- Synthesis and reactivity of platinum-containing heterodinuclear complexes with methyl and 1,2-bis(diphenylphosphino)ethane ligands. X-Ray crystal structure of (dpe)MePt-FeCp(CO)2*THF
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New-platinum-containing heterodinuclear complexes with methyl and 1,2-bis(diphenylphosphino)ethane (dpe) ligands have been prepared by metathetical reactions of PtMe(NO3)(dpe) with Na: MLn = MoCp(CO)3 (1); WCp(CO)3 (2); Mn(CO)5 (3); FeCp(CO)2 (4); Co(CO)4 (5).The molecular structure of (dpe)MePt-FeCp(CO)2*THF (4*THF) has been determined by X-ray crystallography: the geometry at Pt is square planar and the FeCp(CO)2 moiety has a piano-stool type structure.Thermolysis of 4 in C6D6 at 70 deg C for 2 h gives MeFeCp(CO)2 (8) in 30percent yield, but other dinuclear complexes are thermally stable under these conditions.Methyl migration to produce 8 was accelerated by the addition of electron-deficient olefins such as acrylonitrile and fumaronitrile.From the kinetic study, a mechanism involving two pathways is proposed: one is direct thermolysis from 4 to 8, while the other is the associative reductive elimination of 8 from the olefin-coordinated intermediate 9. Key words: Molybdenum; Platinum; Heterobimetallics; Iron; Tungsten; Manganese; Cobalt
- Fukuoka, Atsushi,Sadashima, Takanori,Sugiura, Takeshi,Wu, Xiaosong,Mizuho, Yuji,Komiya, Sanshiro
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- A halogenophilic pathway in the reactions of transition metal carbonyl anions with [(η6-iodobenzene)Cr(CO)3]
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The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in Cr(CO)3 complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack [(η6-iodobenzene)Cr(CO)3] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The reaction with K[CpFe(CO) 2] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)2] (Cp* = η5-C 5Me5) results in nucleophilic substitution to give [(η6-C6H5FeCp*(CO) 2)Cr(CO)3]. Reaction with Na[Re(CO)5] quantitatively gives the iodo(acyl)rhenate anion Na[(η6-C 6H5C(O)ReI(CO)4)Cr(CO)3] and in the case of K[Mn(CO)5] a mixture of σ-aryl complexes [(η6-C6H5Mn(CO)5)Cr(CO) 3] and K[(η6-C6H5Mn(CO) 4I)Cr(CO)3]. An analogous rhenium complex Na[(η6-C6H5Re(CO)4I)Cr(CO) 3] is formed from the initial iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt4] + salt) is established by X-ray diffraction analysis. The reaction of [(η6-chlorobenzene)Cr(CO)3] with K[CpFe(CO) 2], in contrast, proceeds by the common SN2Ar mechanism.
- Sazonov, Petr K.,Ivushkin, Vasiliy A.,Khrustalev, Victor N.,Kolotyrkina, Natal'Ya G.,Beletskaya, Irina P.
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p. 13392 - 13398
(2014/11/07)
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- Isomers of Re(CO)3(CNt-Bu)LX: synthetic strategies starting from MnRe(CO)8(CNt-Bu)L and Re(CO)4LX (X=halogen; L=Group 15 donor ligand)
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Reaction of Re(CO)4LX (L=PMePh2, PMe2Ph, PPh3, P(OMe)3, P(Oi-Pr)3, P(O-o-tol)3; X=Br, I) with t-BuNC in the presence of PdO catalyst gave the new complexes Re(CO)3(CNt-Bu)LX in high yield ( >60percent).The new complexes were shown by spectroscopic techniques (IR, 1H and 31P NMR) to comprise a mixture of mer and fac isomers.The mer/fac ratio decreased with reaction temperatures (e.g.L=P(OMe)3; 10 deg C, ratio=3; 45 deg C, ratio=0.25).At high temperatures (90 deg C) isomerization of the mer to the fac isomers (L=PMe2Ph, P(OMe)3) occurred, suggesting that the mer isomer was the kinetic product of the catalyzed reaction.Reactions induced by Me3NO gave similar effects.Halogen cleavage of MnRe(CO)8(CNt-Bu)L, prepared from MnRe(CO)9(CNt-Bu) and L in the presence of Me3NO, yielded either one or two isomers of Re(CO)3(CNt-Bu)(L)X (X=I, Br; 40percent yield).For large L (e.g.PPh3) a new mer isomer with L trans to X was synthesized, and characterized by IR and NMR spectroscopy.For small L (e.g.P(OMe)3) a mixture of the two different mer products was obtained.The product isomer ratio was determined predominantly by the position of L in the starting dimer. Key words: Rhenium; Carbonyl; Catalysis; Heterobimetallics; Substitution
- Leins, Ann E.,Conville, Neil J.
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p. 183 - 190
(2007/10/02)
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- Pentacarbonylmanganese enolate and dienolate complexes. Preparative and mechanistic considerations
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Reactions of pentacarbonyl manganate anion with 4-halocrotonate esters or 2-halocarboxylate esters result in a complex set of inorganic and organic products, usually including the expected dienolate (or enolate) complexes.The reaction variables include the counterion, solvent, and halo group.The mechanism of the reaction has been investigated by conducting a thorough characterization of the reaction products under various conditions and also by carrying out model reactions.One can rationalize most of the non-organometallic products using either a radical or carbanion mechanism, but the latter seems to fit the available data better.Experimental procedures for optimizing the yield of the organometallic dienolate or enolate complexes have been worked out.
- Masters, Andrew P.,Sorensen, Ted S.
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p. 492 - 501
(2007/10/02)
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- Phenylene-bridged organometallic complexes of iron and manganese
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The synthesis of the complexes 1,3-C6H4(MLn)2,1,4-C 6H4(MLn)2, and 1,3,5-C6H3(MLn)3 (where MLn = (η5-C5H5)Fe(CO)2, (η5-C5H4Me)Fe(CO)2, or Mn(CO)5) is described. These species are best prepared in two steps by metathesis of the organometallic anion, NaMLn, with the appropriate aroyl chloride to give acyl intermediates. These complexes were isolated and then thermally decarbonylated (in refluxing butyl ether and THF for the Fe and Mn complexes, respectively) to give the desired products in 40-90% overall yield. Their perfluoro analogues, 1,4-C6F4Fp?2 (where Fp? = (η5-C5H5)Fe(CO)2 or (η5-C5H4Me)Fe(CO)2), are prepared in 30-60% yield by the metathesis of 1,4-C6F4Li2 with Fp?I. These new materials have been fully characterized by conventional spectroscppic techniques and are shown to contain metal-arene σ bonds. Evidence is provided for partial dimetalloquinone character in the bonding of the para-substituted species. The reactions of the title compounds with phosphines (to give carbonyl substitution products) and with halogens (to give metal-aryl bond cleavage) are also reported.
- Hunter, Allen D.,Szigety, Andrew B.
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p. 2670 - 2679
(2008/10/08)
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