Preparation Of Rh Research Articles

Preparation of Rh[16aneS4-diol](211)At and Ir[16aneS4-diol](211)At complexes as potential precursors for astatine radiopharmaceuticals. Part I: Synthesis.

The goal of this study was to evaluate a new approach that can be applied for labeling biomolecules with (211)At. Many astatine compounds that have been synthesized are unstable in vivo, providing motivation for seeking different (211)At labeling strategies. The approach evaluated in this study was to attach astatide anions to soft metal cations, which are also complexed by a bifunctional ligand. Ultimately, this complex could in principle be subsequently conjugated to a biomolecule with the proper selection of ligand functionality. We report here the attachment of (211)At(-) and *I(-) (*I = (131)I or (125)I) anions to the soft metal cations Rh(III) and Ir(III), which are complexed by the 1,5,9,13-tetrathiacyclohexadecane-3,11-diol (16aneS4-diol) ligand. Radioactive *I(-) anions were used for preliminary studies directed at the optimization of reaction conditions and to provide a baseline for comparison of results with (211)At. Four complexes Rh[16aneS4-diol]*I/(211)At and Ir[16aneS4-diol]*I/(211)At were synthesized in high yield in a one-step procedure, and the products were characterized mainly by paper electrophoresis and reversed-phase HPLC. The influences of time and temperature of heating and concentrations of metal cations and sulfur ligand 16aneS4-diol, as well as pH on the reaction yields were determined. Yields of about 80% were obtained when the quantities of Rh(III) or Ir(III) cations and 16aneS4-diol ligand in the solutions were 62.5 nmol and 250 nmol, respectively, and the pH ranged 3.0-4.0. Syntheses required heating for 1-1.5 h at 75-80 degrees C. The influence of microwave heating on the time and completeness of the complexation reaction was evaluated and compared with the conventional method of heating in an oil bath. Microwave synthesis accelerates reactions significantly. With microwave heating, yields of about 75% for Rh[16aneS4-diol](131)I and Ir[16aneS4-diol](131)I complexes were obtained after only 20 min exposure of the reaction mixtures to microwave radiation. In conclusion, this study has shown that it is possible to attach an astatide anion to soft metal cations in a simple and fast one-step procedure, with high yields. These complexes will be evaluated as reagents for labeling biomolecules.

Rhodium(III) and palladium(II) complexes of some P-heterocycles; synthesis and X-ray structures

Deoxygenation of the syn-3-phosphabicyclo[3.1.0]hexane 3-oxides bearing a 3-phenyl or a 3-(4-methylphenyl) substituent ( 1a, b) by trichlorosilane took place already at mild condition and resulted in the corresponding phosphines ( 2a, b) with retention of configuration at phosphorus, while in the case of 3-(2-methylphenyl)-3-phosphabicyclo[3.1.0]hexane ( 2c), the inversion of the phosphorus atom was observed in solution under ambient conditions that was evaluated by quantum chemical calculations. A further phosphine ligand ( 5) was obtained by the reduction of 4-dichloromethylene-1,4-dihydrophosphinine oxide ( 4). The phosphine ligands ( 2 and 5) were used in the preparation of Rh(III) complexes ( 3 and 6). A Pd(II) complex of type PdCl 2( 5) 2 ( 7) was also prepared. The stereostructures of a series of Rh(III) complexes of 3-aryl-3-phosphabicyclo[3.1.0]hexanes ( 3b- syn, 3c- syn and 3c- anti) were elucidated by single crystal X-ray analysis confirming the relative position of the dichlorocyclopropane and the P-substituent.

Rh4(CO)12-derived functionalized MCM-41-tethered rhodium complexes: preparation, characterization and catalysis for cyclohexene hydroformylation

Abstract The preparation of Rh 4 (CO) 12 -derived functionalized silicate MCM-41-tethered catalysts has been studied by infrared (IR) spectroscopy, X-ray diffraction (XRD) and N 2 adsorption–desorption. Silicate MCM-41 is first functionalized with phosphine, amine and thiol donor ligand groups. Then the functionalized MCM-41 is reacted with Rh 4 (CO) 12 by coordination of surface donor ligands to the rhodium to produce phosphinated and aminated MCM-41-tethered unidentified rhodium carbonyl clusters and MCM-41-tethered [Rh(μ-S(CH 2 ) 3 Si(O s ) 3 )(CO) 2 ] 2 (where O s represents surface oxygen). The functionalized MCM-41 and Rh/functionalized MCM-41 possess the structural ordering of mesoporous MCM-41, but exhibit reduced pore sizes, total pore volumes and BET surface areas. The tethered rhodium carbonyl catalysts behave differently with different donor ligands attached in cyclohexene hydroformylation under equimolar CO and H 2 at 2.7 MPa and 100 °C. Only the aminated MCM-41-tethered catalyst displays good activity, selectivity and recycling for the formation of cyclohexane carboxaldehyde. The influences of supported donor ligands on the activity and stability of tethered catalysts for hydroformylation are discussed. The mesoporous structure of MCM-41 is maintained stable during the catalytic reaction.

Preparation of Rh−Graphite and Rh−Clay Nanocomposites: Model Substances for Nanographite and Induced Magnetization in 4d Transition Metals

Rh nanoparticles in a graphite lattice have been prepared by reduction of a RhCl3−graphite intercalation compound by hydrogen gas at high temperatures (I) or at room temperature by Li−diphenylide (II). In all cases, the reduction was complete. All four samples (natural graphite and HOPG) showed a full set of fcc Rh reflections by selected-area electron diffraction. This indicates a particle thickness from at least four layers. Only in the case of the samples reduced by (II) can additional very strong reflections can be observed. They seem to be due to the occurrence of 2D Rh structures with (2 × agraphite) and (3 × agraphite) superstructures. For a (2 × agraphite) Rh superstructure on graphite or expanded multilayers of fcc Rh, an induced magnetic moment was theoretically predicted. Bright-field electron microscopy shows particles in the size ranges 11−106 nm (I) and 1.5−37.5 nm (II). The magnetism of Rh−Gr is related to the detail of Rh nanoparticles and nanographites, depending on the condition of reduc...

Organometallic Rh(I) and Rh(III) complexes with [2-(dimethylamino)ethyl]cyclopentadiene

The preparation of Rh(I) and Rh(III) complexes with [2-(dimethylamino)ethyl]cyclopentadiene is described. Starting with C 5H 5(CH 2) 2NMe 2 ( 1) or Na[C 5H 4(CH 2) 2NMe 2] ( 2) and using [η 5:η 4-C 5H 4(CH 2) 2N(H)Me 2Rh (I)(cod)] +(BF 4) − ( 8) and [Rh(CO) 2Cl] 2, the complexes [η 5:η 1-C 5H 4(CH 2) 2NMe 2Rh (I)(CO) 2] ( 3), [η 5:η 1-C 5H 4(CH 2) 2N(H)Me 2Rh (I)(CO) 2] +(Cl) − ( 4a), [η 5:η 1-C 5H 4(CH 2) 2N(H)Me 2Rh (I)(CO) 2] +(BF 4) −·Et 2O ( 4b ( 4b·Et 2O), [η 5:η 1-C 5H 4(CH 2) 2N(H)Me 2Rh (III)(CO)I 2] +(Cl) − ( 5), [η 5:η 1-C 5H 4(CH 2) 2NMe 2Rh (III)I 2] ( 6), [η 5:η 1-C 5H 4(CH 2) 2NMe 2Rh (III)I 2](PPh 3)] ( 7), [η 5:μ-C 5H 4(CH 2) 2NMe 2Rh (III)I] 2 2+· (BF 4) 2 − ( 9), and [η 5:μ:η 1-C 5H 4(CH 2) 2N(H)Me 2Rh (III)I 2] 2 2+·(BF 4) 2 − ( 10) were synthesized and characterized by elemental analysis, IR, 1H and 13C NMR and mass spectroscopy. The results show that the dimethylamino side chain can play the role of the auxiliary base required to deprotonate cyclopentadiene and that this group may or not coordinate to the metal, depending on its protonation state and the oxidation state of the metal.

The study of rhodium(III) complexes by paper electrophoresis and ion-exchange chromatography : III. Rhodium(III) in perchlroric acid

The action of HClO4 on rhodium hydroxide was studied with paper electrophoresis and ion exchange chromatography. The existence of chloro-complexes due to precipitation of co-ordinated Cl in the preparation of Rh(OH)3, was demonstrated. These can be decomposed by repeated precipitation or heating with AgNO3.