Browsing by Author "Steedman, Andrew John"

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    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
    (Massey University, 1995) Steedman, Andrew John
    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.