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Synthesis and characterization of some organoruthenium complexes containing 1,4,7-trimethyl-1,4,7-triazacyclononane

by Yang, San-ming

Abstract (Summary)
(Uncorrected OCR) Abstract of thesis entitled "SYNTHESIS AND CHARACTERIZATION OF SOME ORGANORUTHENIUM COMPLEXES CONTAINING 1,4,7TRIAZACYCLONONANE"

submitted by Yang San Ming

For the degree of Doctor of Philosophy

at the University of Hong Kong in February 1997.

The reaction between Ru(Me3tacn)CI3 and silver trifluoromethanesulfonate

(Me3tacn = 1,4,7-trimethyl-I,4,7-triazacyclononane) in ethanol gives a green solution,

which reacts with cyclohexa-I,3-diene to give [Ru(Me3tacll)(1l-C6H6)]2+ (3). In the

presence of zinc, the green solution reacts with I-trimethylsilylcyclopentadiene, 1-

trimethylsilylindene, cyclohexa-I ,3-diene and cycloheptatriene to give [Ru(Me3tacn)(1l-

[Ru(Me3tacn)(1-5-11-C7H9)t (7) complexes respectively. Complex 6 can also be prepared

by the reduction of 3 using NaBH4 in methanol. X-ray diffraction studies of the PF6 salts

of complexes 4-7 have been undertaken; in each case the 1l5-bonded unsaturated

hydrocarbon moiety is almost planar.

Several ruthenium-hydride complexes containing Me3tacn have also heen

synthesized. The reaction between [Ru(cod)Ch]n and Me3tacn in ethanol-water gives

[Ru(Me3tacn)(cod)H]CI04 (8). When tert-butanol is used as the solvent, [Ru(Me3tacn)(1-

5-11-CsHII)]CI04 (9) is obtained. Complex 8 is found to be an active catalyst in the

hydrogenation of alkene and ketone. The reaction between Ru(Me3tacn)Ch and AgOTf in

ethanol gives a green solution which reacts with dppe in the presence of zinc to give

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[Ru(Me3tacn)(dppe)H]PF6 (10). The formation of ruthenium hydride is likely via a (1.hydrogen migration of ethanol. Reaction of RuHCI(CO)(PPh3)3 with Me3tacn in 2methoxyethanol gives [Ru(Me3tacn)(CO)(PPh3)H]PF6 (11). The Ru-H moieties are characterized by IR and I H NMR. However, all the hydride complexes do not react with tenninal alkynes. Complex 11, but not for 8 and 10, reacts with CF3C02H in C~hCb to give [Ru(Me3tacn)(CO)(PPh3)(02CCF3)]PF6 (12) and hydrogen gas. The crystal

structures of the 8,9, 11 and 12 were also determined.

The ruthenium(lI) complexes [Ru(Me3tacn)(LhX]PF6 (L=PMe3, X=02CCF3 (13a); L=PMe3, X=CI (13b); L=1/2 dmpe, X=02CCF3 (13e?are prepared. Only 13a reacts with 1 equivalent of RC=CH (R = Ph and p-tolyl) to give the vinylidene complexes [Ru(Me3tacn)(PMe3)(02CCF3){C=CH(R)} ]PF6 (R = Ph (14a) and p-tolyl (14b?in reflllxing 1,2-dichloroethane. Reaction of 14a and 14b with PMe3 in methanolic KOH solution give the corresponding cr-acetylide complexes [RlI(Me3tacn)(PMe3)2(C=CR)]PF6 (R = Ph (15a) and p-tolyl (15b? Similarly, treatment of 14a with P(OMe3)3 affords [Ru(Me3tacn)(PMe3)(P(OMe)3)(C=CPh)]PF6 (lSe). Oxidative cleavage of the vinylidene ligand in 14 by oxygen gives [Ru(Me3tacn)(PMe3)(02CCF3)(CO)]PF6 (16) and benzaldehyde. Complex 13b reacts with 2.5 equivalents of RC=CH (R = Ph, p-tolyl) and 1.5 equivalents of KOH in methanol to yield 113 -butenynyl [Ru(Me3tacn)(PMe3){ '113RC3=CH(R)}]PF6 (R = Ph (17a) andp-tolyl (17b? In addition, 14a and 14b reacts with RC=CH (R=Ph, p-tolyl) and KOlI in methanol to give 17a and 17b respectively. Treatment of 14a with p-tolylC=CH and KOB In methanol gives

ii

[Ru(Me3tacn)(PMe3){,,3 -PhC3=CH(p-tolyl)} ]PF 6 (17c) and [Ru(Me3tacn)(PMe3){ 113 tolyI)C3=CH(Ph)} ]PF6 (17c') in I: I ratio. Reacting 14b with PhC=CH similarly gives 17c and 17c' in equal amounts. Structures of 15, 17a and 17c1l7c' are established by Xray crystallography. Mechanistic insight from the isolated species suggests that hydrogen shift between the vinylidene and acetylide moieties are an important step in the coupling ofalkynes.

The reaction between [Ru(2,2,2-tet-Me6)Ch]PF6 and phenylacetylene in sodium/methanol solution gives 113 -butenynyl complex [Ru(2,2,2-tet-Me6){ 113PhC3=CH(Ph)} ]PF6 (18). The mechanism for the formation of 113 -butenynyl have also been proposed and suggested that ruthenillm-vinylidene formation and availability of cisfashion coordination sites are important in the coupling of I-alkynes.

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Bibliographical Information:

Advisor:

School:The University of Hong Kong

School Location:China - Hong Kong SAR

Source Type:Master's Thesis

Keywords:organoruthenium compounds synthesis

ISBN:

Date of Publication:01/01/1997

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