ISSN:
1434-1948
Keywords:
Pentacarbonylmetal-tin bonding
;
Alkoxytin compounds
;
Inidene compounds
;
119Sn NMR
;
Bonding
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Dimerized inidene complexes [(CO)5M-Sn(OR)-M(CO)5]22- (M = Cr, W; R = Et, iPr), 1, are obtained from [{(CO)5M}2SnCl2]2- by different routes. Dimerization occurs via alkoxy-donor tin-acceptor bonding by which a planar Sn2O2 ring is formed. The Sn-{M(CO)5} bonds are made in a plane vertical to this ring such that, with the R-O groups being almost coplanar with the Sn2O2 ring, the overall geometry of the compounds shows idealized D2h symmetry. - The 119Sn-NMR resonances of 1 are found at rather low fields (M = Cr: δ ≈ 1400; M = W: δ ≈ 1170) indicating a low-lying tin-centered orbital in the LUMO range. Correspondingly EHT analyses show that the 3-center-4π system, which characterizes monomeric inidene species [LnM-E(X)-MLn]n, is still prevalent in the dimeric species 1. The low-lying π*-type LUMOs of 1 are the rationale for the observed 119Sn-NMR low-field shifts of 1. The dimeric compounds 1 react with 2,4-pentanedione to form chelate compounds of the same type as those characteristically obtained from monomeric inidene complexes: [{(CO)5Cr}2SnOEt]22- (1a) reacts to give [{(CO)5Cr}2Sn(acac)]- (2). The experimental results are verified by X-ray analyses in addition to the usual spectroscopic and analytical investigations.
Type of Medium:
Electronic Resource
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