Control of stereochemistry at the metal center in planar-chiral cyclopentadienyl ruthenium complexes with anchor phosphine on complexation with salicylideneaminato ligands

Citation
K. Onitsuka et al., Control of stereochemistry at the metal center in planar-chiral cyclopentadienyl ruthenium complexes with anchor phosphine on complexation with salicylideneaminato ligands, ORGANOMETAL, 20(15), 2001, pp. 3274-3282
Citations number
71
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ORGANOMETALLICS
ISSN journal
0276-7333 → ACNP
Volume
20
Issue
15
Year of publication
2001
Pages
3274 - 3282
Database
ISI
SICI code
0276-7333(20010723)20:15<3274:COSATM>2.0.ZU;2-Y
Abstract
Reactions of planar-chiral cyclopentadienyl-phosphine ruthenium complexes [ eta (5),eta (1)-{C5H2-(Me)(R)COO(CH2)(2)PPh2}Ru(MeCN)(2)] [PFG(6)] (1a, R = Me; 1b, R = Ph) with sodium salicylideneaminato (2) led to the formation o f salicylideneaminato complexes [eta (5),eta (1)-{C5H2(Me)(R)-COO(CH2)(2)PP h2}Ru(OArC=NR ')] (3 and 4, R = Me; 5 and 6, R = Ph) inducing metal-centere d chirality with a high selectivity (up to > 99% de). The diastereoselectiv ity of products did not depend on the substituent on aromatic ring of salic ylideneaminato ligands, but upon the substituents on the cyclopentadienyl g roup and on nitrogen of the imino group. X-ray diffraction and NMR studies including NOE measurements revealed that the configuration of the major iso mers is SCpRRu/RCpSRu. Similar reactions of planar-chiral cyclopentadienyl ruthenium complexes [eta (5)-{C5H2(Me)(R)COOEt}Ru(PPh3)(MeCN)(2)][PF6] (7) (7a, R = Me; 7b, R = Ph) having no anchor phosphine ligands with 2 also gav e salicylideneaminato complexes [eta (5)-{C5H2(Me)(R)COOEt}Ru(PPh3)(OC6H4C = NR ')] (8 and 9) with a low selectivity. Epimerization of a pure sample o f the major product 5a into a diastereomeric mixture of 5a and 6a showed th at the diastereoselectivity at the ruthenium center is governed by the diff erence in thermodynamic stability between 3 and 4, or 5 and 6.