65 research outputs found
Functionalization of Pentaphosphorus Cations via Complexation
The chemistry of polyphosphorus cations has rapidly developed in recent years, but their coordination behavior has remained mostly unexplored. Herein, we describe the reactivity of [P5R2]+ cations with cyclopentadienyl metal complexes. The reaction of [CpArFe(ÎŒâBr)]2 (CpAr=C5(C6H4â4âEt)5) with [P5R2][GaCl4] (R=iPr and 2,4,6âMe3C6H2 (Mes)) afforded bicyclo[1.1.0]pentaphosphanes (1âR, R=iPr and Mes), showing an unsymmetric âbutterflyâ structure. The same products 1âR were formed from K[CpAr] and [P5R2][GaCl4]. The cationic complexes [CpArCo(η4âP5R2)][GaCl4] (2âR[GaCl4], R=iPr and Cy) and [(CpArNi)2(η3:3âP5R2)][GaCl4] (3âR[GaCl4]) were obtained from [P5R2][GaCl4] and [CpArM(ÎŒâBr)]2 (M=Co and Ni) as well as by using lowâvalent âCpArMIâ sources. Anion metathesis of 2âR[GaCl4] and 3âR[GaCl4] was achieved with Na[BArF24]. The P5 framework of the resulting salts 2âR[BArF24] can be further functionalized with nucleophiles. Thus reactions with [Et4N]X (X=CN and Cl) give unprecedented cyanoâ and chloroâfunctionalized complexes, while organoâfunctionalization was achieved with CyMgCl
Functionalization of Pentaphosphorus Cations by Complexation
The chemistry of polyphosphorus cations has rapidly developed in recent years, but their coordination behavior has remained mostly unexplored. Herein, we describe the reactivity of [P5R2]+ cations with cyclopentadienyl metal complexes. The reaction of [CpArFe(ÎŒâBr)]2 (CpAr=C5(C6H4â4âEt)5) with [P5R2][GaCl4] (R=iPr and 2,4,6âMe3C6H2 (Mes)) afforded bicyclo[1.1.0]pentaphosphanes (1âR, R=iPr and Mes), showing an unsymmetric âbutterflyâ structure. The same products 1âR were formed from K[CpAr] and [P5R2][GaCl4]. The cationic complexes [CpArCo(η4âP5R2)][GaCl4] (2âR[GaCl4], R=iPr and Cy) and [(CpArNi)2(η3:3âP5R2)][GaCl4] (3âR[GaCl4]) were obtained from [P5R2][GaCl4] and [CpArM(ÎŒâBr)]2 (M=Co and Ni) as well as by using lowâvalent âCpArMIâ sources. Anion metathesis of 2âR[GaCl4] and 3âR[GaCl4] was achieved with Na[BArF24]. The P5 framework of the resulting salts 2âR[BArF24] can be further functionalized with nucleophiles. Thus reactions with [Et4N]X (X=CN and Cl) give unprecedented cyanoâ and chloroâfunctionalized complexes, while organoâfunctionalization was achieved with CyMgCl
Iron- and cobalt-catalyzed synthesis of carbene phosphinidenes
In the presence of stoichiometric or catalytic amounts of [M{N(SiMe3)2}2] (M=Fe, Co), N-heterocyclic carbenes (NHCs) react with primary phosphines to give a series of carbene phosphinidenes of the type (NHC)·PAr. The formation of (IMe4)·PMes (Mes=mesityl) is also catalysed by the phosphinidene-bridged complex [(IMe4)2Fe-(m-PMes)]2, which provides evidence for metal-catalysed phosphinidene
transfer
VisibleâLightâTriggered Photoswitching of Diphosphene Complexes
Although diphosphene transition metal complexes are known to undergo E to Z isomerization upon irradiation with UV light, their potential for photoswitching has remained poorly explored. In this study, we present diphosphene complexes capable of reversible photoisomerizations through haptotropic rearrangements. The compounds [(2-Îș2P,Îș6C)Mo(CO)2][OTf] (3âa[OTf]), [(2-Îș2P,Îș6C)Fe(CO)][OTf] (3âb[OTf]), and [(2-Îș2P)Fe(CO)4][OTf] (4[OTf]) were prepared using the triflate salt [(LC)P=P(Dipp)][OTf] (2[OTf) as a precursor (LC=4,5-dichloro-1,3-bis(2,6-diisiopropylphenyl)-imidazolin-2-yl; Dipp=2,6-diisiopropylphenyl, OTf=triflate). Upon exposure to blue or UV light (λ=400â
nm, 470â
nm), the initially red-colored η2-diphosphene complexes 3âa,b[OTf] readily undergo isomerization to form blue-colored η1-complexes [(2-Îș1P,Îș6C)M(CO)n][OTf] (5âa,b[OTf]; a: M=Mo, n=2; b: M=Fe, n=1). This haptotropic rearrangement is reversible, and the (Îș2P,Îș6C)-coordination mode gradually reverts back upon dissolution in coordinating solvents or more rapidly upon exposure to yellow or red irradiation (λ=590â
nm, 630â
nm). The electronic reasons for the reversible visible-light-induced photoswitching observed for 3âa,b[OTf] are elucidated by DFT calculations. These calculations indicate that the photochromic isomerization originates from the S1 excited state and proceeds through a conical intersection
Filling a niche in âligand spaceâ with bulky, electron-poor phosphorus (III) alkoxides
The chemistry of phosphorus(III) ligands, which are of key importance in coordination chemistry, organometallic chemistry and catalysis, is dominated by relatively electron-rich species. Many of the electron-poor P(III) ligands that are readily available have relatively small steric profiles. As such, there is a significant gap in âligand spaceâ where more sterically bulky, electron-poor P(III) ligands are needed. This contribution discusses the coordination chemistry, steric and electronic properties of P(III) ligands bearing highly fluorinated alkoxide groups of the general form PRn(ORF)3-n, where R = Ph, RF = C(H)(CF3)2 and C(CF3)3; n = 1-3. These ligands are simple to synthesize and a range of experimental and theoretical methods suggest that their steric and electronic properties can be âtunedâ by modification of their substituents, making them excellent candidates for large, electron-poor ligands
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Dissolution behaviour and activation of selenium in phosphonium based ionic liquids
The dissolution behaviour of grey selenium in phosphonium based ionic liquids (ILs) has been investigated for the first time by P-31 and Se-77 nuclear magnetic resonance (NMR) experiments. The investigations evidence the formation of trialkylphosphane selenides which can serve as a selenium reservoir in the subsequent formation of metal selenides
1,3âDiphosphacyclobutene Cobalt Complexes
The synthesis and characterization of rare 1,3-diphosphacyclobutene transition-metal complexes is described. Reactions of the cobalt-hydride complex [Co(P(2)C(2)tBu(2))(2)H] (G) with nBuLi, tBuLi, or PhLi afforded [Li(solv)(x){Co(eta(3)-P(2)C(2)tBu(2)HR)(eta(4)-P(2)C(2)tBu(2))}] (1: R=nBu, (solv)(x)=(Et2O)(2); 2: R=tBu, (solv)(x)=(thf)(2); 3: R=Ph, (solv)(x)=(Et2O)(thf)(2)), with an eta(3)-coordinated 1,3-diphosphacyclobutene ligand as a result of organyl-anion attack at one of the phosphorus atoms of the bis(1,3-diphosphacyclobutadiene) backbone. In contrast to the reactions with PhLi, the aryl-magnesium compounds p-tolyl magnesium chloride and p-fluorophenyl magnesium bromide deprotonate [Co(P(2)C(2)tBu(2))(2)H] to give the magnesium salt [Mg(MeCN)(6)][Co(eta(4)-P(2)C(2)tBu(2))(2)](2) (4), which contains a bis(1,3-diphosphacyclobutadiene)-cobaltate anion. The [Co(eta(4)-P(2)C(2)tBu(2))(2)](-) anions are well separated from the octahedral [Mg(MeCN)(6)](2+) cation in the molecular structure of 4. Compound 1 reacts with Me3SiCl to give neutral [Co(eta(3)-P(2)C(2)tBu(2)HnBu)(eta(4)-P(2)C(2)tBu(2)SiMe(3))] (5, 52 % yield) with an SiMe3 group attached to one of the P atoms of the previously unfunctionalized backbone
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