Modeling of the structure and IR spectra of boron difluoride acetylacetonate and its halogen-substituted derivatives

The infrared spectra of the complexes of boron difluoride acetylacetonate and its halogen-substituted derivatives F₂B(aaX) (X = H, Cl, Br, I) in the crystalline state are studied. The substituent effect on the geometry and force field of molecules is revealed from DFT/B3LYP quantum chemical calculations with the 6-311G(d,p) basis set. The detailed assignment of IR absorption bands is performed based on the calculations of normal modes (NMs) and the potential energy distribution (PED). The bands most sensitive to the substituent nature belong to vibrations with prevalent involvement of ring CC and CO bonds and some low-frequency noncharacteristic NMs involving the Х atom. In support of the single crystal XRD data, intermolecular interactions have the strongest effect on the characteristic bands of the BF₂ moiety in the ranges 1280-1220 cm^–1 and 875-835 cm^–1; the sequences of IR band frequency shifts in a series of substituents corresponding to these interactions are reported.     

A study of the crystal structure of chloro-and bromo-substituted acetylacetonates of boron difluoride

The molecular and crystal structure of halogen-substituted acetylacetonates of boron difluoride 2,2-difluoro-5-chloro-4,6-dimethyl-1,3,2-dioxaborin (1) and 2,2-difluoro-5-bromo-4,6-dimethyl-1,3,2-dioxaborin (2) is determined. In both compounds, a noticeable intermolecular interaction between the fluorine and carbon atoms of the chelate ring and between the fluorine atoms and substituents exists. In order to explain the revealed patterns of molecular packing, the charge distribution in the studied chelates is calculated.     

Crystal structure of boron difluoride acetylnaphtholates

The crystal structure of luminescent isomeric boron difluoride acetylnaphtholates: 2-acetyl-1-naphthoboron difluoride (1) and 1-acetyl-2-naphthoboron difluoride (2) has been studied. Molecules of 1 make infinite stacks of coplanar molecules in crystals, and molecules of 2 are arranged in the crystalline cell in the form of isolated π-dimers. Unlike a planar molecule of 1, the methyl group in α-position of the diketonate ring drops out of the molecule plane in a molecule of 2, thus forcing the chelate ring to bend considerably along the line C(11)-B. The structure features of 1 cause a bathochromic shift of the luminescence band in comparison with 2.     

Liquid crystal polymorphism of boron difluoride β-diketonates

Boron difluoride 2-alkyl-β-diketonates possessing liquid crystal polymorphism and luminescence properties were first obtained. Influence of the ligand structure on the liquid crystal properties of the boron difluoride complexes was demonstrated.     

Photoelectron spectra and electron structure of boron difluoride ethyl acetonate,boron difluoride benzoyl acetonate,and its derivatives

The electron structure of boron fluoride acetyl acetonate F₂B(OCCH₃)₂CH, boron fluoride benzoylacetonate, and two its derivatives is investigated by ultraviolet electron spectroscopy and quantum chemistry in an approximation of the all-electron density functional theory. Sequences and preferential localization of the π levels of conjugated cycles are established, and the violation of coplanarity of the cycles in the presence of the methyl group in the ortho site of the substituent is shown. It is concluded that the values of the ionization energy and the calculated data indicate a sequential increase in the contribution of π orbitals of the benzoic cycle in the UOMO (upper occupied molecular orbital) upon substituting CH₃ groups for hydrogen atoms.     

The structure and luminescence of isomeric boron difluoride acetylnaphtholates

A comparative study of the fluorescence of solutions and crystals of isomeric boron difluoride acetylnaphtholates, 2-acetyl-1-naphtholate (1) and 1-acetyl-2-naphtholate (2), was performed. The compounds only differ in the position of the naphthyl group with respect to the chelate ring. An important role played by the stacking factor in the formation of the fluorescent properties of the complexes was revealed. The planar structure of the molecule and effective overlapping of the π systems of neighboring molecules of 1 cause a substantial bathochromic shift of its spectrum and a sharp increase in the intensity of excimeric fluorescence.     

Crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate. π stacking interactions and luminescence of boron difluoride acetyl acetonates

The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band.     

Boron difluoride acetylacetonate sulfenyl(selenyl) halides

By cleavage of disulfide and diselenide derivatives of the boron difluoride acetylacetonate the previously unknown sulfenyl(selenyl) chlorides and bromides were prepared. It was shown that these compounds could be involved into the substitution and addition reactions characteristic of sulfenyl(selenyl) halides.     

The crystal and molecular structure of bis-dimethylaminotitanium difluoride tetramer

The crystal structure of [(Me₂N)₂TiF₂₄ has been determined by single-crystal X-ray diffraction. The crystals are tetragonal, I$\text{4}$, a = b = 11.313(5), c = 12.862(4) Å, Z = 2. The titanium atoms display a distorted octahedral coordination and are linked by TiFTi and TiNMe₂Ti bridges to form a tetramer, which possesses a crystallographic inverse tetrad axis at its centre. One fluorine and one dimethylamino group do not participate in the bridging. The principal bond lenghts are TiF(bridging) 2.00(2) and 2.06(2), TiF (terminal) 1.77(2), TiN(bridging) 2.14(3) and 2.19(3), TiN(terminal) 1.99(30) Å. The structure has been refined to R = 0.077 for 231 visually estimated unique reflections.     

Crystal structure and fluorescence properties of p-nitrobenzoylanisoylmethane and its complex with boron difluoride

The crystal and molecular structures of p- and m-nitrobenzoylanisoylmethanatoboron difluoride were determined. The spectral luminescence properties of these compounds were studied and compared.     

Photodegradation of boron difluoride dibenzoylmethanate in solutions

The UV photostability of boron difluoride dibenzoylmethanate (DBMBF₂) in the aprotic solvents acetonitrile, dimethylsulfoxide, acetone, methyl cyclohexane, dioxane, and tetrahydrofuran has been studied. The DBMBF₂ half-life largely depends on the solvent and varies from 3 min in tetrahydrofuran to 9 h 40 min in acetonitrile. It has been found that the photodegradation of DBMBF₂ involves the detachment of the BF₂ molecule to yield dibenzoylmethane occurring in the ketone (absorption at 220–240 nm) and enol (absorption at 340–345 nm) forms. It has been shown that DBMBF₂ can be stabilized by sterically hindered piperidines, thereby suggesting the participation of singlet oxygen in the photodegradation of DBMBF₂.     

Synthesis and crystal structure determination of Cl-substituted iridium(III) acetylacetonate

γ-Halogen-substituted iridium(III) acetylacetonates of general formula Ir(acacX)₃,where acacX = CH₃ -CO-CX-CO- CH₃,X =Br, I, were synthesized. The compounds are characterized by melting points and chemical analysis data for C, H, Br, and I. An X-ray diffraction analysis was performed for iridium(III) acetylacetonate and its y-substituted analogs, crystal data were obtained, and crystal structures were determined. The crystals are monoclinic;the structures are molecular. Crystal data: Ir(acac)3 _- IrO₆C₁₅H₂₁,a = 13.900(2), b = 16.440(3), c = 7.494(2) ?, γ =98.63(2)‡, V= 1693.2 ?³,space group P2₁/b,Z = 4, d_calc =1.92 g/cm³,sin θ/λ_max = 0.703, F_hkl = 2841, R = 0.044. Ir(acacBr)_3- IrBr₃O₆C₁₅H₁₈,a = 12.794(2), b = 15.753(2), c = 9.990(2) ? Β = 105.76(2)‡, V= 1937.6 ?³,space group P2₁/n,Z =4, d_calc =2.49 g/cm³, sinθ/λ_max = 0.702, F_hkl = 1748, R = 0.048. Ir(acacI)3- M₃O₆C₁₅H₁₈,a = 12.855(2), b = 10.136(2), c =16.338(3)?, Β = 104.6(2)‡, V=2059.8?³,space group P2₁/n, Z =4, d_calc = 2.79g/cm³, θ_max =25‡, F_hkl = 2817, R =0.032. The Ir..Ir distances were estimated to be > 7.49 ? for Ir(acac)3 and > 8.10 ? for Ir(acacBr)3 and Ir(acacl)₃.If the estimate is limited to 10 ?, the intermolecular coordination number (ICN) in the structures is 10. Translated fromZhurnal Struktumoi Khimii, Vol. 40, No. 2, pp. 331–339, March–April, 1999     

The first mesogenic derivative of boron difluoride β-diketonate

Boron difluoride β-diketonate exhibiting liquid crystalline as well as photoluminescence properties was prepared for the first time. It is the promising material for creating supramolecular organized luminescent media.     

Nitrogen-containing analogues of boron difluoride benzoylacetonate: synthesis,structure, luminescence,and quantum chemical modeling

Nitrogen-containing analogues of boron difluoride benzoylacetonate (1), i.e., boron difluoride ketoiminates (boron difluoride 3-amino-1-phenyl-2-buten-1-onate (2) and 3-methylamino-1-phenyl-2-buten-1-onate (3)), were taken as examples to study the influence of a substituent (H, Me) at the nitrogen atom on structure and spectral-luminescent properties. The replacement of the oxygen atom with the nitrogen atom in compound 1 led to a bathochromic shift of the monomeric luminescence maximum. Quantum chemical modeling of absorption spectra for compound 2 was carried out. In contrast to compounds 1 and 3, crystals of compound 2 are characterized by the formation of J-aggregates and excimers on their basis, which leads to a bathochromic shift of the luminescence spectrum and an increase in the luminescence intensity.     

Reversible luminescence thermochromism of dibenzoyl(methanato)boron difluoride

Reversible luminescence thermochromism of dibenzoyl(methanato)boron difluoride was found. A substantial hypsochromic shift of the luminescence band maximum (60 nm) with a temperature decrease from 300 to 77 K was observed, and the luminescence color changed from green to blue. A considerable decrease (by 0.386 Å) in the unit cell parameters along the c axis was detected by X-ray diffractometry when the temperature of the crystal decreased from 293 to 123 K. Shortening of the distances between the planes of adjacent molecules (stacking factor) weakens the interaction between the dimers and enhances the monomeric and excimeric luminescence. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1032–1034, April, 2005.     

Catalytic dealkylation of phosphates with binuclear boron compounds

The Salen(tBu) ligand and its derivatives were used to prepare binuclear boron complexes. These compounds have the formula, L(BBr2)2 (L = Salpen(tBu) and Salben(tBu)). These are formed from the reaction of the corresponding L[B(OMe)2]2 with BBr3. They represent a new type of binuclear boron compound. These compounds are active towards the dealkylation of many phosphates. They are also catalytically active with a stoichiometric amount of BBr3 to trimethylphosphate.     

2-氨基对苯二甲酸双核铜配合物的合成与晶体结构

合成了一种新的铜配合物[Cu2(μ-2-atp)(phen)4].2ClO4(2-atp为2-氨基对苯二甲酸,phen为邻菲咯啉),利用红外光谱和X射线单晶衍射表征了产物的结构,利用元素分析测定了其元素组成,利用热重分析考察了其热分解行为.结果表明,标题化合物属于三斜晶系,P-1空间群,晶胞参数为:a=0.971 0(9)nm,b=1.187 8(1)nm,c=1.234 9(1)nm,α=70.104 0(1)°,β=68.699 0(1)°,γ=86.719 0(1)°,V=1.244 1(2)nm3,Z=1,Dc=1.635g/cm3,μ=1.041mm-1,F(000)=623,R1=0.058 4,wR2=0.129 3.该化合物具有双核铜结构,通过强烈的π-π堆积作用形成二维超分子结构.