36 research outputs found

    The high-pressure metathesis route for the preparation of rare-earth and transition metal nitridophosphates

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    Synthesis, characterization and antitumour activity of trans-complexes Pt(II) and Pt(IV) with pyridine derivatives as ligands.

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    U ovoj doktorskoj disertaciji opisana je sinteza, karakterizacija i antitumorska aktivnost šest kompleksa trans-platine(II) i pet kompleksa trans-platine(IV) sa piridinskim derivatima kao ligandima. Sintetisani kompleksi dobijeni su reakcijom polaznih kompleksa platine, K2[PtCl4] odnosno K2[PtCl6], sa odgovarajućim ligandima u molskom odnosu 1 : 2 u vodi, uz blago zagrevanje. Za sintezu kompleksa korišćeni su komercijalno dostupni ligandi koji predstavljaju piridinske derivate sa acetil supstituentima (3- i 4-acetilpiridin) i sa dve karboksilne grupe (2,3-, 2,4-, 2,5- i 2,6-piridindikarboksilna kiselina)...In this doctoral dissertation, synthesis, characterization and antitumour activity of six trans-platinum(II) and five trans-platinum(IV) complexes with pyridine derivatives as ligands were described. The complexes were synthesized in the reaction of starting compounds of platinum K2[PtCl4] and K2[PtCl6], with the corresponding ligand in a 1 : 2 molar ratio in water, with mild heating. Commercially available ligands used for preparation of complexes could be considered as pyridine derivatives with acetyl substituted (3- and 4-acetylpyridine) and with two carboxylic groups (2,3-, 2,4-, 2,5- i 2,6-pyridinedicarboxylic acid)..

    Transition metal (Rh and Fe) complexes and main-group (Se and B) adducts with N,N?-diphosphanyl NHC ligands: a study of stereoelectronic properties

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    Attempts to evaluate experimentally the donor characteristics of the N,N′-bis(di-tert-butylphosphanyl)-imidazole-2-ylidene (PCNHCP) hybrid ligand are described. Thus, reactions of PCNHCP with [Rh(μ-Cl)(COD)]2 and [Rh(μ-Cl)(CO)2]2 led to the formation of the mononuclear and dinuclear complexes, [Rh(PCNHCP,κP,κCNHC)2]Cl (PCNHCP-RhCl) and [Rh(CO)(PCNHC,κP,κCNHC,κN)]2 (PCNHC-RhCO), respectively, the latter resulting after in situ cleavage of one (t-Bu)2P–Nimid bond of PCNHCP. With ligands acting as a P,C-chelate, a straightforward evaluation of the Tolman electronic parameter (TEP) of the CNHC donor is problematical; the viability of dangling P- and bound CNHC-donors (i.e. κCNHC) has been observed in the trinuclear Fe(II) chain complex [Fe3Cl2(μ-Cl)4(THF)2(PCNHCP,κCNHC)2] (PCNHCP-Fe), obtained by the reaction of PCNHCP with [Fe4Cl8(THF)6] and, recently, established on CrII, CoII and AuI centres. Evaluation of the π-accepting properties of the PCNHCP (and the related Dipp-PCNHC) was based on the 77Se NMR chemical shifts of the corresponding NHC–Se adducts, PCNHCP-Se (and Dipp-PCNHC-Se), which were prepared from the free PCNHCP (and Dipp-PCNHC) and Se. The π-acidity of PCNHCP is found to be higher than that of Dipp-PCNHC but lower than that of SIPr. The donor ability of the CNHC in PCNHCP was explored by its reaction with the Lewis acids tris(pentafluorophenyl)borane (B(C6F5)3) and tris(pentafluorophenyl)boroxine ([(C6F5)BO]3), which resulted in stable donor–acceptor adducts with no FLP reactivity. The steric properties of PCNHCP and Dipp-PCNHC are conformation dependent, with the percent buried volume (%Vbur) of PCNHCP in the structurally characterised conformer calculated at 67.6, the largest value currently reported for NHC ligands. Graphical abstract: Transition metal (Rh and Fe) complexes and main-group (Se and B) adducts with N,N′-diphosphanyl NHC ligands: a study of stereoelectronic propertie

    Electrolytic synthesis and structural chemistry of intermetallic phases with polar metal-metal bonding

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    N-Phosphanyl- and N,N ′-Diphosphanyl-Substituted N-Heterocyclic Carbene Chromium Complexes: Synthesis, Structures, and Catalytic Ethylene Oligomerization

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    The chromium(II) complexes [CrCl2(t‑BuNHC,P- κC)2] (1), [CrCl2(MesNHC,P-κC)2] (2), [CrCl2(DippNHC,P-κC)2] (3), and [CrCl2(P,NHC,P-κC)2] (4) containing the N-phosphanyl- or N,N′-diphosphanyl-substituted N-heterocyclic carbene (NHC) hybrid ligands t‑BuNHC,P (1-(di-tert-butylphosphino)-3- tert-butylimidazol-2-ylidene), MesNHC,P (1-(di-tert-butylphosphino)- 3-mesitylimidazol-2-ylidene), DippNHC,P (1-(di-tert-butylphosphino)- 3-(2,6-diisopropylphenyl)imidazol-2-ylidene), and P,NHC,P (1,3-bis(di-tert-butylphosphino)imidazol-2-ylidene), respectively, were prepared from CrII ([CrCl2(thf)2]) or CrIII ([CrCl3(thf)3] or [Cr(Me)Cl2(thf)3]) precursors. The solid-state structures of these four complexes show square-planar CrII centers, with two trans chloride and two monodentate CNHC donors. Alkylation of 3 and 4 with [Mg(benzyl)2(thf)2] led to the formation of the σ complexes [Cr(benzyl)3(DippNHC,P-κC,κP)] (5) and [Cr(benzyl)3(P,NHC,P-κC,κP)] (6), respectively, with fivecoordinate distorted-square-pyramidal CrIII coordination, comprising a chelating ligand through the CNHC and one P donor and three benzyl groups. These complexes were used as precatalysts in ethylene oligomerization, and it was found that the nature of the cocatalyst used and the metal oxidation state have a remarkable influence on the catalytic properties. The CrIII/MAO systems displayed superior catalytic performance (TOF values up to 16320 mol of C2H4/((mol of Cr) h) for 6) and gave mostly oligomers. Interestingly, the oligomers obtained with complex 3 were almost exclusively 1-hexene and 1-butene when the reaction was initiated at 30 °C. The overall activities and selectivities were also affected by the initial reaction temperature and the nature of the solvent. With AlEtCl2 (EADC) as cocatalyst, polyethylene was predominately formed

    Crystal structures of <i>trans</i>-di­chlorido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II), <i>trans</i>-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II) and <i>trans</i>-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II) diethyl ether disolvate

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    The title compounds, [FeCl₂(C₁₅H₂₀N₂)₄], (I), [FeBr₂(C₁₅H₂₀N₂)₄], (II), and [FeBr₂(C₁₅H₂₀N₂)₄]·2C₄H₁₀O, (IIb), respectively, all have triclinic symmetry, with (I) and (II) being isotypic. The FeII atoms in each of the structures are located on an inversion center. They have octa­hedral FeX₂N₄ (X = Cl and Br, respectively) coordination spheres with the FeII atom coordinated by two halide ions in a trans arrangement and by the tertiary N atom of four aryl­imidazole ligands [1-(2,6-diiso­propyl­phen­yl)-1H-imidazole] in the equatorial plane. In the two independent ligands, the benzene and imidazole rings are almost normal to one another, with dihedral angles of 88.19 (15) and 79.26 (14)° in (I), 87.0 (3) and 79.2 (3)° in (II), and 84.71 (11) and 80.58 (13)° in (IIb). The imidazole rings of the two independent ligand mol­ecules are inclined to one another by 70.04 (15), 69.3 (3) and 61.55 (12)° in (I), (II) and (IIb), respectively, while the benzene rings are inclined to one another by 82.83 (13), 83.0 (2) and 88.16 (12)°, respectively. The various dihedral angles involving (IIb) differ slightly from those in (I) and (II), probably due to the close proximity of the diethyl ether solvent mol­ecule. There are a number of C-H***Missing image substitution***halide hydrogen bonds in each mol­ecule involving the CH groups of the imidazole units. In the structures of compounds (I) and (II), mol­ecules are linked via pairs of C-H...halogen hydrogen bonds, forming chains along the a axis that enclose R₂²(12) ring motifs. The chains are linked by C-H...π inter­actions, forming sheets parallel to (001). In the structure of compound (IIb), mol­ecules are linked via pairs of C-H...halogen hydrogen bonds, forming chains along the b axis, and the diethyl ether solvent mol­ecules are attached to the chains via C-H...O hydrogen bonds. The chains are linked by C-H...π inter­actions, forming sheets parallel to (001). In (I) and (II), the methyl groups of an isopropyl group are disordered over two positions [occupancy ratio = 0.727 (13):0.273 (13) and 0.5:0.5, respectively]. In (IIb), one of the ethyl groups of the diethyl ether solvent mol­ecule is disordered over two positions (occupancy ratio = 0.5:0.5)

    4-Chloro­benzoyl-meso-octa­methyl­calix[2]pyrrolidino[2]pyrrole: an acyl chloride derivative of a partially reduced calix[4] pyrrole

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    In the title compound, C35H47ClN4O, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N—H⋯N hydrogen bonds and a C—H⋯N inter­action. The benzoyl ring is inclined to the adjacent pyrrole ring by 11.66 (11)°, with a centroid–centroid distance of 3.7488 (13) Å. In the crystal, molecules are linked by N—H⋯O hydrogen bonds into helical chains propagating in [010] and C—H⋯O and C—H⋯π interactions are also observed

    2,9-Dimethyl-1,10-phenanthrolin-1-ium (6-carb­oxy-4-hy­droxy­pyridine-2-carboxyl­ato-κ3 O 2,N,O 6)(4-hy­droxy­pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)zincate(II) 2.35-hydrate: a proton-transfer compound

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    In the title compound, (C14H13N2)[Zn(C7H3NO5)(C7H4NO5)]·2.35H2O, the ZnII atom is coordinated by two N atoms and four O atoms from the carboxyl­ate groups of the 4-hy­droxy­pyridine-2,6-dicarboxyl­ate and 6-carb­oxy-4-hy­droxy­pyridine-2-carboxyl­ate ligands, forming a distored octa­hedral geometry. In the anion, the two pyridine rings are inclined to one another by 87.75 (13)°. Two types of robust O—H⋯O hydrogen bond synthons, viz. R 2 2(16) and R 6 6(42), link the anions to form a two-dimensional network parallel to the bc plane. Furthermore, O—H⋯O, N—H⋯O, N—H⋯N and weak C—H⋯O hydrogen bonds connect the two dimensional networks, forming a three-dimensional structure. In the crystal, there are also C—H⋯π and π–π inter­actions [centroid–centroid distances of 3.5554 (18) and 3.7681 (18) Å], and C=O⋯π inter­actions [O⋯centroid distance = 3.117 (2) Å] present. One of the three crystal water molecules shows an occupancy of 0.35
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