Nitrosation of protein sulfhydryl groups to form thionitrites (S-nitrosothiols) has been reported to be important in the biochemistry of nitric oxide. Such S-nitrosation of protein thiol residues has been shown to alter the function of some proteins. In this brief communication, we report the X-ray crystal structure of S-nitroso-l-cysteine ethyl ester hydrochloride. Two rotamers with respect to the NCCS moiety are present in the crystal: the major rotamer is in the gauche+ conformation, and the minor rotamer is in the rare anti (trans, antiperiplanar) conformation for a cysteinyl compound. Importantly, the CSNO groups for both rotamers are in the syn (cis, synperiplanar) form. To the best of our knowledge, this is the first reported high-resolution solid-state structure of an S-nitroso derivative of a cysteine or cysteinyl-containing compound.

Crystal structures of glyme solvates with LiTFSI and LiBETI (TFSI- = bis(trifluoromethanesulfonyl)imide, BETI- = bis(perfluoroethanesulfonyl)imide) have been determined including (monoglyme)1:LiBETI, (diglyme)2:LiTFSI, (diglyme)1/2:LiTFSI, and low-temperature (triglyme)1:LiBETI. These solvates, combined with the phase behavior of the salts with various glymes from DSC analysis, provide insight into the molecular interactions of lithium salts in ethoxy solvents commonly used for solid polymer and liquid electrolytes. Many of the solvates appear to undergo order−disorder solid phase transitions. These are the first reported crystal structures containing the BETI- anion.

The preparation, characterization and reactivity of (eta(5)-cyclopentadienyl)iron complexes of nitrosobenzene are investigated as potential intermediates in the [CpFe(CO)(2)](2) (1)-catalyzed allylic amination of olefins by nitroarenes. The oxidation of 1 by (Cp2Fe](+) in the presence of PhNO produces a novel dinuclear complex {[CpFe-mu-(eta(2)-(N,O)-PhNO)](2)-mu-NHPh)BF4 (2) along with [CpFe(CO)(3)]BF4 and [CpFe(CO)(2)(NH2Ph)]BF4; 2 has been characterized spectroscopically and by X-ray diffraction. Reaction of CpFe(CO)(2)] with PhNO and AgSbF6 produces the mononuclear complex [CpFe(CO)(2)(eta(2)-PhNO)]SbF6 (3) which has also been characterized spectroscopically, crystallographically and by PM3 MO calculations. The reaction of 3 with Of-methyl styrene affords [CpFe(CO)(2)(PhNH2)SbF6] and a trace of N-phenyl-2-phenylallyl amine 4, while the reaction of 3 with 2,3-dimethyl-1,3-butadiene affords the aniline complex and a hetero-Diels-Alder adduct 5, indicative of PhNO dissociation. Together these results preclude the involvement of nitrosoarene complex 3 as an important intermediate in the allylic amination catalyzed by [CpFe(CO)(2)](2)(D (c) 2005 Elsevier B.V. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Linear poly(ethylenimine), [LPEI], is a synthetically versatile polymer host compared to poly(ethylene oxide), in that various groups can be attached to the backbone nitrogen atoms. The interactions of LPEI with sodium cations are modeled by solutions of N,N'-dimethylethylenediamine, DMEDA, containing dissolved sodium triflate [NaTf]. During these studies, the crystalline compound (DMEDA)(2)(NaTf)(5) was discovered and characterized by X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy. The compound crystallizes in polymeric chains in a triclinic unit cell of the P $(1) over bar $ space group. In the crystal, the sodium ions are both five- and six-coordinate. A spectroscopic comparison of DMEDA, the (DMEDA)2(NaTf)5 crystal, and (DMEDA),NaTf solutions over a composition range of 7.5:1 to 1.5:1 [DMEDA:NaTf, molar ratio] was conducted using infrared and Raman spectroscopy. In (DMEDA)(2)(NaTf)(5), the triflate ions vibrate as either [Na2Tf](2+) or [Na3Tf](2+) species due to the coordination of the triflate ion by sodium ions. However, in solution, only the [Na2Tf](+) species is present at high NaTf compositions. At a 7.5:1 DMEDA/NaTf composition, contact ion pairs [NaTf] are the dominant species.

A dimeric silver complex of the bulky bis(N-heterocyclic carbene) ligand 1,1'-dimesityl-3,3'-methylenediimidazol-2,2'-diylidene exhibits a surprisingly static structure in solution, due to a favorable chelate ring conformation, yet serves as a convenient transmetalation reagent for the formation of a new (2)(K)-bis(NHC) rhodium(I) complex. The latter complex demonstrates a strong influence of N-substituent steric bulk on the bis(NHC) binding mode.

The self-assembly of supramolecular copper "tennis balls" that possess unusual magnetic properties using a small pyridyl amide ligand is described. Copper(II) complexes of N-(2-pyridylmethyl)acetamide (HL) were synthesized in methanol. In the absence of base, the mononuclear complex [Cu(HL)(2)](ClO4)(2) (1) was prepared. The structure of 1, determined by X-ray crystallography, contains a copper(II) ion surrounded by bidentate HL ligands coordinated via the pyridyl N atom and the carbonyl O atom in a trans, square planar arrangement. Reactions carried out in the presence of triethylamine resulted in cluster complexes [Cu8L8(OH)(4)](ClO4)(4) and [Cu8L8(OH)(4)](CF3SO3)(4) [2(ClO4)(4) and 2(OTf)(4), respectively]. The cationic portions of 2(ClO4)(4) and 2(OTf)(4) are isostructural, containing eight copper(II) ions, eight deprotonated ligands (L-), and four mu(3)-hydroxide ligands. The top and bottom halves of the cluster are related by a pseudo-S-4 symmetry operation and are held together by bridging L- ligands. Solutions of 2(ClO4)(4) and 2(OTf)(4), which were shown to contain the full [Cu8L8(OH)(4)](4+) fragment by electrospray mass spectrometry and conductance experiments, are EPR silent. Magnetic susceptibility measurements for 2(ClO4)(4) as a function of temperature and magnetic field showed the Cu ions all to exhibit magnetic moments in the range expected for the d(9) configuration. At low temperatures, the magnetization was reduced due to predominantly antiferromagnetic interactions between ions. Analysis showed that partially frustrated interactions among the four Cu ions making up each half of the cluster gave good agreement with the data once a large molecular anisotropy was taken into account, with J(c) = 106 cm(-1,) D = 27 cm(-1,) and g = 2.17.

The reaction of (2,6-Mes2C6H3)2AlH with [Ph3C]+[B(C6F5)4]- afforded the new compound [(2,6-Mes2C6H3)2Al]+[B(C6F5)4]- which contains an almost linear, quasi-two-coordinate, cationic diorganoaluminum center.

Copper(II) complexes were prepared with the new N2S(thioether) ligand 2-methylthio-N-(2-pyridylmethyl)acetamide (2-HLN2S). [Cu(2-LN2S)Cl(MeOH)], which formed in the presence of excess triethylamine, is a distorted square pyramidal complex containing the ligand with the amide nitrogen deprotonated. The structurally analogous complex, [Cu(2-HLN2S)Cl2], which formed in the absence of triethylamine, contains 2-HLN2S in the tautomeric imidic acid form. Neutral copper(II) N2S(thioether)S(thiolate) species were generated by addition of alkyl or aromatic thiolates to [Cu(2-LN2S)Cl(MeOH)] and an unusual decomposition pathway was discovered.

Nitrosoalkanes belong to the family of C-nitroso compounds and are known to bind to the iron center in heme proteins. We have prepared and characterized a series of new nitrosoalkane heme model complexes of the form (por)Fe(RNO)(L) (por=porphyrinato dianion; R=isopropyl; L=MeOH, pyridine, 1-methylimidazole) by infrared and 1H NMR spectroscopy and X-ray crystallography. Within the set of octaethylporphyrinato (OEP) compounds, the infrared stretching frequencies of the NO groups decrease in the order (OEP)Fe(iPrNO)(MeOH)·MeOH (1433 cm−1)>(OEP)Fe(iPrNO)(py) (1429 cm−1)>(OEP)Fe(iPrNO)(1-MeIm) (1423 cm−1), reflecting the increased backdonation of electron density in the 1-methylimidazole derivative. The molecular structures of the compounds as determined by crystallography reveal N-binding of the nitrosoalkane ligands to the formally ferrous metal centers.