligands having different five-coordination stabilizing effects is examined, and data concerning the reactions of propene and styrene are reported. 13 refs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 412003
- Journal Information:
- Organometallics, Vol. 11, Issue 11; Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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