Fluoro-containing complexes of chromium(III). 8. Preparation and characterization of a dimethoxo-bridged dimer of chromium(III)

Abstract

Preparation of Starting Material. trans-Difluorobis(trimethy1-enediamine)chromium(III) chloride was prepared as described in the literature.6 A 9.0-g (33-mmol) sample of crude trans-difluorobis(trimethylenediamine)chromium(III) chloride was dissolved in 4C-50 mL of water at room temperature and the solution was filtered. The filtrate was treated with 5 mL of concentrated hydriodic acid and the reaction mixture was allowed to stand at room temperature for 15 min. At the end of this time the beaker and its contents were cooled in an ice bath for 30 min. The solid product was collected, washed with acetone, and air-dried; yield 4.52 g (28%). Anal. Calcd for tr~ns-[Cr(C~N2H~~)~F~]I.H20: C, 18.7; H, 5.75; N, 14.6. Found: C, 18.5; H, 5.65; N, 14.7. The electronic absorption spectrum in aqueous solution was characterized by A, , , 537 nm (e 16.8 M-I cm-I), A, , , , , 465 nm (e 21.4), A , , 395 nm (e 16.3), and A, , , 360 nm (e 16.3).Preparation of the Bridged Dimer. A 3.0-g (7.85-mmol) sample of tr~ns-[Cr(C,H~~N~)~F21I.H,0 was placed in the thimble of a Soxhlet extractor, and the sample was extracted with methyl alcohol for 48 h. At the end of this time, the blue product which had precipitated in the extraction flask was collected along with some starting material which precipitated during filtration. These solids were placed in the extraction thimble, the filtrate was returned to the extraction flask, and the extraction was continued. At 24-h intervals additional blue solid was collected from the reaction flask and placed in the thimble, the filtrate was returned to the extraction flask, and the extraction was continued. The total reflux time involved was 8 days. At the end of this time the blue solid was collected from the extraction thimble, washed with acetone, and dried at 115 OC for 18 h; yield 0.79 g (52%). An aqueous solution of the blue solid gave a negative test for iodide ion when treated with aqueous silver nitrate.Anal. Calcd for [F2(C3HI~N2)Cr(OCH&Cr(C3H10N2)F2]: C, 24.6; 0 (by difference), 7.9.The molecular weight of the complex was determined by vapor pressure osmometry in water at 65 OC: calcd, 390; found, 386. The infrared spectrum indicated the absence of any water in the complex. A 1 mM aqueous solution of the complex had a molar conductance of 2.4 cmz 52-1 M-I at 25 OC. The molar conductance slowly increased reaching 190 cm2 D-' M-I after 100 h. The electronic spectrum of a freshly prepared aqueous solution of the bridged complex was characterized by A, , , 556 nm (e 78.5 M-' cm-I), A, , , 467 nm (e 11.71, and A, , ,401 (e 36.9). The bridged complex has a moderate solubility in water, and it is insoluble in methyl alcohol, dichloromethane, and chloroform.Hydrolysis Studies. A 226-mg (0.58-mmol) sample of the bridged complex was quickly dissolved in 4.5 mL of water at room temperature, the solution was filtered, and the filtrate was frozen solid in a dry ice-2-propanol slush and was lyophilized. The volatile fraction was collected and analyzed by gas chromatography. The volatile fraction was water ...

Isolation and characterization of a (diphenylamido)ruthenium(IV) porphyrin

“…However, prior to our study, Coliman and co-workers reported a series of diamagnetic monomeric dialkylruthenium(IV) porphyrins. 4 In our case, the diagmagnetism of 3 could be understood by a consideration of the N-Ru it bonding. Considering that all the reported crystal structures of transition-metal diphenylamido complexes show planar geometry about N of the amido ligand,lb•19 it would be probable that the corresponding geometry in complex Chem.…”

“…Such µ-(4-substituted-phenoxo) binuclear complexes of chromium(III) are expected to be one of the most appropriate series which will make possible relating the magnetic interactions to the structural and electronic properties of bridging moieties in comparison with those of similar types of binuclear complexes. We report here a new versatile synthetic route to the novel title binuclear (acetylacetonato)chromium(III) complexes bridged not only by X-phO (X = CH3 (1), H (2), Cl (3), N02 (4), OCH3 ( 5)) but also by X-phS (X = H, CH3) and RO (R = H, CH3, C2H5) together with their characterization, magnetic behavior, and the X-ray structures for two of them (1,2). Among these complexes, only the alkoxo complexes of analogous types have already been reported.3,5…”