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Cycloheptatriene and fulvene Cr(CO) 3 complexes
Author(s) -
Albright Thomas A.,
Hoffmann Roald,
Hofmann Peter
Publication year - 1978
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19781110440
Subject(s) - chemistry , cycloheptatriene , fulvene , cyclobutadiene , annulene , tautomer , methylene , crystallography , stereochemistry , computational chemistry , molecule , medicinal chemistry , organic chemistry
1,6‐Methano[10]annulene‐Cr(CO) 3 and several related complexes adopt an anomalous orientation of the Cr(CO) 3 unit with respect to the polyene, compared to all other hexatriene‐Cr(CO) 3 complexes. A theoretical analysis of this problem shows that these conformational preferences are closely related to the cycloheptatriene‐norcaradiene valence tautomerism. Several strategies for influencing the barrier to internal rotation in these complexes are presented. An analysis of the conformational preference, rotational barrier, and bending of the exocyclic methylene group in fulvene‐Cr(CO) 3 is also discussed. This is extended to the analogous benzyl‐Cr(CO) 3 and cyclobutadiene‐carbinyl‐Fe(CO) 3 cations. Finally, the orientations of these complexes are contrasted to those containing two more electrons.