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The chemistry of mononuclear and polynuclear ruthenium carbonyl complexes containing nitrene and related ligands

by Lee, Ka-hong

Abstract (Summary)
(Uncorrected OCR) Abstract of thesis entitled

THE CHEMISTRY OF MONONUCLEAR AND POLYNUCLEAR RUTHENIUM CAJlBONYL COMPLEXES CONTAINING NITRENE AND RELATED LIGANDS

Submitted by

Lee KaHong

for the Degree of Doctor of Philosophy at The University of Hong Kong

in July 1997

Methylation of the nitrosyl-containing cluster [PPN][Rtt3(CO)Io(J..l-NO)] led to the methoxynitrido cluster [RU3(CO)9(~-CO)(J..l3-NOCHs)] in over 70% yield accompanied by traces of [RU6(J.l-H) (CO)16(IJ.-CO) (/l4C(O)OCI-L}] which possessed a rare hexanuclear 'boat' configuration with a nitrene moiety quadruply bridged over the central square base. Hydrogenation of [Rll3(CO)9(J.l3-CO) (J.l3-NOCI-L)] in refluxing n-hexane resulted in the replacement of the J.l3-CO by two bridging hydrides to give [RU3(J.lNOCfu)]. Further hydrogenation yielded [Rll3(IJ.-H)2(CO)9(!l3-NH)] with the elimination of a methanol from the methoxy group. When [RU3(CO)9(J.l3NOCfu)] was hydrogenated in the presence of [RU3(CO) 12] , two additional clusters, [RU6(Il-H)(COh6(IJ.-CO)z(/l4-NH)(J.l-OCI-L)] and [RUs(J.lNH)(J.l3-0Cfu)] which contained a /l4-nitrene ligand could also be isolated. Thermolysis of [Rll3(CO)9(!l3-CO)(1J.3-NOCfu)] in toluene at 90? for 3h yielded [Rll4(CO)12(/l4-N) (J.l-OCfu)] and [RU6(CO)16(IJ.-CO)2(/l4-NH) (J.l-OCI-L)z] while

vacuum pyrolysis of [RU3(CO)9(~-CO)(Il3-NOClL)] at 1S0? for 10 min gave [RU6(COh6(f..l-C0)2(/l4-NH)(f..l-OClL)(f..l- NCO)] and [RU6(CO)I6(f..l-COh(f..l4- NH)(~OCf:L)2]. When [RU3(CO)9(f..l3-CO)(~-NOCffi)] was heated in refluxing n-octane for O.Sh, [Ru6(CO)I3(f..l-CO)(f..l5-N)(~-NH)(f..l3-0Clli){f..l-ll2-C(O)OClLh] was formed in addition to [RU4(CO)12(f..l4-N) (f..l-OCffi)] in low yield. Vacuum pyrolysis of [RU3(f..l-H)2(CO)9(f..l3-NOCa)] at 140? for 2h afforded [Rll3(~H)(CO)1O(f..l-NH2)], [RU6(CO)IS(f..l-C0)2(f..l4- NH)(f..l-OClL){f..l3-rf- N (H)C(O)OCa)], [RU6(f..l- H)2( CO)14(f..l-C0)2{f..l5-112- NC(O)OClL}] and [RU6(CO)16(f..l-CO)2(f..l4- NH)(J..lOCfI3) (f..l-NCO)]. Reaction of [RU3(CO)9(f..l3-CO) (f..l3-NOCHs)] with PPh3 and dppm yielded phosphine-substituted products, [RU3(CO)9NOClli) (PPh3)n] (n = 1 or 2) and [Rll3(CO)7(f..l3-CO)(~-NOCHs)(f..l-dppm)] respectively, whereas vacuum pyrolysis of [RU3(CO)S(f..l3-CO)(f..l3-NOClli)(PPhs)] afforded [RU3(CO)s(f..l-NCO)2(PPh3)2] which possesses two bridging isocyanate groups. Reaction of [RU3(CO)9(f..l3-CO)(Il3-NOCHs)] with phenyl acetylene gave [RU3(CO)9(f..l3-NOCffi)(f..l3-1l2_HC2Ph)] in which the phenylacetylene adopted a /.1l2-fashion across the open Ru .. ?u edge. [RU3(CO)9(f..l3-CO)(f..l3-NOCHs)] also reacts with [CpMo(COhHl to give?[Ru2Mo(f..l-H)(CO)s(llS-CsHs)(f..l3-NR)] (R = OClli or H) via a metal-exchange mechanism. However, the reaction of [RU3(CO)9(f..l3-CO)(f..l3-NOCfI3)] with [{CpMO(~O)3hHg] in refluxing THF resulted in the isolation of [RU3(CO)1O(f..l-NH2)(f..l3-Hg){Mo(1lS-CsHs)(C0)3}]. Furthermore, a new synthetic approach to the heterometallic nitrido clusters, [RU3CO(f..l4-N)(CO)12-n(PPh3)n] (n = 0 or 1) using the redox condensation of the methoxynitrido moieties is also described.

The reactions of triruthenium and triosmiu1TI: carbonyl clusters with nitrosoarene . gave [RU3(CO)6(f..l-CO) (f..l3-NPh)2(f..l-ll2-0NPh)2] and [OS3(CO)1O(f..lNHAr)(f..l-lf-ONAr)] (Ar = Ph, 3-Tol and 4-Tol} respectively in which the nitroso moieties adopt a novel f..l-ll2-bonding mode across the open metal-metal edges. On the other hand, the reaction of [RU3(CO)t2] with ortho-functionalised

nitrosoarene such as nitrosonaphthols (2-nqoH and l-nqoH) afforded two isomeric mononuclear complexes trans-[Ru{1l2_0ClOH6N(O)h(CO)2] and cis[RU{lf-OClOH6N(O)}2(COh]. For the case of I-nqoH, two unprecedented cluster species, [Rll3(CO)8(fl-1l3-0NClOH60)2] and RU3(CO)8{J,lN(H)CIO&(O)NOC10H6}] were also isolated in addition. The trans-isomers were thermodynamically more stable since the cis-isomers converted irreversibly to the trans-form in an acidic medium at 30?. The carbonyl groups of these dicarbonyl complexes could be substituted by the N-donor ligands (L) in the presence of Me3NO to give mono-substituted products [Ru{112OClOH6N(O)}2(CO) (L)] (L = NCsaCH=NC6aOC16fu3, 4-acetylpyridine, 4vinylpyridine, 4,4'-bipyridine and MeCN, etc.) via the transient intermediates [RU{1'\2_0ClOH6N(O)h(CO)(NMe3)]' The co-ordinated MeCN in [Ru{112OCloH6N(O)}2(CO)(NCMe)] were substitutionally labile towards pyridine-type ligands and CO at elevated temperature, whereas the pendant pyridyl group in cis-[Ru{112-0CloH6N(O)h(CO)(NCsI-L-Cs&N)] was free of co-ordination so that it may be used as synthetic building blocks in co-ordination chemistry.

Bibliographical Information:

Advisor:

School:The University of Hong Kong

School Location:China - Hong Kong SAR

Source Type:Master's Thesis

Keywords:ruthenium compounds analysis carbonyl nitrenes ligands

ISBN:

Date of Publication:01/01/1997

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