Ortho-, Meta-, and Para-Directing Influence of Transition-Metal Fragments in 12-Vertex c loso-Cyclopentadienylmetallaheteroboranes:  Additive Nature of Structural Increments

Cyclopentadienylmetal fragments in 12-vertex closo-cyclopentadienylmetallaheteroboranes have a clear preference with respect to the positions relative to heteroatoms in the thermodynamically most stable isomer. Cyclopentadienyl derivatives of group 9 and 10 metals direct a carbon atom to meta and pa...

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Bibliographic Details
Published in:Organometallics 2006-01, Vol.25 (2), p.485-490
Main Authors: Kiani, Farooq Ahmad, Hofmann, Matthias
Format: Article
Language:English
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Summary:Cyclopentadienylmetal fragments in 12-vertex closo-cyclopentadienylmetallaheteroboranes have a clear preference with respect to the positions relative to heteroatoms in the thermodynamically most stable isomer. Cyclopentadienyl derivatives of group 9 and 10 metals direct a carbon atom to meta and para positions, respectively. CpM fragments of two group 8 metals, i.e., Ru and Os, have the tendency to direct carbon atoms to meta positions, while that of Fe directs carbon atoms to ortho positions. By using increments for two general structural features, i.e., HetHet‘o (two heteroatoms at ortho positions) and HetHet‘m (two heteroatoms at meta positions), the relative stabilities of numerous isomers can be easily predicted. A comparison with DFT-computed relative stabilities of 101 metallaheteroboranes incorporating up to 4 heteroatoms shows good agreement:  the average and standard deviations of the values derived from increments are 1.4 and 1.9 kcal mol-1, respectively.
ISSN:0276-7333
1520-6041
DOI:10.1021/om050814u