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Synthesis and reactions of sterically encumbered, heteroleptic lanthanum phosphides. Structural characterization of [{(Me3Si)2CH}-(C6H4-2-Ch2NMe 2)P]2La(OR) and [{(Me3Si)2CH}- (C6)H4-2-CH2NMe2)P]La(THF)[P(C6H4-2-CH2NMe2)-{CH(SiMe 3)(SiMe2CH2)}] [R =i-Pr, t-Bu]

Lookup NU author(s): Dr Keith Izod, Dr Stephen Liddle, Emeritus Professor William McFarlane, Emeritus Professor Bill Clegg

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Abstract

Metathesis between LaI3 and 2 equiv of {R(C6H 4-2-CH2NMe2)P}K gives the heteroleptic complex {R(C6H4-2-CH2NMe2)P}2LaI (1), which reacts in situ with 1 equiv of KOR′ to give the corresponding mixed phosphide/alkoxide complexes {R(C6H4-2-CH 2NMe2)P}2La(OR′) [R = (Me 3Si)2CH, R′ = t-Bu (2), i-Pr (3)]. A similar in situ reaction between 1 and 1 equiv of any of the alkali metal organometallics R′K [R′ = PhCH2, Me3SiCH2, (Me 3Si)2CH] yields the cyclometalated product {([Me 3Si]2CH)(C6H4-2-CH 2NMe2)P}La(THF)[P(C6H4-2-CH 2NMe2)-[CH{SiMe3}{SiMe2CH 2}] (4) and R′H. Reaction between the homoleptic tris(alkyl) {(Me3Si)2CH}3La and 2 equiv of the secondary phosphine R(C6H4-2-CH2NMe2)PH yields 4 as the exclusive product, suggesting that the cyclometalation reaction is intramolecular in nature. Compounds 2-4 have been characterized by multielement NMR spectroscopy and X-ray crystallography. Variable-temperature 31P and 1H NMR spectra and 2-D NMR experiments reveal that 4 is subject to dynamic processes in toluene solution, which may be attributed to rapid, reversible inversion at phosphorus, which results in rapid equilibria between stereoisomers; La-C cleavage is slow on the NMR time scale.


Publication metadata

Author(s): Izod K, Liddle ST, McFarlane W, Clegg W

Publication type: Article

Publication status: Published

Journal: Organometallics

Year: 2004

Volume: 23

Issue: 11

Pages: 2734-2743

ISSN (print): 0276-7333

ISSN (electronic): 1520-6041

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/om0498798

DOI: 10.1021/om0498798


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