Organophosphines in PtPCOX (X = N,Cl, S), PtPCNX (X = Cl,S, Br,I, As) and PtPCClX (X = S,I, As) derivatives: structural aspects

In this review are classified and analyzed structural parameters of almost 90 monomeric organoplatinum complexes with inner coordination spheres consisting of PtPCOX (X?=?N, Cl, S), PtPCNX (X?=?Cl, S, Br, I, As) and PtPCClX (X?=?S, I, As). These complexes crystallized in three crystal systems: orthorhombic (× 11), triclinic (× 32) and monoclinic (× 45). Distorted square planar arrangements about the Pt(II) atoms are provided by mono-, heterobi- and heterotridentate donor ligands. The chelating ligands create a wide variety of four-, five- and six-membered metallocyclic rings and the effects of both steric and electronic factors influence the L–Pt–L bite angles. There are wide variations in the trans-positions of the donor ligands. Two examples are classified as distortion isomers.     

Syntheses and characterization of Pb(trz) n X2 (X = CH3COO−, NCS−, and n = 1, 2) complexes,and crystal structure of [Pb(trz)2(MeOH)](ClO4)2·H2O

Lead(II) complexes with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (trz) have been synthesized using a direct synthetic method and characterized by IR and ²⁰⁷Pb NMR spectroscopy and CHN elemental analysis. The structure of [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O was confirmed by X-ray crystallography. Single-crystal X-ray data for [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O show the complex to be monomeric with the Pb having an unsymmetrical seven-coordinate geometry, coordinated by six nitrogen atoms of the trz ligands and one oxygen atom of MeOH. The arrangement of the ligands in the [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O complex exhibits a coordination gap around the Pb(II), occupied possibly by a stereoactive lone pair of electrons on lead(II); the coordination around the lead atoms is hemidirected.     

Synthesis,thermal and spectroscopic properties,and crystal structures of [Co(bba)2(H2O)(phen)] and [Ni(bba)2(H2O)(butOH)(phen)] (bba = 2-benzoylbenzoate,phen = 1,10-phenanthroline,butOH = butanol)

Aquabis(2-benzoylbenzoato)(1,10-phenanthroline)cobalt(II) and aquabis(2-benzoylbenzoato)(butanol)(1,10-phenanthroline)nickel(II) have been prepared and characterized by elemental analyses, IR and electronic spectroscopy, magnetic measurements, and single-crystal X-ray diffraction. [Co(bba)₂(H₂O)(phen)] (1) and [Ni(bba)₂(H₂O)(butOH)(phen)] (2) consist of neutral monomeric units and crystallize in the monoclinic (P2(1)) and triclinic (P 1) crystal systems, respectively. The cobalt(II) and nickel(II) sit on inversion centres and exhibit distorted octahedral coordination. Phen is bidentate chelating. In 1, bba is both monodentate and bidentate, whereas in 2 bba is only monodentate. bba ligands are coordinated to metal(II) with carboxylates and IR spectra of both complexes display characteristic absorptions of carboxylate anions {ν(OCO)_asym and ν(OCO)_sym} of bba. Thermal analysis shows that mass losses of 1 from 105°C to 456°C correspond to decomposition of phen and bba, while for 2 these occur at 271–529°C.     

Density functional theory study of the adsorption of NO on CunX (n = 2–8; X = Cu,K) clusters

Density functional theory calculations are performed to analyze the structure and stability of Cu and Cu-K clusters with 3 to 9 atoms. The results indicate that the stability of the clusters decreases after doping with a K atom. With the increase of cluster size, the stability of the clusters shows odd-even alternation. Cu₈ and Cu₇K clusters exhibit the highest stability. Next, different adsorption sites are considered to investigate the geometry of Cu_nNO and Cu_n−1KNO clusters. By calculating the adsorption energy and the HOMO-LUMO energy gap, it is determined that both types of reactions are exothermic processes, indicating stable adsorption of NO. Notably, the Cu_nK clusters are more active (stronger adsorption) for NO than the Cu_n clusters. The most chemically active clusters among Cu_nNO and Cu_n−1KNO clusters are Cu₈NO and Cu₇KNO clusters. Finally, electron transfer and Mayer bond order analysis of Cu₈NO and Cu₇KNO clusters reveal that the N O bond order decreases due to electron transfer when Cu/Cu-K clusters adsorb NO. In this process, the N atom is the electron donor and the Cu atom is the electron acceptor. Fundamental insights obtained in this study can be useful in the design of Cu/Cu-K catalysts.     

Synthesis and chemistry of tris(2-pyridyl)phosphine and bis(2-pyridyl)phenylphosphine complexes of mercury(II) X (X = Br,Cl) and X-ray crystal structural determination of [HgBr2(PPh(2-py)2)2]

Mercury(II) halide complexes [HgX₂(P(2-py)₃)₂] (X?=?Br (1), Cl (2)) and [HgX₂(PPh(2-py)₂)₂] (X?=?Br (3), Cl (4)) containing P(2-py)₃ and PPh(2-py)₂ ligands (P(2-py)₃ is tris(2-pyridyl)phosphine and PPh(2-py)₂ is bis(2-pyridyl)phenylphosphine) were synthesized in nearly quantitative yield by reaction of corresponding mercury(II) halide and appropriate ligands. The synthesized complexes are fully characterized by elemental analysis, melting point determination, IR, ¹H, and ³¹P-NMR spectroscopies. Furthermore, the crystal structure of [HgBr₂(PPh(2-py)₂)₂] determined by X-ray diffraction is also reported.     

Cooperative effect between pnicogen bond and hydrogen bond interactions in typical X…AsH2F…HF complexes (X = NR3, PR3 and OR2; R = CH3, H,F)

Abstract

Ab initio MP2/aug-cc-pVDZ calculations have been carried out to study the effect of F???H···F hydrogen bonds on the As···X pnicogen bond in X…AsH₂F…HF complexes (X?=?NR₃, PR₃ and OR₂; R?=?CH₃, H, F). The formation of F???H···F hydrogen bonds leads to shortening of the As···X distances and strengthening of the As···X interactions. The decrease of the pnicogen bond distance in the complexes is cost of electron-giving of X molecule that increased in the order R?=?CH₃?>?H?>?F for R substituents on X molecule. These effects are studied in the relationships of the structural characteristics, energetic, charge-transfer and electron density assets of the complexes. A satisfactory cooperative effect, with values that ranged between ?0.10 and ?3.98?kcal/mole, is found in the complexes.     

Bis(saccharinato)copper(II) complexes with 2-aminomethylpyridine and 2-aminoethylpyridine: Syntheses,crystal structures,spectral and thermal characterizations of trans-[Cu(sac)2(ampy)2] and [Cu(sac)2(aepy)(H2O)] (ampy = 2-aminomethylpyridine and aepy = 2-aminoethylpyridine)

Two bis(saccharinato)copper(II) complexes with 2-aminomethylpyridine (ampy) and 2-aminoethylpyridine (aepy) have been prepared and characterized by elemental analyses, IR and electronic spectroscopy, magnetic measurements and single-crystal X-ray diffraction. The copper(II) ion in trans-[Cu(sac)₂(ampy)₂] has ?1 site symmetry and is octahedrally coordinated by two neutral ampy and two anionic sac ligands, whereas the copper(II) ion in [Cu(sac)₂(aepy)(H₂O)] is five-coordinate with a distorted square-pyramidal coordination geometry. Both ampy and aepy behave as bidentate (N,N′) chelating ligands, while the saccharinate anion (sac) in the title complexes is N-coordinated. IR spectra of both complexes display typical absorption bands of bidentate aminopyridines and N-bonded sac ligands. Thermal decomposition behavior of the complexes is described in detail.     

The synthesis and crystal structure of two new isopolyoxoanion complexes: [M2(DMF)12(Mo6O19)2] (M = Co,Ni, DMF = dimethylformamide)

Two solid-state materials,?{M₂(DMF)₁₂[Mo₆O₁₉]₂}?(M?=?Co, Ni, DMF?=?dimethylformamide), have been designed, synthesized under mild reaction conditions and characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. The structures exhibit extended 2D networks through hydrogen bonds among polyanions and [M(DMF)₆]²⁺; hydrogen-bonding interactions are responsible for the stability of the crystal.     

Density functional study of S(N) 2 substitution reactions for CH(3) Cl + CX(1) X(2•-) (X(1) X(2) = HH, HF, HCl, HBr, HI, FF, ClCl, BrBr, and II)

A systematic investigation on the S_N2 displacement reactions of nine carbene radical anions toward the substrate CH₃Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6‐31+G (d, p)/relativistic effective core potential (RECP), 6‐311++G (d, p)/RECP, and aug‐cc‐pVTZ/RECP. The studied models are CX¹X^2?? + CH₃Cl → X²X¹CH₃C^? + Cl^?, with CX¹X^2?? = CH₂^??, CHF^??, CHCl^??, CHBr^??, CHI^??, CF₂^??, CCl₂^??, CBr₂^??, and CI₂^??. The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH₂^?? should be a strongest base among the anion‐containing species (CX¹X^2??) and so more favorable nucleophile. (b) Regardless of frontside attacking pathway or backside one, the S_N2 reaction starts at an identical precomplex whose formation with no barrier. (c) The back‐S_N2 pathway is much more preferred than the front‐S_N2 one in terms of the energy gaps [ΔE(front)?ΔE(back)], steric demand, NBO population analysis. Thus, the back‐S_N2 reaction was discussed in detail. On the one hand, based on the energy barriers (ΔE and ΔE) analysis, we have strongly affirmed that the stabilization of back attacking transition states (b‐TSs) presents increase in the order: b‐TS‐CI₂ < b‐TS‐CBr₂ < b‐TS‐CCl₂ < b‐TS‐CHI < b‐TS‐CHBr < b‐TS‐CHCl < b‐TS‐CF₂ < b‐TS‐CHF < b‐TS‐CH₂. On the other hand, depended on discussions of the correlations of ΔE with influence factors (PA, IE, bond order, and ΔE), we have explored how and to what extent they affect the reactions. Moreover, we have predicted that the less size of substitution (α‐atom) required for the gas‐phase reaction with α‐nucleophile is related to the α‐effect and estimated that the reaction with the stronger PA nucleophile, holding the lighter substituted atom, corresponds to the greater exothermicity given out from reactants to products. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012     

Synthesis,stereochemistry, and spectroscopic characterization of [Rh(η4-cod){(R)-2-(X-benzaldimine)-2-phenylethanol-κ 2 N,O}](acetate) (X = H; 2,4-dimethoxy)

Condensation of X-benzaldehyde with (R)-2-amino-2-phenylethanol gives the enantiopure Schiff bases (R)-2-(X-benzaldimine)-2-phenylethanol (X?=?H, HL1; 2,4-dimethoxy, HL2). The Schiff bases coordinate with dinuclear [Rh(η⁴-cod)(µ-O₂CCH₃)]₂ to afford the cationic complexes [Rh(η⁴-cod){(R)-2-(benzaldimine)-2-phenylethanol-κ ² N,O}](acetate), [Rh(η⁴-cod)(HL1)](ac) (1) and [Rh(η⁴-cod){(R)-2-(2,4-dimethoxy-benzaldimine)-2-phenylethanol-κ ² N,O}](acetate), [Rh(η⁴-cod)(HL2)](ac) (2), respectively. The Schiff bases and complexes are isolated as solids in good yields and characterized by elemental analysis, IR, UV-Vis, ¹H/¹³C-NMR, mass spectroscopy, and polarimetry.     

Structures,electronic and magnetic properties of the FemOn@Cx (m = 1–3, n = 1–4, x = 50, 60) clusters

The structures, electronic and magnetic properties of the Fe_mO_n@C_x (m?=?1–3, n?=?1–4, x?=?50, 60) clusters have been investigated by using PBE functional. The C₅₀, C₆₀ can significantly increase the structural stabilities of the Fe_mO_n molecules. Fe₂O₃@C₅₀ and Fe₃O₄@C₅₀ are more chemically stable than the Fe₂O₃@C₆₀ and Fe₃O₄@C₆₀ while FeO@C₆₀ is more chemically stable than the FeO@C₅₀. The spin densities of the Fe_mO_n fragments degenerate to zero. Carbon encapsulation leads to the internal charges of the Fe_mO_n fragments transfer from 4 s to 4p orbital.

     

High-temperature calorimetric measurements on RE2TeO6 (RE = Gd,Er)

Journal of Thermal Analysis and Calorimetry - The ternary compounds of Gd2TeO6 (s)&nbsp;and Er2TeO6 (s)&nbsp;were prepared by solid-state route and characterized by XRD, ICP-AES and ICP-MS...     

Synthesis and characterization of one-dimensional coordination polymers, [M(sac)2(μ–pyz)(H2O)2] n [M=ZnII,CdII, pyz = pyrazine,and sac = saccharinate]

Two new coordination polymers, [M(sac)₂(μ–pyz)(H₂O)₂] _n [M=Zn^II(1), Cd^II(2), pyz =?pyrazine, and sac =?saccharinate], have been prepared and characterized by elemental analysis, FTIR spectroscopy, thermal analysis and single crystal X-ray diffraction. Both complexes are isomorphous and crystallize in the triclinic P 1 space group. The metal(II) ions are octahedrally coordinated by two sac, two aqua and two pyz ligands. The sac ligands are N-coordinated, while the pyz ligands are bridges between the metal centers, leading to one-dimensional linear chains. Intra-chain M–M separations in 1 and 2 are 7.218 and 7.498 Å, respectively. The individual chains are linked by strong OW–H ··· O(sac) hydrogen bonds into two–dimensional layers, which are further assembled into three–dimensional supramolecular networks by aromatic π(sac) ··· π(sac) stackings interactions.     

Synthesis,crystal structures and magnetism of lanthanide(III) binuclear complexes [Ln2(μ1 ,3-CH3CO2)2(SCN−)4L2(H2O)6] (Ln = Gd(III) and Eu(III), L = 4-methylpyridine N-oxide)

Two lanthanide(III) binuclear complexes have been synthesized with acetate as bridging ligand and 4-methylpyridine N-oxide (L), SCN^? and H₂O as terminal ligands and structurally determined by X-ray crystallography. Both crystals [Gd₂(μ_1,3-CH₃CO₂)₂(SCN^?)₄(L)₂(H₂O₆) (1) and [Eu₂(μ_1,3-CH₃CO₂)₂(SCN^?)₄(L)₂(H₂O)₆] (2) belong to monoclinic with space group P2₁/n. The relevant cell parameters are as follows: a?=?9.0034(12)?Å, b?=?15.998(2)?Å, c?=?12.1277(17)?Å, β?=?100.625(2)° for complex 1; and a?=?9.0168(18)?Å, b?=?15.990(3)?Å, c?=?12.142(2)?Å, β?=?100.734(3)° for complex 2; The two lanthanide(III) ions are bridged by two acetate anions forming a binuclear unit, in which L, SCN^? and H₂O as unidentate terminal ligands take part in the coordination. The variable-temperature magnetic susceptibility of 1 was measured in the 4–300?K range; fitting for the susceptibility data reveals that there is no magnetic interaction between the bridged Gd(III) ions.     

Syntheses,structures, and properties of transition metal complexes with 2-( n -pyridyl)benzimidazole ( n = 2, 3, and 4)

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH₃COO)₄] (1), [Cu(3-PBIM)₂(CH₃COO)₂]?·?2H₂O (2), [Cu(4-PBIM)₂(CH₃COO)₂(H₂O)]?·?H₂O (3), and [Fe(4-PBIM)₂(Cl)₂(H₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.