Molecular geometry of the reaction product of α,β-dinitrostilbene with morpholine

X-ray structure analysis has revealed that reaction of either trans- or cis-, -dinitrostilbene with morpholine results in the formation of cis--nitro--(N-morpholino)stilbene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 791–794, April, 1990.     

Synthesis, electronic properties, and X-ray structural characterization of tetrarylbenzo[1,2-b:4,5-b']difuran cation radicals

Electroactive tetraarylbenzo[1,2- b:4,5- b']difuran (BDF) and model diarylbenzofuran derivatives are synthesized and their structures are established by X-ray crystallography. Isolation and X-ray crystallographic characterization of the robust cation-radical salts of BDF derivatives confirm that a single charge in the BDFs is stabilized largely by the benzodifuran and coplanar alpha-aryl groups lying on the longitudinal axis. These findings suggest that the linear arrays of BDFs may allow the construction of molecular wires suitable for long-range electron transport.     

First-row transition-metal complexes of a new pentadentate ligand, alpha,alpha,alpha',alpha'-tetra(pyrazolyl)lutidine

A new pentadentate ligand, alpha,alpha,alpha',alpha'-tetra(pyrazolyl)lutidine, pz 4lut, has been prepared by a CoCl 2-catalyzed rearrangement reaction between 2,6-pyridinedicarboxaldehyde and dipyrazolylthione. The coordination chemistry with some divalent first-row transition metal (Mn, Fe, Co, Ni, Cu, and Zn) chlorides has been explored. The electronic properties indicate that the new kappa (5)N ligand is a slightly stronger-field donor to Ni (2+) and Co (2+) than a related pentadentate ligand with five pyridyl donors presumably because of greater interaction between the metal and axial pyridyl.     

Generation of Molecular Complexity from Cyclooctatetraene: Preparation of Aminobicyclo[5.1.0]octitols

A series of eight stereoisomeric N‐(tetrahydroxy bicyclo‐[5.1.0]oct‐2S*‐yl)phthalimides were prepared in one to four steps from N‐(bicyclo[5.1.0]octa‐3,5‐dien‐2‐yl)phthalimide (±)‐ 7 , which is readily available from cyclooctatetraene (62 % yield). The structural assignments of the stereoisomers were established by ¹H NMR spectral data as well as X‐ray crystal structures for certain members. The outcomes of several epoxydiol hydrolyses, particularly ring contraction and enlargement, are of note. The isomeric phthalimides as well as the free amines did not exhibit β‐glucosidase inhibitory activity at a concentration of less than 100 μM .     

Pyrazolyl methyls prescribe the electronic properties of iron(II) tetra(pyrazolyl)lutidine chloride complexes

A series of iron(II) chloride complexes of pentadentate ligands related to α,α,α',α'-tetra(pyrazolyl)-2,6-lutidine, pz(4)lut, has been prepared to evaluate whether pyrazolyl substitution has any systematic impact on the electronic properties of the complexes. For this purpose, the new tetrakis(3,4,5-trimethylpyrazolyl)lutidine ligand, pz**(4)lut, was prepared via a CoCl(2)-catalyzed rearrangement reaction. The equimolar combination of ligand and FeCl(2) in methanol gives the appropriate 1:1 complexes [FeCl(pz(R)(4)lut)]Cl that are each isolated in the solid state as a hygroscopic solvate. In solution, the iron(II) complexes have been fully characterized by several spectroscopic methods and cyclic voltammetry. In the solid state, the complexes have been characterized by X-ray diffraction, and, in some cases, by M?ssbauer spectroscopy. The M?ssbauer studies show that the complexes remain high spin to 4 K and exclude spin-state changes as the cause of the surprising solid-state thermochromic properties of the complexes. Non-intuitive results of spectroscopic and structural studies showed that methyl substitution at the 3- and 5- positions of the pyrazolyl rings reduces the ligand field strength through steric effects whereas methyl substitution at the 4-position of the pyrazolyl rings increases the ligand field strength through inductive effects.     

New Mixed‐Metal Carbonyl Complexes Containing Bridging 2‐Mercapto‐1‐methylimidazole Ligand

Reaction of [Mn₂(CO)₁₀] with 2‐mercapto‐1‐methylimidazole in the presence of Me₃NO at 25 °C afforded two new dimanganese complexes [Mn₂(CO)₆(μ‐SN₂C₄H₅)₂] ( 1 ) and [Mn₂(CO)₇(μ‐SN₂C₄H₅)₂] ( 2 ). Compound 1 consists of two μ‐SN₂C₄H₅ ligands, each bound through the sulfur atom to two Mn atoms and through the nitrogen atom to one Mn atom forming a four‐membered chelate ring. Compound 2 was found to consist of one μ‐SN₂C₄H₅ ligand in a similar bonding mode to 1 but another μ‐SN₂C₄H₅ ligand coordinates through the sulfur atom to one Mn atom and through the nitrogen atom to another Mn atom. Compound 1 was also obtained as the only product from the reaction of [Mn₂(CO)₈(NCMe)₂] with 2‐mercapto‐1‐methylimidazole. In contrast, a similar reaction of [Re₂(CO)₈(NCMe)₂] with 2‐mercapto‐1‐methylimidazole led to the formation of the di‐, tri‐, and tetranuclear complexes [Re₃(CO)₈(μ‐CO)(μ₃‐SN₂C₄H₅)₂(μ‐H)] ( 3 ), [Re₄(CO)₁₂(μ‐SN₂C₄H₅)₄] ( 4 ), and [Re₂(CO)₆(μ‐SN₂C₄H₅)₂] ( 5 ). Compound 3 provides a unique example of a hydrido trirhenium compound. The reaction of [Cr(CO)₃(NCMe)₃] and [Mo(CO)₃(NCMe)₃] with 1 in refluxing THF afforded the mixed metal complexes [CrMn₂(CO)₈(μ‐CO)₂(μ₃‐SN₂C₄H₅)₂] ( 6 ) and [MoMn₂(CO)₈(μ‐CO)₂(μ₃‐SN₂C₄H₅)₂] ( 7 ), respectively, in which two Mn–M (M = Mo, Cr) bonds were formed. In contrast, a similar treatment of [W(CO)₃(NCMe)₃] with 1 yielded two W‐Mn complexes [Mn₂W(CO)₈(μ‐CO)₂(μ₃‐SN₂C₄H₅)₂] ( 8 ) and [Mn₂W(CO)₇(μ‐CO)₂(SN₂C₄H₅)(μ₃‐SN₂C₄H₅)₂] ( 9 ). Treatment of 1 with [Fe₃(CO)₁₂] at 70‐75 °C afforded the trinuclear mixed‐metal complex [FeMn₂(CO)₈(μ‐CO)(μ₃‐SN₂C₄H₅)₂] ( 10 ) and the diiron side product [Fe₂(CO)₆(μ‐S₂N₂C₄H₅)₂] ( 11 ). Compounds 6 ‐ 10 have a bent open structure of three metal atoms linked by two metal‐metal bonds and all, except 9 and 10 , contain a noncrystallographic two‐fold axis of symmetry. Compound 9 is structurally similar to 8 , but it contains a SN₂C₄H₆ ligand, mono coordinated through the exocyclic sulfur atom to the W atom and a Mn–Mn bond instead of a Mn–W bond. Compound 11 comprises two bridging S₂N₂C₄H₅ ligands, which arise from the coupling of 2‐mercapto‐1‐methylimidazole with sulfur.