Synthesis and Characterization of the First Aluminum-Bridged [1]Ferrocenophane

Schachner, Jörg A.; Lund, Clinton L.; Quail, J. Wilson; Müller, Jens

doi:10.1021/om049004t

Cited by 63 publications

(52 citation statements)

References 33 publications

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“…The 1 H NMR spectrum exhibits six signals in the Cp range, which could either be caused by 4 a ( C 1 symmetry) or the respective [1.1]FCP ( C 2 symmetry), however, the signal pattern reveals the presence of a [1]FCP. Similar as for other known gallium‐bridged [1]FCPs,5a–c, 8 the signals for α protons in 4 a appear upfield compared to those of the β protons. Secondly, the difference in chemical shifts between the peaks of the two α protons is significantly larger than that found between the β protons [ 4 a : δ =3.53 and 3.98 ppm (α‐H); δ =4.46, 4.50, 4.67, and 4.70 ppm (β‐H)].…”

Section: Resultssupporting

confidence: 74%

A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron, Gallium, Silicon, and Tin in Bridging Positions

Sadeh¹,

Schatte²,

Müller³

2013

Chemistry A European J

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The enantiomerically pure dibromoferrocene 3 [(Sp,Sp )-1,1'-dibromo-2,2'-di(isopropyl)ferrocene], equipped with two iPr groups in α positions, was prepared using known "Ugi amine" chemistry. Species 3 was targeted in order to gain access to new [1]ferrocenophanes ([1]FCPs) to be used as monomers for ring-opening polymerization. The iPr groups on the sandwich unit were introduced to stabilize bridging moieties, as well as to increase solubilities of targeted metallopolymers. The planar chiral dibromide 3 can quantitatively be lithiated at 0°C [2 equiv nBuLi, hexanes/thf (9:1), 30 min]. Salt-metathesis reactions with respective element dichloride species gave chiral [1]FCPs with a variety of bridging moieties [ERx =Ga[2-(Me2NCH2)C6H4] (4 a), SiMe2 (4 b), SntBu2 (4 c), BNiPr2 (4 d)]. The new [1]FCPs were fully characterized including single-crystal X-ray analysis. The stabilizing iPr groups on the Cp rings increase the thermal stabilities of 4 b-d compared to known [1]FCPs, equipped with the same bridging moieties. All three compounds 4 b-d are volatile and could be isolated by vacuum sublimation. Our new approach to [1]FCPs has the potential to overcome many of the existing difficulties in ferrocenophane chemistry, such as limited stability of starting monomers and low solubilities of resulting polyferrocenes.

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Section: Resultssupporting

confidence: 74%

A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron, Gallium, Silicon, and Tin in Bridging Positions

Sadeh¹,

Schatte²,

Müller³

2013

Chemistry A European J

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“…(5)], and form the desired [1]ferrocenophanes in moderate to high yields (5: with pytsi 31 %, with Me 2 Ntsi 97 %; 6: with pytsi 59 %, with Me 2 Ntsi 68 %). [20,25] As elements with larger covalent radii are used in the bridge, the tilt angles are, as expected, smaller (Al: a % 158 ( Figure 3); Ga: a % 168) than for boron-bridged [1]ferrocenophanes (a % 328).…”

Section: Summary and Outlook 5077supporting

confidence: 67%

“…[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. [30,31] The syntheses of the monomeric compounds by Müller and co-workers follow a common route for metallocenophane formation: reaction of a doubly deprotonated metallocene with, in these cases, intramolecularly stabilized Group 13 dihalide complexes [Eq.…”

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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“…Often, for the targeted polymers, non-en- [3b] B: ER x = BNiPr 2 , Ga(2-Me 2 NCH 2 C 6 H 4 ), In[6-(Me 2 NCH 2 )-2,4-tBu 2 C 6 H 2 ], SiMe 2 , SntBu 2 ; C: NR 1 cumbered ligands at bridging elements are needed; however, many strained monomers are only accessible with sterically encumbered bridging moieties. [9,10] Another common problem is the lack of solubility of prepared metallopolymers. Recently, we tackled both problems simultaneously through the introduction of isopropyl groups adjacent to the bridging element, which provide steric protection and act as solubilizing groups (B; Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Chiral Bora[1]ferrocenophanes: Syntheses, Mechanistic Insights, and Ring‐Opening Polymerizations

Sadeh

Bhattacharjee

Sarbisheh

et al. 2014

Chemistry A European J

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A series of new boron-bridged [1]ferrocenophanes ([1]FCPs) was prepared by salt-metathesis reactions between enantiomerically pure dilithioferrocenes and amino(dichloro)boranes (Et2 NBCl2 , iPr2 NBCl2 , or tBu(Me3 Si)NBCl2 ). The dilithioferrocenes were prepared in situ by lithium-bromine exchange from the respective planar-chiral dibromides (Sp ,Sp )-[1-Br-2-(HR2 C)H3 C5 ]2 Fe (R=Me or Et). In most of the cases, mixtures of the targeted [1]FCPs 4 and the unwanted 1,1'-bis(boryl)ferrocenes 5 were formed. The product ratio depends on the bulkiness of the amino group, the speed of addition of the amino(dichloro)borane, the alkyl group on Cp rings, and in particular on the reaction temperature. The formation of strained [1]FCPs is strongly favored by increased reaction temperatures. Secondly, CHEt2 groups at Cp rings favored the formation of the targeted [1]FCPs stronger than CHMe2 groups. These discoveries open up new possibilities to further suppress the formation of unwanted byproducts by a careful choice of the reaction temperature and through tailoring the bulkiness of CHR2 groups on ferrocene. Thermal ring-opening polymerizations of selected boron-bridged [1]FCPs gave metallopolymers with a Mw of 10 kDa (GPC).

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Synthesis and Characterization of the First Aluminum-Bridged [1]Ferrocenophane

Cited by 63 publications

References 33 publications

A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron, Gallium, Silicon, and Tin in Bridging Positions

A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron, Gallium, Silicon, and Tin in Bridging Positions

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

Chiral Bora[1]ferrocenophanes: Syntheses, Mechanistic Insights, and Ring‐Opening Polymerizations

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