[1]Metallocenophanes (M = Fe, Ru) of Heavier Group 13 Elements (E = Al, Ga):  Synthesis, Characterization, and Ring-Opening Polymerization

Schachner, Jörg A.; Tockner, Stefan; Lund, Clinton L.; Quail, J. Wilson; Rehahn, and Matthias; Müller, Jens

doi:10.1021/om7004244

Cited by 52 publications

(47 citation statements)

References 29 publications

(40 reference statements)

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“…11 The measured difference of only 0.6°for [1]ruthenocenophanes 7a and 7b is surprisingly small [Al: 20.31 (19)°; Ga: 20.91 (19)°]. 12 Based on the difference of 3.0°found for [1]molybdarenophanes, the calculated difference of 3.3°for 7a and 7b matches with the expectation better than the experimentally determined difference of only 0.6°.…”

Section: Methodsmentioning

confidence: 60%

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Bagh¹,

Schatte²,

Green

et al. 2012

J. Am. Chem. Soc.

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The aluminum and gallium dichlorides (Mamx)ECl(2)1a (E = Al; 82%) and 1b (E = Ga; 79%) (Mamx = 2,4-di-tert-butyl-6-[(dimethylamino)methyl]phenyl) reacted with dilithioferrocene or dilithioruthenocene to give [1]ferrocenophanes (2a, 2b) and [1]ruthenocenophanes (3a, 3b), respectively. The galla[1]ruthenocenophane 3b could be isolated from the reaction mixture through precipitation into hexane (50%), while 2a, 2b, and 3a underwent ring-opening polymerization under the reaction conditions of their formation reactions to give metallopolymers (M(w) (DLS) between 8.07 and 106 kDa). Monomer 3b was polymerized using Karstedt's catalyst resulting in an M(w) of 28.6(±6.3) kDa. In order to get an indication of the structure of polymers, bis(ferrocenyl) compounds (Mamx)EFc(2) (E = Al (4a), 51%; E = Ga (4b), 49%) were prepared and characterized by single crystal X-ray analysis. DFT calculations shed some light on the unexpected high reactivity of these new strained sandwich species. Optimized geometries of known aluminum and gallium-bridged [1]ferrocenophanes (Al(Pytsi) (6a), Ga(Pytsi) (6b); Pytsi = [dimethyl(2-pyridyl)silyl]bis(trimethylsilyl)methyl) and [1]ruthenocenophanes (Al(Me(2)Ntsi) (7a), Ga(Me(2)Ntsi) (7b); Me(2)Ntsi = [(dimethylamino)dimethylsilyl]bis(trimethylsilyl)methyl) matched very well with experimental molecular structures. Geometries of species 2a, 2b, 3a, and 3b were optimized (BP86/TZ2P) and the structural influence of the tBu group of the Mamx ligand in ortho position was evaluated by optimizing molecular structures of the four unknown species where the ortho-tBu group was replaced by an H atom (2a(H), 2b(H), 3a(H), and 3b(H)). The most pronounced structural effect was seen as a change of the orientation of the bridging moiety with respect to the sandwich unit. As the tBu group was removed, the aromatic ligand moved toward the freed-up space. The energetics (ΔE, ΔH(298K), and ΔG(298K)) accompanied by the structural changes were evaluated by a hydrogenolysis reaction of strained species resulting in Cp(2)M (M = Fe, Ru) and respective aluminum and gallium dihydrides. This nonisodesmic reaction showed that [1]metallocenophanes equipped with the ortho-tBu group were on average 5.5 kcal/mol higher strained (ΔH(298K)) than species where the tBu group was lacking. The investigation of the isodesmic reaction between strained species and Cp(2)M yielding bis(metallocenyl) compounds revealed that the ortho-tBu group sterically interacts with one of the metallocenyl units. The bis(metallocenyl) compounds are model compounds for the respective metallopolymers and one can conclude that even though the ortho-tBu group imposes additional strain on the starting metallocenophanes, this effect cancels out in ROPs because the ortho-tBu group imposes a similar strain on the resulting polymers. The uncovered steric repulsion between the ortho-tBu group and the sandwich moieties probably causes the ortho-tBu to act as an unusually sensitive NMR probe of the tacticity of the polymers.

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Section: Methodsmentioning

confidence: 60%

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Bagh¹,

Schatte²,

Green

et al. 2012

J. Am. Chem. Soc.

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“…Being a versatile technique, ROP is employed in the synthesis of various non‐iron‐ as well as non‐ η 5 ‐cyclopentadienyl‐based sandwich complexes‐containing macromolecules . Similar to their ferrocene analogue, the properties of these polymers are dependent on polymerization conditions.…”

Section: Macromolecules Bearing Sandwich Complexes In the Main Chainmentioning

confidence: 99%

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

Abd‐El‐Aziz

Agatemor

Etkin

2014

Macromol. Rapid Commun.

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Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic-based macromolecules. These properties are tunable through well-designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex-containing macromolecules. While the past two decades have seen an ever-growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes.

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“…A related galla[1]ferrocenophane was published by Lund et al (2006). For related literature, see: Bellas & Rehahn (2007) ;Foucher et al (1992); Herbert et al (2007); Lund et al (2007); Osborne & Whiteley (1975); Schachner et al (2005aSchachner et al ( , 2007.…”

Section: Related Literaturementioning

confidence: 99%

The galla[1]ferrocenophane {[dimethyl(2-pyridyl)silyl]bis(trimethylsilyl)methyl-κ²C,N}(ferrocene-1,1′-diyl)gallium(III)

2008

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[1]Metallocenophanes (M = Fe, Ru) of Heavier Group 13 Elements (E = Al, Ga): Synthesis, Characterization, and Ring-Opening Polymerization

Cited by 52 publications

References 29 publications

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

The galla[1]ferrocenophane {[dimethyl(2-pyridyl)silyl]bis(trimethylsilyl)methyl-κ²C,N}(ferrocene-1,1′-diyl)gallium(III)

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[1]Metallocenophanes (M = Fe, Ru) of Heavier Group 13 Elements (E = Al, Ga): Synthesis, Characterization, and Ring-Opening Polymerization

Cited by 52 publications

References 29 publications

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Understanding the Reactivity of Strained Sandwich Compounds with Aluminum or Gallium in Bridging Positions: Experiments and DFT Calculations

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

The galla[1]ferrocenophane {[dimethyl(2-pyridyl)silyl]bis(trimethylsilyl)methyl-κ2C,N}(ferrocene-1,1′-diyl)gallium(III)

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The galla[1]ferrocenophane {[dimethyl(2-pyridyl)silyl]bis(trimethylsilyl)methyl-κ²C,N}(ferrocene-1,1′-diyl)gallium(III)