ISSN:
0009-2940
Keywords:
9-Fluorenylidene(tetramethylpiperidino)borane ligand
;
Iron complexes
;
Cyclopentadienyl ligands
;
Calculations, MO
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The boraolefin 9-fluorenylidene(tetramethylpiperidino)borane L forms complexes 1 - 4 with the isolobal fragments Fe-(CO)4, CpCo(CO), Cp′Mn(CO)2, and C6H6Cr(CO)2, respectively. Compounds FeL(CO)3PR3 (PR3=PMe3, PhPMe2, Ph2-PMe, PCl3, PhPCl2, 1 a - e) are obtained photochemically from Fe(CO)5, L, and PR3 in toluene solution. An X-ray structure analysis 1 and 1 a reveals a distorted trigonal-bipyramidal geometry, with the boron atom of 1 in an equatorial position. 2 contains two independent molecules in the asymmetric unit. The two molecules are enantiomers with Co atoms in a pseudotetrahedral environment. MO calculations demonstrate that the distortion found in 1 is due to electronic rather than steric effects as exemplified by the model compound Fe(CO)4(H2N - B=CH2) (6). π-Back bonding from the metal-centred 2a′ orbital to the boron-centred πBC* orbital contributes significantly to the stabilization of the energy-minimized structure 8. Experimental evidence for this back bonding is provided by the shorter M-B bond in 1 and 2 as compared with the M-C bond to the boraoelfin unit. However, the reverse is true for the manganese complex 3.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19921250113
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