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We have designed and prepared a novel N 3 -donor Schiff base ligand and synthesized the corresponding two mononuclear Fe(II) complexes and compared with their Zn(II) congener. Spectroscopic, Single-crystal XRD, magnetic and DFT calculations investigations reveal that both complexes have Fe__N 6 distorted octahedral geometry and their spin states locked in the low spin state throughout the measured temperature range. [Display omitted] Investigations on the spin states of octahedral Fe(II) complexes have received special attention due to their clear discrimination in the spin states of the d-orbitals. As a means to further understand the factors that influence the spin-crossover (SCO) phenomenon in Fe(II) systems, we herein report two mononuclear Fe(II) complexes, [Fe L 2 ](ClO 4) 2 ·2CH 3 OH (1) and [Fe L 2 ](BF 4) 2 ·CH 3 CN·CH 3 OH (2), derived from a novel N 3 -donor Schiff base ligand, 2,6-bis[(3- methylbenzylimino) methyl ]pyridine (L) with varying counteranion and the diamagnetic [Zn L 2 ](BF 4) 2 congener for a comparative investigation. The complexes have been synthesized and characterized by electrospray-ionization mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, single-crystal X-ray diffraction (XRD) and magnetic susceptibility studies. Structural and magnetic investigations reveal that both 1 and 2 show Fe__N 6 distorted octahedral geometry and are locked in the diamagnetic LS state throughout the entire explored temperature range from 1.8 to 400 K. The LS state of [Fe L 2 ]2+ is also confirmed by comparing the experimentally found structural parameters, NMR chemical shifts and excitation energies in the visible region with density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Abstract: Two copper(II) complexes, [Cu(L)N3]n (1) and [Cu(HL)2](I3)ClO4 (2), where HL = 2-pyridylaldehydesemicarbazone, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Complex 1 crystallizes in monoclinic space group P21/a, whereas, complex 2 crystallizes in triclinic space group P-1. Complex 1 is a stair-like coordination polymer with square pyramidal geometry of copper(II), whereas, complex 2 is a mononuclear cationic bis-ligand complex of octahedral copper(II). Lower coordination ability of tri-iodide or perchlorate compared to azide may be related with variations of the structures of the complexes. [Copyright &y& Elsevier]

Abstract: By changing metal ions in the presence of N2O2-chelating Schiff-base ligand sal2hn [sal2hn= N,N′-bis(salicylidene)-1,2-diaminocyclohexane] and a large excess of NaN3 (reagent ratios (metal:L:)=2:1:8), tetranuclear copper(II) complex [Cu4(μ-sal2hn)2(μ 1,1-N3)2(N3)2] (1) and 1D chain coordination polymer of cobalt(III) complex {Na[Co(μ-sal2hn)(μ 1,1-N3)(N3)(H2O)(μ-O)} n (2) have been successfully obtained. Single-crystal X-ray analyses revealed that in complex 1 the copper(II) ions are bridged alternately by end-on (EO) azido and phenoxo-sal2hn ligands, while in complex 2 the cobalt(III) and sodium ions are bridged alternately by end-on (EO) azido and phenoxo-sal2hn ligands. Complex 1 crystallizes in the monoclinic system, space group P21/n, with a =11.6283(5)Å, b =19.5997(8)Å, c =9.1531(4)Å, β =90.540(6)°, V =2086.00(15)Å3, and Z =2, while complex 2 crystallizes in the monoclinic system, space group C21/c, with a =21.1473(5)Å, b =14.0604(3)Å, c =15.0452(6)Å, β =106.064(3)°, V =4298.9(2)Å3, and Z =8. [Copyright &y& Elsevier]

Abstract: 1-Alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SRaaiNR/, 1) reacts with Co(ClO4)2·6H2O to form [Co(SRaaiNR/)2](ClO4)2 (2). The single crystal X-ray structure of one of the complexes of 2 shows a tridentate chelation N(imidazole), N(azo), S(thioether) system. In the structure one of ClO4 − anions shows disorder and forms an (imidazole)C–H···O(ClO3) interaction leading to a 1-D chain. Co(OAc)2.4H2O and SRaaiNR/ react in the presence of NH4SCN (1:1:2 mole ratio) in methanol and the complex [Co(SRaaiNR/)2(SCN)2] (3) has been separated. The single crystal X-ray structure determination has established the structure of the complexes in which the ligand SRaaiNR/ acts in a bidentate N(imidazole), N(azo) chelation mode. A cyclic voltammogram shows a Co(III)/Co(II) oxidative response at 0.6–0.8V and azo reductions. DFT computation using optimized geometry support the electronic spectral and redox properties of the complexes. [Copyright &y& Elsevier]

Abstract: The syntheses of two new cyclometalated ligands [2-(2′,4′-difluorophenyl)-4-tert-butylpyridine (F2 t Buppy) and 2-(2′,4′-difluorophenyl)-4-oxyhexylpyridine (F2HexOppy)] were carried out. Blue-light emitting iridium(III) complex dopants [Ir(F2 t Buppy)2(acac/pic)] (acac=acetylacetone; pic=picolinic acid) and [Ir(F2HexOppy)2(acac/pic)] were prepared using these cyclometalated ligands with acetylacetone and picolinic acid as their ancillary ligands. The structure of the complexes, [Ir(F2 t Buppy)2(acac)] and [Ir(F2 t Buppy)2(pic)] were authenticated by X-ray single-crystal structure analysis and showed an octahedral geometry. Comparative absorption and emission spectra of thin-films as well as their solution samples were studied. The variation of the lowest emitting states to their corresponding unsubstituted complexes, [Ir(F2ppy)2(acac/pic)] was also discussed. The electroluminescent (EL) device was fabricated using [Ir(F2 t Buppy)2(pic)] as the dopant (D-I) into the emitting layer and compared with two other EL devices where [Ir(F2MeOppy)2(acac)] (D-II) and FIrpic (D-III) dopants were used in the same device structure. The lower driving voltages obtained for D-I with respect to D-II and D-III devices were rationalized. The exceptional lowering of the luminance yield of the substituted dopants containing devices, D-I and D-II, to that of D-III which contains the unsubstituted dopant was also investigated. [Copyright &y& Elsevier]

[Display omitted] [IrIII(O^N^C^O)(PPh 3) 2 ] reacts with p -nitro-phenylazide to give a unique arylimido-bridged iridium-O^N^C^O complex IrIII(O^N^C^O)(N - p -nitrophenyl)(PPh 3). This complex has been isolated as pure crystalline solids in good yield and its structure has been fully established by an X-ray structure analysis. DFT calculations were also performed to gain insight into the electronic structure of this unique complex. [ABSTRACT FROM AUTHOR]