Optical absorption and EPR studies on tenorite mineral

Optical absorption and EPR studies of the mineral tenorite, a cupric oxide, which originated from Mexico and contains 54.40 wt% of CuO. EPR spectral results indicate two Cu(II) closely interacting ions to give a d2 type structure. The calculated spin Hamiltonian at Rt and LNT are g = 2.160 and D = 125 G . The intensity of resonance line is not the same in low and high field regions. The optical absorption spectrum is due to Cu(II) which three sets of energies indicating Cu(II) in two independent tetragonal C4v symmetry, in addition to d2 structure of octahedral coordination. The octahedral and tetragonal field parameters are compared with those reported for several other copper containing minerals

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

Reaction of [(XA₂)­UCl₃{K­(dme)₃}] (XA₂ = 4,5-bis­(2,6-diisopropylanilino)-2,7-di-<i>tert</i>-butyl-9,9-dimethylxanthene) with 2 equiv of ((trimethylsilyl)­methyl)­lithium or neopentyllithium afforded red-orange [(XA₂)­U­(CH₂SiMe₃)₂] (<b>1</b>) and dark red [(XA₂)­U­(CH₂CMe₃)₂] (<b>2</b>), respectively. Reaction of <b>1</b> with an additional 1 equiv of LiCH₂SiMe₃ in THF yielded yellow [Li­(THF)_<i>x</i>]­[(XA₂)­U­(CH₂SiMe₃)₃] (<b>3</b>), and reaction of [(XA₂)­UCl₃{K­(dme)₃}] with 3 equiv of methyllithium in dme afforded yellow [Li­(dme)₃]­[(XA₂)­UMe₃] (<b>4</b>). Reaction of <b>1</b> with 2.1 equiv of LiCH₂CMe₃ in benzene resulted in rapid conversion to <b>2</b>, with release of 2 equiv of LiCH₂SiMe₃. Similarly, reaction of <b>1</b> with 3.3 equiv of MeLi in THF provided <b>4</b> as the [Li­(THF)_<i>x</i>]⁺ salt, accompanied by 2 equiv of LiCH₂SiMe₃. These unusual alkyl exchange reactions resemble salt metathesis reactions, but with elimination of an alkyllithium instead of a lithium halide. Addition of a large excess of LiCH₂SiMe₃ to <b>2</b> or <b>4</b> did not generate detectable amounts of <b>1</b> by NMR spectroscopy, suggesting that the equilibrium in these reactions lies far to the side of complexes <b>2</b> and <b>4</b>. In contrast, the reaction of [(XA₂)­Th­(CH₂SiMe₃)₂] (<b>1-Th</b>) with 2.2 equiv of LiCH₂CMe₃ yielded an approximate 1:1:3:1 mixture of [(XA₂)­Th­(CH₂CMe₃)₂] (<b>2-Th</b>), [(XA₂)­Th­(CH₂SiMe₃)­(CH₂CMe₃)] (<b>5-Th</b>), LiCH₂SiMe₃, and LiCH₂CMe₃