Symmetrical Bis(acetylido)ruthenium(II) Complexes

Field, Leslie D.; Magill, Alison M.; Shearer, Timothy K.; Dalgarno, Scott J.; Bhadbhade, Mohan

doi:10.1002/ejic.201100322

Cited by 18 publications

(2 citation statements)

References 70 publications

(27 reference statements)

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“…Transition-metal-catalyzed dimerizations of terminal alkynes are attractive atom-economical C–C bond forming reactions, which afford products containing structural units in natural products and materials . In most cases, mixtures of regio (head-to-head vs head-to-tail) and stereo ( E / Z -head-to-head) isomers have been obtained.…”

Section: Resultsmentioning

confidence: 99%

POP-Pincer Osmium-Polyhydrides: Head-to-Head (Z)-Dimerization of Terminal Alkynes

et al. 2013

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A wide range of osmium-polyhydride complexes stabilized by the POP-pincer ligand xant(P(i)Pr2)2 (9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) have been synthesized through cis-OsCl2{κ-S-(DMSO)4} (1, DMSO = dimethyl sulfoxide). Treatment of toluene solutions of this adduct with the diphosphine, under reflux, leads to OsCl2{xant(P(i)Pr2)2}(κ-S-DMSO) (2). The reaction of 2 with H2 in the presence of Et3N affords OsH3Cl{xant(P(i)Pr2)2} (3), which can be also prepared by addition of xant(P(i)Pr2)2 to toluene solutions of the unsaturated d(4)-trihydride OsH3Cl(P(i)Pr3)2 (5). Complex 3 reductively eliminates H2 in toluene at 90 °C. In the presence of dimethyl sulfoxide, the resulting monohydride is trapped by the S-donor molecule to give OsHCl{xant(P(i)Pr2)2}(κ-S-DMSO) (6). The reaction of 2 with H2 is sensible to the Brønsted base. Thus, in contrast to Et3N, NaH removes both chloride ligands and the hexahydride OsH6{xant(P(i)Pr2)2} (7), containing a κ(2)-P-binding diphosphine, is formed under 3 atm of hydrogen at 50 °C. Complex 7 releases a H2 molecule to yield the tetrahydride OsH4{xant(P(i)Pr2)2} (8), which can be also prepared by reaction of OsH6(P(i)Pr3)2 (9) with xant(P(i)Pr2)2. Complex 8 reduces H(+) to give, in addition to H2, the oxidized OsH4-species [OsH4(OTf){xant(P(i)Pr2)2}](+) (10, OTf = trifluoromethanesulfonate). The redox process occurs in two stages via the OsH5-cation [OsH5{xant(P(i)Pr2)2}](+) (11). The metal oxidation state four can be recovered. The addition of acetonitrile to 10 leads to [OsH2(η(2)-H2)(CH3CN){xant(P(i)Pr2)2}](2+) (12). The deprotonation of 12 yields the osmium(IV) trihydride [OsH3(CH3CN){xant(P(i)Pr2)2}](+) (13), which is also formed by addition of HOTf to the acetonitrile solutions of 8. The latter is further an efficient catalyst precursor for the head-to-head (Z)-dimerization of phenylacetylene and tert-butylacetylene. During the activation process of the tetrahydride, the bis(alkynyl)vinylidene derivatives Os(C≡CR)2(=C═CHR){xant(P(i)Pr2)2} (R = Ph (14), (t)Bu (15)) are formed.

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Section: Resultsmentioning

confidence: 99%

POP-Pincer Osmium-Polyhydrides: Head-to-Head (Z)-Dimerization of Terminal Alkynes

et al. 2013

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“…Many examples of effective run of the process in the presence of transition metal complexes have been described. Catalytic activity in the process has been reported to be shown by complexes of such metals as palladium [4,[7][8][9][10][11][12][13], rhodium [14][15][16][17][18][19], ruthenium [20][21][22][23][24][25][26][27][28][29], nickel [30], iridium [31][32][33], osmium [34,35], iron [36] and the f-block metals [37][38][39]. However, a highly selective synthesis of conjugated enynes by dimerization is still a challenging process.…”

Section: Introductionmentioning

confidence: 99%