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

Social pedagogical activities in the local municipality of Dubna small rural district for decreasing unjustified non-atendance

Diplomdarbs „Sociālpedagoģiskā darbība Dubnas pagasta pašvaldībā skolēnu neattaisnoto kavējumu novēršanā” pievērš uzmanību sociāli nozīmīgai problēmai. Diplomdarba mērķis ir raksturot sociālpedagoģisko darbību Dubnas pagastā un izstrādāt darba programmu ģimenēm skolēnu neattaisnoto kavējumu novēršanā, teorētiski to pamatot un veikt šīs programmas aprobācijas rezultātu analīzi. Diplomdarbā tiek aplūkota ģimenes, skolas un sabiedrības loma skolēnu neattaisnoto kavējumu novēršanā, kā arī izvērtētas pašvaldības iespējas izglītības apguves sekmēšanā. Darba praktiskajā daļā, pamatojoties uz veikto izpēti, ir analizēti skolēnu neattaisnoto skolas kavējumu iemesli Dubnas pagasta pašvaldībā un izstrādāta sociālpedagoģiska darbības programma ģimenēm skolēnu neattaisnoto kavējumu novēršanā. Izstrādātās programmas aprobācijas analīze liecina, ka savlaicīgi konstatēti problēmas cēloņi un pārdomāta sociālpedagoģiska darbība ģimenē, veicina pozitīvu darba rezultātu neattaisnoto skolas kavējumu novēršanā. Atslēgvārdi: skolēns, ģimene, vecāki, sociālpedagoģiskā darbība, pašvaldība.The diploma paper „Social pedagogical activities in the local municipality of Dubna small rural district for decreasing unjustified non-atendance” raises a socially significant problem. The objective of the diploma paper is to characterize social pedagogical activity in the local authority of Dubna rural district and work out a programme for decreasing unjustified non-attendance, substantiate it theoretically and analyze the results of approbation of the programme. In the diploma paper the role of family, school and society for decreasing unjustified non-atendance has been examined, as well as considered possibilities of the rural municipality to favour advancement. In the practical part of the diploma paper, basing on the research, causes of unjustified non-attendance in the local authority of Dubna rural distict are analysed and social pedagogical activity programme for families is developed for eliminating unjustified non-atendance. The analysis of the approbation of the developed programme testifies that duly established causes of the problem and deliberative social pedagogical activity facilitates a positive result of work in decreasing unjustified non-atendance. Key words: pupil, family, parents, social pedagogical activity, local authorit