Synthesis, Structure, and Properties of Al(Rbpy)3 Complexes (R = t‐Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

The article of record as published may be found at http://dx.doi.org/10.1021/acs.inorgchem.6b00034The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorg- chem.6b00034. Crystallographic data for 1 (CIF) Crystallographic data for 2 (CIF) Characterizationdata(PDF)The neutral homoleptic tris-bpy aluminum complexes Al(Rbpy)3, where R = tBu (1) or Me (2), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral Rbpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that 1 and 2 contain Al3+ metal centers coordinated by three bipyridine (bpy•)1− monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral Rbpy or Rbpy2− dianions, respectively. Magnetic susceptibility measurements (4− 300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the Rbpy ligands to give S = 1/2 ground states with low lying S = 3/2 excited states that are populated above 110 K (1) and 80 K (2) in the solid-state. Complex 2 shows weak 3D magnetic interactions at 19 K, which is not observed in 1 or the related [Al(bpy)3] complex.DTRA (HDTRA-1-12-1-007

Synthesis, Structure, and Properties of Al(^Rbpy)₃ Complexes (R = <i>t</i>‑Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

The neutral homoleptic tris-bpy aluminum complexes Al­(^Rbpy)₃, where R = tBu (<b>1</b>) or Me (<b>2</b>), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral ^Rbpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that <b>1</b> and <b>2</b> contain Al³⁺ metal centers coordinated by three bipyridine (bpy^•)^1– monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral ^Rbpy or ^Rbpy^2– dianions, respectively. Magnetic susceptibility measurements (4–300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the ^Rbpy ligands to give <i>S</i> = ¹/₂ ground states with low lying <i>S</i> = ³/₂ excited states that are populated above 110 K (<b>1</b>) and 80 K (<b>2</b>) in the solid-state. Complex <b>2</b> shows weak 3D magnetic interactions at 19 K, which is not observed in <b>1</b> or the related [Al­(bpy)₃] complex

The Reaction Rates of O₂ with Closed-Shell and Open-Shell Al_<i>x</i>^– and Ga_<i>x</i>^– Clusters under Single-Collision Conditions: Experimental and Theoretical Investigations toward a Generally Valid Model for the Hindered Reactions of O₂ with Metal Atom Clusters

In order to characterize the oxidation of metallic surfaces, the reactions of O₂ with a number of Al_<i>x</i>^– and, for the first time, Ga_<i>x</i>^– clusters as molecular models have been investigated, and the results are presented here for <i>x</i> = 9–14. The rate coefficients were determined with FT-ICR mass spectrometry under single-collision conditions at O₂ pressures of ∼10^–8 mbar. In this way, the qualitatively known differences in the reactivities of the even- and odd-numbered clusters toward O₂ could be quantified experimentally. To obtain information about the elementary steps, we additionally performed density functional theory calculations. The results show that for both even- and odd-numbered clusters the formation of the most stable dioxide species, [M_<i>x</i>O₂]⁻, proceeds via the less stable peroxo species, [M_<i>x</i>⁺···O₂^2–]⁻, which contains M–O–O–M moieties. We conclude that the formation of these peroxo intermediates may be a reason for the decreased reactivity of the metal clusters toward O₂. This could be one of the main reasons why O₂ reactions with metal surfaces proceed more slowly than Cl₂ reactions with such surfaces, even though O₂ reactions with both Al metal and Al clusters are more exothermic than are reactions of Cl₂ with them. Furthermore, our results indicate that the spin-forbidden reactions of ³O₂ with closed-shell clusters and the spin-allowed reactions with open-shell clusters to give singlet [M_<i>x</i>⁺···O₂^2–]⁻ are the root cause for the observed even/odd differences in reactivity

Synthesis, Structure, and Properties of Al(^Rbpy)₃ Complexes (R = <i>t</i>‑Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

The neutral homoleptic tris-bpy aluminum complexes Al­(^Rbpy)₃, where R = tBu (<b>1</b>) or Me (<b>2</b>), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral ^Rbpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that <b>1</b> and <b>2</b> contain Al³⁺ metal centers coordinated by three bipyridine (bpy^•)^1– monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral ^Rbpy or ^Rbpy^2– dianions, respectively. Magnetic susceptibility measurements (4–300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the ^Rbpy ligands to give <i>S</i> = ¹/₂ ground states with low lying <i>S</i> = ³/₂ excited states that are populated above 110 K (<b>1</b>) and 80 K (<b>2</b>) in the solid-state. Complex <b>2</b> shows weak 3D magnetic interactions at 19 K, which is not observed in <b>1</b> or the related [Al­(bpy)₃] complex

Synthesis, Structure, and Properties of Al(^Rbpy)₃ Complexes (R = <i>t</i>‑Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

The neutral homoleptic tris-bpy aluminum complexes Al­(^Rbpy)₃, where R = tBu (<b>1</b>) or Me (<b>2</b>), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral ^Rbpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that <b>1</b> and <b>2</b> contain Al³⁺ metal centers coordinated by three bipyridine (bpy^•)^1– monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral ^Rbpy or ^Rbpy^2– dianions, respectively. Magnetic susceptibility measurements (4–300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the ^Rbpy ligands to give <i>S</i> = ¹/₂ ground states with low lying <i>S</i> = ³/₂ excited states that are populated above 110 K (<b>1</b>) and 80 K (<b>2</b>) in the solid-state. Complex <b>2</b> shows weak 3D magnetic interactions at 19 K, which is not observed in <b>1</b> or the related [Al­(bpy)₃] complex