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In this contribution we describe the general use of aryl-substituted triphosphiranes (Ar3P3; Ar = Mes, Dip, Tip) as phosphinidene transfer reagents towards N-heterocyclic carbenes (NHCs) to give a library of twelve N-heterocyclic carbene phosphinidene adducts of the type ArP＝NHC (NHCPs), in which the NHCs have varying steric profiles, allowing a systematic evaluation of their structural and NMR-spectroscopic properties. In the next series of experiments we utilized 1,3- and 1,4-phenylene bridged bis-NHCs to access a new class of chelating bis(NHCP)s, of which three derivatives could be structurally characterized. The 1,4-phenylene derivatives were shown to be susceptible to P–CNHC bond cleavage when irradiated with an LED (396 nm), providing a rare example of phosphinidene release from NHCPs. The coordination chemistry of 1,3-phenylene bridged bis(NHCP)s towards GeCl2(dioxane) and GaI3 was investigated and revealed the formation of ion-separated cationic complexes, with significant charge transfer from the ligand to the metal center according to NBO analyses. [ABSTRACT FROM AUTHOR]

Primary and secondary amines selectively react with the lactone moiety of γ-valerolactone oxide (GVLO). Several primary amines afforded the resulting epoxyamides with an intact epoxy group. In some cases addition of two equivalents of amine resulted in additional epoxide opening to give α,γ-dihydroxy-β-amino-amides. The selective lactone-opening in GVLO was further corroborated by DFT-studies. [ABSTRACT FROM AUTHOR]

In here we present the deoxygenation of the chalcogen oxides EO2 (E = S, Se) with R-P(PMe3), so-called phospha-Wittig reagents. The reaction of DABSO (DABCO·2SO2) with R-P(PMe3) (R = Mes*, 2,4,6-tBu3-C6H2; MesTer, 2,6-(2,4,6-Me3-C6H2)2-C6H3) resulted in the formation of thiadiphosphiranes (RP)2S (1:R), while selenadiphosphiranes (RP)2Se (2:R) were afforded with SeO2, both accompanied by the formation of OPMe3. Utilizing the sterically more encumbered DipTer-P(PMe3) (DipTer = 2,6-(2,6-iPr2-C6H3)2-C6H3) a different selectivity was observed and (DipTerP)2Se (2:DipTer) along with [Se(μ-PDipTer)]2 (3:DipTer) were isolated as the Se-containing species in the reaction with SeO2. Interestingly, the reaction with DABSO (or with equimolar ratios of SeO2 at elevated temperatures) gave rise to the formation of the OPMe3-stabilized dioxophosphorane (phosphinidene dioxide) DipTerP(O)2-OPMe3 (4:DipTer) as the main product. This contrasting reactivity can be rationalized by two potential pathways in the reaction with EO2: (i) a Wittig-type pathway and (ii) a pathway involving oxygenation of the phospha-Wittig reagents and release of SO. Thus, phospha-Wittig reagents are shown to be useful synthetic tools for the metal-free deoxygenation of EO2 (E = S, Se). [ABSTRACT FROM AUTHOR]

The isolation of the first diarsene radical anion by reduction of a neutral diarsene is presented. Comprehensive characterisation in conjunction with DFT calculations reveals unpaired spin density residing in the antibonding π*-orbital with involvement of the terphenyl ligands. First reactivity studies reveal no pronounced radical, but rather reducing properties. [ABSTRACT FROM AUTHOR]

Phosphanylidenephosphoranes of the type R–P(PR′3), also known as phospha-Wittig reagents, can be utilized in a variety of bond activation reactions exploiting their phosphinidenoid reactivity. Herein, we thoroughly show that a facile PMe3 for H2O exchange gives access to various primary phosphine oxides of the general formula RP(H)2O (R = Mes*, MesTer, DipTer) and the molecular structure of DipTerP(O)H2 was determined. However, phosphanylidenephosphoranes are described to be highly nucleophilic as well. We show that the attachment of main group Lewis acids such as GaCl3 and GaI3 to R–P(PMe3) yielded the highly sensitive, yet stable coordination compounds [(RPGaX3)PMe3] (R = Mes*, DipTer) or [(RPPMe3)2GaCl2]GaCl4 (R = MesTer). In contrast to the free phosphanylidenephosphoranes, these species reacted differently with H2O, which was demonstrated for [(Mes*PPMe3)GaI3]. Here the formation of the phosphino-phosphonium cation [Mes*P(H)PMe3]+ and different anions was observed with combined NMR spectroscopic and SC-XRD (SC-XRD = single crystal X-ray diffraction analysis) studies. This work demonstrates that the ambiphilic character of phosphanylidenephosphoranes can be utilized to manipulate the reactivity of R–P(PMe3) towards water, giving primary phosphine oxides, whereas the Lewis acid adducts [(RPGaX3)PMe3] gave phosphino-phosphonium species. [ABSTRACT FROM AUTHOR]

Classically tetraaryl diphosphanes have been synthesized through Wurtz-type reductive coupling of halophosphanes R2PX or more recently, through the dehydrocoupling of phosphines R2PH. Catalytic variants of the dehydrocoupling reaction have been reported, but are limited to R2PH compounds. Using PEt3 as a catalyst, we now show that TipPBr2 (Tip = 2,4,6-iPr3C6H2) is selectively coupled to give the dibromodiphosphane (TipPBr)2 (1), a compound not accessible using classic Mg reduction. Surprisingly, when using DipPBr2 (Dip = 2,6-iPr3C6H3) in the PEt3 catalysed reductive coupling the diphosphene (PDip)2 (2) with a P＝P double was formed selectively. In benzene solutions (PDip)2 has a half life time of ca. 28 days and can be utilized with NHCs to access NHC-phosphinidene adducts. To show that this protocol is more widely applicable, we show that Ph2PCl and Mes2PX (X = Cl, Br) are efficiently coupled using 10 mol% of PEt3 to give (Ph2P)2 and (Mes2P)2, respectively. Control experiments show that [BrPEt3]Br is a potential oxidation product in the catalytic cycle, which can be debrominated by Zn dust as a sacrificial reductant. [ABSTRACT FROM AUTHOR]

The phospha–Wittig reagent MesTerPPMe3 (MesTer = 2,6-{2,4,6-Me3–C6H2}–C6H3) and arsa–Wittig reagent DipTerAsPMe3 (DipTer = 2,6-{2,6-iPr2-C6H3}–C6H3) have been employed to synthesize the titanocene complexes Cp2Ti(PMe3)PnAr (Pn = P, As) with terminal phosphinidene or arsinidene ligands, respectively. Ab initio studies show that the description as singlet biradicaloids in their ground state is warranted. [ABSTRACT FROM AUTHOR]

Phospha–Wittig reagents, RPPMe3 (R = Mes* 2,4,6-tBu3-C6H2; MesTer 2,6-(2,4,6-Me3C6H2)-C6H3; DipTer 2,6-(2,6-iPr2C6H3)-C6H3), can be considered as phosphine-stabilized phosphinidenes. In this study we show that PMe3 can be displaced by NHCs or NHOs. Interestingly, phosphinidene-like reactivity results in a subsequent C(sp2)–H activation of the exocyclic CH2 group in NHOs. This concept was further extended to allyl-apended NHOs, which resulted in phosphine-substituted allyl species. [ABSTRACT FROM AUTHOR]

Cyclotriarsanes are rare and described herein is a scalable synthetic protocol towards (AsAr)3, which allowed to study their reactivity towards [Cp2Ti(C2(SiMe3)2)], affording titanocene diarsene complexes, and towards N-heterocyclic carbenes (NHCs) to give straightforward access to a variety of NHC-arsinidene adducts. [ABSTRACT FROM AUTHOR]

Terphenyl(bisamino)phosphines have been identified as effective ligands in cationic gold(I) complexes for the hydroamination of acetylenes. These systems are related to Buchwald phosphines and their steric properties have been evaluated. Effective hydroamination was noted even at low catalyst loadings and a series of cationic gold(I) complexes has been structurally characterized clearly indicating stabilizing effects through gold-arene interactions. [ABSTRACT FROM AUTHOR]

New complexes containing N-heterocyclic vinylene-stabilized [B2H5]+ fragments were prepared, and surprisingly it was found that the precursor N-heterocyclic olefins (NHOs) could promote the mild (room temperature) catalytic hydroborylation of ketones and aldehydes. This finding represents an important addition to the burgeoning field of non-metal mediated catalysis. [ABSTRACT FROM AUTHOR]

The reaction of lithium N-trimethylsilyl-amides of the type RN(SiMe3)Li with bismuth(iii) chloride yielded mono-, di- or triaminobismuthanes depending on the sterical demand of the anilide ligand R and the used stoichiometry. For the bulky Mes* substituent the reaction with BiCl3 resulted in the formation of a C–C coupling product as the main product besides a small amount of the expected Mes*N(SiMe3)BiCl2. [ABSTRACT FROM AUTHOR]

Different reactions of Mes* substituted phosphanes (Mes* = 2,4,6-tri-tert-butylphenyl) led to the formation of the bicyclic tetraphosphane Mes*P4Mes* (5) and its unknown Lewis acid adduct 5·GaCl3. In this context, the endo–exo isomer of 5 was fully characterized for the first time. The synthesis was achieved by reactions involving “self-assembly” of the P4 scaffold from P1 building blocks (i.e. primary phosphanes) or by reactions starting from P2 or P4 scaffolds (i.e. a diphosphene or cyclic tetraphosphane). Furthermore, interconversion between the exo–exo and endo–exo isomer were studied by 31P NMR spectroscopy. All compounds were fully characterized by experimental as well as computational methods. [ABSTRACT FROM AUTHOR]

A donor-acceptor complex of HBNH was prepared via thermolysis of a carbene-stabilized azidoborane. The reactivity of the fundamentally important HBNH unit (inorganic alkyne analogue) was explored in detail, including attempts to convert this species and related hydrido(azido)borane cations into molecular complexes of BN. This work provides added impetus for the development of molecular precursors that can release bulk boron nitride (a desirable insulator and thermal conductor) under mild conditions, and from solution.