Synthesis, structure, spectroscopy, and reactivity of a neutral iridathiabenzene

John R. Bleeke, Paul V. Hinkle, Monica Shokeen, Nigam P. Rath

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Treatment of the cationic iridathiabenzene [CH=C(Me)C(Me)=CHS=Ir(PEt 3) 3] +BF 4 - (3) with sodium tert-butylthiolate leads to the production of a stable neutral iridathiabenzene, CH=C(Me)C(Me)=CHS=Ir(PEt 3) 2(S-t-Bu) (4). Compound 4 exists in solution as an equilibrating mixture of two square pyramidal isomers, "cis" 4a and "trans" 4b. When 4 is cooled to -30 °C in acetonitrile, it precipitates as an acetonitrile adduct, CH=C(Me)C(Me)=CHSIr(PEt 3) 2 (S-t-Bu)(NCMe) (6), featuring an iridathiacyclohexa-1,3-diene ring system. Compound 6 reverts back to 4 upon redissolving and warming to room temperature. Treatment of 4 (or 6) with excess PMe 3 results in addition of PMe 3 to the iridium center and replacement of the bulky PEt 3 ligands with PMe 3's, producing CH=C(Me)C(Me)=CHSIr(PEt 3) 3(S-t-Bu) (7) as a mixture of equilibrating isomers, "cis" 7a and "trans" 7b. Compound 7, like 6, includes a nonaromatic iridathiacyclohexa-1,3-diene ring. When 4 in acetonitrile solvent (or 6) is reacted with trifluoromethanesulfonic acid, protonation occurs at the thiolate sulfur, causing loss of thiol. The resulting cationic fragment dimerizes to produce {[CH=C(Me)C(Me)=CHSIr-(PEt 3) 2(NCMe)] 2} 2+(O 3SCF 3 -) 2 (8), in which the two iridium centers are bridged by the two ring sulfurs. Finally, treatment of 4 (or 6) with [(η 5-C 5Me 5)Ru(NCMe) 3] +O 3SCF 3 - results in production of the sandwich compound {η 5-[CH=C(Me)C(Me)=CHSIr(PEt 3) 2(S-t-Bu)]Ru(η 5-C 5Me 5)} +O 3SCF 3 - (9), which exists in solution as an equilibrating mixture of isomers, "cis" 9a and "trans" 9b. Compounds 4a, 7a, 8, and 9a have been structurally characterized by X-ray diffraction.

Original languageEnglish
Pages (from-to)4139-4149
Number of pages11
JournalOrganometallics
Volume23
Issue number17
DOIs
StatePublished - Aug 16 2004

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