Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion
Deprotonation of [(mu-H)Ir4(CO)10(mu-PPh2)], 1, gives [Ir4(CO)10(mu-PPh2)]- that reacts with Ph2PCCPh and CH3I to afford [Ir4(CO)8(CH3)(mu4-eta³-Ph2PCCPh)(mu-PPh2)], 2 (34%), besides [Ir4(CO)9(mu3-eta³-Ph2PC(H)CPh)(mu-PPh2)] and [(mu-H)Ir4(CO)9(Ph2PC<FONT FACE=Symbol>º</FONT>CPh)(mu-PPh2...
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| Format: | Article |
| Language: | English |
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Sociedade Brasileira de Química
1999-01-01
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| Series: | Journal of the Brazilian Chemical Society |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000100007 |
| _version_ | 1818163741230891008 |
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| author | Braga Dario Fujiwara Fred Y. Grepioni Fabrizia Pereira Regina M.S. Vargas Maria D. |
| author_facet | Braga Dario Fujiwara Fred Y. Grepioni Fabrizia Pereira Regina M.S. Vargas Maria D. |
| author_sort | Braga Dario |
| collection | DOAJ |
| description | Deprotonation of [(mu-H)Ir4(CO)10(mu-PPh2)], 1, gives [Ir4(CO)10(mu-PPh2)]- that reacts with Ph2PCCPh and CH3I to afford [Ir4(CO)8(CH3)(mu4-eta³-Ph2PCCPh)(mu-PPh2)], 2 (34%), besides [Ir4(CO)9(mu3-eta³-Ph2PC(H)CPh)(mu-PPh2)] and [(mu-H)Ir4(CO)9(Ph2PC<FONT FACE=Symbol>º</FONT>CPh)(mu-PPh2)]. Compound 2 was characterised by a single crystal X-ray diffraction analysis and exhibits a flat butterfly of metal atoms, with the Ph2PCCPh ligand interacting with all four Ir atoms and the methyl group bonded terminally to a wingtip Ir atom. Carbonylation of 2 yields initially (25 °C, 20 min) a CO addition product that, according to VT 31P{¹H} and 13C{¹H} studies, exists in solution in the form of two isomers 4A and 4B (8:1), and then (40 °C, 7 h), the CO insertion product [Ir4(CO)8{C(O)CH3}(mu4-eta³-Ph2PCCPh)(mu-PPh2)], 5. The molecular structure of 5, established by an X-ray analysis, is similar to that of 2, except for the acyl group that remains bound to the same Ir atom. The process is reversible at both stages. Treatment of 2 with PPh3 and P(OMe)3 affords the CO substitution products [Ir4(CO)7L(CH3)(mu4-eta³-Ph2PCCPh)(mu-PPh2)] (L = PPh3, 6 and P(OMe)3, 7), instead of the expected CO inserted products. According to the ¹H and 31P{¹H} NMR studies, the PPh3 derivative 6 exists in the form of two isomers (1:1) that differ with respect to the position of this ligand. |
| first_indexed | 2024-12-11T16:54:23Z |
| format | Article |
| id | doaj.art-36779c1012d34fa3a9208c6f91654a82 |
| institution | Directory Open Access Journal |
| issn | 0103-5053 |
| language | English |
| last_indexed | 2024-12-11T16:54:23Z |
| publishDate | 1999-01-01 |
| publisher | Sociedade Brasileira de Química |
| record_format | Article |
| series | Journal of the Brazilian Chemical Society |
| spelling | doaj.art-36779c1012d34fa3a9208c6f91654a822022-12-22T00:58:00ZengSociedade Brasileira de QuímicaJournal of the Brazilian Chemical Society0103-50531999-01-011013545Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO InsertionBraga DarioFujiwara Fred Y.Grepioni FabriziaPereira Regina M.S.Vargas Maria D.Deprotonation of [(mu-H)Ir4(CO)10(mu-PPh2)], 1, gives [Ir4(CO)10(mu-PPh2)]- that reacts with Ph2PCCPh and CH3I to afford [Ir4(CO)8(CH3)(mu4-eta³-Ph2PCCPh)(mu-PPh2)], 2 (34%), besides [Ir4(CO)9(mu3-eta³-Ph2PC(H)CPh)(mu-PPh2)] and [(mu-H)Ir4(CO)9(Ph2PC<FONT FACE=Symbol>º</FONT>CPh)(mu-PPh2)]. Compound 2 was characterised by a single crystal X-ray diffraction analysis and exhibits a flat butterfly of metal atoms, with the Ph2PCCPh ligand interacting with all four Ir atoms and the methyl group bonded terminally to a wingtip Ir atom. Carbonylation of 2 yields initially (25 °C, 20 min) a CO addition product that, according to VT 31P{¹H} and 13C{¹H} studies, exists in solution in the form of two isomers 4A and 4B (8:1), and then (40 °C, 7 h), the CO insertion product [Ir4(CO)8{C(O)CH3}(mu4-eta³-Ph2PCCPh)(mu-PPh2)], 5. The molecular structure of 5, established by an X-ray analysis, is similar to that of 2, except for the acyl group that remains bound to the same Ir atom. The process is reversible at both stages. Treatment of 2 with PPh3 and P(OMe)3 affords the CO substitution products [Ir4(CO)7L(CH3)(mu4-eta³-Ph2PCCPh)(mu-PPh2)] (L = PPh3, 6 and P(OMe)3, 7), instead of the expected CO inserted products. According to the ¹H and 31P{¹H} NMR studies, the PPh3 derivative 6 exists in the form of two isomers (1:1) that differ with respect to the position of this ligand.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000100007migratory insertioniridium carbonyl clustersalkyl clusterscarbonylation |
| spellingShingle | Braga Dario Fujiwara Fred Y. Grepioni Fabrizia Pereira Regina M.S. Vargas Maria D. Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion Journal of the Brazilian Chemical Society migratory insertion iridium carbonyl clusters alkyl clusters carbonylation |
| title | Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion |
| title_full | Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion |
| title_fullStr | Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion |
| title_full_unstemmed | Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion |
| title_short | Synthesis and Structural Characterisation of [Ir4(CO)8(CH3)(m4-h3-Ph2PCCPh)(m-PPh2)] and of the Carbonylation Product [Ir4(CO)8{C(O)CH3}(m4-h3-Ph2PCCPh)(m-PPh2)]; First Evidence for the Formation of a CO Cluster Adduct before CO Insertion |
| title_sort | synthesis and structural characterisation of ir4 co 8 ch3 m4 h3 ph2pccph m pph2 and of the carbonylation product ir4 co 8 c o ch3 m4 h3 ph2pccph m pph2 first evidence for the formation of a co cluster adduct before co insertion |
| topic | migratory insertion iridium carbonyl clusters alkyl clusters carbonylation |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000100007 |
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