Coordination chemistry of mercury-containing anticrowns. Synthesis and structures of the complexes of cyclic trimeric perfluoro-o-phenylenemercury with ethanol, THF and bis-2,2′-tetrahydrofuryl peroxide

Cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ (1) is capable of reacting with ethanol to form a 1:1 complex, {[(o-C₆F₄Hg)₃](EtOH)} (2), having a pyramidal structure. The ethanol molecule in 2 is coordinated through the oxygen atom to all Hg atoms of the macrocycle. The interaction of 1 with THF followed by drying of the product obtained in vacuum also gives the corresponding pyramidal 1:1 complex {[(o-C₆F₄Hg)₃](THF)} (3). However, when a THF solution of 1 is slowly concentrated to a small volume and the resulting crystals are not dried, three cocrystallized adducts, viz., {[(o-C₆F₄Hg)₃](THF)₂} (4), {[(o-C₆F₄Hg)₃](THF)₃} (5) and {[(o-C₆F₄Hg)₃](THF)₄} (6), containing two, three and even four THF molecules, respectively, are produced. Complex 4 has a bipyramidal structure. Complexes 5 and 6 are also characterized by the presence of a bipyramidal fragment formed by two coordinated THF species. The topological analysis of the DFT-calculated function of the electron density distribution in the crystals of 2 and 3 revealed the critical points (3, −1) on each of the three Hg···O lines, which is in accord with the X-ray diffraction data indicating on the presence of the triply coordinated Lewis base molecule in both adducts. If a THF solution of 1 is held for a month at 20 °C on air under stirring, a sandwich complex of 1 with previously unknown bis-2,2′-tetrahydrofuryl peroxide (THFPO) is formed. The THFPO ligand in this sandwich, {[(o-C₆F₄Hg)₃]₂(THFPO)} (7), provides all its four oxygen atoms for the bonding to the molecules of 1. Two of these oxygen atoms, belonging to the tetrahydrofuryl moieties, are cooperatively bound each by three Hg atoms of the neighbouring macrocyclic unit whereas two others, belonging to the peroxide group, coordinate to a single Hg atom of the adjacent macrocycle.     

Coordination chemistry of anticrowns: Complexation of cyclic trimeric perfluoro-o-phenylenemercury with nitro compounds

Cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ (1) is capable of reacting with nitromethane to give complex {[(o-C₆F₄Hg)₃](CH₃NO₂)} (2) containing one molecule of the nitro compound per one macrocycle molecule. In this complex, the nitromethane ligand is bound to 1 by its both oxygen atoms, one of which is simultaneously coordinated to all three Hg centres of the macrocycle while the other interacts with a single Hg centre. The complex of similar composition, {[(o-C₆F₄Hg)₃](C₆H₅NO₂)} (3), is produced in the interaction of 1 with nitrobenzene. In this complex too, the both oxygen atoms of the nitro group are involved in the bonding to the macrocycle. A distinctive feature of 3 is that here one oxygen atom of the coordinated nitro derivative is bound by only two Hg centres of 1 whereas the other interacts again with a single Hg site. The reaction of 1 with 5-nitroacenaphthene affords a 1:1 complex, {[(o-C₆F₄Hg)₃](C₁₂H₉NO₂)} (4), having a polydecker sandwich structure in the crystal. Unlike in 3, the aromatic rings of the nitroarene units in 4 are disposed virtually in parallel to the macrocycles. The nitro compound in 4 behaves again as a bidentate ligand, forming three Hg-O bonds with one of the adjacent macrocycles and a single Hg-O bond with another molecule of 1. The complex is characterized also by shortened Hg-C contacts between the Hg centres of 1 and the carbon atoms of the nitroarene moiety as well as shortened C-C contacts between the carbon atoms of the nitroarene and the macrocycle. In the interaction of 1 with 1-nitropyrene, complexes of two compositions, viz. {[(o-C₆F₄Hg)₃](C₁₆H₉NO₂)} (5) and {[(o-C₆F₄Hg)₃](C₁₆H₉NO₂)₃} (6) are formed. An X-ray diffraction study of 6 has shown that in this adduct two of three coordinated molecules of the nitro compound are located on one side of the metallacycle plane while the third nitroarene molecule is disposed on its other side. The aromatic rings of all three nitropyrene ligands in 6 are practically parallel to the mean plane of the macrocycle. In contrast to 2-4, each molecule of the nitroarene in 6 is bonded to 1 by a single oxygen atom which is coordinated only to one Hg centre. In the case of one of the nitropyrene ligands that forms much longer Hg-O bond with 1 than two others, an additional contribution to the bonding is made by shortened Hg-C contacts between the macrocycle and the carbon atoms of the aromatic pyrene core and also by shortened C-C contacts between the carbon atoms of the coordinated nitroarene and 1. The synthesized adducts are the first examples of complexes of an anticrown with nitro compounds.     

Crown compounds for anions. Sandwich complexes of cyclic trimeric perfluoro-o-phenylenemercury with hexacyanoferrate(III) and nitroprusside anions

Cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ (1) is able to bind hexacyanoferrate(III) and nitroprusside anions to form complexes {[(o-C₆F₄Hg)₃]₂[Fe(CN)₆]}³⁻ and {[(o-C₆F₄Hg)₃]₂[Fe(CN)₅NO]}²⁻, respectively, which contain one anionic species per two macrocycles. According to X-ray diffraction data, the complexes have unusual sandwich structures wherein the anionic guest is located between the planes of two molecules of 1 and is coordinated to each of these through two types of Fe-C-N-Hg bridges. One type is the simultaneous coordination of a cyanide ligand to all three Hg centres of the cycle. The other type is the coordination of a cyanide group to a single Hg atom of the macrocycle. In both types, the bonding of the anionic guest with the macrocyclic host is accomplished with the participation of π-electrons of the cyanide ligands. The synthesized compounds are the first examples of host-guest complexes of a macrocyclic multidentate Lewis acid with anionic metal complexes.     

Coordination chemistry of anticrowns. Complexation of cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 with compounds containing an active methylene group

The reactions of three-mercury anticrown (o-C₆F₄Hg)₃ (1) with acetoacetic ester (AE), malonic ester (ME), and malonodinitrile (MN) afford 1: 1 complexes {[(o-C₆F₄Hg)₃](AE)} (3), {[(o-C₆F₄Hg)₃](ME)} (4), and {[(o-C₆F₄Hg)₃](MN)} (5). The structures of complexes 3–5 were determined by X-ray diffraction analysis. Complex 3 has a discrete structure in the solid state, whereas complexes 4 and 5 form in the crystal extended stacks representing polydecker sandwiches with alternating molecules of 1 and ME or MN. According to the X-ray diffraction and IR spectral data, the molecule of AE in complex 3 is in the keto form.     

Crown compounds for anions. Sandwich complex of cyclic trimeric perfluoro-o-phenylenemercury with [B12H11SCN]2– anion

The reaction of cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ (1) with the polyhedral [B₁₂H₁₁SCN]^2– anion in THF at 20 °C affords the {[(o-C₆F₄Hg)₃](B₁₂H₁₁SCN)}^2– (4) and {[(o-C₆F₄Hg)₃]₂(B₁₂H₁₁SCN)}^2– (5) complexes. Complex 5 was isolated as the tetrabutylammonium salt. X-ray diffraction analysis showed that this complex has a bent-sandwich structure in which the [B₁₂H₁₁SCN]^2– anion is located between the planes of two molecules 1 and is coordinated to both these molecules through B—H—Hg bridges and S—Hg bonds. The stability constants of complexes 4 and 5 in THF (20 °C), which were determined from the IR spectroscopic data, are 16 L mol^–1 and 992 L² mol^–2, respectively.     

Crown compounds for anions. Unusual complex of trimetric perfluoro-o-phenylenemercury with the bromide anion having a polydecker sandwich structure

Here we show that cyclic trimetric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ is capable of forming complexes with [PPh₄]⁺Br⁻, [PPh₃Me]⁺I⁻ and [PPh₄]⁺Cl⁻ of the composition [(o-C₆F₄Hg)₃X]⁻ [PR₃R′]⁺ (X = Br, R = R′ = Ph; X = I, R = Ph, R′ = Me) or {[(o-C₆F₄Hg)₃X₂}²⁻[PR₃R′]⁺₂ (X = Cl, R = R′ = Ph). An X-ray study of the complex with [PPh₄]⁺Br⁻ revealed that it has the unusual structure of the polydecker bent sandwich wherein each Br⁻ anion is coordinated with six mercury atoms of two neighbouring molecules of (o-C₆F₄Hg)₃.     

Perfluorinated polymercuramacrocycles as anticrowns. Applications in catalysis

The catalytic and complexing properties of two perfluorinated polymercuramacrocycles, viz., cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ and cyclic pentameric perfluoroisopropylidenemercury [(CF₃)₂CHg]₅, are analyzed. These macrocycles contain several Lewis acidic centers in the ring and can be considered as peculiar antipodes of crown ethers and their thia and aza analogs. Both macrocycles can efficiently bind various anions to form unique complexes, in which the anionic species is simultaneously coordinated to all Lewis acidic atoms of the ring. For the (o-C₆F₄Hg)₃ macrocycle, unusual complexes with various neutral Lewis bases, such as nitriles, carbonyl compounds, aromatic hydrocarbons, etc., were also described. Data on the activity of polymercury-containing macrocycles in phase transfer catalysis of electrophilic reactions and proton transfer from an aqueous to an organic phase are surveyed and discussed.     

Coordination chemistry of anticrowns. Complexation of cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 with the cyanoborohydride anion [H3BCN]− and triethylamineborane Et3NBH3

As was shown by IR spectroscopy, the reaction of the three-mercury anticrown (o-C₆F₄Hg)₃ (1) with the [H₃BCN]ion in THF affords the complexes {[(o-C₆F₄Hg)₃][H₃BCN](5) and [(o-C₆F₄Hg)₃]₂[H₃BCN](6). Complex 6 was isolated from solution in the analytically pure state. According to X-ray diffraction data, complex 6 has a double-decker sandwich structure, in which the borohydride group of the [H₃BCN]^? anion is bound to one anticrown molecule by three B-H-Hg bridges, whereas the cyanide group is cooperatively coordinated by three mercury centers of another molecule 1 through the nitrogen atom. The reaction of compound 1 with triethylamineborane Et₃NBH₃ in THF affords the 1: 1 complex ～[(o-C₆F₄Hg)₃][Et₃NBH₃]～ (7). In this adduct, the binding of the aminoborane to the mercury anticrown is also accomplished by B-H-Hg bridges. The stability constants of complexes 5 and 6 in THF were determined.     

Binding of ferrocene by cyclic trimeric perfluoro-<Emphasis Type="Italic">o</Emphasis>-phenylenemercury. Synthesis and structure of the first double-decker sandwich complex of a sandwich

The first double-decker sandwich complex of a sandwich was synthesized and fully characterized. The complex was prepared by the reaction of cyclic trimeric perfluoro-o-phenylene-mercury (o-C₆F₄Hg)₃ (1) with ferrocene in an ethereal solution at 20 °C and has the composition {[(o-C₆F₄Hg)₃]₂(Cp₂Fe)} (2). The ferrocene sandwich in 2 is located between the planes of two mercury-containing macrocycles and is coordinated to each of them through donation of the -electrons of the ⁵-Cp ligands to vacant orbitals of the mercury atoms of the adjacent molecule 1. It was concluded that all carbon atoms of the ⁵-Cp rings in complex 2 are involved in the bonding to the macrocycles. Complexation with 1 leads to considerable shifts of the (C-H) and (C-H) bands of ferrocene in the IR spectrum to high frequencies. The structure of complex 2 was determined by X-ray diffraction.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2754–2756, December, 2004.     

Photoinitiated Reactions of Haloperfluorocarbons with Gold(I) Organometallic Complexes: Perfluoroalkyl Gold(I) and Gold(III) Complexes

The study of perfluoroalkyl metal complexes is key to understand and improve metal-promoted perfluoroalkylation reactions. Herein, we report the synthesis of the first gold complexes with primary or secondary perfluoroalkyl ligands by photoinitiated reactions between Au^I organometallic complexes and iodoperfluoroalkanes. Complexes of the types LAuR_F (L=PPh₃ or N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; R_F=n-C₄F₉, n-C₆F₁₃, i-C₃F₇, c-C₆F₁₁) and [Au(R_F)(Ar)I(PPh₃)] (Ar=2,4,6-trimethylphenyl) have been isolated and characterized. Alkynes R_FC≡CR were formed by reaction of Ph₃PAuC≡CR (R=Ph, nHex) with IR_F (R_F=n-C₄F₉, i-C₃F₇). According to the evidences obtained, this transformation undergoes through a photoinitiated radical mechanism. Au^III complexes [Au(n-C₄F₉)(X)(Y)L] (X=Y=Cl, Br, I, Me; X=Me, Y=I) have been prepared or in situ generated, and their thermal or photochemical decomposition reactions have been studied.     

Crown compounds for anions. The nature of chemical bonds in the complexes of halide anions with cyclic trimeric perfluoro-o-phenylenemercury and some of its analogs

Geometries and electronic structures of the complexes of halide anions with cyclic trimerico-phenylenemercury, (o-C₆H₄Hg)₃, perfluoro-o-phenylenemercury, (o-C₆F₄Hg)₃, vinylenemercury, (C₂H₂Hg)₃, and perfluorovinylenemercury, (C₂F₂Hg)₃, were modelled by the MNDO method. Calculations were performed for [L-X]^– semisandwich complexes, [X-L-X]^2– bipyramidal complexes, and [L-X-L]^– sandwich complexes (where X=Hal,L is a mercury-containing macrocycle). Based on the results of calculations, we concluded that it was advantageous to describe the chemical bonding between halide anions and mercury-containing macrocycles in terms of generalized chemical bonds, which were successfully used for -complexes of transition metals. In the [L-X]^– semisandwich complexes, the halide anion and the metallacycle are involved in the formation of three generalized chemical bonds: one headlight-shaped -bond and two two-lobe -bonds. In the [X-L-X]^2– bipyramidal complexes, each halide anion forms three generalized chemical bonds with the macrocycle. It is possible because the macrocycleL has unoccupied molecular orbitals suitable for the formation of such bonds; these MOs consist mainly of the orbitals of mercury atoms directed toward both the upper and lower halogen atoms. In the [L-X-L]^– sandwich complexes, the halide anion cannot be bonded to each ringvia three bonds, and, hence, an unsymmetrical structure is formed, in which the rings are located at different distances from the central atom: the [L-X]^– semisandwich complex solvated by macrocycleL.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1035–1042, June, 1995.The authors are grateful to V. I. Faustov for valuable remarks.This work was supported by the Russian Foundation for Basic Research (Project No. 93-03-18342).     

A comparative study of the coordination behavior of cyclo-P5 and cyclo-As5 ligand complexes towards the trinuclear Lewis acid complex (perfluoro-ortho-phenylene)mercury

Reactions of the cyclo-E₅ sandwich complexes [Cp*Fe(η⁵-P₅)] (1) and [Cp*Fe(η⁵-As₅)] (2) with the planar Lewis acid trimeric (perfluoro-ortho-phenylene)mercury [(o-C₆F₄Hg)₃] (3) afford compounds that show distinctly different assemblies in the solid state. The phosphorus containing ligand 1 forms dimeric coordination units with two molecules of 3, with one P atom of each cyclo-P₅ ligand positioned in close proximity to the center of a molecule of 3. In contrast to the coordination behavior of 1, the arsenic analog 2 shows simultaneous interaction of three As atoms with the Hg atoms of 3. A DFT study and subsequent AIM analyses of the products suggest that electrostatic forces are prevalent over donor–acceptor interactions in these adducts, and may play a role in the differences in the observed coordination behavior. Subsequently, a series of [Cp^RFe(η⁵-P₅)] (Cp^R = C₅H_5–n tBu_n, n = 1–3, 6a–c) sandwich complexes was prepared and also reacted with [(o-C₆F₄Hg)₃]. In the solid state the obtained products 7a–c with increasing steric demand of the Cp^R ligands show no significant change in their assembly compared to the Cp* analog 4. All of the products were characterized by single crystal X-ray structure analysis, mass spectrometry and elemental analysis as well as NMR spectroscopy and IR spectrometry.     

The interaction of AgI,ZnII and PbII with a pyridinyl-derived n5-macrocycle

The interaction of Ag^I, Zn^II and Pb^II with the macrocycle L¹ containing an N₅-donor set has been investigated. The ¹H nuclear magnetic resonance spectra of the complexes showed broad peaks, suggesting a slow exchange of metal ions between complexed and uncomplexed sites. The 1?:?1 (metal?:?ligand) stoichiometry was confirmed by first atom bombardment mass spectrometry and elemental microanalysis, solvent molecules being included when suggested by the infrared spectra. The X-ray crystal structures of [AgL¹]ClO₄, [ZnL¹](ClO₄)₂ and [PbL¹(NO₃)₂] have been determined. The metal atoms in complexes are endomacrocyclic with the silver atom and zinc atom in a pentacoordinate environment comprising the ligand N₅-donor set. The lead atom prefers seven coordination derived from the full donor set of the macrocycle and two oxygens from dinitrate anions.     

The thiolate anion as a nucleophile Part III. Reactions with various fluorobenzenes

The reactions of the fluorobenzenes, C₆F₅H, o-C₆H₂F₄, m-C₆H₂F₄, p-C₆H₂F₄, 1,3,5-C₆F₃H₃, 1,2,4-C₆F₃H₃, o-C₆F₂H₄, m-C₆F₂H₄, p-C₆F₂H₄ and C₆F₅H with thiolate anion nucleophiles RS^? (primarily MeS^?), have been studied in ethylene glycol/pyridine mixtures as a solvent. Multiple replacement of fluorine atoms was observed in the more highly fluorinated compounds, but in all cases two aromatic fluorine atoms were not replaced. Difluorobenzene and fluorobenzene did not react. The product orientations have been deduced from their NMR spectra. The mass spectra of the isomeric products C₆F₂H₃(SMe), C₆F₃H₂(SMe) and C₆F₂H₂(SMe)₂ have been examined.     

Mercury(II) thiolate complexes of two flexible benzimidazole‐based ligands

The structure of catena‐poly[[{bis[4‐(trimethylammonio)benzenethiolate‐κS]mercury(II)}‐μ‐1,1′‐(ethane‐1,2‐diyl)bis(1H‐benzimidazole)‐κ²N³:N^3′] bis(hexafluoridophosphate) 0.25‐hydrate], {[Hg(C₁₆H₁₄N₄)(C₉H₁₃NS)₂](PF₆)₂·0.25H₂O}_n, contains a one‐dimensional zigzag chain. The Hg^II cation is coordinated by two S atoms of two 4‐(trimethylammonio)benzenethiolate (Tab) ligands and by two N atoms from two different 1,1′‐(ethane‐1,2‐diyl)bis(1H‐benzimidazole) ligands, forming a distorted seesaw‐shaped coordination geometry. The F atoms of the hexafluoridophosphate anion interact with the H atoms of the Tab ligand, generating a two‐dimensional network. Furthermore, this layer is connected to neighbouring layers via H...π interactions, thereby forming a three‐dimensional hydrogen‐bonded structure. In catena‐poly[[{[4‐(trimethylammonio)benzenethiolate‐κS]mercury(II)}bis[μ‐4‐(trimethylammonio)benzenethiolate‐κ²S:S]{[4‐(trimethylammonio)benzenethiolate‐κS]mercury(II)}‐μ‐1,1′‐(hexane‐1,6‐diyl)bis(1H‐benzimidazole)‐κ²N³:N^3′] tetrakis(hexafluoridophosphate)], {[Hg₂(C₂₀H₂₂N₄)(C₉H₁₃NS)₄](PF₆)₄}_n, each Hg^II cation is coordinated by two S atoms of two Tab ligands and one N atom of the 1,1′‐(hexane‐1,6‐diyl)bis(1H‐benzimidazole) (hbbm) ligand, forming a distorted T‐shaped coordination geometry, while longer secondary Hg...S bonds join two such units across a centre of inversion to give the tetravalent cation. Adjacent {[Hg(Tab)₂]₂(μ‐hbbm)}⁴⁺ cations are linked through the centrosymmetric hbbm ligands to afford a one‐dimensional chain extending along the b axis. Several F atoms interact with the H atoms of the Tab and hbbm ligands, while the S atom interacts with an aromatic H atom of a different Tab ligand, to afford a complex intra‐ and intermolecular hydrogen‐bonding arrangement in a three‐dimensional structure.     

稀土配合物[Nd(o-NO2-C6H4COO)3(DMF)2]2的合成及其晶体结构

合成了一种新的双核倒反中心的稀土钕配合物[Nd(o-NO₂-C₆H₄COO)₃(DMF)₂]₂. 通过元素分析, 核磁共振谱和红外光谱对配合物的组成和结构进行了表征, 用热重分析研究了该配合物的热稳定性, 用X射线单晶衍射法测定了其晶体的结构. 钕配合物[Nd(o- NO₂-C₆H₄COO)₃(DMF)₂]₂晶体属三斜晶系, 空间群P-1, 晶胞参数a＝1.18652(12) nm, b＝1.24784(13) nm, c＝1.29958(13) nm, α＝64.220 (1)°, β＝66.306 (1)°, γ＝71.825 (1)°, V＝1.5645 (3) nm³, D_c＝2.167 mg/m³, Z＝2, μ＝3.415 mm^－1, F(000)＝986. 配合物中每个Nd(Ш)被4个邻硝基苯甲酸根桥联, Nd(Ш)的配位数为8, 配位原子分别来自于5个邻硝基苯甲酸羧酸根的6个氧原子和2个DMF的羰基氧原子. 配合物中的氢键和π…π 堆积作用使其成为三维立体结构. 同时发现了标题配合物固体具有光致发光现象, 发光性能测试表明该配合物具有很好的荧光性质.     

Dinuclear Macrocyclic Quinoline Bridged Mercury and Silver Bis(N‐heterocyclic Carbene) Complexes: Synthesis,Structure, and Spectroscopic Studies

Quinoline bridged imidazolium precursors 5,8‐bis(N‐R‐imidazolylidenylmethylene)quinoline PF₆^– salts [H₂L](PF₆)₂ [R = Me ( 1a ), R = naphthylmethyl ( 1b )] were prepared by quaternization of N‐methylimidazole and N‐naphthylmethylimidazole with 5,8‐bis(bromomethyl)quinoline, respectively. Reaction of the imidazolium ligands 1a and 1b with Hg(OAc)₂ and Ag₂O in acetonitrile gave the macrocyclic transition metal carbene complexes [Hg₂L₂](PF₆)₄ ( 2a and 2b ) and [Ag₂L₂](PF₆)₂ ( 3a and 3b ), respectively. All the N‐heterocyclic carbene complexes were characterized in detail by NMR, ESI‐MS, and elemental analysis. Structures of complexes 2a and 3a were determined by X‐ray diffraction studies. Structural studies revealed that the coordination arrangement of the central mercury atom in complex 2a displays a tricoordinate mode and the molecular conformation results in a“closed” form with the bridging quinoline functionality in the macrocycle, whereas the silver complex 3a does not show an coordiantion between the bridging quinoline and the Ag^I ion, which results in an “open” conformation of the macrocycle. The Hg^II and Ag^I NHC complexes showed similar UV absorption and luminescence in acetonitrile solutions.     

Hexakis(1H‐imidazole‐κN3)­nickel(II) bis­[O,O′‐diiso­propyl di­thio­phos­phate(1–)]

In the title complex, [Ni(Im)₆](ⁱPr‐dtp)₂ or [Ni(C₃H₄N₂)₆](C₆H₁₄O₂PS₂)₂, the coordination around the Ni atom, located on an inversion centre, is octhahedral with all positions being occupied by tertiary N atoms of the imidazole moieties. Hydro­gen bonds link the anions and cations into a two‐dimensional network in the bc plane.     

The solid state structure of arene-mercury(II) complexes from magic-angle spinning carbon-13 NMR and the solution carbon-13 NMR of some complexes of mercury(II) with arenes having bulky aliphatic substituents

The cross-polarization magic angle spinning ¹³C NMR spectra of Hg(SbF₆)₂ - 2 Arene (Arene = C₆HMe₅, 1,2,4,5-C₆H₂Me₄, 1,2,3,4-C₆H₂Me₄, or C₆H₆) have been measured. The spectra of the complexes of C₆HMe₅ and 1,2,4,5-C₆H₂Me₄ are consistent with static η¹-bonding of the mercury to the arene at an unsubstituted carbon atom, while the spectra of the 1,2,3,4-C₆H₂Me₄ and C₆H₆ complexes show the arene to have time-averaged C_s or C₂, and C₆ symmetry respectively, at the temperature of measurement (300 K).The reduced temperature ¹³C NMR spectra of Hg(Arene)_n²⁺ (n = 1 or 2; Arene = 1,3,5-C₆H₃R₃ (R = Me, i-Pr, or t-Bu)) in SO₂ solution are also reported and affirm that in these intramolecularly mobile species the mercury bonds in an η¹-manner, with unsubstituted aryl carbon atoms being the strongly preferred point of mercury attachment. This site preference is further demonstrated by the solution ¹³C NMR spectra of Hg(Arene)_n²⁺ (Arene = 1,2,3,4-C₆H₂-Me₄, n = 1 or 2; Arene = 1,4-C₆H₄R₂, R = Me or t-Bu, n = 1). The spectra of the 1,4-C₆H₄R₂ complexes and Hg(p-C₆H₄-t-BuMe)²⁺ provide clear evidence for steric influence of the binding site.Like Hg(C₆Me₆)₂²⁺, but unlike most of the complexes of substituted benzenes which have been studied, Hg(1,3,5-C₆H₃-i-Pr₃)₂²⁺ exchanges only slowly with excess free ligand.     

Theoretical study of [Hg3(o-C6F4)3]n · {benzene} (n = 1, 2) complexes

The electronic structure and spectroscopic properties of [Hg₃(o-C₆F₄)₃]_n · {benzene} (n = 1, 2) were studied at the HF, MP2 and PBE levels. The interaction between [Hg₃(o-C₆F₄)₃] and benzene at the HF and MP2 levels was analyzed. Secondary π-interactions (Hg–benzene) were found to be the main contribution short-range stability in the [Hg₃(o-C₆F₄)₃] · {benzene} complex. At the MP2 and PBE levels equilibrium Hg–C distances of 338.4 and 361.4 pm; and interaction energies of 46.6 and 29.2 kJ/mol were found, respectively. The absorption spectra of these complexes were calculated by the single excitation time-dependent method at PBE level.