Synthesis and structural characterization of the first metal organic thallium antimonide

The first metal organic thallium antimonide, the heterocycle [Me2TlSb(SiMe3)2]3, was synthesized by reaction of [Me2AlSb(SiMe3)2]3 with the Lewis acid-base adduct dmap-TlMe3 (dmap = 4-dimethylaminopyridine). The analogous TlBi heterocycle [Me2TlBi(SiMe3)2]3 couldn't be isolated due to its limited thermal stability in solution.     

Allopurinol complexes with first row transition metal perchlorates

Summary Complexes of allopurinol (apH) with Fe^III and several 3d metal(II) (e.g. Fe, Co, Ni and Cu) perchlorates were prepared. The solid complexes isolated included two monomeric hexacoordinated adducts of the type [Fe(apH)₃-(OClO₃) (OH₂)₂]ClO₄ and [Fe(apH)₃(OClO₃)₂(OH₂)]ClO₄, involving N(8)-bound neutral apH ligands, and polymeric Co, Ni or Cu complexes containing both neutral apH and monoanionic ap^- ligands. The latter three complexes involved both N(8)-bound terminal apH and N(1), N(8)- or N(1), N(9)-bound bridging ap^- ligands, and were of the following types: [(apH)₂Cu(ap)] _n (ClO₄) _n , tetrahedral; [(apH)(H₂O)(OClO₃)Co(ap)] _n , pentacoordinated; and [(apH)₂(H₂O)(OClO₃)Ni(ap)] _n , hexacoordinated.Presented in part at the 203rd. American Chemical Society National Meeting; see Ref. 1.     

Urate complexes of dipositive first row transition metal ions

Summary The following complexes were prepared by reacting uric acid (uaH₂) with 3d metal(II) perchlorates in non-aqueous media: trans-[Mn(uaH)₂(OH₂)₄], octahedral, and [Co-(uaH)₂(OH₂)₂] tetrahedral, both involving O(8)-bound hydrogenurate; [Cu(ua)(OH₂)₃], tetrahedral, with the urate dianion binding via a ring nitrogen; and [Ni₂(uaH)₂-(uaH₂)(ClO₄)₂(H₂O)₃] formulated as a pentacoordinated linear polymetric species, involving bidentate bridging hydrogenurate, binding through O(8) and a ring nitrogen.Presented in part at the 4th Chemical Congress of North America (Ref. 1).     

Direct solvothermal synthesis of early transition metal nitrides

Solvothermal reactions of TaCl5 with LiNH2 in benzene result in nanocrystalline Ta3N5 at 500 or 550 degrees C. The approximately 25 nm Ta3N5 particles have a band gap of 2.08-2.10 eV. The same reactions in mesitylene resulted in a higher crystallization temperature and large amounts of carbon incorporation due to solvent decomposition. Reactions of Ta(NMe2)5 with LiNH2 under the same conditions resulted in TaN. Rocksalt-type MN phases are obtained for Zr, Hf, or Nb when their chlorides (ZrCl4, HfCl4, or NbCl5) or dialkylamides (M(NEtMe)4, M = Zr, Hf) are reacted with LiNH2 under similar conditions. With the amides, there is some evidence for nitrogen-rich compositions (HfN >1), and carbon is incorporated into the products through pyrolysis of the dialkylamide groups.     

Structure and bonding in [M6X8] units of nonmetallic transition metal cluster compounds

A simple quantum mechanical method, based on the Wolfsberg-Helmholtz approximation, has been applied to some nonmetallic4d and5d transition metal cluster compounds containing M₆X₈ units. Our aim was to calculate bonding energies ofM₆ clusters as a function of electronic configuration and symmetry. Energy sequences of clusters containing elements adjacent to each other in the periodic table are discussed, in particular, niobium and molybdenum as well as tungsten and rhenium. Compared with experimentally well-characterized compounds, the computional results show good qualitative agreement. So the occurrence ofM₆ clusters withO_h or lower symmetry can be explained by electronic effects.     

过渡金属-4, 4'-联吡啶配合物的合成及其晶体结构

由过渡金属与4,4'-联吡啶反应,得到两种新型配合物[Zn(4,4'-bpy)~2(H~2O)~2](pic)~2·(4,4'-bpy)·(H~2O)(1)与[Cu(4,4'-bpy)(pic)~2](2)(4,4'bpy:4,4'-联吡啶,pic^-:苦味酸根),进行了元素分析、红外光谱、X射线衍射等表征。X射线衍射结果表明,晶体1属单斜晶系,空间群为C~c,晶胞参数为：a=2.2716(2)nm,b=1.6191(3)nm,c=1.6166(2)nm,β=131.085(7)°,V=4.481(2)nm^3,Z=4;该配合物由4,4'-联吡啶与金属配位形成多孔的二维网,二维网再由未配位的4,4'-联吡啶通过氢键作用沿a方向堆积得三维网状结构,未配位的4,4'-联吡啶、水、苦味酸根离子就被包含在这种网络之中,展示出一定的包合现象,晶体2属三斜晶系,空间群为P1,晶胞参数为：a=0.6100(2)nm,b=1.0186(3)nm,c=1.1046(2)nm,α=107.230(10)°,β=101.992(2)°,γ=97.87(7)°,V=0.6266(3)nm^3,Z=1。在该配合物中,4,4'-联吡啶分子、苦味酸根离子均与铜离子配位,形成一维链状结构。     

Synthesis, crystal structure, and properties of MnNCN, the first carbodiimide of a magnetic transition metal

Synthesis, single-crystal structure determination, and magnetic properties are reported for manganese carbodiimide, MnNCN. The presumably unstable but inert phase adopts the trigonal system (R3m) with a = 3.3583(4) A, c = 14.347(2) A, V = 140.13(3) A3, and Z = 3. Divalent manganese is octahedrally coordinated by nitrogen atoms at 2.26 A, and the NCN(2-) unit adopts the linear [N=C=N](2-) carbodiimide shape with two C=N double bonds of 1.23 A. MnNCN contains high-spin Mn(II) with five unpaired electrons and behaves like an antiferromagnet with an ordering temperature below 30 K.     

Nicotinoyl hydrazide complexes of some first row transition metal ions

Summary Nicotinoyl hydrazide, L, complexes of the MLCl₂ · n EtOH type [M = manganese(II), iron(ll), cobalt(II), nickel(II) and copper(II); n = 0 or 1], WL₂) (NO₃)₂ [M = cobalt(II) and nickel(II)] and mixed metal complexes such as HgCo₂ L₂ Cl₆ and (NiL₂)HgI₄ have been prepared and their nature and structure studied by molar conductance, magnetic susceptibility, electronic, e.s.r. and i.r. spectral measurements. Octahedral structures have been proposed for all the complexes except MnLCl₂, CoLCl₂ and HgCo₂ L₂ C1₆ for which tetrahedral geometry is suggested.     

A stable alkyl hydride of a first row transition metal

Hydrogenolysis of a Cr(III) dialkyl precursor produced a binuclear chromium complex with a bridging hydride and a bridging alkyl; this structurally characterized organometallic compound is thermally very stable and does not undergo the expected reductive elimination of alkane.     

Performance of density functionals for first row transition metal systems

This article investigates the performance of five commonly used density functionals, B3LYP, BP86, PBE0, PBE, and BLYP, for studying diatomic molecules consisting of a first row transition metal bonded to H, F, Cl, Br, N, C, O, or S. Results have been compared with experiment wherever possible. Open-shell configurations are found more often in the order PBE0>B3LYP>PBE approximately BP86>BLYP. However, on average, 58 of 63 spins are correctly predicted by any functional, with only small differences. BP86 and PBE are slightly better for obtaining geometries, with errors of only 0.020 A. Hybrid functionals tend to overestimate bond lengths by a few picometers and underestimate bond strengths by favoring open shells. Nonhybrid functionals usually overestimate bond energies. All functionals exhibit similar errors in bond energies, between 42 and 53 kJmol. Late transition metals are found to be better modeled by hybrid functionals, whereas nonhybrid functionals tend to have less of a preference. There are systematic errors in predicting certain properties that could be remedied. BLYP performs the best for ionization potentials studied here, PBE0 the worst. In other cases, errors are similar. Finally, there is a clear tendency for hybrid functionals to give larger dipole moments than nonhybrid functionals. These observations may be helpful in choosing and improving existing functionals for tasks involving transition metals, and for designing new, improved functionals.     

Toward accurate theoretical thermochemistry of first row transition metal complexes

The recently developed correlation consistent Composite Approach for transition metals (ccCA-TM) was utilized to compute the thermochemical properties for a collection of 225 inorganic molecules containing first row (3d) transition metals, ranging from the monohydrides to larger organometallics such as Sc(C(5)H(5))(3) and clusters such as (CrO(3))(3). Ostentatiously large deviations of ccCA-TM predictions stem mainly from aging and unreliable experimental data. For a subset of 70 molecules with reported experimental uncertainties less than or equal to 2.0 kcal mol(-1), regardless of the presence of moderate multireference character in some molecules, ccCA-TM achieves transition metal chemical accuracy of ±3.0 kcal mol(-1) as defined in our earlier work [J. Phys. Chem. A2007, 111, 11269-11277] by giving a mean absolute deviation of 2.90 kcal mol(-1) and a root-mean-square deviation of 3.91 kcal mol(-1). As subsets are constructed with decreasing upper limits of reported experimental uncertainties (5.0, 4.0, 3.0, 2.0, and 1.0 kcal mol(-1)), the ccCA-TM mean absolute deviations were observed to monotonically drop off from 4.35 to 2.37 kcal mol(-1). In contrast, such a trend is missing for DFT methods as exemplified by B3LYP and M06 with mean absolute deviations in the range 12.9-14.1 and 10.5-11.0 kcal mol(-1), respectively. Salient multireference character, as demonstrated by the T(1)/D(1) diagnostics and the weights (C(0)(2)) of leading electron configuration in the complete active self-consistent field wave function, was found in a significant amount of molecules, which can still be accurately described by the single reference ccCA-TM. The ccCA-TM algorithm has been demonstrated as an accurate, robust, and widely applicable model chemistry for 3d transition metal-containing species with versatile bonding features.     

Recent advancements in the anticancer potentials of first row transition metal complexes

The frequently severe effects of currently utilized platinum-based complexes have prompted researchers to develop less toxic transition metal based anticancer drugs. Transition metal complexes have recently gained considerable attention as promising anticancer agents due to their efficient drug design and fast optimisation. Some transition metal complexes displayed better anticancer activity than cis-platin. This led to the transition metal complexes for clinical application of chemotherapeutic drugs for cancer therapy. Cytotoxicity of the complexes has been evaluated on the basis of their IC₅₀ values. In this review, we have focussed on recent findings about the anticancer mechanism of action of first row transition metal complexes during the last ten years.     

Energetics of the first and second coordination spheres of transition metal ions

For complexes of transition metals (manganese, iron, cobalt, nickel) with monodentate ligands, equilibrium metal-ligand distances and ligand bond energies in the first and second coordination spheres have been calculated by the CNDO method. Some effects of ligand bond energies in different coordination spheres are analyzed. These effects significantly differ between the first and second coordination spheres. In the first sphere, the ligand bond energy is mainly determined by the nature of the central ion and the type of donor atom of the ligand, but weakly depends on the structure of the ligand. Conversely, in the second coordination sphere, the ligand bond energy weakly depends on the nature of the central ion and the type of donor atom, but considerably depends on the structure of the ligands in the first coordination sphere. In the second coordination sphere, ligand binding is determined by ligand interactions with both the central ion and the ligands of the first sphere. In the general case, when strong specific interactions between ligands are absent, the energetics of the second sphere is determined by the size of the inner-spheric ligands, which may be considered to be a specific steric effect. V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 370–374, March–April, 1995. Translated from L. Smolina     

Trinuclear first row transition metal complexes of a hexapyridyl, trialkoxy 1,3,5-triarylbenzene ligand

Trinuclear complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized using a ligand architecture based upon a 1,3,5-triarylbenzene core decorated with six pyridines and three alkoxide moieties. Characterization via X-ray diffraction, NMR, and magnetism studies is discussed.     

Valence 4p functions for the first-row transition metal atoms

For the valence 4p orbitals of the first-row transition metal atoms Sc through Zn, Gaussian-type basis functions are developed referring to excited 3d ^m 4s ¹4p ¹ electronic configurations. Molecular tests of the present work 4p sets are performed for the Cu atom, the diatomic Cu₂ molecule, and Cu₉ and Cu₁₃ clusters, and the results are compared with those from two literature sets. Received: 17 January 2000 / Accepted: 30 May 2000 / Published Online: 11 September 2000     

Some first row transition metal complexes of nicotinamide and nicotinic acid

Some complexes of the chlorides and bromides of manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) with nicotinamide and nicotinic acid have been prepared. These complexes have stoichiometryML ₂X₂ whereM is a metal ion,L is an organic ligand andX is a halide ion. Spectral and magnetic properties indicate that these compounds have octahedral polymeric structures. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis. In only one instance was a decomposition product of the formulaMLX₂ obtained. Its structure was also octahedral.

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Zusammenfassung Einige Komplexe der Chloride und Bromide von Mangan(II), Eisen(II), Cobalt(II), Nickel(II) und Kupfer(II) mit Nikotinamid und NikotinsÄure wurden hergestellt. Diese Komplexe sind von der StöchiometrieML ₂ X ₂ , wobeiM ein Metallion,L ein organischer Ligand undX ein Halogenidion ist. Die spektralen und magnetischen Eigenschaften deuten auf oktaedrische Polymerstrukturen dieser Komplexe hin. Die Zersetzung der Komplexe wurde durch Thermogravimetrie und Differentialthermoanalyse untersucht. In einem einzigen Falle wurde ein Zersetzungsprodukt der FormelMLX ₂ erhalten, dessen Struktur ebenfalls oktaedrisch war.

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Résumé Plusieurs complexes donnés par les chlorures et bromures de manganèse(II), fer(II), cobalt(II), nickel(II) et cuivre(II) avec le nicotinamide et l'acide nicotinique ont été préparés. Ces complexes répondent à la formule stchiométriqueML ₂X₂, oùM représente l'ion mé tallique,L un ligand organique etX un ion halogène. Les propriétés spectrales et magnétiques indiquent que ces composés ont une structure polymère octaédrique. La décomposition de ces complexes a été étudiée par thermogravimétrie et par analyse thermique différentielle. Dans un seul cas un produit de décomposition de formuleMLX₂ a été obtenu. Sa structure est également octaédrique.

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(II), (II), (II), (II) (II) . ML ₂ X ₂ , M — ,L — ,X — . , . . MLX ₂ , .