Rhodium

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Rhodium

Ohne Zusammenfassung     

Rhodium

Ohne Zusammenfassung     

Rhodium

Analytical and Bioanalytical Chemistry -     

Rhodium und Iridium

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湿法消解-电感耦合等离子体原子发射光谱(ICP-AES)法测定含铑废催化剂冶金废水中铑

摘 要：建立了硫酸、过氧化氢湿法消解、ICP-AES测定铑派克洗水铑的含量的分析方法。确定了硫酸碳化有机物,过氧化氢溶解煮沸,氢氟酸除硅,于4mol/L盐酸体系,碲共沉淀富集铑,10%盐酸介质,电感耦合等离子体发射光谱仪测定铑量。在选定条件下,测定含铑有机物洗水中0.0003 g/L～0.010 g/L的铑,相对标准偏差（RSD,n=7）和加标回收率分别为：铑0.545%～2.91%和99.62%%～100.55%。。方法准确、快速、简便,测定结果与火试金富集分析方法结果吻合。     

Rhodium/iridium-titanium azaheterometallocubanes

Treatment of [[Ti(eta5-C5Me5)(mu-NH)]3(mu3-N)] (1) with the diolefin complexes [[MCl(cod)]2] (M = Rh, Ir; cod = 1,5-cyclooctadiene) in toluene afforded the ionic complexes [M-(cod)(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)]Cl [M = Rh (2), Ir (3)]. Reaction of complexes 2 and 3 with [Ag(BPh4)] in dichloromethane leads to anion metathesis and formation of the analogous ionic derivatives [M(cod)(mu3-NH)3Ti3-(eta5-C5Me5)3(mu3-N)][BPh4] [M = Rh (4), Ir (5)]. An X-ray crystal structure determination for 5 reveals a cube-type core [IrTi3N4] for the cationic fragment, in which 1 coordinates in a tripodal fashion to the iridium atom. Reaction of the diolefin complexes [[MCl(cod))2] (M = Rh, Ir) and [[RhCl(C2H4)2]2] with the lithium derivative [[Li(mu3-NH)2(mu3-N)-Ti3(eta5-C5Me5)3(mu3-N)]2] x C7H8 (6 C7H8) in toluene gave the neutral cube-type complexes [M(cod)(mu-NH)2(mu3-N)Ti3-(eta5-C5Me5)3(mu3-N)] [M = Rh (7), Ir (8)] and [Rh(C2H4)2(mu3-NH)2(mu3-N)Ti3(eta5-C5Me5)3(mu3-N)] (9), respectively. Density functional theory calculations have been carried out on the ionic and neutral azaheterometallocubane complexes to understand their electronic structures.     

Spektralphotometrische Bestimmung von Rhodium

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Rhodium complexes of some cyclo-olefins

Dicarbonyl(pentane-2,4-dionato)rhodium(I) does not form a complex with, or induce a skeletal rearrangement in, cycloheptatriene. 5-Exo-methylene-2-norbornene is present as an impurity in cycloheptatriene and is complexed by Rh(I) complexes as its endocyclic tautomer. Rhodium complexes of 1,3,5-cyclooctatriene, bicyclo [3.2.1] octa-2,6-diene, cyclooctatetraene, cyclooctatetraene epoxide, bicyclo [6.1.0] nonatriene and 9,9-dimethyl bicyclo [6.1.0] nonatriene are also reported.     

Rhodium catalyzed hydroformylation of olefins

DFT and CCSD(T) methods were used to examine 61 different rhodium catalysts for the hydroformylation of ethylene. The carbon monoxide (CO) stretching frequency was a key electronic parameter to understand the π-accepting nature of the ligand. Normally, π-accepting ligands lead to increased CO stretching frequencies and a reduction in CO dissociation energy. There was no relationship between CO dissociation energy and CO stretching frequency. However, a clear relationship exists between the ethylene insertion barrier (from the rhodium dicarbonyl hydride resting state) and the CO stretching frequency as stronger π-accepting ligands systematically led to a reduction in the barrier. Due to the multistep nature of the rate-limiting step, the overall barrier can be divided into the CO/ethylene equilibrium and an intrinsic ethylene insertion barrier and both are systematically reduced as the π-accepting nature of the ligand is increased. A comparison of the carbonylation transition state (TS) to the ethylene insertion TS allowed us to understand reversibility of olefin insertion. While the ethylene insertion TS systematically decreases with increasing CO stretching frequency, the carbonylation TS is relatively flat. The lines cross at 2156 cm⁻¹ implying a change in the rate-limiting step in this region given a standard set of process conditions. © 2018 Wiley Periodicals, Inc.     

Silicophosphates of Rhodium and Indium

Single crystals of Rh(Si₂O)(PO₄)₃ and In₄(Si₂O) · (PO₄)₆ were prepared by chemical transport reactions in silica tubes and their structures were determined. Crystal data of Rh(Si₂O)(PO₄)₃: trigonal, space group P 3 c1, a = 8.088(3) Å, c = 8.740(2) Å, Z = 2, R(F²) = 0.0379, R_w(F²) = 0.0518 for 601 unique reflections. In₄(Si₂O)(PO₄)₆: hexagonal, space group P6₃/m, a = 8.5149(10) Å, c = 7.7481(12) Å, Z = 1, R(F²) = 0.0436, R_w(F²) = 0.0522 for 509 unique reflections. Both of the compounds have hexagonal close packed array of phosphate groups with metal atoms and SiOSi units in the octahedral interstices, where the SiOSi units show occupational disorder. The structure of the indium compound is considered to be a disordered structure of the reported Mo₄Si₂P₆O₁₃ structure, and contains confacial bioctahedral units.     

Terminal Imido Rhodium Complexes

Compounds of the late transition metals with M?X multiple bonds (X=CR₂, NR, O) represent a synthetic challenge, partly overcome by preparative chemists, but with noticeable gaps in the second‐ and third‐row elements. For example, there are no isolated examples of terminal imido rhodium complexes known to date. Described herein is the isolation, characterization, and some preliminary reactivity studies of the first rhodium complexes [Rh(PhBP₃)(NR)] (PhBP₃=PhB{CH₂PPh₂}₃) with a multiple and terminal Rh?N bond. These imido compounds result from reactions of organic azides with the corresponding rhodium(I) complex having a labile ligand, and display a pseudo‐tetrahedral core geometry with an almost linear Rh‐N‐C arrangement [177.5(2)°] and a short Rh? N bond [1.780(2) Å]. We also show that the Rh?N bond undergoes protonation at the nitrogen atom or addition of H₂, and also engages in nitrene‐group transfer and cycloaddition reactions.