New Bis‐o‐Benzoquinoid Ligands with Ethylene Bridge and Their Metal Complexes

The treatment of di‐o‐quinone 4,4′‐(ethane‐1,2‐diyl)‐bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH₂–CH₂–Q, 1 ) leads to its rearrangement to form di‐p‐quinomethide 4,4′‐(ethane‐1,2‐diylidene)bis(2‐hydroxy‐3,6‐di‐tert‐butyl‐cyclohexa‐2,5‐dienone) ( 2 ). The subsequent oxidation of 2 by an alkaline solution of K₃[Fe(CN)₆] yielded the new di‐o‐quinone 4,4′‐(ethene‐1,2‐diyl)bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH=CH–Q, 3 ), which contains an ethylene bridge. The formation of mono‐ and poly‐reduced derivatives of 2 and 3 with potassium, thallium was studied by EPR technique. The dinuclear thallium derivative of 3 , Tl(SQ–CH=CH–SQ)Tl, was found to exist in the diamagnetic quinomethide form. The most stable derivatives of 2 and 3 are triphenyltin(IV) bis‐p‐quinomethide‐phenolate ( 4 ) and triphenylantimony(V) bis‐catecholate ( 5 ), which have been synthesized and isolated. The molecular structures of 2 , 3 , and 5 were characterized by single‐crystal X‐ray diffraction.     

Oxamido‐bridged N4 Macrocyclic Complexes CuII/MII/CuII (M = Mn,Co): Synthesis,Crystal Structures and Magnetic Properties

Two new oxamido‐bridged N₄ macrocyclic complexes [(CuL)₂Mn(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 1 ) and [(CuL)₂Co‐(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 2 ) (H₂L = 2,3‐dioxo‐5,6:14,15‐di‐benzo‐7,13‐diphenyl‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐diene) have been synthesized and structurally characterized by X‐ray crystallographic investigations. In the two complexes, all copper(II) ions adopt a slightly distorted square‐planar configuration and the central manganese(II) and cobalt(II) ions are set in a distorted octahedral coordination sphere, connected to the other CuL fragments through exo‐cis oxamido bridges. The analyses of the magnetic properties were carried out by means of the theoretical expression of the magnetic susceptibility deduced from the spin Hamiltonian ? = –2J?₁?₂, leading to J = –14.58 cm^–1 for complex 1 and J = –26.95 cm^–1 for complex 2 , respectively.     

Synthesis and Characterisation of a New Schiff‐Base‐like Ligand and its Iron(II) Complexes

The reaction of iron(II) acetate with the tetradentate Schiff base like ligand H₂L [(E,E)‐[{diethyl 2,2’‐[4,5‐dihydroxy‐1,2‐phenylenebis(iminomethylidyne)]bis3‐oxobutanato}]) leads to the formation of the octahedral N₂O₄ coordinated complex [FeL(MeOH)₂] · MeOH ( 1 ). Conversion of 1 with N‐methylimidazole (N‐meim) leads to the N₄O₂ coordinated complex [FeL(N‐meim)₂] · MeOH ( 2 ). Both complexes are pure HS compounds that were characterised using magnetic measurements and X‐ray crystallography. A special attention was given to the role of the two hydroxyl groups at the phenyl ring on the formation of a hydrogen bond network and the influence of this network on the magnetic properties.     

Crystal Structure and Magnetic Properties of Copper(II) and Nickel(II) Binuclear Complexes with Bisacylhydrazones Based on 2,6‐Diformyl‐4‐methylphenol

The series of binuclear Cu(II) and Ni(II) complexes with an asymmetrical exchange fragment based on 2,6‐diformyl‐4‐methylphenol bishydrazone has been synthesized for the first time. The compositions and structures of both ligands and its complexes have been established with the data of IR, ¹H NMR, and extended X‐ray absorption fine structure (EXAFS) spectroscopical studies as well as magnetic measurements. The structure of [Ni₂L₃(μ‐Pz)] · 2CH₃OH (L = triply deprotonated form of bishydrazone, Pz = pyrazol) was confirmed by X‐ray crystallographic analysis. In this complex, the coordination environment of two nickel ions is quite different, one nickel atom is square‐planar and the other is distorted octahedral coordinated. The values of exchange parameter calculated in terms of HDVV theory have been compared with the features of an asymmetrical exchange fragment's electronic and geometrical structure.     

2,6‐Bis(pyrazol‐3‐yl)pyridine as Meridional Capping Ligand: Synthesis,Characterization, and Crystal Structure of the First Corresponding Hexanuclear Iron(III) Complex

Based on the 2,6‐bis(pyrazol‐3‐yl)pyridine ligand (H₂bpp) the hexanuclear iron(III) complex [Fe₆(bpp)₄(μ₃‐O)₂(μ‐OMe)₃(μ‐OH)Cl₂] ( 1 ) was synthesized. The reaction with iron(II) chloride and additional pyridine leads to the exclusive formation of the complex through self‐assembly process. Six octahedrally coordinated iron atoms are linked through the pyrazolido groups of four H₂bpp ligands. These are further linked through bridging hydroxido, methoxido, and oxido groups. The complex has been characterized by IR spectroscopy, ESI mass spectrometry, elemental analysis and X‐ray crystallography. Temperature‐dependent magnetic measurements indicate strong antiferromagnetic exchange interaction between the high‐spin iron(III) ions within the complex, which leads to an S = 0 spin ground state. As a result of the two Fe3(μ₃‐O) fragments two frustrated exchange pathways are present. In addition the properties of H₂bpp as a potential capping ligand for the synthesis of heteroleptic trinuclear complexes based on the triaminoguanidine core is investigated.     

Synthesis,Characterization, and X‐ray Crystal Structures of (Diphosphine)Ni(dmit) and (Diphosphine)Ni(dmio) (Diphosphine = dppv,dppb) Complexes

Four complexes with the ligands dmit and dmio were synthesized. Reaction of (PhCO)₂(dmit) and (PhCO)₂(dmio) with MeONa afforded the intermediates 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate dianion and 2‐oxo‐1,3‐dithiole‐4,5‐dithiolate dianion, respectively. Reaction of the two dianions with (diphosphine)NiCl₂ [diphosphine = (Z)‐1, 2‐bis(diphenylphosphanyl)ethane (dppv), 1,2‐bis(diphenylphosphanyl)benzene (dppb)] gave (dppv)Ni(dmit) ( 1 ), (dppb)Ni(dmit) ( 2 ), (dppv)Ni(dmio) ( 3 ), and (dppb)Ni(dmio) ( 4 ). This synthesis route was found to be an efficient pathway to prepare dmit and dmio ligand complexes. Complexes, 1 – 4 were fully characterized by elemental analysis and IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. In addition, the molecular structures of 1 , 3 and 4 were established by X‐ray diffraction.     

Synthesis and Characterisation of Schiff Base‐like Iron(II) Complexes with Imidazole as Axial Ligand

Four new six‐coordinate and one pentacoordinate iron(II) complexes with imidazole as axial ligand were synthesised and characterised. For two of the complexes crystals suitable for X‐ray structure analysis were obtained and an extended network of hydrogen bonds was observed in both cases. Magnetic susceptibility studies revealed, that two of the octahedral complexes are high‐spin complexes in the entire temperature range, whereas for the other two gradual spin transitions are observed.     

Synthesis and X‐ray Crystallography of Two Lead(II) Decahydro‐closo‐Decaborate Hydrates

The reaction of Pb[CO₃] with an aqueous solution of (H₃O)₂[B₁₀H₁₀] in an equimolar ratio leads to two lead(II) decahydro‐closo‐decaborate hydrates both as triclinic, pale yellow single crystals. The water‐rich compound with the formula [Pb(H₂O)₃]₂Pb[B₁₀H₁₀]₃ · 5.5H₂O crystallizes in the space group P1 (a = 711.72(4), b = 1243.14(8), c = 2064.83(12) pm, α = 81.806(3), β = 83.795(3), γ = 80.909(3)°) with Z = 2. The compound with the lower water content, [Pb(H₂O)₃]Pb[B₁₀H₁₀]₂ · 1.5H₂O, also crystallizes in P1 (a = 718.46(4), b = 1288.75(8), c = 1279.91(8) pm, α = 70.145(3), β = 75.976(3), γ = 80.324(3)°) with Z = 2. Both structures can be described as layered arrangements and contain one Pb²⁺ cation each, which is only coordinated by the hydridic hydrogen atoms of the hydroborate anions. All the others are primarily surrounded by three water molecules in a non‐planar fashion and additional hydrogen atoms of [B₁₀H₁₀]^2– anions. The non‐lead‐bonded crystal water molecules in both structures are all connected via hydrogen bonds to the water molecules, which coordinate the Pb²⁺ cations, as well as via non‐classical hydrogen bonds to the cluster anions and reside between the layers. The [B₁₀H₁₀]^2– anions show only slight distortions from their ideal shape as bicapped square antiprisms.     

Synthesis,Characterization, and X‐ray Structures of Ru3(CO)9(dotpm)(L) Complexes [L = PPh3, P(C6H4Cl‐p)3, and PPh2(C6H4Br‐p)]

The reaction of Ru₃(CO)₁₀(dotpm) ( 1 ) [dotpm = (bis(di‐ortho‐tolylphosphanyl)methane)] and one equivalent of L [L = PPh₃, P(C₆H₄Cl‐p)₃ and PPh₂(C₆H₄Br‐p)] in refluxing n‐hexane afforded a series of derivatives [Ru₃(CO)₉(dotpm)L] ( 2 – 4 ), respectively, in ca. 67–70 % yield. Complexes 2 – 4 were characterized by elemental analysis (CHN), IR, ¹H NMR, ¹³C{¹H} NMR and ³¹P{¹H} NMR spectroscopy. The molecular structures of 2 , 3 , and 4 were established by single‐crystal X‐ray diffraction. The bidentate dotpm and monodentate phosphine ligands occupy equatorial positions with respect to the Ru triangle. The effect of substitution resulted in significant differences in the Ru–Ru and Ru–P bond lengths.     

X‐ray studies on the double melting behavior of poly(butylene terephthalate)

The double melting behavior of poly(butylene terephthalate) (PBT) was studied with differential scanning calorimetry (DSC) and wide‐angle X‐ray analysis. DSC melting curves of melt‐crystallized PBT samples, which we prepared by cooling from the melt (250 °C) at various cooling rates, showed two endothermic peaks and an exothermic peak located between these melting peaks. The cooling rate effect on these peaks was investigated. The melt‐crystallized PBT sample cooled at 24 K min^?1 was heated at a rate of 1 K min^?1, and its diffraction patterns were obtained successively at a rate of one pattern per minute with an X‐ray measurement system equipped with a position‐sensitive proportional counter. The diffraction pattern did not change in the melting process, except for the change in its peak height. This suggests that the double melting behavior does not originate from a change in the crystal structure. The temperature dependence of the diffraction intensity was obtained from the diffraction patterns. With increasing temperature, the intensity decreased gradually in the low‐temperature region and then increased distinctly before a steep decrease due to the final melting. In other words, the temperature‐dependence curve of the diffraction intensity showed a peak that is interpreted as proof of the recrystallization in the melting process. The peak temperature was 216 °C. The temperature‐dependence curve of the enthalpy change obtained by the integration of the DSC curve almost coincided with that of the diffraction intensity. The double melting behavior in the heating process of PBT is concluded to originate from the increase of crystallinity, that is, recrystallization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2005–2015, 2001     

Total‐reflection X‐ray diffraction study of friction‐transferred poly(tetrafluoroethylene) film

The orientational structure of the friction‐transferred poly(tetrafluoroethylene) (PTFE) film, which consists of highly oriented polymer strands, was evaluated with energy‐dispersive total‐reflection X‐ray diffractometry. In the film, each PTFE molecule is oriented along the friction direction, and PTFE crystallites have a preferred orientation with respect to the substrate surface. The orientational distribution of the chain direction was quantitatively evaluated. The half‐width of the distribution was determined to be about 3°. The dependence of the orientational distribution on temperature is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 432–438, 2001     

Synthesis,Spectroscopy, X‐ray Crystallography,and DFT Computations of Nanosized Phosphazenes

Nanoparticles of nine phosphazenes with general formula 4‐CH₃C₆H₄S(O)₂N=PX₃ [X = Cl ( A ), NC₄H₈ ( 1 ), NC₆H₁₂ ( 2 ), NC₄H₈N–C(O)OC₂H₅ ( 3 ), NC₄H₈N–C(O)OC₆H₅ ( 4 ), NC₄H₈O ( 5 ), NHCH₂–C₄H₇O ( 6 ), N(CH₃)(C₆H₁₁) ( 7 ), NHCH₂–C₆H₅ ( 8 ), and 2‐NH‐NC₅H₄ ( 9 )] were synthesized using ultrasonic method and characterized by ¹H, ¹³C, ³¹P NMR, FT‐IR, fluorescence, as well as UV/Vis spectroscopy and additionally with XRD, FE‐SEM, N₂ sorption, and elemental analysis. The ³¹P NMR spectra of compounds 1 – 9 reveal the most up field shift δ(³¹P) for 9 at –11.45 ppm reflecting the most electron donation of 2‐aminopyridinyl rings through resonance to the phosphorus atom. The ¹H, ¹³C NMR spectra of 7 exhibit two sets of signals for the hydrogen and carbon atoms of its two isomers present in the solution state in 1:4 ratio. The FE‐SEM micrographs illustrate that the nanoparticles of compounds 1 – 9 have spherical morphology and a size of 27–42 nm. From the XRD patterns, the crystal sizes were estimated to about 24–86 nm. The highest bandgap was measured for 3 (3.81 eV) whereas the smallest was measured for 8 (3.50 eV). The structures of two polymorphs of compound 5 ( 5 , 5′ ) were determined by X‐ray crystallography at 120 K. Both of these polymorphs are triclinic with P1 space group but 5 has a doubled unit cell volume and two symmetrically independent molecules ( 5a and 5b ). In structures 5a and 5′ , the phosphorus and all endocyclic atoms of two morpholinyl rings display disorder, whereas the molecule 5b does not show disorder. The strong intermolecular O–H ··· O hydrogen bonds plus weak intermolecular C–H ··· O and C–H ··· N interactions create three‐dimensional polymers in the crystalline networks of 5 and 5′ . The DFT computations illustrate that molecule 5b is more stable than 5a by –1.1062 and –0.9779 kcal · mol^–1 at B3LYP and B3PW91 levels, respectively. The NBO calculations presented sp³d hybridization for phosphorus and sulfur atoms and sp², sp³ hybrids for the nitrogen and oxygen atoms.     

X‐Ray and Electron Diffraction Study of Poly(p‐dioxanone)

Summary: Solution‐grown lamellar crystals of poly(p‐dioxanone) (PPDX) have been crystallized isothermally from butane‐1,4‐diol at 100 °C. The crystal structure of PPDX has been determined by interpretation of X‐ray fiber diagrams of PPDX fibers and electron diffraction diagrams of lozenge‐shaped chain‐folder lamellar crystals. The unit cell of PPDX is orthorhombic with space group P2₁2₁2₁ and parameters: a = 0.970 nm, b = 0.742 nm, and c (chain axis) = 0.682 nm. There are two chains per unit cell, which exist in an antiparallel arrangement.

Transmission electron micrograph of PPDX chain‐folded lamellar crystals obtained by isothermal crystallization and its electron diffraction diagram.     

Stable Anilinyl Radicals Coordinated to Nickel: X‐ray Crystal Structure and Characterization

Two anilinosalen and a mixed phenol‐anilinosalen ligands involving sterically hindered anilines moieties were synthesized. Their nickel(II) complexes 1 , 2 , and 3 were prepared and characterized. They could be readily one‐electron oxidized (E_1/2=?0.30, ?0.26 and 0.10 V vs. Fc⁺/Fc, respectively) into anilinyl radicals species [ 1]⁺ , [ 2]⁺ , and [ 3]⁺ , respectively. The radical complexes are extremely stable and were isolated as single crystals. X‐ray crystallographic structures reveal that the changes in bond length resulting from oxidation do not exceed 0.02 Å within the ligand framework in the symmetrical [ 1]⁺ and [ 2]⁺ . No quinoid bond pattern was present. In contrast, larger structural rearrangements were evidenced for the unsymmetrical [ 3]⁺ , with shortening of one C_ortho? C_meta bond. Radical species [ 1]⁺ and [ 2]⁺ exhibit a strong absorption band at around 6000 cm^?1 (class III mixed valence compounds). This band is significantly less intense than [ 3]⁺ , consistent with a rather localized anilinyl radical character, and thus a classification of this species as class II mixed‐valence compound. Magnetic and electronic properties, as well as structural parameters, have been computed by DFT methods.     

Cobalt(III) Complexes of D‐Galactosylamine

The β‐pyranose isomer of D ‐galactosylamine ( 1 ) formed complexes with three different cobalt(III) fragments. Crystals containing the dication [Co(tren)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 3 ) showed coordination through the anomeric amino group (N1) and the deprotonated hydroxy group (O2) of the ⁴C₁ β‐pyranose form, which is also the major isomer of free galactosylamine. The cationic complexes [Co(fac‐dien)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 4 ) and [Co(phen)₂(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 5 ) were analysed by NMR spectroscopy and showed the same coordination mode as 3 . In terms of available ligand isomers it was shown that 1 exhibits an anomeric equilibrium in solution of both pyranose and both furanose forms as is typical for the parent glycose, galactose.     

Facile Access to Transition‐Metal–Carbonyl Complexes with an Amidinate‐Stabilized Chlorosilylene Ligand

Three transition‐metal–carbonyl complexes [V( L )(CO)₃(Cp)] ( 1 ), [Co( L )(CO)(Cp)] ( 2 ), and [Co( L₂ )(CO)₃]⁺[CoCO)₄]^? ( 3 ), each containing stable N‐heterocyclic‐chlorosilylene ligands ( L ; L =PhC(NtBu)₂SiCl) were synthesized from [V(CO)₄(Cp)], [Co(CO)₂(Cp)], and Co₂(CO)₈, respectively. Complexes 1 , 2 , 3 were characterized by NMR and IR spectroscopy, EI‐MS spectrometry, and elemental analysis. The molecular structures of compounds 1 , 2 , 3 were determined by single‐crystal X‐ray diffraction.     

Synthesis,Characterization, and X‐ray Crystal Structure of Macrocyclic Nickel/Iron/Sulfur Cluster Complexes

A series of macrocyclic Ni/Fe/S cluster complexes were synthesized and structurally characterized. The macrocyclic type of (diphosphine)Ni‐bridged double butterfly Fe/S complexes [μ‐SCH₂CH₂OCH₂CH₂S‐μ][(μ‐S=CS)Fe₂(CO)₆]₂‐[Ni(diphosphine)] ( 1 – 3 ; diphosphine = dppe, dppv, dppb) were prepared by treatment of the dianion [{μ‐SCH₂CH₂OCH₂CH₂S‐μ}{(μ‐CO)Fe₂(CO)₆}₂]^2–, generated in situ from Fe₃(CO)₁₂, Et₃N, and HSCH₂CH₂OCH₂CH₂SH with excess CS₂ followed by treatment of the resulting dianion [{μ‐SCH₂CH₂OCH₂CH₂S‐μ}{(μ‐SC=S)Fe₂(CO)₆}₂]^2– with (diphosphine)NiCl₂. The three complexes 1 – 3 were characterized by elemental analysis and IR, ¹H NMR, and ³¹P NMR spectroscopy. In addition, the molecular structures of 2 and 3 were established by X‐ray crystallography.     

Regioselective Synthesis and Characterization of Multinuclear Convex‐Bound Ruthenium‐[n]Cycloparaphenylene (n=5 and 6) Complexes

Mono‐ and multinuclear complexes of ruthenium and [n]cycloparaphenylene (CPP, n=5 and 6) were synthesized in excellent yields through ligand exchange of the cationic complex [(Cp)Ru(CH₃CN)₃](PF₆) with CPP. In the multinuclear complexes, ruthenium selectively coordinated to alternate paraphenylene units to give bis‐ and tris‐coordinated Ru complexes for [5] and [6]CPPs, respectively. Single‐crystal X‐ray analysis revealed the Ru was coordinated with η⁶‐hapticity on the convex surface of CPP.