Molecular Structures of Free Boron Clusters

Hnyk, Drahomı́r; Wann, Derek A.

doi:10.1007/978-3-319-22282-0_2

Cited by 21 publications

(19 citation statements)

References 74 publications

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“…Carborane-derived complexes constitute icosahedral polyhedrons with interesting magnetic, photophysical, and photochemical properties. − They are air-stable structures with pseudo aromaticity, which can be composed of one isolated unit or several units connected by means of bridging molecules. − Much attention has been paid to the utilization of carboranes in organometallics, medical chemistry, and for luminescence applications. However, there are only a few works attempting to introduce carboranes as ligands in single molecule magnets.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

et al. 2018

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We analyze the magnetic properties of three mononuclear Co(II) coordination complexes using quantum chemical complete active space self-consistent field and N-electron valence perturbation theory approaches. The complexes are characterized by a distorted tetrahedral geometry in which the central ion is doubly chelated by the icosahedral ligands derived from 1,2-(HS)-1,2-CBH (complex I), from 1,2-(HS)-1,2-CBH and 9,12-(HS)-1,2-CBH (complex II), and from 9,12-(HS)-1,2-CBH (complex III), which are two positional isomers of dithiolated 1,2-dicarba- closo-dodecaborane (complex I). Complex I was realized experimentally recently (Tu, D.; Shao, D.; Yan, H.; Lu, C. Chem. Commun. 2016, 52, 14326) and served to validate the computational protocol employed in this work, while the remaining two proposed complexes can be considered positional isomers of I. Our calculations show that these complexes present different axial and rhombic zero-field splitting anisotropy parameters and different values of the most significant components of the g tensor. The predicted axial anisotropy D = -147.2 cm for complex II is twice that observed experimentally for complex I, D = -72.8 cm, suggesting that this complex may be of interest for practical applications. We also analyze the temperature dependence of the magnetic susceptibility and molar magnetization for these complexes when subject to an external magnetic field. Overall, our results suggest that o-carborane-incorporated Co(II) complexes are worthwhile candidates for experimental exploration as single-ion molecular magnets.

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Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

et al. 2018

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“…BH 3 has a very low-lying LUMO orbital (0.056 a.u. at HF/II, II stands for a Huzinaga-type basis set developed for NMR computations; for further applications see ref ), which is responsible for the strongly deshielding contributions from the BH bonds. Replacement of H with CH 3 changes this situation very little.…”

Section: Resultsmentioning

confidence: 99%

Nuclear Magnetic Shielding of Monoboranes: Calculation and Assessment of¹¹B NMR Chemical Shifts in Planar BX₃and in Tetrahedral [BX₄]⁻Systems

et al. 2017

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B NMR chemical shifts of tricoordinated BX and tetracoordinated BX compounds (X = H, CH, F, Cl, Br, I, OH, SH, NH, and CH═CH) were computed, and the shielding tensors were explored not only within the nonrelativistic GIAO approach but also by application of both relativistic ZORA computations including spin-orbit coupling as well as scalar nonrelativistic ZORA computations (BP86 level of density functional theory). The contributions of the spin-orbit coupling to the overall shieldings are decisive for X = Br and I in both series. No relationship was found between the 2p orbital occupancies or 1/ΔE (difference between LUMO and suitably occupied MO that can be coupled with LUMO) with the shielding tensors (or their principal values) in the BX series. However, a multidimensional statistical approach known as factor analysis (frequently used in chemometrics) revealed that three factors account for 92% of the cumulative proportion of total variance. The main components of the first factor are occupancies in the 2p and 2p orbitals and 1/ΔE; the second factor is mainly the occupancy in the 2p orbital and the inductive substituent parameters by Taft. Finally, the third factor consists exclusively (98.4%) of the electrostatic potential (V), which is directly related to the so-called π-hole magnitudes.

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“…In the hundred-year-history of boron hydrides and their successors (polyhedral boranes, carboranes and other heteroboranes) and derivatives, the number, molecular shape, reactivity and applications of these species have become enormous, thus establishing a self-consistent field of chemistry 1 – 3 . Examples in synthetic organic chemistry and catalysis include the early use of diborane in organic chemistry as a reducing agent 4 ; ionic closo -carboranes as weakly-coordinating anions, transfer agents 5 or recently as a supporting scaffold for the stabilisation of low-valent main-group elements by silylenes 4 – 10 ; and low-coordinate boron species for the one-pot reduction of dinitrogen to ammonium chloride 11 – 13 .…”

Section: Introductionmentioning

confidence: 99%

Access to cationic polyhedral carboranes via dynamic cage surgery with N-heterocyclic carbenes

et al. 2021

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Polyhedral boranes and heteroboranes appear almost exclusively as neutral or anionic species, while the cationic ones are protonated at exoskeletal heteroatoms or they are instable. Here we report the reactivity of 10-vertex closo-dicarbadecaboranes with one or two equivalents of N-heterocyclic carbene to 10-vertex nido mono- and/or bis-carbene adducts, respectively. These complexes easily undergo a reaction with HCl to give cages of stable and water soluble 10-vertex nido-type cations with protonation in the form of a BHB bridge or 10-vertex closo-type cations containing one carbene ligand when originating from closo-1,10-dicarbadecaborane. The reaction of a 10-vertex nido mono-carbene adduct with phosphorus trichloride gives nido-11-vertex 2-phospha-7,8-dicarbaundecaborane, which undergoes an oxidation of the phosphorus atom to P = O, while the product of a bis-carbene adduct reaction is best described as a distorted C2B6H8 fragment bridged by the (BH)2PCl2+ moiety.

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Molecular Structures of Free Boron Clusters

Cited by 21 publications

References 74 publications

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

Nuclear Magnetic Shielding of Monoboranes: Calculation and Assessment of¹¹B NMR Chemical Shifts in Planar BX₃and in Tetrahedral [BX₄]⁻Systems

Access to cationic polyhedral carboranes via dynamic cage surgery with N-heterocyclic carbenes

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Molecular Structures of Free Boron Clusters

Cited by 21 publications

References 74 publications

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

Magnetic Properties of Mononuclear Co(II) Complexes with Carborane Ligands

Nuclear Magnetic Shielding of Monoboranes: Calculation and Assessment of11B NMR Chemical Shifts in Planar BX3and in Tetrahedral [BX4]−Systems

Access to cationic polyhedral carboranes via dynamic cage surgery with N-heterocyclic carbenes

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Nuclear Magnetic Shielding of Monoboranes: Calculation and Assessment of¹¹B NMR Chemical Shifts in Planar BX₃and in Tetrahedral [BX₄]⁻Systems