G. G. Furin

Coordination chemistry of polymercuramacrocycles. Complexation of cyclic trimeric perfluoro-o-phenylenemercury with neutral oxygeneous Lewis bases

Cyclic trimeric perfluoro- o -phenylenemercury ( o -C 6 F 4 Hg) 3 ( I ) readily reacts with N , N -dimethylformamide and hexamethylphosphoramide to form complexes {[( o -C 6 F 4 Hg) 3 ](HCONMe 2 ) 2 } ( II ) and {[( o -C 6 F 4 Hg) 3 ][(Me 2 N) 3 PO] 2 } ( III ), respectively, which contain two amide ligands per one macrocycle molecule. An X-ray diffraction study of II and III has shown that they have bipyramidal structures wherein the molecules of an amide are located above and below the metallacycle plane and each of them is simultaneously bonded via the oxygen atom to all Hg atoms of the cycle. The reaction of I with dimethylsulfoxide affords complex {[( o -C 6 F 4 Hg) 3 ](Me 2 SO) 3 } ( VI ) containing three Lewis basic species per molecule of I . According to X-ray diffraction data, two of three dimethylsulfoxide ligands in VI are also coordinated through the oxygen atom with all mercury centres of the macrocycle, forming a bipyramidal structure, while the third sulfoxide ligand is bonded only to one Hg atom of the cycle. The complex of similar composition and structure, {[( o -C 6 F 4 Hg) 3 ](MeCOOEt) 3 } ( IV ), is produced in the interaction of I with ethyl acetate but this complex is much less stable than VI . The latter correlates with a considerably lower Lewis basicity of ethyl acetate as compared to that of dimethylsulfoxide.

Complexation of cyclic trimeric perfluoro-o-phenylenemercury with nitriles. A remarkable sensitivity of the composition and structure of the resulting complexes to the nature of a nitrile

Abstract Cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 (I) is capable of reacting with nitriles to form complexes whose composition and structure are dramatically dependent on the nature of the nitrile used. In the case of acrylonitrile, the complex, [(o-C6F4Hg)3(CH2CHCN)], containing one nitrile molecule per one molecule of I is produced. According to an X-ray structure analysis, the acrylonitrile ligand in this complex is bonded to all Hg atoms of the cycle through the nitrogen atom. The reaction of I with acetonitrile gives complex [(o-C6F4Hg)3(MeCN)2] which contains two nitrile ligand per one molecule of the macrocycle. This complex has a shape of a spinning top the equatorial girdle of which is the mercury-containing metallacycle, whilst the axis direction is fixed by the linear MeCN ligands located above and below the metallacycle plane. Finally, the isolated complex of I with benzonitrile, [(o-C6F4Hg)3(PhCN)3], contains three molecules of the coordinated nitrile per one macrocycle molecule. A remarkable structural feature of this complex is that here all the nitrile ligands are located on one side of the metallacycle plane and, in addition, differ from each other in the geometry of coordination with the Hg atoms.

Interaction of bis(trimethylsilyl)acetylene complex of titanocene with tris(pentafluorophenyl)borane. Synthesis and structure of a new type of zwitterionic metallocene (η5-C5H5){η5-[C5H4B(C6F5)3]}Ti

Abstract In the interaction of the bis(trimethylsilyl)acetylene complex of titanocene Cp 2 Ti(Me 3 SiC 2 SiMe 3 ) with an equimolar amount of B(C 6 F 5 ) 3 in toluene at 20°C, electrophilic substitution of a hydrogen atom in one of the η 5 -C 5 H 5 rings by a B(C 6 F 5 ) 3 group takes place and the paramagnetic zwitterionic titanium complex (η 5 -C 5 H 5 ){η 5 -[C 5 H 4 B(C 6 F 5 ) 3 ]}Ti ( I ) is produced. The formation of I is accompanied by liberation of molecular hydrogen. Bis(trimethylsilyl)acetylene and 1,2-bis(trimethylsilyl)ethane were found in organic products of the reaction. An X-ray diffraction study of complex I revealed the coordination of the ortho -fluorine atoms of two C 6 F 5 groups with the positively charged titanium centre. In contrast to other known titanium, zirconium and hafnium zwitterionic metallocenes, complex I contains a metal in the +3 oxidation state and does not contain any σ-bonded organic radicals at the metal atom.

Crown compounds for anions. Spectroscopic and theoretical studies of complexation of borohydride anions with cyclic trimeric perfluoro-o-phenylenemercury

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 (1) is capable of binding borohydride anions in THF and 1,2-dichloroethane solutions to form complexes {[(o-C6F4Hg)3](BH4)2}2− (2) and {[(o-C6F4Hg)3]2(BH4)}− (3). According to the IR data, complex 2 contains both terminal and coordinated B–H bonds while all four B–H bonds of the BH4− ion are coordinated with the mercury atoms in complex 3. The use of NMR spectroscopy provided the identification of one more complex of 1 with BH4−, which can be formulated as {[(o-C6F4Hg)3](BH4)}− (4). The stability constants of complexes 2 and 3 have been determined by IR spectroscopy. Quantum-chemical calculations of 2–4 by the AM1 method suggest that the complexes have the unusual bipyramidal, sandwich and half-sandwich structures, respectively. In contrast to 1, the interaction of (C6F5)2Hg with BH4− anions in THF gives a single complex {[(C6F5)2Hg](BH4)}− (5) independently of the reagent ratio. This complex is much less stable than 2 and 3.

Coordination chemistry of macrocyclic multidentate Lewis acids. Synthesis and structures of complexes of cyclic trimeric perfluoro-o-phenylenemercury with N,N-dimethylacetamide and n-butyronitrile

Cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 readily reacts with N,N-dimethylacetamide and n-butyronitrile to form the complexes {[(o-C6F4Hg)3](MeCONMe2)2} and {[(o-C6F4Hg)3](PrnCN)}, respectively. According to X-ray diffraction data, the amide ligands are located above and below the plane of the macrocycle, each being coordinated to all Hg atoms of the macrocycle through the O atom. The nitrile ligand is bound to the macrocycle through the N atom, all Hg atoms being also involved in this bonding.

Use of tris (pentafluorophenyl) bismuth as an arylating reagent

It has been shown that tris(pentafluorophenyl)bismuth arylates polyfluorinated electrophilic compounds in the presence of cesium fluoride.

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.

Electronic structure and OKα spectra of carbonyl-containing pentafluorobenzene derivatives

The OKα spectra have been obtained for several pentafluorobenzene derivatives, using acetone as a reference molecule. The MNDO calculations have been performed for all the compounds under study, and simulated spectra have been plotted. The π-interaction between the carbonyl group and the pentafluorophenyl ring has been shown to occur mostly in the system of inner molecular orbitals.

Reaction of secondary amines with 2-(imidazol-1-yl)-perfluoro-5,5-dimethyl-4-ethylidene-2-thiazoline

Reactions of 2-(imidazol-1-yl)-perfluoro-5,5-dimethyl-4-ethylidene-2-thiazoline with a series of secondary amines in THF resulted in the replacement of the imidazole moiety by the amine moiety.

REACTION OF PERFLUORO-2-METHYLPENT-2-ENE WITH AZOLES

Perfluoro-2-methylpent-2-ene reacts with pyrazole, imidazole, 1,2,4-triazole, and benzotriazole to give products of the replacement of the vinylic fluorine atom. In the case of imidazole, the product of allylic fluorine substitution, 1,3-bisimidazolylperfluoro-2-methylpent-2-ene, is also formed. The structures of the products were confirmed by spectral data.