Organoaluminum Complexes with Bonds to s-Block, p-Block, d-Block, and f-Block Metal Centers

Schulz, Stephan

doi:10.1007/3418_2012_33

Cited by 12 publications

(3 citation statements)

References 177 publications

(159 reference statements)

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“…In the case of late transition metals, which feature higher electronegativities in comparison to Al (1.61 on the Pauling scale), the binding of hard Al-based ligands, acting as σ-acceptors, can reverse the classical ligand→TM bonding situation and confer unique electronic properties to the resulting complexes, which opens up attractive opportunities for cooperative reactivity. Although a range of Z-type metal–alane L n M–AlX 3 Lewis adducts are known, − complexes featuring X-type metal–aluminum L n M–AlX 2 (L′ m ) ( m = 0, 1) covalent bonds are much more rare (Scheme ) and their reactivity remains almost unexplored. − …”

Section: Introductionmentioning

confidence: 99%

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

et al. 2021

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The iridium tetrahydride complex Cp*IrH4 reacts with a range of isobutylaluminum derivatives of general formula Al(iBu) x (OAr)3–x (x = 1, 2) to give the unusual iridium aluminum species [Cp*IrH3Al(iBu)(OAr)] (1) via a reductive elimination route. The Lewis acidity of the Al atom in complex 1 is confirmed by the coordination of pyridine, leading to the adduct [Cp*IrH3Al( i Bu)(OAr)(Py)] (2). Spectroscopic, crystallographic, and computational data support the description of these heterobimetallic complexes 1 and 2 as featuring strongly polarized Al(III)δ+–Ir(III)δ− interactions. Reactivity studies demonstrate that the binding of a Lewis base to Al does not quench the reactivity of the Ir–Al motif and that both species 1 and 2 promote the cooperative reductive cleavage of a range of heteroallenes. Specifically, complex 2 promotes the decarbonylation of CO2 and AdNCO, leading to CO (trapped as Cp*IrH2(CO)) and the alkylaluminum oxo ([(iBu)(OAr)Al(Py)]2(μ-O) (3)) and ureate ({Al(OAr)( i Bu)[κ2-(N,O)AdNC(O)NHAd]} (4)) species, respectively. The bridged amidinate species Cp*IrH2(μ-CyNC(H)NCy)Al( i Bu)(OAr) (5) is formed in the reaction of 2 with dicyclohexylcarbodiimine. Mechanistic investigations via DFT support cooperative heterobimetallic bond activation processes.

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Section: Introductionmentioning

confidence: 99%

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

et al. 2021

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“…It is likely that the pincer-type diphosphino-aluminyl ligand forms a strong σ-donation interaction with transition metals because of the smaller electronegativity and interacts with various substrates using its empty 3p orbital because of the larger atomic radius, i.e., larger orbital size. However, synthesis of a strongly σ-electron-donating X-type anionic aluminyl ligand has been very limited − compared to many reports about σ-electron-accepting Z-type Al ligands. − …”

Section: Introductionmentioning

confidence: 99%

Characterization of Rh–Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe₃)₂ (L = AlMe₂, Al(NMe₂)₂, BR₂, SiR₃, CH₃, Cl, or OCH₃): Theoretical Insight

et al. 2019

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The unique Rh–Al bond in recently synthesized Rh(PAlP) 1 {PAlP = pincer-type diphosphino-aluminyl ligand Al[NCH2(P i Pr2)]2(C6H4)2NMe} was investigated using the DFT method. Complex 1 has four doubly occupied nonbonding d orbitals on the Rh atom and one Rh d orbital largely participating in the Rh–Al bond which exhibits considerably large bonding overlap between Rh and Al atoms like in a covalent bond. Interestingly, Rhδ−−Alδ+ polarization is observed in the bonding MO of 1, which is reverse to Rhδ+−Eδ− (E = coordinating atom) polarization found in a usual coordinate bond. This unusual polarization arises from the presence of the Al valence orbital at significantly higher energy than the Rh valence orbital energy. Characteristic features of 1 are further unveiled by comparing 1 with similar Rh complexes RhL(PMe3)2 (2 for L = AlMe2, 3 for L = Al(NMe2)2, 4 for L = BMe2, 5 for L = SiMe3, 6 for L = SiH3, 7 for L = CH3, 8 for L = OMe, and 9 for L = Cl). As expected, 7, 8, and 9 exhibit usual Rhδ+−Eδ− polarization (E = coordinating atom) in the Rh–E bonding MO. On the other hand, the reverse Rhδ−−Eδ+ polarization is observed in the Rh–E bonding MOs of 2–5 like in 1, while the Rh–Si bond is polarized little in 6. These results are clearly understood in terms of the valence orbital energy of the ligand. Because the LUMO of 1 mainly consists of the Rh 4dσ, 5s, and 5p orbitals and the Al 3s and 3p orbitals, both Rh and Al atoms play the role of coordinating site for a substrate bearing a lone pair orbital. For instance, NH3 and pyridine coordinate to both Al and Rh atoms with considerably large binding energy. PAlP exhibits significantly strong trans influence, which is as strong as that of SiMe3 but moderately weaker than that of BMe2. The trans influence of these ligands is mainly determined by the valence orbital energy of the ligand and the covalent bond radius of the coordinating E atom.

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“…Understanding working of mitochondria at low temperatures can certainly help to engineer crops with better power houses -mitochondria -to cope with sub-physiological temperatures. Mitochondria are functionally "immature" in the seeds before germination and develop to fully functional organs during imbibition [84][85][86][87][88][89]. Yin et al [11] found that after imbibition at 22°C for 24 h soybean axes' cells have all the cell organelles in fully functional form, whereas in the axes imbibed at 10 and 4°C it was difficult to find endoplasmic reticulum, the intercellular space was looser and the cytoplasmic layer was irregular (also see Fig.…”

Section: Energy Metabolism In Germinating Seedsmentioning

confidence: 99%

Engineering Germination Fitness for Sub-Physiological Temperatures in Plants

Javeed¹,

Cheng²,

Song³

et al. 2012

Int J Mol Biol

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Abstract-Germination is a key event in plant life cycle and imbibition temperature is an important factor for the major reorganization processes in the germinating seeds. Sub-physiological temperature at this stage affects virtually all aspects of cellular function including protein folding, kinetic parameters of membrane fluidity, protein assembly, and general metabolic processes. In this article we will review the research which has been carried out to decipher the basic mechanisms of low temperature (LT) stress with special emphasis on germination. With the better understanding of LT tolerance in some plant species we will also discuss how these attributes can be transferred in the important food crops to attain better germination stamina at sub-physiological temperatures. At germination stage, the cellular machinery in the embryo is not at its proper place and is going through reorganisation and any environmental severity has devastating effects on the fragile plant. But LT resistant species have evolved the ability to acclimatise, with the remodelling of cell and tissue structures and the reprogramming of metabolism and gene expression. Metabolic networks are redirected towards the synthesis of cryoprotectant molecules, which in association with other proteins bring about physical and biochemical restructuring of cell membranes through changes in the lipid composition and induction of other non-enzymatic proteins that alter the freezing point of water. Genetic engineering of crops for enhanced seed germination performance will certainly help to achieve optimum agricultural yields.. Germination physiology in low temperatureAll environmental stresses disrupt the normal functioning of a living system. To re-establish metabolic homeostasis, living systems require an adjustment of metabolic pathways in a process usually referred to as acclimation. For temperate plants, low temperature (LT) is a major non-living element of the environmental that affects water and nutrient uptake, membrane fluidity and protein and nucleic acid conformation, drastically influencing cellular metabolism directly by reducing the rates of biochemical reactions [1], accompanied by changes in the transcriptome, proteome and metabolome [2]. Chilling temperatures (0 to 15°C) frequently occur in nature and affect many species of plants, especially those of tropical origin (such as rice, corn, tomato and soybean), by causing wilting, chlorosis, or necrosis, thus restricting their growth and development. Metabolic rates are lowered which create energy imbalance. Freezing (0°C and below) temperatures cause membrane injury [3], decrease the respiration rate and ATP content [4], resulting in poor germination, reduced seedling emergence, decreased seedling vigour, and ultimately severe loss in yield of the food crops of tropical and subtropical origins [5][6][7][8][9]. Embryos, excised from seed coats of soybeans, leak profusely during the first minutes of imbibition. In the embryos imbibed at 10°C or lower, disproportionately more solutes leak ...

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Organoaluminum Complexes with Bonds to s-Block, p-Block, d-Block, and f-Block Metal Centers

Cited by 12 publications

References 177 publications

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Characterization of Rh–Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe₃)₂ (L = AlMe₂, Al(NMe₂)₂, BR₂, SiR₃, CH₃, Cl, or OCH₃): Theoretical Insight

Engineering Germination Fitness for Sub-Physiological Temperatures in Plants

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Organoaluminum Complexes with Bonds to s-Block, p-Block, d-Block, and f-Block Metal Centers

Cited by 12 publications

References 177 publications

Strongly Polarized Iridiumδ−–Aluminumδ+ Pairs: Unconventional Reactivity Patterns Including CO2 Cooperative Reductive Cleavage

Strongly Polarized Iridiumδ−–Aluminumδ+ Pairs: Unconventional Reactivity Patterns Including CO2 Cooperative Reductive Cleavage

Characterization of Rh–Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe3)2 (L = AlMe2, Al(NMe2)2, BR2, SiR3, CH3, Cl, or OCH3): Theoretical Insight

Engineering Germination Fitness for Sub-Physiological Temperatures in Plants

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Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Strongly Polarized Iridium^δ−–Aluminum^δ+ Pairs: Unconventional Reactivity Patterns Including CO₂ Cooperative Reductive Cleavage

Characterization of Rh–Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe₃)₂ (L = AlMe₂, Al(NMe₂)₂, BR₂, SiR₃, CH₃, Cl, or OCH₃): Theoretical Insight