Unusual Inorganic Ring Systems of Scandium and Yttrium Containing Group 13 Metals: Coordination of Monomeric Me2InOMe to Yttrium

High-yield synthesis of a unique Mn(iii) siloxide complex through KMnO4 oxidation of a Mn(ii) precursor

A unique trivalent manganese siloxide complex, blue-violet Mn^IIILi₂Cl[(Ph₂SiO)₂O]₂(THF)₄·2THF (3) has been prepared by a straightforward two-step synthetic protocol. Lithiation of (Ph₂SiOH)₂O (1) followed by reaction with MnCl₂(THF)₂ gave the structurally remarkable Mn(ii) precursor Mn^IILi₄Cl₂[(Ph₂SiO)₂O]₂(THF)₅·2THF (2). Surprisingly, the final oxidation step could be achieved using KMnO₄ in THF to provide the Mn(iii) species 3 in high yield (91%). Both title compounds were structurally characterized by single-crystal X-ray diffraction.

Synthesis and structural study of new metallasilsesquioxanes of potassium and uranium

The first metallasilsesquioxanes comprising potassium and uranium have been synthesized and structurally characterized by single-crystal X-ray diffraction.

Molecular rare earth metal alumosilicates

The resulting structure of the rare-earth metal alumosilicates depends strongly on the lanthanide radii and the acidity of Al–OH and Si–OH groups.

The Recently Synthesized Dimagnesiabutadiene and the Analogous Dimetalla-Beryllium, -Calcium, -Strontium, and -Barium Compounds

The 2014 synthesis of the remarkable dimagnesium compound Mg₂ [C₄ (CH₃ )₂ (Si(CH₃ )₃ )₂ ](C₃ H₇ )₂ (C₄ H₈ O)₂ may point the way to a new chapter in alkaline earth organometallic chemistry. Accordingly, we have studied the known Mg compound and the analogous Be, Ca, Sr, and Ba structures. Although most of our theoretical predictions come from density functional methods, the latter have been benchmarked using coupled cluster theory including single, double, and perturbative triplet excitations, CCSD(T) using cc-pVTZ basis sets. Among our most important predictions are the energies for dissociation to the butadiene plus the RM-MR [R=(C₃ H₇ )₂ (C₄ H₈ O)₂ ; M=Be, Mg, Ca, Si, and Ba] entities. The most reliable predictions for the dissociation energies are 99-104 (Be), 85-93 (Mg), 90-99 (Ca), 83-92 (Sr), and 83-94 (Ba) kcal mol^-1 . Thus, there is reason to anticipate that the four unknown compounds should be achievable synthetically. The predicted metal-metal distances (not single bonds) are 2.89 Å (Mg⋅⋅⋅Mg), 3.46 Å (Ca⋅⋅⋅Ca), 3.75 Å (Sr⋅⋅⋅Sr), and 4.04 Å (Ba⋅⋅⋅Ba). The separated RM-MR compounds have longer M-M distances but genuine metal-metal single bonds. This perhaps counter intuitive result is due to the presence of the bridging carbons in the alkaline earth butadiene compounds. All five compounds incorporate metal-carbon ionic interactions.

Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties

This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.

Synthesis of heteroboroxines with MB₂O₃ core (M = Sb, Bi, Sn)--an influence of the substitution of parent boronic acids

The synthesis and structure of stiba-, stanna- and bismaheteroboroxines of a general formula L(E)M[(OBR)2O] supported by a N,C,N-chelating ligand L [where L = C6H3-2,6-(CH2NMe2)2, M, E = Sb, lone pair or Sn, Ph or Bi, lone pair] is reported. The target compounds are prepared by straightforward one-step reactions between oxides (LMO)2 (M = Sb or Bi) or organotin(iv) carbonate L(Ph)Sn(CO3) with four or two molar equivalents of corresponding organoboronic acid. All compounds were characterized with the help of elemental analysis, multinuclear NMR spectroscopy and on several occasions the molecular structure was determined using single-crystal X-ray diffraction analysis. The influence of both the substitution of the parent organoboronic acid and the central atom used on the feasibility of the condensation reaction was addressed. Furthermore, several heteroboroxines containing nitrogen donor functionality (i.e. NH2, NMe2, CN or 4-pyridyl) included in the boronic acid residue were synthesized and characterized with the aim to prepare boroxine-based covalent frameworks (through intermolecular N→B interactions) containing metal atoms in their structures. Although no such intermolecular bonding was detected in solution of these compounds, it was shown that the organotin(iv) heteroboroxine substituted by 4-pyridyl group forms an infinite polymeric chains via N→B interactions in the solid state. This polymer collapsed back to monomeric units upon dissolution.