Recent Advances in Synthesis of Molecular Heteroleptic Osmium and Iridium Phosphorescent Emitters

The application of new procedures of organometallic synthesis based on alternative starting complexes has given rise to a significant enhancement in the preparation of osmium(IV), osmium(II), and iridium(III) emitters, since 2012. The choice of the precursors should be done taking into account its ligands, since they may cooperate in the emitter synthesis. Three different functions are clearly pointed out in the revised procedures: the ligands of the starting compounds can direct the selectivity of competitive ruptures of sigma-bonds of the chromophores, without having direct participation in the activation; on the contrary, they can directly participate in the generation of a ligand, being a part of the new coordinated group; and the ligands can also act as internal base in sigma-bond heterolytic activation reactions. In addition, the ability of the polyhydrides OsH6((PPr3)-Pr-i)(2) and IrH5((PPr3)-Pr-i)(2) to activate C-H bonds is pointed out as one of the determining factors of the success in many cases

Formation of osmium-allylphosphinomethanide complexes by coupling of an isopropenyldiisopropylphosphine and monosubstituted allenes

Complex [Os(η5-C5H5){κ3-P,C,C-PiPr2[C(Me)═CH2]}(MeCN)]PF6 (1) reacts with cyclohexylallene and ethyl carboxylate allene to give the allylphosphinomethanide derivatives [Os(η5-C5H5){κ5-P,Ca,Cb,Cc,Cd-PiPr2[Ca(Me)CH2Cb(CcH2)CdHR]}]PF6 (R = Cy (2), CO2Et (3)). In fluorobenzene at 95 °C, complexes 2 and 3 evolve into the corresponding γ-allyl-α-alkenyldiisopropylphosphine compounds [OsH(η5-C5H5){κ4-P,Ca,Cb,Cc-PiPr2[C(═CH2)CH2Ca(CbH2)CcHR]}]PF6 (R = Cy (4), CO2Et (5)). Complexes 2 and 4 have been characterized by X-ray diffraction analysis.Financial support from the Spanish MICINN (Projects CTQ2011-23459 and Consolider Ingenio 2010 (CSD2007- 00006)), the Diputación General de Aragón (E35), and the European Social Fund is acknowledged.Peer Reviewe

Deacylative Alkylation vs. Photoredox Catalysis in the Synthesis of 3,3'‐Bioxindoles

The synthesis of 3,3'‐bioxindoles employing deacylative alkylations (DaA) in one‐pot process, where the 3‐bromooxindoles are generated in situ, is described. Good yields and moderate diastereoselections are obtained. By the modification of this procedure the synthesis of pure 3‐bromooxindoles through a deacylative bromination (DaB) is achieved. These bromides are efficiently employed in a photoredox dimerization process to get the desired 3,3'‐bioxindoles in good yields and low diastereoselections. In this single‐electron‐transfer (SET) mechanism the presence of a high quantum‐yield iridium(III) complex ensures high conversions in short reaction times.We gratefully acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (projects CTQ2016-81893REDT, and RED2018-102387-T) the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, CTQ2016-80375-P and CTQ2017-82935-P), the Generalitat Valenciana (PROMETEOII/2014/017), the University of Alicante, and Gobierno de Aragón (Group E06_17R and project LMP148_18). A. O.-M. thanks MINECO for a predoctoral fellowship

Ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenenes

We report a ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH2Cl2(PiPr3)2, which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3.2.0]heptane skeletons featuring cyclobutane rings. © 2011 American Chemical Society.This work was supported by the Spanish MICINN (Projects SAF2007-61015, SAF2010-20822-C02, CTQ2008-00810, and Consolider-Ingenio 2010 CSD2007-00006), CSIC, Xunta de Galicia (GRC2010/12, INCITE09 209 122 PR), Comunidad de Madrid (CCG08-CSIC/PPQ3548), Diputación General de Aragón (E35), the Marie Curie Foundation (PERG06-GA-2009- 256568), and the European Social Fund. M.G. thanks the Xunta de Galicia for a Parga Pondal Contract. A.C. thanks the CSIC for her JAE Grant.Peer Reviewe

Selective meta-C-H bond activation of substituted 1,3-chlorobenzenes promoted by an osmium pyridyl complex

Ethylene displaces both the acetone and phosphine ligands of [OsTp{κ1C-HNC5H3Me}(κ1- OCMe2)(PiPr3)]BF4 (2; Tp = hydrydotris(pyrazolyl)borate). The reaction takes place by stages. Initially the replacement of acetone gives the mono(olefin) derivative [OsTp{κ 1-C-[HNC5H3Me]}(η2-CH 2=CH2)(PiPr3)]BF4 (3). The substitution of the phosphine occurs at 120 °C and leads to the bis(olefin) complex [OsTp{κ1-C[HNC5H 3Me]}(η2-CH2=CH2) 2]BF4 (4). The NH wingtip of 3 and 4 undergoes deprotonation with tert-butoxide to afford the corresponding pyridyl compounds [OsTp{κ1-C[NC5H3Me]}(η2- CH2=CH2)(PiPr3)] (5) and [OsTp{κ1-C[NC5H3Me]}(η2- CH2=CH2)2] (6). At 60 °C, the solvents chloro-3-fluorobenzene, 1,3-dichlorobenzene, and 3-chlorotoluene displace the pyridyl ligand of 6 to yield the haloaryl derivatives [OsTp(3,5-C 6H3ClX)(η2-CH2=CH 2)2] (X = F (7), Cl (8), Me (9)) as a result of the selective meta-C-H bond activation of the haloarenes. © 2014 American Chemical Society.Financial support from the Spanish MINECO (Projects CTQ2011-23459 and Consolider Ingenio 2010 (CSD2007-00006)), the DGA (E35), and the European Social Fund (FSE) is acknowledged.Peer Reviewe