Premium
Cationic and Neutral Diphenyldiazomethanerhodium( I ) Complexes as Catalytically Active Species in the CC Coupling Reaction of Olefins and Diphenyldiazomethane
Author(s) -
Werner Helmut,
Schneider Michael E.,
Bosch Marco,
Wolf Justin,
Teuben Jan H.,
Meetsma Auke,
Troyanov Sergei I.
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20000818)6:16<3052::aid-chem3052>3.0.co;2-c
Subject(s) - rhodium , cationic polymerization , chemistry , catalysis , medicinal chemistry , acetone , pyridine , styrene , selectivity , electrophile , propene , coordination sphere , stereochemistry , photochemistry , polymer chemistry , organic chemistry , molecule , copolymer , polymer
Cationic rhodium( I ) complexes cis ‐[Rh(acetone) 2 (L)(L′)] + ( 2 : L=L′=C 8 H 14 ; 3 : L=C 8 H 14 ; L′=P i Pr 3 ; 4 : L=L′=P i Pr 3 ), prepared from [{RhCl(C 8 H 14 ) 2 } 2 ] and isolated as PF 6 salts, catalyze the CC coupling reaction of diphenyldiazomethane with ethene, propene, and styrene. In most cases, a mixture of isomeric olefins and cyclopropanes were obtained which are formally built up by one equivalent of RCH=CH 2 (R=H, Me, Ph) and one equivalent of CPh 2 . The efficiency and selectivity of the catalyst depends significantly on the coordination sphere around the rhodium( I ) center. Treatment of 4 with Ph 2 CN 2 in the molar ratio of 1:1 and 1:2 gave the complexes trans ‐[Rh(P i Pr 3 ) 2 (acetone)(η 1 ‐N 2 CPh 2 )]PF 6 ( 8 ) and trans ‐[Rh(P i Pr 3 ) 2 (η 1 ‐N 2 CPh 2 ) 2 ]PF 6 ( 9 ), of which 8 was characterized by X‐ray crystallography. Since 8 and 9 not only react with ethene but also catalyze the reaction of C 2 H 4 and free Ph 2 CN 2 , they can be regarded as intermediates (possibly resting states) in the CC coupling process. The lability of 8 and 9 is illustrated by the reactions with pyridine and NaX (X=Cl, Br, I, N 3 ) which afford the mono(diphenyldiazomethane)rhodium( I ) compounds trans ‐[Rh(P i Pr 3 ) 2 (py)(η 1 ‐N 2 CPh 2 )]PF 6 ( 10 ) and trans ‐[RhX(η 1 ‐N 2 CPh 2 )(P i Pr 3 ) 2 ] ( 11 ‐ 14 ), respectively. The catalytic activity of the neutral complexes 11 ‐ 14 is somewhat less than that of the cationic species 8, 9 and decreases in the order Cl>Br>I>N 3 .