Early/late bimetallic complexes: MCo2 (MTi, Zr) derivatives

Bartik, Tamás; Windisch, Harald; Sorkau, A.; Thiele, K.‐H.; Kriebel, Christian; Herfurth, Anke; Tschoerner, C. Matthias; Zucchi, Claudia; Pályi, Gyula

doi:10.1016/0020-1693(94)04207-1

Cited by 11 publications

(2 citation statements)

References 57 publications

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“…24 More recently, Pa ´lyi et al gave a preliminary account of the generation of [Cp 2 Zr{Co-(CO) 4 } 2 ] by salt metathesis or alkane elimination. 25 We recently developed several new amido ligands to be employed in difunctional building blocks for heterooligonuclear complexes, among them tripodal diamido-pyridine systems. [26][27][28] However, for the synthesis of heterotrinuclear complexes derived from a difunctional group 4 complex fragment, the use of a simple bidentate chelating amido ligand proved to be most successful.…”

Section: Introductionmentioning

confidence: 99%

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

et al. 1999

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Reaction of the dichlorozirconium complex [CH2(CH2NSiMe3)2ZrCl2(thf)2] (1), containing a chelating amido ligand and having a trans disposition of the chloro ligands established by an X-ray diffraction study, with the carbonylmetalate derivatives K[MCp(CO)2] (Cp = C5H5) and Na[Co(CO)3(PPh3)] gave the heterotrinuclear complexes [CH2(CH2NSiMe3)2Zr{MCp(CO)2}2] (M = Fe (2), Ru (3)) and [CH2(CH2NSiMe3)2Zr{Co(CO)3(PPh3)}2] (4), respectively. Of these, 2 and 3 were structurally characterized by X-ray crystallography, establishing two unsupported metal−metal bonds in each of the compounds [2, d(Zr−Fe) = 2.665(2), 2.664(2) Å; 3, d(Zr−Ru) = 2.7372(7), 2.7452(7) Å]. Reaction of 2 and 3 with 1 in a 1:1 molar ratio led to a quantitative redistribution of complex fragments, yielding the dinuclear complexes [CH2(CH2NSiMe3)2(Cl)Zr−MCp(CO)2] (M = Fe (5), Ru (6). Both products as well as the Zr−Co complex [CH2(CH2NSiMe3)2(Cl)Zr−Co(CO)3(PPh3)] (7) were also obtained in moderate yields by reacting 1 with 1 molar equiv of the carbonylmetalate. Reacting 5−7 with NaCp gave the corresponding CpZr complexes [CH2(CH2NSiMe3)2(Cp)Zr−MCp(CO)2] (M = Fe (8), Ru (9)) and [CH2(CH2NSiMe3)2(Cp)Zr−Co(CO)3(PPh3)] (10), of which 9 was characterized by a single-crystal X-ray structure analysis [d(Zr−Ru) = 2.8297(14) Å]. Compounds 5, 6, 8, and 9 insert methyl isonitrile to give the heterobimetallic metallaiminoacylzirconium complexes [CH2(CH2NSiMe3)2(Cl)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (11), Ru (12)) and [CH2(CH2NSiMe3)2(Cp)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (13), Ru (14)), respectively. Reaction of the heterotrinuclear compounds 2 and 3 with isonitriles exclusively gave the products of the insertion into one of the unsupported metal−metal bonds, [CH2(CH2NSiMe3)2Zr{η2-C(NCH3)MCp(CO)2}{MCp(CO)2}] (M = Fe, R = Me, n Bu, Cy, Tol (15a−d); M = Ru, R = Me, n Bu, Cy, Tol (16a−d)). A crystal structure analysis of 16a established the insertion into one of the metal−metal bonds while the intact Zr−Ru bond was elongated in comparison to that of 3 [d(Zr−Ru) = 2.8639(6) Å]. Cleavage of both metal−metal bonds in 2 and 3 was observed in reactions with sulfoxides. Transfer of the S-bound oxygen atom to a carbonyl ligand led to CO2-linked trinuclear complexes in which the thioether thus generated was coordinated to the late transition metal center. The reaction at the two metal−metal bonds occurred cooperatively, precluding the isolation of intermediates.

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Section: Introductionmentioning

confidence: 99%

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

et al. 1999

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“…However, the expected product of this displacement is (η 5 -C 5 H 5 ) 2 Ti(Cl)(μ-OC)Co(CO) 3 or (η 5 -C 5 H 5 ) 2 Ti(Cl)Co(CO) 4 , and further explanation is required for the formation of the Ti−Co 3 complex. Similarly, formation of complexes having a Ti IV −(μ 4 -OC)Co 3 (CO) 9 moiety was reported in the reaction of (η 5 -C 5 H 5 )TiCl 3 with NaCo(CO) 4 , the expected products of which must have Ti IV −(μ-OC)Co(CO) 3 or Ti IV −Co(CO) 4 moieties. , How can we account for the formation of the Ti IV −(μ 4 -OC)Co 3 (CO) 9 moiety in these reactions? For a mechanism related to the formation of the Ti−Co 3 complexes described above, Moïse and co-workers proposed the reaction of (η 5 -C 5 H 5 ) 2 Ti(Cl)(μ-OC)Co(CO) 3 with Co 2 (CO) 8 to form (η 5 -C 5 H 5 ) 2 Ti(Cl)(μ-OC)Co 3 (CO) 9 ; however, only IR evidence was given to support this proposal .…”

Section: Introductionmentioning

confidence: 81%

Novel Titanium−Cobalt Complexes Formed by Reductive Cleavage of a Co−Co Bond in Co₂(CO)₈ by Titanocene tert-Butoxides: Synthesis, Characterization, and Mechanistic Aspects for Metal−Metal Bond Recombination

et al. 2003

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Reactions of titanium(III) complexes (η5-C5R5)2TiOtBu (R = H (1), Me (4)) with Co2(CO)8 are found to be efficient methods to synthesize Ti−Co heterobimetallic complexes. A Ti−Co3 complex, (η5-C5H5)2Ti(OtBu)(μ4-OC)Co(CO)9 (3), was formed from 1 and Co2(CO)8, whereas a Ti−Co bimetallic complex, (η5-C5Me5)2Ti(OtBu)(μ-OC)Co(CO)3 (5), was obtained by the reaction of 4 with Co2(CO)8. In both cases, the reaction was complete within 5 min. The products were completely characterized by NMR, IR, and X-ray crystallography. Complex 3 contains a quadruply bridging CO group, the oxygen terminus of which is connected to the Ti moiety, whereas the carbon terminus is bound to three Co atoms in the Co3(CO)9 moiety. In contrast, complex 5 is dinuclear, and its Ti atom is connected to the Co(CO)3 group by an isocarbonyl bridge. A η5-C5H5 analogue of 5, [(η5-C5H5)2Ti(OtBu)(μ-OC)Co(CO)3] (6), was formed at the initial stage of the reaction of 1 with Co2(CO)8 in toluene. This dinuclear complex 6 was isolated from a reaction medium of a 5:1 mixture of 1 and Co2(CO)8, being characterized by spectroscopy. As further evidence for the formation of the Ti−Co heterobimetallic complex, reaction of 6 with THF gave the Ti−Co complex [(η5-C5H5)2Ti(OtBu)(η-THF)]+[Co(CO)4]- (7), which was completely characterized by spectroscopy, crystallography, and elemental analysis. Thermal decomposition of 6 produced a mixture of 3 and 1, whereas treatment of 6 with Co2(CO)8 gave 3; this is good evidence for the intermediacy of 6 in the formation of 3 from 1 with Co2(CO)8.

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Stark polare Metall-Metall-Bindungen in Heterodimetallkomplexen des „Early-Late”-Typs

Gade

2000

Angewandte Chemie

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Bindungspolarität in ihrer extremsten Form in Metall‐Metall‐Bindungen der Übergangsmetalle findet man in Zwei‐ und Mehrkernkomplexen, in denen Komplexfragmente der Metalle von beiden Enden des d‐Blocks im Periodensystem direkt aneinander gebunden sind. Diese Verknüpfung von Metallzentren mit sehr unterschiedlichen redoxchemischen Eigenschaften durch eine direkte Metall‐Metall‐Bindung war lange Zeit eine große Herausforderung für den präparativ arbeitenden Komplexchemiker. Die Unterdrückung von Reaktionswegen, die über Einelektronentransfer zur Zersetzung der Komplexe führen, sowie die Abschirmung der hochgradig Lewis‐aciden frühen Übergangsmetalle durch geeignet konzipierte Ligandensphären haben die systematische Erforschung dieser Verbindungsklasse erst ermöglicht. Zeitgleich mit dieser Entwicklung haben jüngste konzeptionelle Fortschritte bei der theoretischen Beschreibung der Bindungspolarität unser Verständnis der Eigenschaften dieser Metall‐Metall‐Bindungen verfeinert. Den stärksten Anreiz für die Entwicklung auf diesem Gebiet bietet die Untersuchung der kooperativen Reaktivität zweier oder mehrerer Koordinationszentren gegenüber organischen Substraten. Diese Kooperativität, die sich in den unterschiedlichen Funktionen der Metalle bei der Umwandlung organischer Verbindungen manifestierte, bietet vielversprechende Ansätze für die Entwicklung neuer stöchiometrischer oder sogar katalytischer Reaktionstypen.

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Early/late bimetallic complexes: MCo2 (MTi, Zr) derivatives

Cited by 11 publications

References 57 publications

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

Novel Titanium−Cobalt Complexes Formed by Reductive Cleavage of a Co−Co Bond in Co₂(CO)₈ by Titanocene tert-Butoxides: Synthesis, Characterization, and Mechanistic Aspects for Metal−Metal Bond Recombination

Stark polare Metall-Metall-Bindungen in Heterodimetallkomplexen des „Early-Late”-Typs

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Early/late bimetallic complexes: MCo2 (MTi, Zr) derivatives

Cited by 11 publications

References 57 publications

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

Novel Titanium−Cobalt Complexes Formed by Reductive Cleavage of a Co−Co Bond in Co2(CO)8 by Titanocene tert-Butoxides: Synthesis, Characterization, and Mechanistic Aspects for Metal−Metal Bond Recombination

Stark polare Metall-Metall-Bindungen in Heterodimetallkomplexen des „Early-Late”-Typs

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Novel Titanium−Cobalt Complexes Formed by Reductive Cleavage of a Co−Co Bond in Co₂(CO)₈ by Titanocene tert-Butoxides: Synthesis, Characterization, and Mechanistic Aspects for Metal−Metal Bond Recombination