Tadeusz J. Bartczak

Bond-valence parameters of lanthanides.

Ln-O and Ln-N bond-valence parameters have been computed in coordination complexes for lanthanides (Ln) at oxidation states other than +3 (Ce(IV), Sm(II), Eu(II) and Yb(II)). Moreover, Ln-Cl, Ln-S and Ln-C(pi-bonded) bond-valence parameters are presented, as calculated for coordination compounds. In general, the bond-valence parameters decrease in the order Ln-O > Ln-C > Ln-N > Ln-Cl > Ln-S. It has been found that the values of bond-valence parameters decrease with increasing lanthanide atomic number for coordination compounds. As expected, the values of lanthanide-oxygen and lanthanide-nitrogen bond-valence parameters diminish with increasing lanthanide oxidation state. Several examples are given where the total valence of the lanthanide ion is apparently incorrectly assigned, as well as cases where bond-valence method calculations confirm the doubtful oxidation state assignment.

THE SYNTHESIS, CRYSTAL, MOLECULAR AND ELECTRONIC STRUCTURES OF TRIBROMO(NITROSYL) BIS(TRIPHENYLPHOSPHINE OXIDE) RHENIUM(II) AND TRIBROMO(NITROSYL) BIS(TRIPHENYLPHOSPHINE)RHENIUM(I)

Abstract Gaseous nitric oxide reacts with a benzene solution of [ReOBr3(PPh3)2] to give [ReBr3(NO) (OPPh3)2] (1). When the reaction is carried out in the presence of an excess of free triphenyl-phosphine, the product is [ReBr3(NO)(PPh3)2] (2). The latter is also isolated in the reaction of 1 with PPh3. This paper, apart from the synthetic methods, presents spectroscopic and magneto-chemical measurements, and crystal, molecular and electronic structures for 1 and 2.

THE SYNTHESIS, CRYSTAL, MOLECULAR AND ELECTRONIC STRUCTURE OF TRICHLORO(NITROSYL)BIS(TRIPHENYL-PHOSPHINE OXIDE)RHENIUM(II)

Abstract A new rhenium nitrosyl complex has been synthesized and characterized by IR, electronic and 31P NMR spectroscopy and magnetochemical measurements. Its electronic structure has been determined (Dq = 3333, Ds = -4732 and Dt = 387cm−1). The crystal and molecular structure of [ReCl3(NO)(OPPh3)2] has been solved by the heavy atom method and refined anisotropically to R = 0.466 for 3032 unique observed reflections. The title compound crystallizes in the mono-clinic space group C2/c, with a = 13.887(2), b = 13.154(2), c = 19.629(4)A, β = 96.78(2)° and Z = 4. The Re atom is of six-coordinate distorted octahedral configuration and the linear nitrosyl ligand is trans to one of triphenylphosphine oxide molecules. The OPPh3 groups of [ReCl3(NO)(OPPh3)2] are in cis positions.

Coordination sphere geometry changes of lanthanoid(III) nitrate complexes with hexamethylenetetramine

The 1 : 2 adducts of lanthanoid nitrate complexes with hexamethylenetetramine (hmta) have been synthesized and characterized by X-ray crystallography, IR spectroscopy, and bond valence calculations. The effect of lanthanoid contraction is observed. The lanthanoids create three isostructural groups: La–Nd (group I), Sm–Gd (group II), and Dy–Lu (group III). As an example, one structure for each group is presented in detail. There is a change in the composition of the lanthanoid coordination sphere, geometry, and coordination number with changing size of the lanthanoid. As the ionic radii decrease, the number of water molecules increases, whereas the nitrate ions move outside the inner coordination shell forming three isostructural groups. The hmta molecules are not coordinated to the central atom. Group I is formed by 10-coordinate complexes with the nitrate ions and water molecules in the inner and outer coordination sphere ([Ln(NO3)2(H2O)6]+ · · 2hmta · 2H2O). Group II includes the adducts of general formula ([Ln(NO3)(H2O)7]2+ · 2 · 2hmta · 3H2O) with nine-coordinate lanthanoid. Group III consists of eight-coordinate lanthanoid with general formula [Ln(H2O)8]3+ · 3 · 2hmta · 2H2O].

The Molecular and Electronic Structure of [ReOX3(AsPh3)(OAsPh3)] Complexes (X = Cl, Br)

New rhenium oxo-complexes [ReOX3(OAsPh3)(AsPh3)] (X = Cl and Br) have been synthesised and characterised by X-ray diffraction, IR, electronic and magnetochemical measurements. They were obtained in high yield in reactions between [ReOX3(AsPh3)2] and acetonitrile in air.

SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF DIAQUADI(ACETATO-O)-BIS(2,4′-BIPYRIDYL) MANGANESE(II)

Abstract The title complex [Mn(H2O)2(ac-O)2(2,4′-bipy)2] (1) (ac = CH3COO−, 2,4′-bipy = 2,4′-bipyridyl) has been synthesized and characterized by elemental and thermal analysis, IR, magnetic and conductivity studies. The structure of [Mn(H2O)2(ac-O)2(2,4′-bipy)2] has been determined by single crystal X-ray methods; the complex crystallizes in the monoclinic system, space group P21/c with Z = 2, a = 8.035(1), b = 5.660(1), c = 26.130(5) A, β = 97.05(1)°, V = 1179.36 A3. The structure was solved by the Patterson method and refined by full-matrix least-squares techniques using F 2 values to conventional R = 0.050 for 2322 independent reflections with F 0 > 4[sgrave](F 0). The central Mn atom lies on a centre of symmetry and is six-coordinated to two CH3COO− groups, two water molecules and two bipyridyl groups.

Synthesis, spectroscopic characterization, crystal and molecular structure of fac-[ReO3Br(phen)]

A new rhenium oxo-complex fac-[ReO3Br(phen)] has been obtained in high yield from the direct reaction of ammonium perrhenate with 1,10-phenanthroline in hydrobromic acid and characterized by X-ray diffraction and IR and UV-Vis spectra.

The Synthesis, Crystal, Molecular and Electronic Structure of [ReCl2(NO)(py)3]

In line with our investigations of rhenium nitrosyl complexes, we have studied the reaction of [ReCl3(NO)(OPPh3)(PPh3)] with pyridine. The [ReCl2(NO)(py)3] complex obtained in this reaction has been characterised by IR, electronic spectra and magnetochemical measurements; ligand field parameters and the electronic structure have been determined. The crystal and molecular structure of [ReCl2(NO)(py)3] has been solved by the heavy atom method. Crystals of [ReCl2(NO)(py)3] contain distorted octahedral molecules with the pyridine ligands in the mer-arrangement. The nitrosyl group is coordinated linearly to the rhenium atom as NO+.

Synthesis, spectroscopic investigation and molecular structures of [ReBr2(N2COPh)(C3N2H4)(PPh3)2] and [ReBr2(N2COPh)(bpy)(PPh3)]

[ReBr2(η2-N2COPh-N′,O)(PPh3)2] reacts with bipyridine (bpy) and pyrazole to give [ReBr2(N2COPh)(bpy)(PPh3)] and [ReBr2(N2COPh)(C3N2H4)(PPh3)2], respectively. Both complexes have been characterized by IR, electronic and1H NMR spectroscopy, magnetic measurements and X-ray structure determination.