Electrophilic–Nucleophilic Dualism of Nickel(II) toward Ni···I Noncovalent Interactions: Semicoordination of Iodine Centers via Electron Belt and Halogen Bonding via σ-Hole

Abstract

The nitrosoguanidinate complex [Ni{NH═C(NMe)NN(O)}] (1) was cocrystallized with I and sym-trifluorotriiodobenzene (FIB) to give associates 1·2I and 1·2FIB. Structures of these solid species were studied by XRD followed by topological analysis of the electron density distribution within the framework of Bader's approach (QTAIM) at the M06/DZP-DKH level of theory and Hirshfeld surface analysis. Our results along with inspection of XRD (CCDC) data, accompanied by the theoretical calculations, allowed the identification of three types of Ni···I contacts. The Ni···I semicoordination of the electrophilic nickel(II) center with electron belt of I was observed in 1·2I, the metal-involving halogen bonding between the nucleophilic nickel(II)-d center and σ-hole of iodine center was recognized and confirmed theoretically in the structure of [FeNi(CN)(IPz)(HO)] (IPz = 4-N-coordinated 2-I-pyrazine), whereas the arrangement of FIB in 1·2FIB provides a boundary case between the semicoordination and the halogen Ni···I bondings. In 1·2I and 1·2FIB, noncovalent interactions were studied by variable temperature XRD detecting the expansion of noncovalent contacts with preservation of covalent bond lengths upon the temperature increase from 100 to 300 K. The nature and energies of all identified types of the Ni···I noncovalent interactions in the obtained (1·2I and 1·2FIB) and in the previously reported ([FeNi(CN)(IPz)(HO)], [NiL](I)·2I (L = o-phenylene-bis(dimethylphosphine), [NiL]I (L = 1,4,8,11-tetra-azacyclotetradecane), Ni(en)][AgI] (en = ethylenediamine), and [NiL](ClO) (L = 4-iodo-2-((2-(2-(2-pyridyl)ethylsulfanyl)ethylimino)methyl)-phenolate)) structures were studied theoretically. The estimated strengths of these Ni···I noncovalent contacts vary from 1.6 to 4.1 kcal/mol and, as expected, become weaker on heating. This work is the first emphasizing electrophilic-nucleophilic dualism of any metal center toward noncovalent interactions.

(Isocyano Group π‐Hole)⋅⋅⋅[d‐MII] Interactions of (Isocyanide)[MII] Complexes, in which Positively Charged Metal Centers (d8‐M=Pt, Pd) Act as Nucleophiles

“…Variable‐temperature XRD experiments for a crystal of complex [ 4 ]Cl(BF 4 )⋅2 MeCN were conducted to estimate the effect of temperature on the intermolecular interactions and to get a deeper insight into the dynamic features of the crystal packing. The thermally induced transformation of supramolecular bonding was especially interesting, considering our recent examples of semicoordination with a Ni II center and of a bifurcated halogen bond that involved a Pt II center . For this purpose, XRD experiments for the same single crystal of complex [ 4 ]Cl(BF 4 )⋅2 MeCN were performed at 100, 150, 200, 250, and 300 K. The analysis of the obtained structural data indicates that the heating leads only to linear and reversible changes of the intermolecular distances, whereas the covalent bond lengths and interaction angles remain almost the same.…”

“…The noncovalent πh⋅⋅⋅[M] interactions are less studied than covalent metal–(π system) bonding or noncovalent cation⋅⋅⋅π interactions and metal⋅⋅⋅(π system) semicoordination . The currently recognized types of πh donors towards nucleophilic, albeit positively charged, metal centers are restricted mostly to electrophilically activated arenes .…”

“…Besides classic covalent metal–(π system) bonding (Figure , top row; for reviews on sandwich compounds, see ref. ), several types of noncovalent interactions between π systems and metal centers are known, they include cation⋅⋅⋅π interactions, metal⋅⋅⋅(π system) semicoordination, and π‐hole⋅⋅⋅metal (abbreviated here as πh⋅⋅⋅[M]) interactions …”

Polymeric Lead(II) Iodoacetate: Pb···I and I···I Non‐Covalent Interactions in the Solid State

“…In order to investigate the nature of the Pb ··· I and I ··· I contacts in 1 , DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method) were performed for oligomeric cluster of 1 (see Supporting Information). Previously, this approach was used by us for upon studies of various non‐covalent interactions in solid state , . Results are summarized in Table ; the Poincare–Hopf relationship was satisfied, and all critical points were found.…”

Intra-/Intermolecular Bifurcated Chalcogen Bonding in Crystal Structure of Thiazole/Thiadiazole Derived Binuclear (Diaminocarbene)PdII Complexes

“…These results are accordingly discussed in the sections that follow. In the continuation of our projects focused on metal-mediated reactions of isocyanides [15,[58][59][60][61][62][63][64][65][66][67][68] and on non-covalent interactions [15,58,[69][70][71][72][73][74][75][76][77], we recently reported on the coupling between cis-[PdCl 2 (CNXyl) 2 ] (Xyl = 2,6-Me 2 C 6 H 4 ) and various thiazol-and thiadiazol-2-amines that leads to a mixture of two regioisomeric binuclear diaminocarbene complexes corresponding to kinetically (3a-d) or thermodynamically (4a-d) controlled regioisomers (Scheme 1). There is an equilibrium between these two species in CHCl 3 solutions that depends on the energy difference between two types of intramolecular CBs, viz.…”