Facile Dissociation of [(LNi^II)₂E₂] Dichalcogenides: Evidence for [LNi^IIE₂] Superselenides and Supertellurides in Solution

Abstract

Easy breakage to open-shells: The diamagnetic butterfly-like dichalcogen complexes 1 (E = Se) and 2 (E = Te) with a {Ni(II)(2)E(2)} core, undergo facile dissociation in solution via spin crossover to give the unprecedented mononuclear paramagnetic superselenide and supertelluride species 1' and 2', respectively, along with the nickel(I) fragment [LNi(I)]; R = 2,6-diisopropylphenyl.

Synthesis and reactivity of a nickel(ii) thioperoxide complex: demonstration of sulfide-mediated N2O reduction

“… 18 This distance is comparable to those reported for other Ni II (η 2 -S 2 ) complexes. 42 – 49 The Ni–S distances (2.202(2) and 2.199(2) Å) in 3 are consistent with single bonds, and are much longer than the Ni–S bond length in the starting material ( I , 2.064(2) Å). Finally, the Ni–N bonds in 3 are similar to those found in other square planar Ni II β-diketiminate complexes.…”

X‐ray Absorption Spectroscopic, Crystallographic, Theoretical (DFT) and Chemical Evidence for a Chalcogen–Chalcogen Two‐Center/Three‐Electron Half Bond in an Unprecedented “Subselenide” Se23− Ligand

“…Compound 1 was first synthesized by Sitzmann and co‐workers in 2001,7 and attracted our interest for several reasons. First, the reported Se⋅⋅⋅Se distance in 1 , 2.85 Å (Scheme , B ) is intermediate with respect to the distances expected for Ni 2 Se 2 compounds containing no SeSe bond (e.g., 3.29 Å in (CpNiSePh) 2 ,8 C in Scheme ) or a SeSe single bond (e.g., 2.33 Å in (LNiSe) 2 with L=β‐diketiminate,9 A in Scheme ). Second, the sulfur and tellurium analogues of 1 were also reported to have unusual E⋅⋅⋅E bond distances 7.…”

“…Sitzmann and co‐workers were unsatisfied with their ability to describe the electronic structure of their compounds and concluded that, “ the complexes appear to be neither Ni II complexes with an E 2 2− bridge nor Ni III complexes with two E 2− bridges .” Thus, we hypothesized that Sitzmann’s compounds might contain half‐bonded E 2 3− bridges. Since Sitzmann’s room temperature crystal structure contained significant disorder of the Se atoms, we obtained a new crystal structure of 1 at 100 K resulting in a more reliable Se⋅⋅⋅Se distance of 2.915(2) Å, which is still intermediate between the covalent single bond distance of 2.32 Å9 and the 3.3 Å sum of Se van der Waals radii 10. 11…”

Solvothermal and ionothermal syntheses and structures of amine- and/or (poly-)chalcogenide coordinated metal complexes

“…In contrast, Sheldrick's series of [{Mn x (Se y )(amine)} z ], x = 1, 2, y = 4-6, z = 1, 2 [20,21], [Mn x (amine) x As y Se z ] with x/y/z = 3/2/8 or 2/2/6 [22], as well as [25], and [ZnSe 4 (NMeIm) 2 ] (N-MeIm = N-methylimidazole), synthesized in an elegant way by in situ degeneration of N-MeIm and redox reaction of elemental Zn and Se [26]. As not all reactions within ILs that have been reported today require amine auxiliaries, further non-amine ligated precursors such as {M[Me 2 SiCp 2 ]Se 5 } (M = Ti, Zr, Hf) [27], [Cp*Re(Se 3 ) (μ-Se 2 )] 8 [28], [Cp* 2 Mo(η 2 -Se 4 )] [29] would be also worth trying.…”