Multiple metal-carbon bonds. 9. Preparation and characterization of several alkylidene complexes, M(.eta.5-C5H5)2(alkylidene)X (M = tantalum or niobium), and the x-ray structure of Ta(.eta.5-C5H5)2(CHC6H5)(CH2C6H5). An investigation of alkylidene ligand rotation

Richard R Schrock; Louis W Messerle; Clayton D Wood; Lloyd J Guggenberger

doi:10.1021/ja00480a024

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Journal article

Multiple metal-carbon bonds. 9. Preparation and characterization of several alkylidene complexes, M(.eta.5-C5H5)2(alkylidene)X (M = tantalum or niobium), and the x-ray structure of Ta(.eta.5-C5H5)2(CHC6H5)(CH2C6H5). An investigation of alkylidene ligand rotation

Richard R Schrock, Louis W Messerle, Clayton D Wood and Lloyd J Guggenberger

Journal of the American Chemical Society, Vol.100(12), pp.3793-3800

06/01/1978

DOI: 10.1021/ja00480a024

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Abstract

The reaction of Ta(CH2Ph)3Cl2 or M(CH2CMe3)2Cl3 with T1C5H5 gives TaCp2(CHPh)(CH2Ph) or MCp2(CHCMe3)Cl (M=Nb or Ta), respectively. Cl in TaCp2(CHCMe3)Cl can be replaced by CHPh2 or PMe3 (to give a cationic complex); TaCp2(CHSiMe3)(CH3) is prepared by deprotonating [TaCp2(CH2SiMe3)(CH3)]+Br-. All TaCp2(CHR)(X) complexes are pseudotetrahedral molecules in which the ⎓CHR ligand is oriented approximately perpendicular to the C(alkylidene)-Ta-X plane according to 13C and 1HNMR studies. The ⎓CHR ligand in all neutral complexes rotates about the C(alkylidene)-Ta bond axis into the C-Ta-X plane with a ΔG‡rot inversely proportional to the size of R. An x-ray structure of TaCp2(CHPh)(CH2Ph) shows that the benzylidene ligand (Ta=C 2.07 Å) is in fact not strictly perpendicular to the C(alkylidene)-Ta-X plane in the ground state but is already tipped 5.7° to the inside because of unfavorable steric interaction in what is a rather crowded molecule. These structural results are compared with others. © 1978, American Chemical Society. All rights reserved.

Details

Title: Subtitle: Multiple metal-carbon bonds. 9. Preparation and characterization of several alkylidene complexes, M(.eta.5-C5H5)2(alkylidene)X (M = tantalum or niobium), and the x-ray structure of Ta(.eta.5-C5H5)2(CHC6H5)(CH2C6H5). An investigation of alkylidene ligand rotation
Creators: Richard R Schrock
Louis W Messerle
Clayton D Wood
Lloyd J Guggenberger
Resource Type: Journal article
Publication Details: Journal of the American Chemical Society, Vol.100(12), pp.3793-3800
Publisher: American Chemical Society
DOI: 10.1021/ja00480a024
ISSN: 0002-7863
eISSN: 1520-5126
Language: English
Date published: 06/01/1978
Academic Unit: Chemistry; Radiology
Record Identifier: 9984216575802771

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