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Synthesis, Structural Characterization, and Catalytic Activity of Indenyl Tris( N ‐pyrrolyl)phosphine Complexes of Ruthenium
Author(s) -
Stark Matthew J.,
Shaw Michael J.,
Rath Nigam P.,
Bauer Eike B.
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201501381
Subject(s) - ruthenium , chemistry , phosphine , steric effects , ligand (biochemistry) , cyclopentadienyl complex , medicinal chemistry , catalysis , stereochemistry , tris , organic chemistry , biochemistry , receptor
The synthesis, characterization, and catalytic activity of new ruthenium complexes of the tris( N ‐pyrrolyl)phosphine ligand [P(pyr) 3 ] are described. The new ruthenium complexes [RuCl(ind)(PPh 3 ){P(pyr) 3 }] and [RuCl(ind){P(pyr) 3 } 2 ] (ind = indenyl, η 5 ‐C 9 H 7 – ) were synthesized in 73 and 63 % isolated yields, respectively, by thermal ligand exchange of [RuCl(ind)(PPh 3 ) 2 ] with P(pyr) 3 . The electronic and steric properties of the new complexes were studied through analysis of the X‐ray structures and cyclic voltammetry. The new complexes [RuCl(ind)(PPh 3 ){P(pyr) 3 }] and [RuCl(ind){P(pyr) 3 } 2 ] and the known complex [RuCl(ind){(PPh 3 ) 2 }] differed only slightly in their steric properties, as seen from the comparable bond lengths and angles around the ruthenium centers. The oxidation potentials of [RuCl(ind)(PPh 3 ){P(pyr) 3 }] and [RuCl(ind){P(pyr) 3 } 2 ] of +0.34 and +0.71 V versus Cp 2 Fe 0/+ (Cp = cyclopentadienyl) are substantially higher than that of [RuCl(ind)(PPh 3 ) 2 ] (–0.023 V), in accordance with the enhanced π‐acidity of the P(pyr) 3 ligand. The new complexes are catalytically active in the etherification of propargylic alcohols and in the first ruthenium‐catalyzed formation of known and new xanthenones from propargylic alcohols and diketones (18 to 72 h at 90 °C in ClCH 2 CH 2 Cl or toluene, 1–2 mol‐% catalyst, 69–22 % isolated yields).