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Steric Control of Cyclometallation Reactions in Schiff‐Base Complexes of Cobalt( I ) Containing an Anchoring Diphenylphosphanyl Group
Author(s) -
Klein HansFriedrich,
Beck Robert,
Flörke Ulrich,
Haupt HansJürgen
Publication year - 2002
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 - 10.1002/1099-0682(200212)2002:12<3305::aid-ejic3305>3.0.co;2-a
Subject(s) - chemistry , steric effects , ligand (biochemistry) , cobalt , stereochemistry , medicinal chemistry , carbonylation , schiff base , catalysis , carbon monoxide , receptor , organic chemistry , biochemistry
2‐(Diphenylphosphanyl)alkyliminobenzaldehydes(2‐Ph 2 PC 6 H 4 CHNR) react with [CoCH 3 (PMe 3 ) 4 ] forming five‐membered metallacycles in complexes [(2‐Ph 2 PC 6 H 4 CNR‐ C , P )Co(PMe 3 ) 3 ] [ 1 : R = C 2 H 5 , 2 : R = CH(CH 3 ) 2 , 3 : R = cyclo ‐C 6 H 11 ] while the ortho ‐metallation pathway is selectively followed in the formation of [{2‐Ph 2 PC 6 H 3 (CHNR)‐ C 1 , P }Co(PMe 3 ) 3 ] [ 4 : R = C(CH 3 ) 3 ]. The presence of a four‐membered cobaltocycle in the molecular structure of 4 was confirmed by X‐ray analysis. Carbonylation of 2 and 3 gives the monocarbonyl derivatives [(2‐Ph 2 PC 6 H 4 CNR‐ C , P )Co(CO)(PMe 3 ) 2 ] [ 5 : R = CH(CH 3 ) 2 , 6 : R = cyclo ‐C 6 H 11 ] while 4 undergoes ring expansion by insertion forming [{2‐Ph 2 PC 6 H 3 (CHNR)CO‐ C , P }Co(CO)(PMe 3 ) 2 ] [ 7 : R = C(CH 3 ) 3 ]. Monosubstitution occurs under 1 bar of ethene giving the π‐ethene complexes [(2‐Ph 2 PC 6 H 4 CNR‐ C , P )Co(C 2 H 4 )(PMe 3 ) 2 ] [ 8 : R = CH(CH 3 ) 2 , 9 : R = cyclo ‐C 6 H 11 ] and [{2‐Ph 2 PC 6 H 3 (CHNR)‐ C 1 , P }Co(C 2 H 4 )(PMe 3 ) 2 ] [ 10 : R = C(CH 3 ) 3 ]. The molecular structure of 9 shows an equatorial π‐ethene ligand. Iodomethane oxidizes 2 and 3 to afford the cobalt( II ) complexes [(2‐Ph 2 PC 6 H 4 CNR‐ C , P )CoI(PMe 3 ) 2 ] [ 11 : R = CH(CH 3 ) 2 , 12 : R = cyclo ‐C 6 H 11 ] and oxidatively adds to 4 to give mer ‐ trans ‐[{2‐Ph 2 PC 6 H 3 (CHNR)‐ C 1 , P }CoI(CH 3 )(PMe 3 ) 2 ] [ 13 : R = C(CH 3 ) 3 ]. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)