Zofia Janas

Insertion of CO2 into the metal—nitrogen bond formed in the reaction with molecular nitrogen

Abstract The fixation reaction of carbon dioxide was examined in the following systems; MCl 4 MgTHFN 2 (M = Ti, V) and Cp 2 TiCl 2 MgTHFN 2 . In these systems insertion of CO 2 into the metal—nitrogen bond has been found, which results in the formation of the isocyanate compounds [(THF) 3 Cl 2 Mg 2 OM(NCO)] and Cp 2 TiNCO. In the Cp 2 TiCl 2 MgTHFN 2 CO 2 system the Cp 2 Ti(CO) 2 carbonyl was also formed.

Preparation and crystal structures of the mononuclear vanadium phenoxide complexes [VCl(OC6H3Pri2-2,6)2(C4H8O)2] and [VO(OC6H3Pri2-2,6)3]: procatalysts for ethylene polymerisation

Abstract The complexes [VCl(OC 6 H 3 Pr i 2 -2,6) 2 (thf) 2 ] 1 (thf, tetrahydrofuran) and [VO(OC 6 H 3 Pr i 2 -2,6) 3 ] 2 have been prepared and structurally characterised. Compound 1 has a distorted trigonal bipyramidal structure with apical thf ligands [d(V–O phenox ) 1.865(2), d(V–O thf ) 2.120(3) and d(V–Cl) 2.277(2) A]. It reacts with Li[SC 6 H 2 Me 3 -2,4,6] to give [V(SC 6 H 2 Me 3 -2,4,6)(OC 6 H 3 Pr i 2 -2,6) 2 (thf) 2 ]. Compound 2, which has trigonal pyramidal geometry, is disordered about a 2-fold crystallographic axis [d(V=O) 1.564(4), d(V–O av ) 1.761(1) A]. Compounds 1 and 2 are pro-catalysts for the polymerisation of C 2 H 4 .

Formation of a nitrogen—carbon bond from N2 and CO. Influence of MgCl2 on the N2 reduction process in the system TiCl4/Mg

Abstract TiCl 4 (THF) 2 is reduced by Mg in tetrahydrofuran under N 2 to TiNMg 2 Cl 2 (THF) (I), which reacts further with CO. As a result, TiCONMg 2 Cl 2 (THF) is obtained, which reacts with CH 3 I to produce (CH 3 ) 2 NCOCH 3 in 73% yield. This is indicative of the amide character of nitrogen in I. Upon reaction with I 2 , the amide nitrogen in I is oxidized to imide. The new compound, TiNMgCl(THF) (II), was found to form Ti(NCO)MgCl(THF) on reaction with CO. TiCl 4 (THF) 2 , recognized as a strong Lewis acid, detaches one Cl − from MgCl 2 (THF) 2 formed in the reaction. The [MgCl(THF) n ] + cation influences the N 2 reduction and determines the amide character of the nitrogen atom in species I.

MgCl2 - one of the factors controlling the mechanism of the reaction between grignard reagents and titanium or zirconium tetrachloride. II

Summary Treatment of a Grignard reagent of [MgR 2 (THF) 2 ] with zirconium or titanium tetrachloride gives [MgCl 2 (THF) 2 ], which when treated with [MCl 4 (THF) 2 ] (M = Ti or Zr) yields the compounds: [Mg(THF) 6 ][ZrCl 6 ] (I), [Mg(THF) 6 ][ZrCl 5 (THF)] 2 (II), [Mg(THF) 6 ][TiCl 5 (THF)] 2 ] (IV), [(THF) 4 Mg(μ-Cl) 2 TiCl 4 ] (V) and [Mg 2 (μ-Cl) 3 (THF) 6 [TiCl 5 (THF)] (VI), along with MR 4 . The zirconium compounds I and II are insoluble in THF, which results in a decrease of the ZrR 4 yield. The titanium compounds IV, V and VI are transient intermediates in the formation of TiR 4 .

Polynuclear aggregation of cobalt and manganese dichlorides. Synthesis, properties and structures of monomeric [CoCl2(tmen)], ionic [Co3(µ3-Cl)2(µ-Cl)3(tmen)3][BPh4], polymeric MnCl2·tmen and tetranuclear [Mn4-(µ-Cl)6Cl2(tmen)4](tmen = Me2NCH2CH2NMe2)

The complexes [CoCl2(tmen)]1, [Co3(µ3-Cl)2(µ-Cl)3(tmen)3][BPh4]·[CoCl2(tmen)]2, MnCl2·tmen 3 and [Mn4(µ-Cl)6Cl2(tmen)4]4(tmen = Me2NCH2CH2NMe2) have been synthesized and structurally characterized by X-ray diffraction. The crystals of 1 consist of the tetrahedral [CoCl2(tmen)] molecules. The structure of the co-crystallite 2 is composed of two independent species, ionic [Co3(µ3-Cl)2(µ-Cl)3(tmen)][BPh4] and molecular [CoCl2(tmen)]. In the first compound the trinuclear [Co3(µ3-Cl)2(µ-Cl)3(tmen)3]+ cations consist of triangulo-{Co3Cl3} units defined by three cobalt atoms with three bridging chloride atoms in the same plane. The remaining two µ3-chloride atoms are symmetrically placed above and below the molecular plane. The polymeric chain of compound 3 is formed by six-co-ordinate manganese(II) centres linked by double chloride bridges. Two nitrogen atoms from the co-ordinate tmen complete the octahedral co-ordination of the manganese. The crystals of compound 4 consist of tetranuclear molecules in which two internal six-co-ordinate and two peripheral five-co-ordinate Mn atoms are linked by double chloride bridges. The natures of the ligand and solvent as key factors promoting the particular aggregation of the cobalt and manganese dichlorides is discussed.

Interaction of tin chlorides with iron, chromium and vanadium chlorides in tetrahydrofuran. Crystal structures of [Fe2(µ-Cl)3(thf)6][SnCl5(thf)], [Sn2(µ-OH)2Cl6(thf)2]·2thf and trans-[CrCl2(thf)4][SnCl5(thf)]

The reaction of FeCl3 with SnCl2 in tetrahydrofuran (thf) yields the salt [Fe2(µ-Cl)3(thf)6][SnCl5(thf)]1. In the [Fe2(µ-Cl)3(thf)6]+ cation, two six-co-ordinate Fe2+ ions separated by an Fe ⋯ Fe distance of 3.086(2)A are bonded through three bridging Cl atoms. Compound 1 undergoes partial decomposition under reflux in thf to give [Fe4(µ3-Cl)2(µ-Cl)4Cl2(thf)6]2 and [SnCl4(thf)2]. The compound [Sn2(µ-OH)2Cl6(thf)2]·2thf 3 is formed under the influence of moisture during the crystallization of [SnCl4(thf)2]. It is a dimeric complex of SnIV in which each tin atom is surrounded octahedrally by three chlorine atom, one thf molecule and two bridging hydroxide groups. An additional two thf molecules are hydrogen-bonded to the oxygen atoms of the hydroxide groups. By contrast with FeCl3, the reactions of [SnCl4(thf)2] with [MCl3(thf)3](M = V or Cr) in thf give tin(IV) salts of the type trans-[MCl2(thf)4][SnCl5(thf)].

Interaction of titanium and tin chlorides in tetrahydrofuran, the X-ray crystal structure of [trans-TiCl2(THF)4]+[SnCl5(THF)]−

Abstract The direct reaction between [TiCl4(THF)2] and SnCl2 in tetrahydrofuran (THF) yields the green paramagnetic salt [trans-TiCl2(THF)4][SnCl5(THF)]. The same compound is also formed in the reaction between [TiCl3(THF)3] and SnCl4 in THF. Crystals of the title compound are monoclinic with a = 8.442(4), b = 21.589(9), c = 9.262(5) A, β = 107.91(5)°, Z = 2, space group P21/m. Both metal ions are in an octahedral environment. The titanium atom in the cation [TiCl2(THF)4]+ lies on the symmetry centre. The tin atom in [SnCl5(THF)]− is located on the mirror plane.

The application of 13C and 1H NMR spectroscopy to the investigation of the dinitrogen fixation process in the system (η-C5H5)2TiCl2-Mg

Abstract The N 2 reduction reaction in the system (η-C 5 H 5 ) 2 TiCl 2 -Mg in tetrahydrofuran was examined. The 13 C and 1 H NMR results as well as the chemical properties of the products formed revealed that the reaction yielded a mixture of compounds in which the titanium atom was bonded both to the μ-(η 5 : η 5 -fulvalene) ligand and to the cyclopentadienyl ligands. In this system dinitrogen undergoes reduction to N 3− , which then forms M 3 N bridges (M = Ti, Mg). The nitride nitrogen may readily be oxidized to imide nitride N −1 , which may react further, e.g. with carbon monoxide to produce isocyanates, or, with excess oxidizing agent N 2 . THF in this system undergoes polymerisation. In addition, a −OC 4 H 9 alkoxy group is formed which makes the substitution of the cyclopentadienyl group bonded to the titanium atoms possible.

SYNTHESIS AND CRYSTAL STRUCTURES OF THE HEPTAMAGNESIUM CATIONIC AND MIXED MAGNESIUM(II)/NICKEL(II) MOLECULAR 2-TETRAHYDROFURFUROXO AGGREGATES

Direct reaction of metallic magnesium with 2-tetrahydrofurfuryl alcohol (THFFOH) produces the alkoxo magnesium compound of composition Mg(THFFO)2, 1. Compound 1 reacts with FeCl2 and NiCl2 to create two different species: the ionic [Mg7(µ3,η2-THFFO)6(µ,η2-THFFO)6][FeCl4]·3CH2Cl2, 2, and the mixed [(MgII/NiII)4(µ3,η2-THFFO)4Cl4(C2H5OH)4]·0.5C2H5OH molecular complex 3, respectively. Complexes 2 and 3 have been structurally characterized. The cation of compound 2 consists of a Mg7 unit comprising a central Mg atom held within a Mg6 puckered hexagon by six µ3-O(alkoxo) groups from the THFFO ligands. Complex 3 consists of four crystallographically independent distorted octahedral metal sites, distributed unequally (Mg0.7 and Ni0.3), which together with alkoxo oxygen atoms form a cubane-like framework.

New intermediates for the synthesis of alkene polymerization catalysts: the complex [Mg4{µ3,η2-OCH2CH(CH2)3O}2{µ,η2-OCH2CH(CH2)3O}4Cl2]; crystal structure and properties

The preparation and molecular structure of the title compound, obtained from the reaction of Mg[OCH2CH(CH2)3O]2 with MgCl2, are reported; the compound exists as the centrosymmetric tetranuclear species with two different types of magnesium centres corresponding to octahedral MgO6 and trigonal-bipyramidal MgOl4Cl coordination.