Phosphine boran

Ir-catalyzed hydrosilylation of the alkenyl phosphine borane complex 1 was achieved to give the corresponding products 2 . Because the phosphino group coordinates with metals and is unstable under aerobic conditions, the formation of the corresponding borane adduct was effective not only to promote the target hydrosilylation but also to keep 1 stable under aerobic conditions. The removal of coordinated borane from 2 was readily performed with the treatment by 1,4-diazabicyclo[2.2.2]octane to apply to further transformations...

The electronic features of gold-aluminyl complexes have been thoroughly explored. Their similarity with Group 14 dimetallenes and other metal-aluminyl complexes suggests that their reactivity with small molecules beyond carbon dioxide could be accessed. In this work, the reactivity of the [tBu3PAuAl(NON)] complex towards water, ammonia, sulfur dioxide and nitrous oxide is computationally explored. The reaction mechanisms computed for each substrate strongly suggest that all activation processes are in principle experimentally feasible...

The reactivity of [PB{SiX2 }] (X = Cl, Br; PB = 1,2-i Pr2 (C6 H4 )BCy2 ; E = Si, Ge) adducts is described, with an initial focus on reduction attempts to access [PB{E}] x species; however, in all cases only free PB ligand was formed as the soluble product. Moreover, computations were performed to evaluate the energy penalty associated with EX2 dissociation from the PB chelates. Moving up the periodic table, the formal methylene adduct [PB{CH2 }] was isolated and its reactivity was compared with its heavier element congeners of [PB{EH2 }]...

Phosphine ligands are the most important class of ligands for cross-coupling reactions due to their unique electronic and steric properties. However, metalloproteins generally rely on nitrogen, sulfur, or oxygen ligands. Here, we report the genetic incorporation of P3BF, which contains a biocompatible borane-protected phosphine, into proteins. This step is followed by a straightforward one-pot strategy to perform deboronation and palladium coordination in aqueous and aerobic conditions. The genetically encoded phosphine ligand P3BF should significantly expand our ability to design functional metalloproteins...

Air-stable amine- and phosphine-boranes are discovered as donors to integrate with pyridinium acceptor for generating photoactive electron-donor-acceptor (EDA) complexes. Experimental results and DFT calculations suggest a dihydrogen bond bridging the donor and acceptor. Illuminating the EDA complex enables an intramolecular single electron transfer to give boron-centered radical for dehydrogenative borylation with no need of external photosensitizer and radical initiator. The deprotonation of Wheland-like radical intermediate rather than its generation is believed to determine the good ortho -selectivity based on DFT calculations...

An amphiphilic block copolymer of polyphosphinoborane has been prepared by a mechanism-led strategy of the sequential catalytic dehydropolymerization of precursor monomers, H3B·PRH2 (R = Ph, n-hexyl), using the simple pre-catalyst [Rh(Ph2PCH2CH2PPh2)2]Cl. Speciation, mechanism and polymer chain growth studies support a step-growth process where reversible chain transfer occurs, i.e. H3B·PRH2/oligomer/polymer can all coordinate with, and be activated by, the catalyst. Block copolymer [H2BPPhH]110-b-[H2BP(n-hexyl)H]11 can be synthesized and self-assembles in solution to form either rod-like micelles or vesicles depending on solvent polarity...

The title compound, alternatively called (4-bromophenyl)dihydrido(triphenylphosphanyl)boron, C24 H21 BBrP, crystallizes in the space group P-1 with one symmetry-independent molecule in the asymmetric unit. The B and P atoms both adopt the expected tetrahedral geometry. A possible intramolecular B-Hδ- ...δ+ H-C dihydrogen bond exists between an arene group on phosphorus and the borane center. In the solid state, the title molecule is connected to its neighbors by intermolecular C-H...π interactions, with the arene rings on the P atom acting as hydrogen-bond donors and the arene ring of the borane acting as the acceptor...

An intramolecular phosphine-borane frustrated Lewis pair (FLP) chelate, i Pr2 P(C6 H4 )BCy2 or PB (Cy = cyclohexyl), was used to coordinate aminoborane (H2 BNH2 ) and iminoborane (HBNH) units via donor-acceptor stabilization. Attempts to induce dehydrogenation from these B-N adducts with known metal catalysts (or pre-catalysts) have been unsuccessful thus far, and related observations were noted with an H2 BNH2 complex supported by a modified FLP chelate bearing a geometrically constrained bicyclic 9-borabicyclo(3...

Stoichiometric reaction of phosphine-borane adducts RR'PH•BH 3 (R = Ph, R' = H, Ph, Et, and R = R' = t Bu) with the strong acid, HNTf 2 (Tf = SO 2 CF 3 ) leads to H 2 elimination and the formation of the triflimido derivatives, RR'PH•BH 2 (NTf 2 ). Subsequent deprotonation using bases such as diisopropylethylamine or the carbene IPr (IPr = N,N' -bis(2,6-diisopropylphenyl)imidazol2-ylidene) results in the formation P-mono- or -disubstituted polyphosphinoboranes [RR'P-BH 2 ] n . Evidence for the intermediacy of transient phosphinoborane monomers, RR'PBH 2 , was provided by trapping reactions...

Two borane-functionalized bidentate phosphine ligands that vary in tether length have been prepared to examine cooperative metal-substrate interactions. Ni(0) complexes react with aryl azides at low temperatures to form structurally unusual κ2 -( N,N )-N3 Ar adducts. Warming these adducts affords products of N2 extrusion and in one case, a Ni-imido compound that is capped by the appended borane. Reactions with 1-azidoadamantane (AdN3 ) provide a distinct outcome, where a proposed nickel imido intermediate activates the sp2 C-H bonds of arenes, even in the presence of benzylic C-H sites...

We report a diversification strategy that enables the direct substituent exchange of tertiary phosphines. Alkylated phosphonium salts, prepared by standard alkylation of phosphines, are selectively dearylated in a nickel-catalysed process to access alkylphosphine products via a formal substitution at the phosphorus center. The reaction can be used to introduce a wide range of alkyl substituents into both mono- and bisphosphines. We also show that the alkylation and dearylation steps can be conducted in a one-pot sequence, enabling accelerated access to derivatives of the parent ligand...

The reactions of FLPs with diazomethanes leads to the rapid loss of N2 . In contrast, in this work, we reported reactions of phosphine/borane FLPs with chlorodiazirines which led to the reduction of the N=N double bond, affording linked phosphinimide/amidoborate zwitterions of the general form R3 PNC(Ar)NR'BX(C6 F5 )2 . A detailed DFT mechanistic study showed that these reactions proceed via FLP addition to the N=N bond, followed by subsequent group transfer reactions to nitrogen and capture of the halide anion...

Glycoconjugation is a powerful tool to improve the anticancer activity of metal complexes. Herein, we modified commercial arylphosphanes with carbohydrate-derived fragments for the preparation of novel glycoconjugated ruthenium(II) p-cymene complexes. Specifically, d-galactal and d-allal-derived vinyl epoxides (VEβ and VEα) were coupled with (2-hydroxyphenyl)diphenylphosphane, affording the 2,3-unsaturated glycophosphanes 1β and 1α. Ligand exchange with [Ru(C2 O4 )(η6 -p-cymene)(H2 O)] gave the glycoconjugated complexes Ru1β and Ru1α which were subsequently dihydroxylated with OsO4 /N-methylmorpholine N-oxide to Ru2β and Ru2α containing O-benzyl d-mannose and d-gulose units respectively...

Reactions of PAr 3 /B(C 6 F 5 ) 3 (Ar = o -Tol, Mes, Ph) FLPs with diethyl azodicarboxylate (DEAD) afford the corresponding FLP addition products 1-3 in which P-N and B-O linkages are formed. In contrast, the reaction of BPh 3 , PPh 3 and DEAD gave the product 4 where P-N and N-B binding was confirmed. In all cases, other binding modes were computed to be both higher in energy and readily distinguishable by 31 P and 11 B NMR parameters. These data clarify the binding mode in previously reported FLP polymers and illustrate the influence of steric demands and electronic structures on the nature of the products of FLP reactions with DEAD...

Despite the high levels of interest in the synthesis of bio-inspired [FeFe]-hydrogenase complexes, H2 oxidation, which is one specific aspect of hydrogenase enzymatic activity, is not observed for most reported complexes. To attempt H-H bond cleavage, two disubstituted diiron dithiolate complexes in the form of [Fe2 (μ-pdt)L2 (CO)4 ] (L: PMe3 , dmpe) have been used to play the non-biomimetic role of a Lewis base, with frustrated Lewis pairs (FLPs) formed in the presence of B(C6 F5 )3 Lewis acid. These unprecedented FLPs, based on the bimetallic Lewis base partner, allow the heterolytic splitting of the H2 molecule, forming a protonated diiron cation and hydrido-borate anion...

The accurate prediction of the basicity of tertiary phosphines in acetonitrile and water is reported by the linear correlation between computed Δp K a 's obtained by density functional theory (DFT) and experimental values extracted from the literature. This method is applied to the prediction of p K a values of 9-phosphatriptycene derivatives and showed that they are weaker Brønsted bases than their triphenylphosphine analogues. This lower reactivity is attributed to their high pyramidalization that increases their lone pair 3s character, stabilizing its energy level...

The primary phosphines MesPH2 and tBuPH2 react with 9-iodo-m-carborane yielding B9-connected secondary carboranylphosphines 1,7-H2 C2 B10 H9 -9-PHR (R=2,4,6-Me3 C6 H2 (Mes; 1 a), tBu (1 b)). Addition of tris(pentafluorophenyl)borane (BCF) to 1 a, b resulted in the zwitterionic compounds 1,7-H2 C2 B10 H9 -9-PHR(p-C6 F4 )BF(C6 F5 )2 (2 a, b) through nucleophilic para substitution of a C6 F5 ring followed by fluoride transfer to boron. Further reaction with Me2 SiHCl prompted a H-F exchange yielding the zwitterionic compounds 1,7-H2 C2 B10 H9 -9-PHR(p-C6 F4 )BH(C6 F5 )2 (3 a, b)...

Generation of dihydrogen from water splitting, also known as water reduction, is a key process to access a sustainable hydrogen economy for energy production and usage. The key step is the selective reduction of a protic hydrogen to an accessible and reactive hydride, which has proven difficult at a p-block element. Although frustrated Lewis pair (FLP) chemistry is well known for water activation by heterolytic H-OH bond cleavage, to the best of our knowledge, there has been only one case showing water reduction by metal-free FLP systems to date, in which silylene (SiII ) was used as the Lewis base...

While of interest, synthetically feasible access to boryl ligands and complexes remains limited, meaning such complexes remain underexploited in catalysis. For bidentate boryl ligands, oxidative addition of boranes to low-valent IrI or Pt0 are the only examples yet reported. As part of our interest in developing improved group 10 ethylene polymerization catalysts, we present here an optimized synthesis of a novel, rigid borane/phosphine ligand and its Ni0 σ-borane complex. From the latter, an unprecedented oxidative dehydrochloroborylation, to give a NiII boryl complex, was achieved...

A highly versatile synthesis of amine-boranes via carbonyl reduction by sodium borohydride is described. Unlike the prior bicarbonate-mediated protocol, which proceeds via a salt metathesis reaction, the carbon dioxide-mediated synthesis proceeds via reduction to a monoformatoborohydride intermediate. This has been verified by spectroscopic analysis, and by using aldehydes and ketones as the carbonyl source for the activation of sodium borohydride. This process has been used to produce borane complexes with 1°-, 2°-, and 3°-amines, including those with borane reactive functionalities, heteroarylamines, and a series of phosphines...