Unusual Ar-H/Rh-H J(HH) NMR coupling in complexes of rhodium(III): experimental evidence and theoretical support for an eta1-arene structure

The synthesis and structural properties of three new hydridorhodium(III) complexes are reported. Hydrogenolysis of the cyclometalated rhodium dichloride complexes [RhCl2{(S,S)-benbox(Me-2)}] (2a-c) leads to formation of the new complexes [RhCl2(H){(S,S)-ip-benbox(Me-2)H}] (3a-c) in 45% to 85% yield. Compounds 3a-c were found to have unusual features by NMR spectroscopy: in particular, downfield shifted aryl proton resonances (8.88-9.03 ppm) that were coupled to the rhodium hydride resonances. Using X-ray crystallographic studies, a variety of solid- and solution-state characterization techniques, and DFT calculations, these features were attributed to the presence of weak pi-type eta(1)-arene interactions in 3a-c

Ligand Rearrangement and Hemilability in R hodium(I) and Iridium(I) Complexes Bearing Terphenyl Phosphines

We describe the synthesis of a series of cationic rhodium(I) and iridium(I) compounds stabilized by sterically demanding phosphines that contain a terphenyl substituent, PMe 2 Ar’ (Ar’ = 2,6-diarylphenyl radical). Salt metathesis of metal precursors [MCl(COD)(PMe 2 Ar’)] (M = Rh, Ir; COD = cyclooctadiene) with NaBAr F (BAr F = B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ) results in a series of cationic complexes in which the loss of the chloride ligand is compensated by the appearance of relatively weak π-interactions with one of the flanking aryl rings of the terphenyl substituent. The same experiments carried out with carbonyl compounds [MCl(CO) 2 (PMe 2 Ar’)] led to the corresponding cationic carbonyl complexes, whose CO-induced rearrangement reactivity has been investigated, both experimentally and computationally. The differences in reactivity between rhodium and iridium complexes, and as a result of varying the sterics of terphenyl phosphines are discusse

Rh-POP Pincer Xantphos Complexes for C-S and C-H Activation. Implications for Carbothiolation Catalysis

The neutral Rh­(I)–Xantphos complex [Rh­(κ³-_P,O,P-Xantphos)­Cl]_<i>n</i>, <b>4</b>, and cationic Rh­(III) [Rh­(κ³-_P,O,P-Xantphos)­(H)₂]­[BAr^F₄], <b>2a</b>, and [Rh­(κ³-_P,O,P-Xantphos-3,5-C₆H₃(CF₃)₂)­(H)₂]­[BAr^F₄], <b>2b</b>, are described [Ar^F = 3,5-(CF₃)₂C₆H₃; Xantphos = 4,5-bis­(diphenylphosphino)-9,9-dimethylxanthene; Xantphos-3,5-C₆H₃(CF₃)₂ = 9,9-dimethylxanthene-4,5-bis­(bis­(3,5-bis­(trifluoromethyl)­phenyl)­phosphine]. A solid-state structure of <b>2b</b> isolated from C₆H₅Cl solution shows a κ¹-chlorobenzene adduct, [Rh­(κ³-_P,O,P-Xantphos-3,5-C₆H₃(CF₃)₂)­(H)₂(κ¹-ClC₆H₅)]­[BAr^F₄], <b>3</b>. Addition of H₂ to <b>4</b> affords, crystallographically characterized, [Rh­(κ³-_P,O,P-Xantphos)­(H)₂Cl], <b>5</b>. Addition of diphenyl acetylene to <b>2a</b> results in the formation of the C–H activated metallacyclopentadiene [Rh­(κ³-_P,O,P-Xantphos)­(ClCH₂Cl)­(σ,σ-(C₆H₄)­C­(H)CPh)]­[BAr^F₄], <b>7</b>, a rare example of a crystallographically characterized Rh–dichloromethane complex, alongside the Rh­(I) complex <i>mer</i>-[Rh­(κ³-_P,O,P-Xantphos)­(η²-PhCCPh)]­[BAr^F₄], <b>6</b>. Halide abstraction from [Rh­(κ³-_P,O,P-Xantphos)­Cl]_<i>n</i> in the presence of diphenylacetylene affords <b>6</b> as the only product, which in the solid state shows that the alkyne binds perpendicular to the κ³-POP Xantphos ligand plane. This complex acts as a latent source of the [Rh­(κ³-_P,O,P-Xantphos)]⁺ fragment and facilitates <i>ortho</i>-directed C–S activation in a number of 2-arylsulfides to give <i>mer</i>-[Rh­(κ³-_P,O,P-Xantphos)­(σ,κ¹-Ar)­(SMe)]­[BAr^F₄] (Ar = C₆H₄COMe, <b>8</b>; C₆H₄(CO)­OMe, <b>9</b>; C₆H₄NO₂, <b>10</b>; C₆H₄CNCH₂CH₂O, <b>11</b>; C₆H₄C₅H₄N, <b>12</b>). Similar C–S bond cleavage is observed with allyl sulfide, to give <i>fac</i>-[Rh­(κ³-_P,O,P-Xantphos)­(η³-C₃H₅)­(SPh)]­[BAr^F₄], <b>13</b>. These products of C–S activation have been crystallographically characterized. For <b>8</b> in situ monitoring of the reaction by NMR spectroscopy reveals the initial formation of <i>fac</i>-κ³-<b>8</b>, which then proceeds to isomerize to the <i>mer</i>-isomer. With the <i>para</i>-ketone aryl sulfide, 4-SMeC ₆H₄COMe, C–H activation <i>ortho</i> to the ketone occurs to give <i>mer</i>-[Rh­(κ³-_P,O,P-Xantphos)­(σ,κ¹-4-(COMe)­C₆H₃SMe)­(H)]­[BAr^F₄], <b>14</b>. The temporal evolution of carbothiolation catalysis using <i>mer</i>-κ³-<b>8</b>, and phenyl acetylene and 2-(methylthio)­acetophenone substrates shows initial fast catalysis and then a considerably slower evolution of the product. We suggest that the initially formed <i>fac</i>-isomer of the C–S activation product is considerably more active than the <i>mer</i>-isomer (i.e., <i>mer</i>-<b>8</b>), the latter of which is formed rapidly by isomerization, and this accounts for the observed difference in rates. A likely mechanism is proposed based upon these data

Methyl Complexes of the Transition Metals

Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, that is, based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition-metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition-metal complexes containing M-CH fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last five years. After a panoramic overview on M-CH compounds of Groups 3 to 11, which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.Ministerio de Ciencia e Innovación Projects CTQ2010–15833, CTQ2013-45011 - P and Consolider - Ingenio 2010 CSD2007 - 00006Junta de Andalucía FQM - 119, Projects P09 - FQM - 5117 and FQM - 2126EU 7th Framework Program, Marie Skłodowska - Curie actions C OFUND – Agreement nº 26722

Sicherung der Altersvorsorge durch Aufgabenteilung zwischen Individualversicherung und gesetzlicher Rentenversicherung: Moeglichkeiten e. Neuordnung u. gesamtwirtschaftl. Auswirkungen ; Gutachten im Auftr. d. Gesamtverbandes d. Deutschen Versicherungswirtschaft (abgeschlossen 1985)

SIGLEAvailable from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel A 160373 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

JNDS, Volume 23, Number 4

Letter from Michael Krumper to the editor reviewing Anthony Peake's (2004) article "Cheating the Ferryman.

A Generalist approach to social work practice : model and synthesis

The purpose of this research practicum is twofold. First, to present a synthesis of current generalist literature and to formulate a practice model which is both comprehensive and representative of current generalist practice in direct services. To our knowledge there is no single reference or source which in and of itself accomplishes this purpose. Therefore, such a model would make an important contribution to the field. Second, to develop a questionnaire which could be used to conduct a descriptive survey of generalist social work practice in Oregon. It would determine the extent to which practitioners in Oregon are practicing as generalists. We are interested in discovering 1) the relationship between generalist practice and the personal characteristics of practitioners, as well as 2) the relationship between generalist practice and the type of agency in which the practitioner works. It appears to us that certain agencies encourage ineffective, inappropriate, and uni-dimensional practice, while others tend to encourage more effective and holistic practices