Evgeniya Pavlovna Doronina

Molecular design of cage phosphine oxides (6-phospha-1,3,9,12-tetrasila-bicyclo[4.4.4]tetradecan-6-oxides) with four Si-containing acceptor fragments and one P=O donor fragment was performed using density functional theory methods (B3PW91 and ωB97X-D). Substituents at the silicon and phosphorus atoms were selected to favor the existence of the structures in the endo form containing a P=O···Si interaction. The competition of four silicon atoms for bonding to the phosphoryl oxygen atom was used to assess the coordinating ability of the phosphoryl group and to determine the nature of the P=O bond in phosphine oxides.

A single phosphine ligand system exhibits switching between κ-P, μ ₂ -P, and μ ₃ -P coordination modes in Cu( i ) complexes.

The structure of 1-chlorosilatrane was studied using gas-phase electron diffraction (GED). Compared to 1-fluorosilatrane, 1-chlorosilatrane has a shorter coordination Si←N bond in the gas phase. This result shows that the Si←N bond length in 1-halosilatranes decreases when the halogen is replaced by an atom that forms a weaker bond with Si, rather than by a more electronegative atom. This observation supports the applicability of the three-center four-electron model to describe bonding in these compounds. A significant anharmonicity effect on the structure of 1-chlorosilatrane was also detected in the GED experiment. Theoretical modeling of the photoelectron spectrum (using CCSD(T), EOM-IP-CCSD, OVGF methods, as well as the linear vibronic coupling model) allowed for band assignment in the experimental photoelectron spectrum and facilitated the study of the valence electronic structure of 1-chlorosilatrane. Both orbital and quantum topological approaches indicate the presence of a covalent component in the Si···N interaction in this molecule.

Structural data from X‐ray diffractometry (XRD) of oligosilanylsilatranes with a common coordination center SiSiO ₃ N are used to map the S _N 2 substitution pathway at silatrane Si ^IV atom using the Bürgi–Dunitz method of structural correlation (MSC). A classical hyperbola‐like reaction coordinate is featured using the nonlinear least squares method. This representation perfectly corresponds to the ideal MSC pattern imposed by the conservation of the total order of the axial bonds in silatranes. At the analytical level, it describes the inverse relationship of the internuclear distances SiSi and N → Si of the axial fragment N → SiSi and provides an experimental (XRD) support for the presence of a covalent contribution in the dative contact N → Si in oligosilanylsilatranes. Theoretical bond orders determined by various methods are analyzed from the point of view of their ability to describe the inverse relation between the axial 3c4e bonds of the oligosilanylsilatrane unit and the conservation of their overall order. The nature of N → Si bond in oligosilanylsilatranes is considered within orbital and quantum‐topological approaches.

Unprecedented Cu^I, Ag^I and Au^I clusters with pronounced metallophilic Au–X (X = Cu, Ag, Au) or Ag–Ag contacts have been assembled using 1,2-bis[bis(pyridin-2-ylmethyl)phosphino]ethane (L), an innovative P,P′(N,N′)₂-ligand. Its interaction with AuCl/KPF₆, AuI or (AuCCPh)_n yields complexes of the type [Au₂L₂]²⁺, [Au₂I₂L₂] and [Au₂(CCPh)₂L]_x (x = 2 or n), respectively. The reaction of L with AgPF₆ affords a [Ag₄L₂]⁴⁺ cluster, while the treatment with AgNO₃ leads to a nine-nuclear [Ag₉L₃(NO₃)₃]⁶⁺ cluster. The latter was transformed into a heterometallic [Au₂Ag₄L₂(NO₃)₂(H₂O)]⁴⁺ cluster by treatment with [Au(tht)Cl]. Sequential reaction of L with Au(I) halides and [Cu(MeCN)₄]PF₆ provides heterometallic [Au₂Cu₄(μ₂-Cl)₂L₂]⁴⁺ and [Au₂Cu₄L₂I₂(MeCN)₄]⁴⁺ ensembles. Most of the title clusters exhibit a charge transfer photoluminescence in the green to orange region with the quantum efficiencies up to an impressive 77%. Surprisingly, the [Au₂Cu₄L₂I₂(MeCN)₄]⁴⁺ cluster shows an abnormal (negative) thermal quenching of the luminescence, which is unprecedented for Au(I) derivatives. The practical utility of the designed clusters was demonstrated by their application as innovative vapor-responsive emission inks for advanced anticounterfeiting.

A series of octahedral Cu₄X₄ clusters supported by 2-Py(t-Bu)₂P and t-BuP(2-Py)₂ ligands exhibit bright phosphorescence as well as polymorphic and mechanochromic luminescence.

Electrochemical oxidation of 1-R-substituted silatranes 1 (R = Me, vinyl, (CH₂)₂CN, CH₂Ph, CH₂(C₁₀H₇), Ph, C₆H₄Me, p-Cl-C₆H₄, Cl)—classical representatives of pentacoordinated silicon compounds—and the formation of their short living cation radicals upon reversible or quasi-reversible one-electron withdrawal were studied by means of cyclic and square-wave voltammetry, faradaic impedance spectroscopy and real-time temperature-dependent EPR spectroelectrochemistry supported by DFT B3PW91/6-311++G(d,p) (C-PCM, acetonitrile) calculations. The main reaction responsible for the decay of 1^+• is shown to be their deprotonation, and ways of increasing the stability of these species are proposed.

The family of practically requested “common” silatrane derivatives of triethanolamine X-Si(OCH₂CH₂)₃N, 1, was enlarged with the first representatives of 3,4,6,7,10,11-tribenzo-2,8,9trioxa-5-aza-1-silatricyclo(3.3.3.0^1,5^)undecanes X-Si(O-para-R-C₆H₃)₃N, tribenzsilatranes 2 (R = H (a), Me (b), F (c)), carrying the substituent R in the side aromatic rings. These compounds were prepared via the transesterification of phenyl trimethoxysilane with the corresponding triphenol amines and studied using XRD and DFT calculations. These derivatives of 1-X-(4-R-2,2′,2′′-nitrilotriphenoxy)silane are expected to have, as their parent “common” silatranes 1, diverse biological and pharma activities. A common characteristic feature of the molecular structures of both 1 and 2 is the presence of an intramolecular dative bond N→Si whose existence is evidenced by geometric and quantum topological (AIM) criteria. In the crystals, the length of this bond (d_SiN) is noticeably longer in tribenzsilatranes than in 1. The results of DFT B3PW91/6-311++G(d,p) calculations suggest the reason for this to be the more rigid nature of the potential functions of the N→Si bond deformation in 2 compared to 1. The relative degree of “softness”/”hardness” of the potential functions can be assessed from the difference in the calculated values of d_SiN in isolated molecules 1 and 2a–c and in their crystals.

Exploiting 2-(alkylsulfonyl)pyridines as 1,3-N,S-ligands, herein we have constructed 1D CuI-based coordination polymers (CPs) bearing unprecedented (CuI)_n chains and possessing remarkable photophysical properties. At room temperature, these CPs show efficient TADF, phosphorescence or dual emission in the deep-blue to red range with outstandingly short decay times of 0.4–2.0 μs and good quantum performance. Owing to great structural diversity, the CPs demonstrate a variety of emissive mechanisms, spanning from TADF of ¹(M + X)LCT type to ³CC and ³(M + X)LCT phosphorescence. Moreover, the designed compounds emit strong X-ray radioluminescence with the quantum efficiency of up to an impressive 55% relative to all-inorganic BGO scintillators. The presented findings push the boundaries in designing TADF and triplet emitters with very short decay times.

Covalent immobilization of TEMPO at carbon and gold via an aliphatic –(CH₂)₆– linker was achieved via cathodic grafting of a diamagnetic precursor, tetramethylpiperidine, with subsequent >NH to >NO oxidation to give TEMPO-capped paramagnetic interfaces (Γ_TEMPO = 5.2 × 10⁻¹⁰ mol cm⁻²); catalytic and spin switching potential of the thus prepared systems was demonstrated.