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Methyl(2‐phosphanylphenolato[ P , O ])nickel(II) Complexes – Synthesis, Structure, and Activity as Ethene Oligomerization Catalysts
Author(s) -
Heinicke Joachim,
He Mengzhen,
Dal Attila,
Klein HansFriedrich,
Hetche Olaf,
Keim Wilhelm,
Flörke Ulrich,
Haupt HansJürgen
Publication year - 2000
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/(sici)1099-0682(200003)2000:3<431::aid-ejic431>3.0.co;2-q
Subject(s) - chemistry , nickel , catalysis , isopropyl , trigonal bipyramidal molecular geometry , dissociation (chemistry) , medicinal chemistry , alkyl , crystal structure , yield (engineering) , stereochemistry , crystallography , organic chemistry , materials science , metallurgy
Reactions of various substituted 2‐phosphanylphenols 1a–f with half‐molar amounts of cis ‐[MeNi(μ‐OMe)(PMe 3 )] 2 have been found to yield square‐planar methyl(2‐phosphanylphenolato)(trimethylphosphane)nickel(II) complexes 2a–f . 2 J PP coupling constants of 305–316 Hz at low temperature indicate a trans ‐configuration for the products, while broad 31 P‐NMR signals at room temperature can be attributed to rapid dissociation of PMe 3 . Reaction with excess 1 gave rigid bis(2‐phosphanylphenolato)nickel(II) complexes as exemplified by 3e , whereas addition of PMe 3 to 2a led to the pentacoordinate methyl(2‐phosphanylphenolato)bis(trimethylphosphane)nickel(II) complex 4a . Higher yields of 4a and 4d were obtained by reactions of 1a and 1d with Me 2 Ni(PMe 3 ) 3 . Single‐crystal X‐ray diffraction analyses of 3e and 4a have revealed the structures as square‐planar trans ‐bis‐ and trigonal‐bipyramidal mono(2‐phosphanylphenolato)nickel(II) P 1 O‐chelate complexes, respectively. The methylnickel complexes 2 and 4 have been found to be effective one‐component catalysts for the oligomerization of ethene. High conversions (> 96%) were achieved with the P‐basic derivatives 2e , 2f , and 4d bearing one or two branched alkyl groups (isopropyl, tert ‐butyl), whereas the diphenylphosphanyl derivatives were less active; 4d gave shorter oligomers than 2e or 2f .