An investigation of Ru(II) complexes containing sterically demanding imido ligands : a thesis presented to Massey University in partial fulfilment of the requirements for the degree of Master of Science
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Date
1995
DOI
Open Access Location
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Journal ISSN
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Publisher
Massey University
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The Author
Abstract
Monomeric, low oxidation state, ruthenium imido compounds, (η6
-arene) RuN-Ar' (arene= p-cymene and C6
Me6
; Ar'= 2,4,6-tri-tert-butylphenyl) have been synthesized from [(η6
-arene) RuCl2
]2
and 4 equiv of LiNHAr' in THF. An X-ray crystal structure of (η6
-p-cymene) Ru=NAr' showed a short Ru-N distance (1.753(3)Ǻ) and a near linear Ru-N-C angle (177.8(4)°
) consistent with ruthenium to nitrogen multiple bonding. Reaction of [(η6
-p- cymene) RuCl2
]2
with 4 equiv of LiNHR (R= 2,6-dimethylphenyl or 2,6-diisopropylphenyl) in THF afforded the dimeric ruthenium imido compounds [(η6
-p-cymene) Ru(µ-NR)]2.
An X-ray crystal structure of [(η6
-p-cymene) Ru(µ-NAr)]2
(Ar= 2,6-diisopropylphenyl) showed an averaged Ru-N distance of 1.974(8)Ǻ and features characteristic of Ru(II) bridging imido complexes. Addition of 2 equiv of LiNHAr to [(η6
-C6
Me6
) RuCl2
]2
gave a HCl adduct, (η6
-C6
Me6
) RuClNHAr, characterisation of the complex was obtained by X-ray diffraction. Reaction of the HC1 adduct with phenylisocyanate gave the ureylene metallacycle, (η6
-C6
Me6
) RuN(Ar)C(0)N(Ph), indicating the presence of an imido intermediate. This complex was shown to have a υ(CO) band at 1596cm
-1
and is comparable with other monomeric ureylene complexes. In addition, the complex [(η6
-p-cymene) Ru(µ-NAr)]2
was made from 2 equiv of the amine, ArNH2
, and [(η6
-p-cymene) RuCl2
]2
and dehydrochlorinated with KN(SiMe3
)2
providing an alternative route. Further, an X-ray crystal structure of the amine complex, (η6
-p-cymene) RuCl2
(ArNH2
) was obtained. The reaction of (bpy)2
RuCl2
(bpy= 2,2'-bipyridine) with LiNHAr' in THF afforded the complex, (bpy)2
Ru=NAr', characterised by nmr and elemental analysis.
Description
Keywords
Ligands, Transition metal complexes