56,509 research outputs found
TETRAHYDROFURAN AND 1,2-DIMETHOXYETHANE DERIVATIVES OF VANADIUM(II) AND VANADIUM(III)
No full textThe vanadium(II) derivatives [V-2(mu-Cl)(3)(THF)(6)](2)[M(2)Cl(6)] (M = Mn, Fe) have been prepared by reduction of VCl3(THF)(3) with manganese or iron metal powders in THF and structurally characterized for M = Mn. [V-2(mu-Cl)(3)(THF)(6)](2)[Mn2Cl6] crystallizes in the triclinic space group P (1) over bar (No. 2) with a = 10.867(6), b = 11.626(8), c = 15.486(6) Angstrom, alpha = 75.70(4), beta = 71.25(4), gamma = 80.29(5)degrees, V = 1787(2) Angstrom(3), Z = 1. The structure contains discrete [V-2(mu-Cl)(3)(THF)(6)](+) cations and [Mn2Cl6](2-) anions, the anion consisting of two MnCl4 tetrahedra sharing an edge. By treatment of VCl3(THF)(3) with DME the new vanadium(III) coordination compound VCl3(DME)(THF) has been obtained which crystallizes in the space group Pnma (No. 62) with unit cell dimensions a = 14.193(8), b = 11.99(1), c = 7.92(1) Angstrom, V = 1347(2) Angstrom(3), Z = 4. VCl3(DME)(THF) shows a fac-stereochemistry of the ligands in a distorted octahedral coordination around the vanadium atom. The same compound has been obtained by reaction of VCl3(DME)(1.5) with a stoicheiometric amount of THF in toluene
Topotactic reversible phase transition between room temperature and a low-temperature modification in the MCl3(THF)3 system
No full textBoth single crystals of VCI3(THF) 3 as well as isotypic cocrystals of the composition MC13(THF)3,
M = Ti/V ~ 1/3, undergo a topotactic reversible phase transition to a hitherto unknown lowtemperature
modification. The close relationship between this new structure and the room-temperature
phase determined by Cotton et al. is discussed from the molecular and the intermolecular
point of view: Both modifications are built up by conformationally very similar molecules which
change their arrangement during the phase transition. Lattice energy calculations confirm that
these two alternative arrangements correspond to minima of almost the same packing energy
Redox reactions of low-valent Group 4 organometallics with 9,10-phenanthrenequinone (PQ). Crystal and molecular structure of a 10-membered tetraoxometallacycle of bis(cyclopentadienyl)zirconium(IV)
No full textThe bis(arene) derivative of titanium(0), Ti(h6-toluene)2, reacts with 9,10-phenanthrenequinone (PQ) with release of tile arene ligands
and formation of a diamagnetic brown compound best formulated as a dinuclear titanium(IV) derivative containing both 9,10-phenanthrenesemiquinone
(PSQ) and 9,10-phenanthrenediolato (PDA) ligands. MCp2(CO) 2 (M = Zr, Hf) react with PQ to give MCp2PDA which
has been characterized by single crystal X-ray diffractometry for M = Zr. Crystal data: C48H 3604Zr2, M = 859.26 g mol-1, monoclinic,
space group P21/n (No. 14), a = 11.647(8), b = 17.07(1), c = 18.80(1),~, /3= 97.17(6) °, V= 3709(7)A 3, Z= 4, dcalc := 1.539gcm -3,
bt = 5.97 cm -~, F(000) = 1744. The structure consists of dinuclear [ZrCp2PDA] 2 units, the two ZrCp2 groups being bridged by the PDA
ligands to give a 10-membered tetraoxazirconacycle
Tetra-, penta-, and hexacoordination in iron (II) adducts of aliphatic bidentate amines : Crystal and molecular structure of the mononuclear complexes Fe(dienMe)Cl2 and Fe(tmeda)I2 ; Dedicated to Professor René Poilblanc in recognition of his outstanding scientific contributions. dienMe = bis(2-dimethyl-aminoethyl)methylamine; tmeda = N,N,N′,N′-tetramethylethylenediamine
No full textThe thf adduct of FeCl2, FeCl2(thf)1.5, reacts with bidentate aliphatic nitrogen bases in toluene as medium to give the corresponding adducts of FeCl2. X-ray crystallography of Fe(dienMe)Cl2 (dienMe = bis(2-dimethylaminoethyl)methylamine) has shown the compound to be mononuclear with pentacoordinated iron, thus confirming an earlier suggestion by Ciampolini and Speroni based on spectroscopic and magnetic data. Crystal data: C9H23Cl2FeN3; M = 300.06 g mol-1; monoclinic; space group P21/c (No.14); a = 8.396(3); b = 29.556(8); c = 12.108(3) Å ; g= 101.22(4)° ; V = 2947(3) Å 3; Z = 8; dcalc = 1.352 g.cm-3; lAg-Ka = 0.56087 Å ; mu = 7.02 cm-1; F(000) = 1264; T = 293 K. Bromo- and iodo complexes of iron(II) have been prepared by using cis-FeX2(CO)4 (X = Br, I) as precursors. The reaction of cis-Fe(CO)4X2 (X = Br, I) with N,N’-dimethylethylenediamine (dmeda) or N,N,N’,N’-tetramethylethylenediamine (tmeda) in heptane as medium affords adducts of general formula Fe(NN)nX2 - X = Br, I; NN = dmeda, n = 2, NN = tmeda, n = 1. The iodo derivative Fe(tmeda)I2 has been characterized by X-ray crystallography and found to be mononuclear with tetracoordinated iron(II) in a distorted tetrahedral arrangement of two iodo- and two nitrogen atoms of the bidentate amine. Crystal data: C6H16FeI2N2; M = 425.86 gmol-1; orthorhombic; space group Pbca (No. 61); a = 14.724(2); b = 15.151(4); c = 24.173(3) Å ; U = 5392(2) Å 3; Z = 16; dcalc = 2.098 g cm-3; Ag-Ka = 0.56087 Å ; mu = 29.52 cm-1; F(000) = 3168; T = 293 K
Synthesis, reactivity and structures of mono- and dihaloacetato complexes of copper(I) and copper(II)
No full textThe reactions of copper(I) oxide with the carboxylic acids CH3nXnCOOH (X/Cl, Br, n/1, 2; X/I, n/1) and dioxygen give
the corresponding haloacetates of copper(II) Cu(CH3nXnCOO)2 or Cu(CH3nXnCOO)2L, L/RCOOH, H2O. Lewis base
adducts of general formula Cu2(CH3nXnCOO)4L2 (X/Cl, n/1, L/THF; X/Cl, n/2, L/CH3CN; X/Br, n/1, L/py)
have been obtained and structurally characterized. They are dinuclear compounds showing the typical paddle-wheel dinuclear
structure, i.e., with four bridging haloacetato groups and two axial ligands. Monohaloacetato complexes of copper(I) have been
prepared by reacting Cu2O with CH2ClCOOH or by haloacetato exchange from Cu(CF3COO) in excellent (X/Cl, Br) or low (X/
I) yields. The copper(I) derivatives Cu(CH2XCOO) reversibly bind carbon monoxide both in the solid state and in toluene, the
carbonyl derivative Cu(CH2ClCOO)(CO) being quantitatively obtained by carbonylation of Cu(CH2ClCOO) in the solid state
Niobium(I) and tantalum(I) tetracarbonyl derivatives containing nitrogen ligands
No full textDiamino derivatives of niobium(l) and tantalum(l) of general formula MX(CO)4(NN), MNb, Ta; XCl, 1; NNethylendiamine
(en), N,N%dimethylethylendiamine (dmen), N,N,N%,N%-tetramethylethylendiamine (tmen), 2,2-dipyridyl (2,2%-dipy), 4,4%-
dipyridyl (4,4%-dipy), have been prepared by oxidation of the [M(CO)6] anions with either 1,1%-dimethyl-4,4%-dipyridilium
diiodide (methylviologen, mvI2) in the presence of the diamine or the diprotonated salt of the corresponding diamine,
[(NN)H2]Cl2. Alternatively, these derivatives have been obtained by amine exchange reactions on [MCl(CO)4(4,4-dipy)]n or by
chloride substitution on the dinuclear anion [Nb2(m-Cl)3(CO)8]. The MX(CO)4(NN) derivatives have been characterized by
analytical, spectroscopic and, in the case of TaI(CO)4 (tmen), also by single crystal diffractometry. Crystal data. TaI(CO)4(tmen),
monoclinic, space group P21:c (No. 14); a16.222 (5); b12.855 (3); c16.452 (6) A°
, b117.67 (2)°, M536.10 g mol1;
V3038.4 (1) A°
3; Z8; Dc2.344 g cm3; l0.7107 A°
; T203 K; m91.71 cm1; F(000)1984; R0.045; Rw0.048
Synthesis and characterization of mono and bimetallic derivatives of Groups 4 and 5 with 2,5dimethoxy1,4benzoquinone
No full textThe ligating properties of 2,5-dimethoxy-1,4-benzoquinone, C8H8O4 1 towards metallic Lewis acids and organometallics
in low oxidation states has been investigated. The title compound reacts with Group 4 tetrahalides to give adducts of
formula MCl4(C8H8O4) (M = Ti 4a; M = Zr 4b) and (TiCl4)2(C8H8O4) 5. Moreover, bis-cyclopentadienyl derivatives of
titanium() (TiCp2L2; L = CO, PMe3) and vanadium() (VCp2) react with 1 affording both 1 : 1 and 2 : 1 derivatives
of general formula MCp2(C8H8O4) (M = Ti 10; M = V 7), (MCp2)2(C8H8O4) (M = Ti 11; M = V 6). The molecular
structure of 6 has been determined by X-ray diffraction showing the presence of bimetallic units, with two [VCp2]
fragments bonded to a quinonoid oxygen atom of a bridging 2,5-dimethoxy-1,4-benzenedialcoholato. The derivatives
[(MCp2)2(C8H8O4)][BPh4]n (M = Ti, V; n = 1 12a, b; n = 2 12c, d) have been prepared by oxidation of (MCp2)2(C8H8O4)
(M = Ti 11; M = V 6) with a stoichiometric amount of [FeCp2][BPh4]. The reaction of the vanadium derivative
VCp2(C8H8O4) 7 with TiCl4 affords the heterobimetallic compound VCp2(C8H8O4)TiCl4 8. The magnetic properties
of the 1 : 1 and 2 : 1 species are reported
The first crystallographically established bis-qtpy (qtpy-=-2,2 :6 ,2 :6 ,2 -quaterpyridine) metal complex
No full textThe first example of a crystallographically established bis-adduct of tridentate 2,2':6',2:6',2"'-quaterpyridine (qtpy) of formula [Fe(qtpy)(2)][ClO4](2) has been obtained by treating an aqueous solution of iron(II) perchlorate with the ligand in the presence of triethylamine
Redox reactions with bis(h6-arene) derivatives of early transition metals
No full textThe reactivity of M(h6{arene)2 derivatives of early transition metals (M = Ti, Cr, Mo, arene = MeC6H5; M = V, Nb, arene = 1,3,5-h6{Me3C6H3) has been investigated and the syntheses of new and known compounds are described. The derivatives M(CH3COO)3, M = Ti, V, Nb, Cr; M(CF3COO)3, M = Ti, Nb, Cr; M(acac)3, M = Ti, V, Mo, acac = acetylacetonato, and M(F6acac)3, F6acac = hexafluoroacetylacetonato, M = V, Nb have been prepared by reaction of the metal bis(arene) derivatives with the appropriate Lewis acid. The crystal and molecular structure of V(F6acac)3 has been determined. Hydrogen halides or halogens react with M(h6{arene)2 with formation of metal halides, a highly reactive form of VCl3 being obtained from V(h6{1,3,5-{Me3C6H3)2 and hydrogen chloride in heptane. TiCl4 oxidizes Ti(h6{arene)2 with complete loss of the arene ligands. An electron transfer process affording ionic derivatives of formula [M(h6{MeC6H5)2][TiCl4(THF)2], M = Cr (structurally characterized), Mo, has been observed between the THF-adduct of TiCl4 and the appropriate metal-arene derivative of Group 6
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