Inorganic Chemistry Communications (v.8, #2)

Contents list (iii-ix).

PhC CH and [(PMe2Ph)2PtB8H12] (1) give carbons-apart [7,7-(PMe2Ph)2-isonido-7,6,8-PtC2B6H7-6-Ph] (2) in a ‘converse’ metallacarbaborane synthesis. The B(3)–B(4) diagonal distance 2.541(8) Å in the stretched quadrilateral isonido open face of 2 is one of the longest so far observed in a metallanonaborane-type compound, and results from orbital control of the {PtC2B6} cluster bonding system by the {Pt(PMe2Ph)2} centre.Reaction between PhCCH and [4,4-(PMe2Ph)2-arachno-4-PtB8H12] (1) gives carbons-apart [7,7-(PMe2Ph)2-isonido-7,6,8-PtC2B6H7-6-Ph] (2), in a ‘converse’ synthesis of a metallacarbaborane, viz. in a synthesis by addition of carbon centres into a pre-formed metallaborane, rather than by metal-centre addition to a pre-formed carbaborane. The long B(3)–B(4) diagonal distance of 2.541(8) Å in the quadrilateral open face is one of the longest so far observed in a metallanonaborane-type compound, and results principally from a restricted orbital contribution of the {Pt(PMe2Ph)2} centre to the {PtC2B6} cluster bonding system.
Keywords: Borane cluster; X-ray structure; NMR spectroscopy; Metallaborane; Metallacarbaborane; Platinum-borane cluster compound; Platinadicarbaborane; Acetylene incorporation into a metallaborane cluster;

[(PPh3)RuB9H9{RuCl2(PPh3)2}2] has an isocloso 10-vertex {RuB9} core geometry that is partially encapsulated by exo-polyhedral {RuCl2(PPh3)2} units. The structure engenders focus on the several new compound classes emerging in polyhedral boron-containing cluster chemistry.[RuCl2(Ph3)2] with [arachno-B9H14] gives [(PPh3)RuB9H9{RuCl2(PPh3)2}2], which has an isocloso 10-vertex {RuB9} core geometry that is partially encapsulated by exo-polyhedral {RuCl2(PPh3)2} units that cap {RuB2} triangular faces with one {RuClRu} and two {RuHB} bridges each. The structure engenders focus on the several new compound classes emerging in polyhedral boron-containing cluster chemistry.
Keywords: Metallaboranes; Encapsulated clusters; Cluster categories; Ruthenium-borane cluster; Transition-element hydrides; NMR spectroscopy; X-ray diffraction;

Syntheses and structures of 1D and 2D coordination polymers derived from pyridine-2,4,6-tricarboxylic acid by Hong-Ling Gao; Bin Ding; Long Yi; Peng Cheng; Dai-Zheng Liao; Shi-Ping Yan; Zong-Hui Jiang (151-154).
Using the pyridine-2,4,6-tricarboxylic acid ligand (ptcH3), two 1D coordination polymers {[Fe(H2O)6][Fe(ptc)(H2O)2]2  · 2H2O} n (1), {[Co(H2O)6][Co(ptc)(H2O)2]2  · 2H2O} n (2) and a 2D polymer {[Cu3(ptc)2(H2O)8] · 4H2O} n (3) were obtained with two kinds of coordinated motifs of the ligand, which are the important factors to induce the title coordination polymers vary from 1D to 2D.The reactions of pyridine-2,4,6-tricarboxylic acid (ptcH3) and FeSO4  · 7H2O, CoCl2  · 6H2O or Cu(ClO4)2  · 6H2O gave rise to three novel coordination polymers {[M(H2O)6][M(ptc)(H2O)2]2  · 2H2O} n (M = Fe(II) (1), Co(II) (2)) and {[Cu3(ptc)2(H2O)8] · 4H2O} n (3). 1 and 2 are one-dimensional (1D) polymers while 3 exhibits two-dimensional (2D) coordination network, which are due to the different bonding modes of ptcH3 with metal(II) ions in 13.
Keywords: Pyridine-2,4,6-tricarboxylic acid; Crystal structures; Coordination polymers;

Isolation and authentication of a sodium bispyrazolylaluminate by Sara Cortes-Llamas; Miguel-Ángel Velázquez-Carmona; Miguel-Ángel Muñoz-Hernández (155-158).
Reaction of [Na(Me2pz)(thf)]4 (2) with [(Me2pz)AlMe2]2 in THF generates sodium bispyrazolylaluminate [Na{Al(Me2pz)2Me2}] (1), the first example of a structurally characterized aluminum analog of a polypyrazolylborate.Reaction of [Na(Me2pz)(thf)]4 (2) with [(Me2pz)AlMe2]2 in THF generates sodium bispyrazolylaluminate [Na{Al(Me2pz)2Me2}] (1), the first example of a structurally characterized aluminum analog of a polypyrazolylborate. The X-ray structure of complex 1 shows in the solid state unusual Na–CH3–Al bridges and pyrazolyl η5-coordination to sodium.
Keywords: Main group element chemistry; Pyrazolates; Aluminates; Polydentate ligands;

Substitution of the dimethylsilyl group in Si8O20[Si(CH3)2H]8 for another silyl group by Isao Hasegawa; Tatsuya Niwa; Toshio Takayama (159-161).
The reaction of the dimethylsilyl derivative of the double eight-membered ring silicate anion, Si8O20[Si(CH3)2H]8, with X(CH3)2SiCl (X = CH3, CH2Cl, CH2Br) in a hexane/acetic acid solution afforded Si8O20[Si(CH3)2X]8 in ⩾90% yield, indicating that the dimethylsilyl group of Si8O20[Si(CH3)2H]8 can be substituted for another silyl groups under the conditions.The reaction of Si8O20[Si(CH3)2H]8 with X(CH3)2SiCl (X = CH3, CH2Cl, CH2Br) in a hexane/acetic acid solution gave Si8O20[Si(CH3)2X]8 in ⩾90% isolation yield, indicating that the dimethylsilyl group of Si8O20[Si(CH3)2H]8 can be substituted for another silyl group with retaining the double eight-membered ring silicate core.
Keywords: Silicate anion; Si 8 O 20 8 - ; Silyl derivatives; Monochlorosilane; Substitution; Siloxane bond;

Synthesis, characterization and crystal structure of bis(5′-methyl-2,2′-bipyridine-6-carboxylato) ruthenium(II) by Athanassios I. Philippopoulos; Evangelia Chatzivasiloglou; Aris Terzis; Catherine P. Raptopoulou; Pierre Tisnès; Claude Picard; Polycarpos Falaras (162-165).
A Ru(II) complex with the ligand 5′-methyl-2,2′-bipyridine-6-carboxylate has been synthesized following a one step reaction and fully characterized. The molecular structure was confirmed by X-ray crystallography.A homoleptic ruthenium(II) complex with the ligand (5′-methyl-2,2′-bipyridine-6-carboxylate) has been prepared and characterized by elemental analysis, FT-IR, 1H, 13C NMR 1D and 2D and electronic absorption spectroscopy. The X-ray crystal structure of the complex has also been determined. It crystallizes in the triclinic crystal system space group P 1 ¯ , exhibiting a distorted octahedral geometry around the ruthenium atom.
Keywords: Ruthenium(II) complex; Substituted 2,2′-bipyridine; 5′-methyl-2,2′-bipyridine-6-carboxylate;

Hydrothermal synthesis and structural characterization of the first indium phosphite In2(HPO3)3(H2O) by Zhuo Yi; Chao Chen; Shougui Li; Guanghua Li; He Meng; Yanjie Cui; Yulin Yang; Wenqin Pang (166-169).
The first indium phosphite In2(HPO3)3(H2O) has been synthesized hydrothermally. The structure of the compound consists of In2O10 dimer and pseudo pyramidal [HPO3]2−, which are connected by sharing vertexes to form indium phosphite layers in the ac plane. These undulate layers are stacked in ABAB sequence along the crystallographic b-axis through bonds of P–O–In, generating the 3D framework with a In/P ratio of 2/3.A novel indium phosphite, In2(HPO3)3(H2O) was hydrothermally prepared and characterized by single-crystal X-ray diffraction. The structure of the compound consists of In2O10 dimer and pseudo pyramidal HPO3, which are connected by sharing vertexes to form the 3D inorganic framework with a In/P ratio of 2/3. In2(HPO3)3(H2O) is the first indium phosphite synthesized by hydrothermal technique. Presence of the In–O–In linkage leading to a In2O10 dimer in the framework is a noteworthy feature. It was characterized by powder X-ray diffraction, ICP, elemental analysis and IR spectra.
Keywords: Hydrothermal synthesis; Characterization; Indium phosphite; Structure;

Homonuclear dinickel complexes: structural mimics for the dinickel subsite of the A-cluster of acetyl-CoA synthase by Samantha E. Duff; J. Elaine Barclay; Siân C. Davies; David J. Evans (170-173).
The homonuclear dinickel complexes [Ni(ema)(μ-S,S′)Ni(dppp)] and [Ni(ema)(μ-S,S′)Ni(dppe)] have been prepared as synthetic structural analogues of the Ni–Ni subsite of the A-cluster of the enzyme acetyl-CoA synthase.[Ni(ema)(μ-S,S′)Ni(dppp)] (1) and [Ni(ema)(μ-S,S′)Ni(dppe)] (2) have been prepared as synthetic structural analogues of the Ni–Ni subsite of the A-cluster of the enzyme acetyl-CoA synthase by reaction of [Ni(ema)]2−, H4ema is N,N′-ethylenebis(2-mercaptoacetamide), with [NiCl2(diphos)], diphos is 1,2-bis(diphenylphosphino)propane (dppp) or 1,2-bis(diphenylphosphino)ethane (dppe). A similar reaction with 1,2-bis(diethylphosphino)ethane did not give the dinuclear product but the trinuclear complex [NEt4]2[Ni{Ni(ema)(μ-S,S′)}2] (3). Complexes 1 and 3 have been crystallographically characterised.
Keywords: Nickel complexes; Acetyl-CoA synthase; Bioinorganic chemistry;

Nickel(II) complexes with 18-membered decaaza macrocyclic ligands have been prepared from the one-pot template condensation reaction of formaldehyde, 2,3-butanedihydrazone with alkyl and benzyl amine in the presence of nickel(II) ion within the nanodimensional pores of zeolite Y. The new materials were characterized by several techniques: chemical analysis and spectroscopic methods (FT-IR, UV–VIS, XRD, BET, DRS).Nickel(II) complexes with 18-membered decaaza macrocyclic ligands “1,10-dialkyl-5,6,14,15-tetramethyl-1,3,4,7,8,10,12,13,16,17-decaazacyclooctadecane” [Ni(R2Me4[18]aneN10)](ClO4)2 (R = H, Me, Et, Pr, Bu, benzyl), have been prepared from the one-pot template condensation reaction of formaldehyde, 2,3-butanedihydrazone with alkyl and benzyl amine in the presence of nickel(II) ion within the nanodimensional pores of zeolite Y. The new materials were characterized by several techniques: chemical analysis and spectroscopic methods (FT-IR, UV–VIS, XRD, BET, DRS).
Keywords: Nanoscale; Microreactor; Encapsulation; Nickel(II); Template;

{[GdAg2(dtpa)(H2O)] · 3H2O} n : the first 2D Gd–Ag coordination polymer with Ag–Ag interaction by Bin Zhao; Xiao-Yan Chen; Wen-Zhen Wang; Peng Cheng; Bin Ding; Dai-Zheng Liao; Shi-Ping Yan; Zong-Hui Jiang (178-181).
A 4d–4f polymer {[GdAg2(dtpa)(H2O)] · 3H2O} n (1) (dtpa = diethylenetriamine pentaacetate) was synthesized and characterized. Its 1D ladderlike chains built upon tetranuclear rings are further connected by Ag–O and Ag–Ag interactions to form a lamellar 2D packing.A novel 4d–4f coordination polymer {[GdAg2(dtpa)(H2O)] · 3H2O} n (1) (dtpa = diethylenetriamine pentaacetate) was synthesized and characterized by magnetic and EPR studies. Its one-dimensional Gd–Ag ladder-like chains built upon tetranuclear rings are further connected by Ag–O bonds and Ag–Ag interactions to form a lamellar 2D packing.
Keywords: Gadolinium; Silver; Crystal structure; Two-dimensional layer; Ag–Ag interaction;

The first cyanuric acid adduct incorporated with metal complex: a novel bi-layered structure constructed by hydrogen bonds by A-Qing Wu; Guang-Hua Guo; Fa-Kun Zheng; Xi Liu; Guo-Cong Guo; Jin-Shun Huang (182-185).
The synthesis and molecular packing analysis of the first example of cyanuric acid adduct with the insertion of the metal complex moiety have been reported.The synthesis and molecular packing analysis of the first example of cyanuric acid adduct with the insertion of the metal complex moiety have been reported. In this compound of cyanuric acid with Cu(pic)2(H2O) in a 2:1 ratio (Hpic = picolinic acid), cyanuric acid forms molecular tapes through the formation of strong cyclic N–H⋯O hydrogen bonds between the adjacent molecules. These tapes are further arranged in layered structure by hydrogen bonds such that the guest molecules (metal complex, Cu(pic)2(H2O)) are being incorporated between the tapes. The layers are organized in pairs by hydrogen bonds into novel bi-layered structure.
Keywords: Cyanuric acid adduct; Host–guest compound; Metal complex; Hydrogen bond;

Synthesis, structure and property of copper(II) complex with macrocyclic multidentate ligand by Ai-Rong Song; You Song; Xing-Mei Ouyang; Yi-Zhi Li; Wei-Yin Sun (186-189).
A novel dinuclear Cu(II) complex with macrocyclic multidentate ligand was synthesized and characterized by X-ray crystallography, electrospray mass spectroscopy (ES-MS), and magnetic measurement.A novel coordination complex [Cu2L(4,4′-bpy)(H2O)](ClO4)4  · 3H2O was synthesized by treatment of Cu(ClO4)2  · 6H2O and 4,4′-bipyridine (4,4′-bpy) with a macrocyclic multidentate ligand L containing two diethylenetriamine units as coordination moieties and two biphenylene groups as rigid spacers. The compound was characterized by X-ray crystallography, electrospray mass spectroscopy (ES-MS), and its magnetic property was studied.
Keywords: Macrocyclic ligand; Copper(II) complex; Crystal structure; Electrospray mass spectroscopy; Magnetic property;

A new ligand 4′-phenyl-4,2′:6′,4″-terpyridine and its zinc complex have been prepared and structurally characterized by single-crystal X-ray diffraction. The complex is a 1D helical polymer. Both ligand and complex display strong photoluminescence in the solid state at room temperature.A new ligand 4′-phenyl-4,2′:6′,4″-terpyridine (L) and its zinc complex [Zn(L)Cl2] n (1) have been prepared and structurally characterized by single-crystal X-ray diffraction. In 1, the ligand L, with three non-planar pyridyl rings, links two zinc ions through two terminal pyridines to construct a 1D helical polymer chain, the intrachain Zn⋯Zn distance is 13.040 Å. Both L and 1 display strong photoluminescence in the solid state at room temperature.
Keywords: Zinc complex; 4′-phenyl-4,2′:6′,4″-terpyridine; Helical chain; Crystal structure; Photoluminescence;

Two new isostructural binuclear complexes of Zn(II) and Co(II) with a bis-N,O-bidentate Schiff-base ligand, 2,5-bis(N-salicylidene-3-aminophenyl)-1,3,4-oxadiazole (L), have been synthesized and characterized. In each complex, the L ligands adopt two different conformations (Cisoid-I (close) and Cisoid-II (open)), respectively, to incorporate with the metal centers to form a box-like structure.In our efforts to design discrete polynuclear metal complexes with tailored structures, a novel bis-N,O-bidentate Schiff-base ligand, 2,5-bis(N-salicylidene-3-aminophenyl)-1,3,4-oxadiazole (L), have been synthesized. The reaction of L with Zn(OAc)2  · 2H2O or Co(OAc)2  · 4H2O in a CH3OH/CHCl3 medium yielded two new complexes, [Zn2 L 2](CHCl3)1/2 (1) and [Co2 L 2](CHCl3)1/2 (2), which exhibit novel discrete dinuclear structure in which the metal centers take pseudo-tetrahedral coordination mode. In each of the two complexes, the L ligands adopt two different conformations (Cisoid-I (close) and Cisoid-II (open)), respectively, to incorporate with the metal centers into box structure. π–π stacking interactions were found to play important roles in the self-assembly processes.
Keywords: Schiff-base; Dinuclear structure; π–π stacking interactions; Self-assembly;

The indium–carboxylate chain structure with the rectangular tunnels by Zhengzhong Lin; Lian Chen; Feilong Jiang; Maochun Hong (199-201).
A novel metal-organic material, {[In2(btc)2(2,2′-bpy)2] · 4H2O} n (1), with the one-dimensional double stranded chain framework has been prepared under hydrothermal condition and characterized by X-ray diffraction. The structure of polymer 1 is also characteristic of neutral independent rectangular tunnels decorated with 2,2′-bipy molecules. The emission spectrum and TGA of 1 are reported.A novel metal-organic material, {[In2(btc)2(2,2′-bpy)2] · 4H2O} n (1) (H3btc = 1,3,5-benzenetricarboxylic acid; 2,2′-bipy = 2,2′-bipyridine), with the one-dimensional double stranded chain framework has been prepared under hydrothermal condition and characterized by single-crystal X-ray diffraction analysis. The structure of polymer 1 is also characteristic of neutral independent rectangular tunnels decorated with 2,2′-bipy molecules. The emission spectrum, IR spectrum and thermogravimetric analysis of 1 are reported.
Keywords: Indium; 1,3,5-benzenetricarboxylic acid; 2,2′-bipyridine; Hydrothermal; Crystal structure;

The photoinitiated oxidative addition of 1 equiv. of SnCl4 to [W(CO)422-1,5-C8H12)] (1) affords the first cyclooctadiene complex of tungsten(II) [W(μ-Cl)(SnCl3)(CO)322-1,5-C8H12)] (2). The structure of compounds 1 and 2 in solution has been established by IR, 1H and 13C NMR spectroscopic methods and determined by single-crystal X-ray diffraction studies.The photoinitiated oxidative addition of 1 equiv. of SnCl4 to [W(CO)422-1,5-C8H12)] (1) affords the first cyclooctadiene complex of tungsten(II) [W(μ-Cl)(SnCl3)(CO)322-1,5-C8H12)] (2). The structure of compounds 1 and 2 in solution has been established by IR, 1H and 13C NMR spectroscopic methods and found to be in accordance with the crystal structure determined by X-ray diffraction studies.
Keywords: Tungsten; Tin; Heterobimetallic compound; Cyclooctadiene complexes; Crystal structure; NMR;

Complexation of the uranyl ion (UO2)2+ with a tetraphenylimidodiphosphinate ligand: the first trinuclear uranyl complex comprising a double μ2-oxo (UO2) bridge by Raymundo Cea-Olivares; Graciela Canseco-Melchor; Mónica M. Moya-Cabrera; Verónica García-Montalvo; José G. Alvarado-Rodríguez; Rubén A. Toscano (205-207).
Reaction of K[(OPPh2)2N] with UO2(NO2)2  · 6H2O resulted in [UO2[(OPPh2)2N]2]3. The structure is a unique trinuclear uranyl compound and may be regarded as a linear U3O2 core engaging two different types of environments for the uranium atoms.Reaction of K[(OPPh2)2N] with UO2(NO2)2  · 6H2O resulted in the formation of compound [UO2[(OPPh2)2N]2]3 (1). Single-crystal diffraction analysis of 1 reveals an elaborated and unique trinuclear uranyl compound, where the central UO2 moiety exhibits Lewis basic properties through an equatorial U⋯O=U=O⋯U bridging towards two outer uranyl units comprised in a six-membered ring array. The central and outer UO2 groups are also bridged by means of four eight-membered rings containing the ancillary ligand. The overall morphology of this compound may be regarded as a linear U3O2 core engaging two different types of environments for the uranium atoms.
Keywords: Actinides; Tetraphenylimidodiphosphinate; X-ray structure determination; Oxo-bridging; Uranyl complexes; Trinuclear complex;

MeOH-coordinated Mn12 single-molecule magnet: structure and magnetic properties of [Mn12O12(OAc)16(MeOH)4] by Guo-Qing Bian; Takayoshi Kuroda-Sowa; Nozomu Gunjima; Masahiko Maekawa; Megumu Munakata (208-211).
Complex [Mn12O12(OAc)16(MeOH)4] having MeOH-coordination was synthesized and characterized, whose magnetic behaviors indicate it is a single-molecule magnet with the largest U eff/k B of 76.2 K.Complex [Mn12O12(OAc)16(MeOH)4] having MeOH-coordination was synthesized and characterized, whose magnetic behaviors indicate it is a single-molecule magnet with the largest U eff/k B of 76.2 K.
Keywords: Single-molecule magnet; Mn12 complex; Methanol coordination; Magnetic properties; Crystal structure;

Three isomorphous cadmium coordination polymers, namely 2 4[Cd(pyim)2X2] n (X=Cl, 1; Br, 2; I, 3), have been synthesized from a hybrid ligand N-(4-pyridylmethyl)imidazole by slow diffusion methods. The X-ray analysis showed that the highly distorted basic grid is hourglass-shaped. In addition, the crystal packing of the complex molecules is influenced by the presence of the face to face π–π interactions.Three cadmium(II) coordination polymers formed from pyim [pyim =  N-(4-pyridylmethyl)imidazole], namely 2 4[Cd(pyim)2X2] n (X=Cl, 1; Br, 2; I, 3), have been synthesized and characterized by IR, and fluorescence spectroscopy as well as TG analysis.
Keywords: Metal–organic compound; Hybrid; Unsymmetrical; Flexibility; Counter anions;

A new macrocyclic manganese(III) 18-azametallacrown-6 was synthesized and characterized. The complex has an oval-shaped cavity and is aligned approximately along the crystallographic c-axis, and one-dimensional channels are formed.A new macrocyclic manganese(III) 18-azametallacrown-6 compound with the formula of [Mn6(4-ohashz)6(CH3OH)6] · 12CH3OH (4-ohashz =  N-acetyl-(4-hydroxysalicylhydrazidate)) was synthesized and characterized. In this complex, the metal ion is forcing the stereochemistry of the ligands arranged into a propeller shape with alternating Λ/Δ configurations. The disc-shaped hexanuclear complex has a cavity in the center with a dimension of 8.69′ in diameter and 3.13′ in thickness and aligned approximately along the crystallographic c-axis, one-dimensional channels are formed.
Keywords: Metallacrown; Manganese complex; Crystal structure;

Designed construction of a non-interpenetrated 2D bilayer framework with large guest-clathrated channels by Chengbing Ma; Mingqiang Hu; Changneng Chen; Qiutian Liu (219-221).
A non-interpenetrated 2D bilayer framework [Mn(dpe)(ip)] n (ip = isophthalate) has been rationally constructed in which [Mn(ip)] n double-chains are combined by trans-1,2-bis(4-pyridyl)ethylene (dpe). Solvate H2O and dpe are trapped into the channels.Manganese isophthalate [Mn(ip)] n double-chains are deliberately combined by axial connector (E)-1,2-bis(4-pyridyl)ethylene (dpe) to construct a non-interpenetrated 2D bilayer framework which possesses large rectangular channels to trap dpe and H2O molecules.
Keywords: Crystal structure; Isophthalate; Manganese complex; 2D bilayer network;

Zwitterionic complexes arising from the reaction of tucked-in titanocenes with tris(pentafluorophenyl)borane by Vojtech Varga; Pavel Šindelář; Ivana Císařová; Michal Horáček; Jiřı́ Kubišta; Karel Mach (222-226).
Doubly tucked-in titanocene 5 reacts with B(C6F5)3 by one methylene group to give 6. Its crystal structure revealed that one hydrogen of the methylene group attached to boron agostically interacts with Ti(IV).Single tucked-in titanocene [Ti(η5-C5Me5)(η51-C5Me4CH2)] adds to B(C6F5)3 to give the paramagnetic cationic complex [Ti(η5-C5Me5){η5-C5Me4CH2B(C6F5)3}] (1). Doubly tucked-in titanocene [Ti(η5-C5Me5){η34-C5Me3(CH2)2}] reacts with B(C6F5)3 by one methylene group to give [Ti(η5-C5Me5){η51-C5Me3(CH2)CH2B(C6F5)3}] (6). The crystal structure of 6 revealed that one hydrogen of the methylene group attached to boron agostically interacts with Ti(IV).
Keywords: Titanium; Tucked-in titanocene; Borate ligand; Zwitterions; Cationic complexes; X-ray crystallography;

Tuning the spin crossover above room temperature: iron(II) complexes of substituted and deprotonated 2,6-bis(benzimidazol-2-yl)pyridine by Roman Boča; Franz Renz; Miroslav Boča; Hartmut Fuess; Wolfgang Haase; Guido Kickelbick; Wolfgang Linert; Martina Vrbová-Schikora (227-230).
The complex [Fe(tzimpy)2](ClO4)2  · 2H2O (tzimpy = 2,4,6-tris-(benzimidazol-2-yl)pyridine) shows an abrupt spin crossover (S  = 0–2 transition) above room temperature centered at T c  = 323 K with a hysteresis width of ΔT  = 35 K. The neutral iron(II) complex with deprotonated bzimpy ligands (bzimpy = 2,6-bis(benzimidazol-2-yl)pyridine) exhibits a gradual spin transition on the first heating with T c  = 424 K. There are irreversible changes between T  = 503 and 523 K: the liberation of the crystal water, the color change (blue–green) followed by a structure change. Next thermal cycles are reproducible, though heating/cooling paths are different from the first heating.The complex [Fe(tzimpy)2](ClO4)2  · 2H2O (tzimpy = 2,4,6-tris-(benzimidazol-2-yl)pyridine) shows an abrupt spin crossover (S  = 0–2 transition) above room temperature centered at T c  = 323 K with a hysteresis width of ΔT  = 35 K. The neutral iron(II) complex with deprotonated bzimpy ligands (bzimpy = 2,6-bis(benzimidazol-2-yl)pyridine) exhibits a gradual spin transition on the first heating with T c  = 424 K. There are irreversible changes between T  = 503 and 523 K: the liberation of the crystal water, the color change (blue–green) followed by a structure change. Next thermal cycles are reproducible though, heating/cooling paths are different from the first heating.
Keywords: Iron(II) complexes; Spin crossover; Magnetism; Cooperativeness;

The first metal chelate of un-substituted 2,6-pyridine-dicarboxamide (pdcam): synthesis, molecular and crystal structure, and properties of [CuII(pdc)(pdcam)] · 2H2O (pdc = 2,6-pyridine-dicarboxylato(2−) ligand) by Marı́a Pilar Brandi-Blanco; Duane Choquesillo-Lazarte; Carlos Gustavo Garcı́a-Collado; Josefa Marı́a González-Pérez; Alfonso Castiñeiras; Juan Niclós-Gutiérrez (231-234).
A novel mixed-ligand copper(II) derivative with 2,6-pyridine-dicarboxylato(2−) ligand and its primary diamide derivative, namely 2,6-pyridine-dicarboxamide (pdcam), was synthesised and characterised by X-ray crystallography, and thermal, spectral and magnetic methods. The tridentate pdcam ligand is flexible enough to bind Cu(II) atom in a mer-N(equatorial) + O2(apical) conformation.The compound (2,6-pyridine-dicarboxamide)(2,6-pyridine-dicarboxylato)copper(II) dihydrate ([Cu(pdc)(pdcam)] · 2H2O, compound 1) has been synthesised by reaction of Cu2(CO3)(OH)2, H2pdc acid and pdcam in an aqueous-ethanol medium. The new compound has been characterised by thermal, spectral, magnetic and X-ray diffraction methods. Its crystal consists of a 3D hydrogen bonded network where all N–H(amide) bonds of pdcam act as H-donors for O carboxyl(pdc) or water acceptor atoms. The Cu(II) atom exhibits an elongated octahedral coordination, type 4 + 2. Both pdc and pdcam ligands define a nearly orthogonal dihedral angle (88.4°). The anionic pdc acts as mer-NO2(equatorial) tridentate ligand, supplying three among the four closest to the metal donor atoms (Cu–N 1.913(2), Cu–O 2.022(2) and 2.055(2) Å). The diamide pdcam ligand displays a mer-N(equatorial) + O2(apical) role (Cu–N 2.007(2), Cu–O(amide) 2.295(2) and 2.305(2) Å), thus showing a remarkable conformational flexibility.
Keywords: 2,6-pyridinedicarboxylic acid; 2,6-pyridinedicarboxamide; Crystal structure; Amide; Copper(II) complex;