The first 1,2-dibora-[2]ferrocenophane and its dynamic behaviour in solution

Herberhold, Max; Dörfler, Udo; Wrackmeyer, B.

doi:10.1016/s0022-328x(96)06470-4

Cited by 47 publications

(47 citation statements)

References 51 publications

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“…1 H NMR (500.13 MHz, C 6 D 6 , 297 K): d = 0.90 (dt, J = 13.85, 7.60 Hz, 9 H; P(CH 2 CH 3 ) 3 ), 1.13 (dt, J = 14.15, 7. (12), P1-Pt1-P2 99.18(2), B2-Pt1-P1 165.98(9), B1-Pt1-P2 168.92 (9), Cr-X Cp 1.800, Cr-X Cht 1.422, X Cp -Cr-X Cht 176.91 (X = centroid).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of ansa‐[2]Boracyclopentadienylcycloheptatrienylchromium and Its Reaction to the ansa‐Platinabis(boryl) Complex by Oxidative Addition of the BoronBoron Bond

2005

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Metalation reactions are of great importance in metallocene chemistry since they provide access to a wide variety of functionalized sandwich complexes. Among those, the dilithiation of ferrocene [1] and related compounds such as bis(benzene)chromium, [2] for which an alkyllithium base is employed in the presence of a chelating amine (typically N,N,N',N'-tetramethylethylenediamine = tmeda), are the most prominent examples to accomplish this goal. Recently, Mulvey and co-workers reported the selective tetrametalation of ferrocene [3] and monometalation of bis-(benzene)chromium [4] by the use of mixed alkali-metalmagnesium amide bases.Our interest focused on cyclopentadienylcycloheptatrienylchromium [(h 5 -C 5 H 5 )Cr(h 7 -C 7 H 7 )] (trochrocene 1), [5] which is isoelectronic to bis(benzene)chromium and was intensively studied by Fischer and co-workers. [6,7] Although the metalation of trochrocene was the subject of a series of studies, in which either n-amylsodium [7] or mixtures comprising nBuLi/tmeda [8] were employed, there is no precedence for the metalation of both the Cp and the Cht ring. We achieved the double lithiation of trochrocene by using a tBuLi/tmeda mixture, which resulted in the formation of the base-stabilized compound [(h 5 -C 5 H 4 Li)Cr(h 7 -C 7 H 6 Li)]·tmeda (2) in yields of up to 80 %. The 1 H NMR spectrum of 2 is in agreement with an overall C S -symmetric compound in solution and features two signals for the Cp ligand (d = 3.51 and 3.86 ppm) and two signals for the Cht ring (d = 5.23-5.30 and 5.70 ppm) with a relative intensity of 2:2:4:2. However, the 13 C NMR spectrum exhibits only five resonances for the aromatic carbon atoms; the ipso-carbon atoms are undetectable at room temperature, a fact which is probably due to the quadrupolar moment of the Li atom. [9] Dilithiotrocrocene (2) was subsequently treated with stoichiometric amounts of Br(NMe 2 )BÀB(NMe 2 )Br to afford the [2]boratrochrocenophane 3, which was isolated from pentane solutions at À30 8C as green crystals in 35-45 % yields (Scheme 1). The most noteworthy feature in the 1 H NMR spectrum of 3 is the splitting of the Cp resonances

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Section: Methodsmentioning

confidence: 99%

Synthesis of ansa‐[2]Boracyclopentadienylcycloheptatrienylchromium and Its Reaction to the ansa‐Platinabis(boryl) Complex by Oxidative Addition of the BoronBoron Bond

2005

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“…[c] pytsi = C( [19] Aluminum and Gallium While sterically demanding p-donor ligands have been used to stabilize bora [1]ferrocenophanes, the Al-and Gabridged [1]ferrocenophanes 5 and 6 employ bulky trisylderived ligands (trisyl = tris(trimethylsilyl)methyl; pytsi = C-(SiMe 3 ) 2 SiMe 2 (2-C 5 H 4 N); Me 2 Ntsi = C(SiMe 3 ) 2 SiMe 2 NMe 2 ) to provide steric shielding from the trimethylsilyl groups and intramolecular stabilization through a pendant N donor. [20,25] Notably, use of a smaller intramolecularly stabilizing ligand leads to [1.1]ferrocenophanes (7) bridged by two base-stabilized Group 13 metal centers, presumably a result of diminished steric protection.…”

Section: Summary and Outlook 5077mentioning

confidence: 99%

Strained Metallocenophanes and Related Organometallic Rings Containing π‐Hydrocarbon Ligands and Transition‐Metal Centers

2007

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The structures, bonding, and ring-opening reactions of strained cyclic carbon-based molecules form a key component of standard textbooks. In contrast, the study of strained organometallic molecules containing transition metals is a much more recent development. A wealth of recent research has revealed fascinating nuances in terms of structure, bonding, and reactivity. Building on initial work on strained ferrocenophanes, a broad range of strained organometallic rings composed of a variety of different metals, pi-hydrocarbon ligands, and bridging elements has now been developed. Such strained species can potentially undergo ring-opening reactions to functionalize surfaces and ring-opening polymerization to form easily processed metallopolymers with properties determined by the presence of the metal and spacer. This Review summarizes the current state of knowledge on the preparation, structural characterization, electronic structure, and reactivity of strained organometallic rings with pi-hydrocarbon ligands and d-block metals.

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“…Die ipso-Kohlenstoffatome sind bei Raumtemperatur nicht detektierbar, ein Umstand, der wahrscheinlich auf das Quadrupolmoment der Li-Atome zurückzuführen ist. [9] Dilithiotrochrocen (2) [10] Um mehr Einblick in die strukturellen Eigenschaften von 3 zu erhalten, wurde eine Einkristall-Röntgenstrukturanalyse durchgeführt (Abbildung 1). [11] In Einklang mit der Molekül-struktur von [(h 5 -C 5 H 5 )Cr(h 7 -C 7 H 7 )] [12] sind die Metall-Kohlenstoff-Abstände zum Siebenring [2.1370(18)-2.1683(20) ] und zum Fünfring [2.1616(20)-2.2056(18) ] vergleichbar.…”

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“…Das Pt-Zentrum weist eine verzerrt quadratisch-planare Koordination auf, wobei die Pt-B-[Pt1-B1 2.108(3), Pt1-B2 2.096(3) ] und Pt-P-Abstände [Pt1-P1 2.3463(7), Pt1-P2 2.3399 (6) [19c, 20a,20b, 22c, 22e] Zusammenfassend haben wir über die Synthese und strukturelle Charakterisierung des ersten [2] (7), Pt1-P2 2.3399(6); B1-Pt1-P1 90.27 (8),, , P1-Pt1-P2 99.18(2), B2-Pt1-P1 165.98(9), B1-Pt1-P2 168.92 (9), Cr-X Cp 1.800, Cr-X Cht 1.422, X Cp -Cr-X Cht 176.91 (X = Zentroid).…”

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Synthese von ansa‐[2]Boracyclopentadienylcycloheptatrienylchrom und Reaktion zum ansa‐Platinabis(boryl)‐Komplex durch oxidative Addition der Bor‐Bor‐Bindung

2005

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The first 1,2-dibora-[2]ferrocenophane and its dynamic behaviour in solution

Cited by 47 publications

References 51 publications

Synthesis of ansa‐[2]Boracyclopentadienylcycloheptatrienylchromium and Its Reaction to the ansa‐Platinabis(boryl) Complex by Oxidative Addition of the BoronBoron Bond

Synthesis of ansa‐[2]Boracyclopentadienylcycloheptatrienylchromium and Its Reaction to the ansa‐Platinabis(boryl) Complex by Oxidative Addition of the BoronBoron Bond

Strained Metallocenophanes and Related Organometallic Rings Containing π‐Hydrocarbon Ligands and Transition‐Metal Centers

Synthese von ansa‐[2]Boracyclopentadienylcycloheptatrienylchrom und Reaktion zum ansa‐Platinabis(boryl)‐Komplex durch oxidative Addition der Bor‐Bor‐Bindung

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