V. B. Shur

Novel acetylene complexes of titanocene and permethyltitanocene without additional ligands. Synthesis spectral characteristics and X-ray diffraction study

Abstract New acetylene complexes of titanocene and permethyltitanocene Cp 2 Ti(R 1 C 2 R 2 ) and Cp 2 *Ti(R 1 C 2 R 2 ) (R 1 R 2 SiMe 3 ; R 1 Ph, R 2 SiMe 3 ) without additional ligands have been prepared by the reaction of Cp 2 TiCl 2 and Cp 2 *TiCl 2 with equimolar amounts of Mg and the appropriate acetylene R 1 C 2 R 2 in THF. The complexes have been isolated from the reaction mixture in an analytically pure state and characterized by spectral methods. The structures of complexes Cp 2 Ti(PhC 2 SiMe 3 ), Cp 2 *Ti(PhC 2 SiMe 3 ) and Cp 2 *Ti(Me 3 SiC 2 SiMe 3 ) have been proved by an X-ray diffraction study. Some chemical properties of the synthesized complexes have been investigated.

Complex of titanocene with tolane. Isolation, spectral characteristics, reactivity

Abstract The interaction of Cp 2 TiCl 2 with equimolar amounts of Mg and tolane in THF results in the formation of a tolan complex of titanocene Cp 2 Ti(C 2 Ph 2 ). The complex has been isolated from the reaction mixture as a definite compound and identified by spectral and chemical means. From the data obtained the conclusion has been made that the complex has a structure close to that of titanacyclopropene.

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

Abstract Here we show that cyclic trimetric perfluoro- o -phenylenemercury ( o -C 6 F 4 Hg) 3 is capable of forming complexes with [PPh 4 ] + Br − , [PPh 3 Me] + I − and [PPh 4 ] + Cl − of the composition [( o -C 6 F 4 Hg) 3 X] − [PR 3 R′] + (X = Br, R = R′ = Ph; X = I, R = Ph, R′ = Me) or {[( o -C 6 F 4 Hg) 3 X 2 } 2− [PR 3 R′] + 2 (X = Cl, R = R′ = Ph). An X-ray study of the complex with [PPh 4 ] + 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 -C 6 F 4 Hg) 3 .

Synthesis and x-ray structure determination of an organometallic titanoxane [Cp2TiC(Ph)CH(Ph)]2O. Evidence for the formation of a titanocene complex with tolane

Abstract The reaction of Cp2TiCl2 with magnesium in THF in the presence of tolane at a Cp2TiCl2 : Mg : Ph2C2 ratio of 1 : 1 : 1 results in formation of a dark red-brown solution which yields cis-stilbene when treated with HCl in ethanol, the titanacyclopentadiene complex Cp2 TiC(Ph)C(Ph)C(Ph)C (Ph) when treated with tolane, and the organometallic titanoxane [Cp2TiC(Ph)CH(Ph)]2O when treated with water. It is suggested that in the solution the titanocene complex with tolane [Cp2Ti(Ph2C2)], postulated previously as an intermediate in the catalytic hydrogenation of tolane to dibenzyl under the action of Cp2Ti(CO)2 is present. The structure of [Cp2TiC(Ph)CH(Ph)]2O has been established by an X-ray analysis.

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.

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.

Crown Compounds for Anions: Sandwich and Half-Sandwich Complexes of Cyclic Trimeric Perfluoro-o-phenylenemercury with Polyhedralcloso-[B10H10]2− andcloso-[B12H12]2− Anions

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively.

13C1H NMR studies of selected transition metal alkyne complexes

Abstract 13 C 1 H NMR spectra of selected nickel alkyne complexes (Ph 3 P) 2 Ni(RC 2 R) have been recorded and the results are compared with the relevant data for other alkyne complexes of transition metals. It has been found that the complexes with two-electron alkyne ligands such as (Ph 3 P) 2 Ni(RC 2 R), (Me 3 P) 2 Ni(RC 2 R), (Ph 3 P) 2 Pt(RC 2 R) and the complexes with four-electron alkyne ligands such as Cp 2 Ti(RC 2 R), Cp 2 ★ Ti(RC 2 R) (Cp ★ = η 5 -C 5 Me 5 ), CpV(PMe 3 ) 2 (RC 2 R), W-(OCMe 3 ) 4 (RC 2 R) are characterized by the markedly different influence the electronic parameters of the substituents R have on the value of the 13 C NMR downfield shift, Δδ(CC), on going from free to complexed CC bond. The IR spectra of the two types of complexes show no specific differences in the influence of various alkyne substituents R on the relevant Δν(CC) values.

Crown compounds for anions. A spinning top-shaped complex of cyclic pentameric perfluoroisopropylidenemercury with two chloride anions

Abstract It has been found that cyclic pentameric perfluoroisopropylidenemercury, [(CF 3 ) 2 CHg] 5 , is capable of forming complexes with [PPh 4 ] + Cl − and [PPh 4 ] + Br − of the type {[(CF 3 ) 2 CHg] 5 X 2 } 2− [PPh 4 ] 2 + (X = Cl or Br). According to an X-ray diffraction study, the chloride anions in the complex of [(CF 3 ) 2 CHg] 5 with [PPh 4 ] + Cl − are located above and below the mercury-containing metallacycle, each Cl − anion being coordinated with all the five mercury atoms of [(CF 3 ) 2 CHg] 5 .

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.