Structure of 1,5-diselenoniabicyclo[3.3.0]octane bis(tetrafluoroborate) acetonitrile solvate

Linear Multiselenium Interactions in Dicationic Oligomers of 1,5-(Diselena)canes: Behavior of Semc σ(mc c-ne e) (6≤mc ≤16) Elucidated with QTAIM Dual Functional Analysis

The intrinsic dynamic and static nature mc center-ne electron interactions of the σ-type σ(mc c-ne e) were elucidated for the Se-Se interactions in dicationic oligomers of Se(CH2 CH2 CH2 )2 Se (1 (Se, Se)) [n2+ (Se, Se): n=1-8], especially for mc ≥6, where n2+ (Se, Se: n=1-8) are abbreviated by n2+ (n=1-8), respectively. QTAIM dual functional analysis (QTAIM-DFA) was applied to the interactions. Perturbed structures generated using coordinates derived from the compliance constants (Cii ) were employed for QTAIM-DFA. Each Se-*-Se in 12+ and 22+ has the nature of CT-TBP (trigonal bipyramidal adduct formation through CT) and Cov-w (weak covalent), respectively, which supply the starting points of the investigations. The asterisk emphasizes the existence of a bond critical point on the interaction. All Se-*-Se in 32+ are classified by the regular closed shell (r-CS) interactions and characterized as CT-MC (molecular complex formation through CT), which are denoted as r-CS/CT-MC, except for the central interaction, of which nature is r-CS/CT-TBP. Most interactions in 42+ -82+ are r-CS/t-HBwc (typical-HB with covalency) but some are pure-CS/t-HBnc (t-HB with no covalency). The linear Se2n 2+ interactions in 22+ -82+ seem close to those without any limitations, since the nature of Se-*-Se inside and outside of (CH2 CH2 CH2 )2 are very similar with each other. The linear Se2n 2+ interactions in 32+ -82+ are shown to be analyzed as σ(mc c-ne e: 6≤mc ≤16), not by the accumulated σ(3c-4e).

A diradical based on odd-electron σ-bonds

The concept of odd-electron σ–bond was first proposed by Linus Pauling. Species containing such a bond have been recognized as important intermediates encountered in many fields. A number of radicals with a one-electron or three-electron σ-bond have been isolated, however, no example of a diradical based odd-electron σ-bonds has been reported. So far all stable diradicals are based on two s/p-localized or π-delocalized unpaired electrons (radicals). Here, we report a dication diradical that is based on two Se∴Se three-electron σ–bonds. In contrast, the dication of sulfur analogue does not display diradical character but exhibits a closed-shell singlet.

Stable diradicals are generally based on two s/p-localized or π-delocalized unpaired electrons (radicals). Here, the authors report a dication diradical that is based on two Se∴Se three-electron σ-bonds.

Linear Four-Chalcogen Interactions in Radical Cationic and Dicationic Dimers of 1,5-(Dichalcogena)canes: Nature of the Interactions Elucidated by QTAIM Dual Functional Analysis with QC Calculations

The dynamic and static nature of extended hypervalent interactions of the ^BE···^AE···^AE···^BE type are elucidated for four center-seven electron interactions (4c-7e) in the radical cationic dimers (1·⁺) and 4c-6e in the dicationic dimers (1²⁺) of 1,5-(dichalcogena)canes (2: ^AE(CH₂CH₂CH₂)₂^BE: ^AE, ^BE = S, Se, Te, and O). The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied for the analysis. Total electron energy densities H_b(r_c) are plotted versus H_b(r_c) - V_b(r_c)/2 [= (ℏ²/8m)∇²ρ_b(r_c)] at bond critical points (BCPs) of the interactions, where V_b(r_c) values show potential energy densities at BCPs. Data from the fully optimized structures correspond to the static nature of the interactions. Those from the perturbed structures around the fully optimized ones are also plotted, in addition to those of the fully optimized ones, which represent the dynamic nature of interactions. The ^BE···^AE-^AE···^BE interactions in 1²⁺ are stronger than the corresponding ones in 1·⁺, respectively. On the one hand, for 1²⁺ with ^AE, ^BE = S, Se, and Te, ^AE···^AE are all classified by the shared shell interactions and predicted to have the weak covalent nature, except for those in 1a²⁺ (^AE = ^BE = S) and 1d²⁺ (^AE = ^BE = Se), which have the nature of regular closed shell (r-CS)/trigonal bipyramidal adduct formation through charge transfer (CT-TBP). On the other hand, ^AE···^BE are predicted to have the nature of r-CS/molecular complex formation through charge transfer for 1a²⁺, 1b²⁺ (^AE = Se; ^BE = S), and 1d²⁺ or r-CS/CT-TBP for 1c²⁺ (^AE = Te; ^BE = S), 1e²⁺ (^AE = Te; ^BE = Se), and 1f²⁺ (^AE = ^BE = Te). The ^BE···^AE-^AE···^BE interactions in 1·⁺ and 1²⁺ are well-analyzed by applying QTAIM-DFA.

Electrochemically informed synthesis: oxidation versus coordination of 5,6-bis(phenylchalcogeno)acenaphthenes

Chalcogen dications: Facile synthesis of E--E bonded dications can be readily achieved. Radical cations are identified as the intermediates.

Unexpected reactivity and coordination in gallium(III) and indium(III) chloride complexes with geometrically constrained thio- and selenoether ligands

Reaction of GaCl(3) with 1 mol equiv of [14]aneS(4) in anhydrous CH(2)Cl(2) gives the exocyclic chain polymer [GaCl(3)([14]aneS(4))] (1) whose structure confirms trigonal bipyramidal coordination at Ga with a planar GaCl(3) unit. In contrast, using [16]aneS(4) and GaCl(3) or [16]aneSe(4) and MCl(3) (M = Ga or In) in either a 1:1 or a 1:2 molar ratio produces the anion-cation complexes [GaCl(2)([16]aneS(4))][GaCl(4)] (2) and [MCl(2)([16]aneSe(4))][MCl(4)] (M = Ga, 3 and M = In, 4) containing trans-octahedral cations with endocyclic macrocycle coordination. The ligand-bridged dimer [(GaCl(3))(2){o-C(6)H(4)(SMe)(2)}] (5) is formed from a 2:1 mol ratio of the constituents and contains distorted tetrahedral Ga(III). This complex is unusually reactive toward CH(2)Cl(2), which is activated toward nucleophilic attack by polarization with GaCl(3), producing the bis-sulfonium species [o-C(6)H(4)(SMeCH(2)Cl)(2)][GaCl(4)](2) (6), confirmed from a crystal structure. In contrast, the xylyl-based dithioether gives the stable [(GaCl(3))(2){o-C(6)H(4)(CH(2)SEt)(2)}] (8). However, replacing GaCl(3) with InCl(3) with o-C(6)H(4)(CH(2)SEt)(2) preferentially forms the 4:3 In:L complex [(InCl(3))(4){o-C(6)H(4)(CH(2)SEt)(2)}(3)] (9) containing discrete tetranuclear moieties in which the central In atom is octahedrally coordinated to six bridging Cl's, while the three In atoms on the edges have two bridging Cl's, two terminal Cl's, and two mutually trans S-donor atoms from different dithioether ligands. GaCl(3) also reacts with the cyclic bidentate [8]aneSe(2) to form a colorless, extremely air-sensitive adduct formulated as [(GaCl(3))(2)([8]aneSe(2))] (10), while InCl(3) gives [InCl(3)([8]aneSe(2))] (14). Very surprisingly, 10 reacts rapidly with O(2) gas to give initially the red [{[8]aneSe(2)}(2)][GaCl(4)](2) (11) and subsequently the yellow [{[8]aneSe(2)}Cl][GaCl(4)] (12). The crystal structure of the former confirms a dimeric [{[8]aneSe(2)}(2)](2+) dication, derived from coupling of two mono-oxidized {[8]aneE(2)}(+•) cation radicals to form an Se-Se bond linking the rings and weaker transannular 1,5-Se···Se interactions across both rings. The latter (yellow) product corresponds to discrete doubly oxidized {[8]aneSe(2)}(2+) cations (with a primary Se-Se bond across the 1,5-positions of the ring) with a Cl(-) bonded to one Se. Tetrahedral [GaCl(4)](-) anions provide charge balance in each case. These oxidation reactions are clearly promoted by the Ga(III) since [8]aneSe(2) itself does not oxidize in air. The new complexes have been characterized in the solid state by IR and Raman spectroscopy, microanalysis, and X-ray crystallography where possible. Where solubility permits, the solution characteristics have been probed by (1)H, (77)Se{(1)H}, and (71)Ga NMR spectroscopic studies.