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 [Cp^ArFe(μ‐Br)]₂ (Cp^Ar=C₅(C₆H₄‐4‐Et)₅) with [P₅R₂][GaCl₄] (R=iPr and 2,4,6‐Me₃C₆H₂ (Mes)) afforded bicyclo[1.1.0]pentaphosphanes ( 1‐R , R=iPr and Mes), showing an unsymmetric “butterfly” structure. The same products 1‐R were formed from K[Cp^Ar] and [P₅R₂][GaCl₄]. The cationic complexes [Cp^ArCo(η⁴‐P₅R₂)][GaCl₄] ( 2‐R [GaCl₄], R=iPr and Cy) and [(Cp^ArNi)₂(η^3:3‐P₅R₂)][GaCl₄] ( 3‐R [GaCl₄]) were obtained from [P₅R₂][GaCl₄] and [Cp^ArM(μ‐Br)]₂ (M=Co and Ni) as well as by using low‐valent “Cp^ArM^I” sources. Anion metathesis of 2‐R [GaCl₄] and 3‐R [GaCl₄] was achieved with Na[BArF₂₄]. The P₅ framework of the resulting salts 2‐R [BArF₂₄] can be further functionalized with nucleophiles. Thus reactions with [Et₄N]X (X=CN and Cl) give unprecedented cyano‐ and chloro‐functionalized complexes, while organo‐functionalization was achieved with CyMgCl.     

Stabilization and Transfer of the Transient [Mes*P4]− Butterfly Anion Using BPh3

The transient bicyclo[1.1.0]tetraphosphabutane anion, generated from white phosphorus (P₄) and Mes*Li (Mes*=2,4,6‐tBu₃C₆H₂), can be trapped by BPh₃ in THF. This Lewis acid stabilized anion can be used as an [RP₄]^? transfer agent, reacting cleanly with neutral Lewis acids (B(C₆F₅)₃, BH₃, and W(CO)₅) to afford unique singly and doubly coordinated butterfly anions, and with the trityl cation to form a neutral, nonsymmetrical, all‐carbon‐substituted P₄ derivative. This reaction path enables a simple, stepwise functionalization of white phosphorus.     

A Tricyclic Hexaphosphane

The reaction of the functionalized cyclo‐tetraphosphane [ClP(μ‐PMes*)]₂ (Mes*=2,4,6‐tri‐tert‐butylphenyl) with different Lewis bases led to the formation of an unprecedented tricyclic hexaphosphane, Mes*P₆Mes*. The formation of this compound was investigated by spectroscopic and theoretical methods, revealing an unusual ring expansion reaction. The title compound was fully characterized by experimental and computational methods.     

Selective [3+1] Fragmentations of P4 by “P” Transfer from a Lewis Acid Stabilized [RP4]− Butterfly Anion

Two [3+1] fragmentations of the Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutanide Li[Mes*P₄⋅ BPh₃] (Mes*=2,4,6‐tBu₃C₆H₂) are reported. The reactions proceed by extrusion of a P₁ fragment, induced by either an imidazolium salt or phenylisocyanate, with release of the transient triphosphirene Mes*P₃, which was isolated as a dimer and trapped by 1,3‐cyclohexadiene as a Diels–Alder adduct. DFT quantum chemical computations were used to delineate the reaction mechanisms. These unprecedented pathways grant access to both P₁‐ and P₃‐containing organophosphorus compounds in two simple steps from white phosphorus.     

CsF als Fluoridierungsmittel für Organometall-Verbindungen der Elemente der Gruppe 13

CsF as Fluoridation Agent for Organometal Compounds of the Elements of Group 13 Cs[i-Bu₃AlF] ( 1 ) can be obtained by the reaction of Al(i-Bu)₃ with CsF in toluene. In a halide exchange reaction of Mes*GaCl₂ with CsF in acetonitrile not the desired product Mes*GaF₂ (Mes* = 2,4,6-(t-Bu)₃C₆H₂) was isolated but the metalate Cs[Mes*GaF₃] ( 2 ), formed by the addition of a third unit CsF. A ligand distribution was observed by the treatment of [(PhCH₂)₂GaTe(t-Bu)]₂ with CsF in THF. The triorganofluoro gallate [Cs{(PhCH₂)₃GaF}]₂ ( 3 ) was isolated. The triorganofluoro gallate Cs[Me₃GaF] does not react with dry O₂ in THF. With S₈ in THF a reaction was achieved and the diorganodifluoro gallate [Cs(THF)_0,5(Me₂GaF₂)] ( 4 ) could be characterized. The treatment of MesInBr₂ with CsF in acetonitrile gives as only identified compound the indate Cs[MesInBr₃] ( 5 ).     

Cationic Functionalisation by Phosphenium Ion Insertion

The reaction of [Cp′′′Ni(η³-P₃)] ( 1 ) with in situ generated phosphenium ions [RR′P]⁺ yields the unprecedented polyphosphorus cations of the type [Cp′′′Ni(η³-P₄R₂)][X] (R=Ph ( 2 a ), Mes ( 2 b ), Cy ( 2 c ), 2,2′-biphen ( 2 d ), Me ( 2 e ); [X]⁻=[OTf]⁻, [SbF₆]⁻, [GaCl₄]⁻, [BAr^F]⁻, [TEF]⁻) and [Cp′′′Ni(η³-P₄RCl)][TEF] (R=Ph ( 2 f ), tBu ( 2 g )). In the reaction of 1 with [Br₂P]⁺, an analogous compound is observed only as an intermediate and the final product is an unexpected dinuclear complex [{Cp′′′Ni}₂(μ,η³:η¹:η¹-P₄Br₃)][TEF] ( 3 a ). A similar product [{Cp′′′Ni}₂(μ,η³:η¹:η¹-P₄(2,2′-biphen)Cl)][GaCl₄] ( 3 b ) is obtained, when 2 d [GaCl₄] is kept in solution for prolonged times. Although the central structural motif of 2 a – g consists of a “butterfly-like” folded P₄ ring attached to a {Cp′′′Ni} fragment, the structures of 3 a and 3 b exhibit a unique asymmetrically substituted and distorted P₄ chain stabilised by two {Cp′′′Ni} fragments. Additional DFT calculations shed light on the reaction pathway for the formation of 2 a – 2 g and the bonding situation in 3 a .     

Aluminium Diphosphamethanides: Hidden Frustrated Lewis Pairs

The synthesis and characterisation of two aluminium diphosphamethanide complexes, [Al(tBu)₂{κ²P,P′‐Mes*PCHPMes*}] ( 3 ) and [Al(C₆F₅)₂{κ²P,P′‐Mes*PCHPMes*}] ( 4 ), and the silylated analogue, Mes*PCHP(SiMe₃)Mes* ( 5 ), are reported. The aluminium complexes feature four‐membered PCPAl core structures consisting of diphosphaallyl ligands. The silylated phosphine 5 was found to be a valuable precursor for the synthesis of 4 as it cleanly reacts with the diaryl aluminium chloride [(C₆F₅)₂AlCl]₂. The aluminium complex 3 reacts with molecular dihydrogen at room temperature under formation of the acyclic σ²λ³,σ³λ³‐diphosphine Mes*PCHP(H)Mes* and the corresponding dialkyl aluminium hydride [tBu₂AlH]₃. Thus, 3 belongs to the family of so‐called hidden frustrated Lewis pairs.     

Diverse Reactivity of an Electrophilic Phosphasilene towards Anionic Nucleophiles: Substitution or Metal–Amino Exchange

The reaction of MesLi (Mes=2,4,6‐trimethylphenyl) with the electrophilic phosphasilene R₂(NMe₂)Si‐RSi=PNMe₂ ( 2 , R=Tip=2,4,6‐triisopropylphenyl) cleanly affords R₂(NMe₂)Si‐RSi=PMes and thus provides the first example of a substitution reaction at an unperturbed Si=P bond. In toluene, the reaction of 2 with lithium disilenide, R₂Si=Si(R)Li ( 1 ), apparently proceeds via an initial nucleophilic substitution step as well (as suggested by DFT calculations), but affords a saturated bicyclo[1.1.0]butane analogue as the final product, which was further characterized as its Fe(CO)₄ complex. In contrast, in 1,2‐dimethoxyethane the reaction of 1 with 2 results in an unprecedented metal–amino exchange reaction.     

Structural Diversity of Calcium Organocuprates(I): Synthesis of Mesityl Cuprates via Addition and Transmetalation Reactions of Mesityl Copper(I)

The addition of [(L)₄Ca(I)Mes] (Lewis base L=thf, Et₂O) to mesityl copper(I) and the transmetalation reaction of mesityl copper(I) with activated calcium are suitable pathways for the synthesis of dimesityl cuprates(I) of calcium. However, the structures of the calcium cuprates(I) depend on the preparative procedure. The transmetalation reaction leads to the formation of [Mes‐Cu‐Mes]^? anions whereas the addition yields dinuclear [(Mes‐Cu)₂(μ‐Mes)]^? anions. The solvent‐separated counterions are [Ca(thf)₆]²⁺ and [(thf)₅CaI]⁺, respectively. In contrast to these findings, the addition of [(L)₄Ca(I)Mes] to mesityl copper(I) in an Et₂O/toluene mixture led to formation of tetrameric solvent‐free iodocalcium dimesityl cuprate(I) [ICa(μ‐η¹,η⁶‐Mes₂Cu)]₄, representing a rare example of a heavy Normant‐type organocuprate.     

Synthesis of Cationic R2P5+ Cages and Subsequent Chalcogenation Reactions

Cationic R₂P₅⁺ cage compounds ( 1 ⁺) have been synthesized by the stoichiometric reaction of R₂PCl, GaCl₃ and P₄. The reaction conditions depend on the substituent R. Alkyl‐substituted derivatives ( 1 a – 1 d [GaCl₄]) are best synthesized under solvent‐free conditions, whereas aryl‐substituted derivatives ( 1 e – 1 h [GaCl₄]) are formed in C₆H₅F. All compounds have been prepared on a multi‐gram scale in good to excellent yields and have been fully characterized with an emphasis on ³¹P NMR spectroscopy in solution and single‐crystal structure determination. Subsequent chalcogenation reactions of cations R₂P₅⁺ ( 1 a ⁺, 1 e ⁺) and trication Ph₆P₇³⁺ ( 3 ³⁺) with elemental sulfur (α‐S₈) or grey selenium (Se_grey) yielded a series of unique polyphosphorus–chalcogen cations ( 4 a ⁺, 4 e ⁺, 5 a ⁺, 6 ²⁺ and 7 ²⁺), possessing nortricyclane‐type molecular structures. An in‐depth study of the ³¹P{¹H} and ⁷⁷Se NMR spectroscopic parameters is presented, and correlations between the substitution pattern and the observed structural features have been investigated in detail.     

Unusual Reactivity of Sodium Tetramesityltetraphosphanediide towards Cyclohexyl Isocyanide

The reaction of [Na₂(thf)₄(P₄Mes₄)] (Mes=2,4,6‐Me₃C₆H₂) with cyclohexyl isocyanide (2:5) resulted in the formation of the heterocyclic N‐(tetramesityltetraphosphacyclopentylidene)cyclohexylamine [cyclo‐{P₄Mes₄C(NCy)}] ( 2 ) (30–35 %), the unusual 1,3,5‐triphospha‐1,4‐pentadiene ( 3 ) (40–45 %), and small amounts of the dimeric iminomethylidenephosphane cyclo‐{PMesC(NCy)}₂ ( 4 ). With catalytic amounts of AgBF₄, 2 was the major product. The reaction of 2 with [CuBr(SMe₂)] (1:1) produced bromido‐bridged dimeric Cu^I complex 5 . Molecular structures of compounds 3 , 4 , and 5 were obtained.     

The Complexed 1,3‐Diphospha‐2‐Arsaallyl Radical and Its Cationic and Anionic Derivatives

Photolysis of [Cp*As{W(CO)₅}₂] ( 1 a ) in the presence of Mes*P?PMes* (Mes*=2,4,6‐tri‐tert‐butylphenyl) leads to the novel 1,3‐diphospha‐2‐arsaallyl radical [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄] ( 2 a ). The frontier orbitals of the radical 2 a are indicative of a stable π‐allylic system that is only marginally influenced by the d orbitals of the two tungsten atoms. The SOMO and the corresponding spin density distribution of the radical 2 a show that the unpaired electron is preferentially located at the two equivalent terminal phosphorus atoms, which has been confirmed by EPR spectroscopy. The protonated derivative of 2 a , the complex [(CO)₅W(μ,η²:η¹‐P₂As(H)Mes*₂)W(CO)₄] ( 6 a ) is formed during chromatographic workup, whereas the additional products [Mes*P?PMes*{W(CO)₅}] as the Z‐isomer ( 3 ) and the E‐isomer ( 4 ), and [As₂{W(CO)₅}₃] ( 5 ) are produced as a result of a decomposition reaction of radical 2 a . Reduction of radical 2 a yields the stable anion [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄]^? in 7 a , whereas upon oxidation the corresponding cationic complex [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄][SbF₆] ( 8 a ) is formed, which is only stable at low temperatures in solution. Compounds 2 a , 7 a , and 8 a represent the hitherto elusive complexed redox congeners of the diphospha‐arsa‐allyl system. The analogous oxidation of the triphosphaallyl radical [(CO)₅W(μ,η²:η¹‐ P₃Mes*₂)W(CO)₄] ( 2 b ) also leads to an allyl cation, which decomposes under CH activation to the phosphine derivative [(CO)₅W{μ,η²:η¹‐P₃(Mes*)(C₅H₂tBu₂C(CH₃)₂CH₂)}W(CO)₄] ( 9 ), in which a CH bond of a methyl group of the Mes* substituent has been activated. All new products have been characterized by NMR spectrometry and IR spectroscopy, and compounds 2 a , 3 , 6 a , 7 a , and 9 by X‐ray diffraction analysis.     

Synthesis of a Molecule with Four Different Adjacent Pnictogens

The synthesis of a molecule containing four adjacent different pnictogens was attempted by conversion of a Group 15 allyl analogue anion [Mes*NAsPMes*]^? (Mes*=2,4,6‐tri‐tert‐butylphenyl) with antimony(III) chloride. A suitable precursor is Mes*N(H)AsPMes* ( 1 ) for which several syntheses were investigated. The anions afforded by deprotonation of Mes*N(H)AsPMes* were found to be labile and, therefore, salts could not be isolated. However, the in situ generated anions could be quenched with SbCl₃, yielding Mes*N(SbCl₂)AsPMes* ( 4 ).     

Aggregation and Degradation of White Phosphorus Mediated by N‐Heterocyclic Carbene Nickel(0) Complexes

The reaction of zerovalent nickel compounds with white phosphorus (P₄) is a barely explored route to binary nickel phosphide clusters. Here, we show that coordinatively and electronically unsaturated N‐heterocyclic carbene (NHC) nickel(0) complexes afford unusual cluster compounds with P₁, P₃, P₅ and P₈ units. Using [Ni(IMes)₂] [IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene], electron‐deficient Ni₃P₄ and Ni₃P₆ clusters have been isolated, which can be described as superhypercloso and hypercloso clusters according to the Wade–Mingos rules. Use of the bulkier NHC complexes [Ni(IPr)₂] or [(IPr)Ni(η⁶‐toluene)] [IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene] affords a closo‐Ni₃P₈ cluster. Inverse‐sandwich complexes [(NHC)₂Ni₂P₅] (NHC=IMes, IPr) with an aromatic cyclo‐P₅^? ligand were identified as additional products.     

Syntheses and Crystal Structures of Di‐ and Trimercury Chlorogallates

Mercury(I) chloride reacts with gallium(III) chloride in benzene/1, 2‐dichlorobenzene solution to give the binuclear compound Hg₂(GaCl₄)₂ ( 1 ). Reduction of mercury(I) chloride with mercury in gallium(III) chloride‐benzene mixture leads to the trinuclear compound Hg₃(GaCl₄)₂ ( 2 ). The crystal structures of 1 and 2 were determined by single‐crystal X‐ray diffraction {Hg₂(GaCl₄)₂: triclinic, P1¯, a = 645.21(3), b = 654.44(3), c = 927.17(7) pm, α = 83.526(2)°, β = 74.915(2)°, γ = 61.863(3)°; Hg₃(GaCl₄)₂: monoclinic, P2₁/c, a = 715.79(1), b = 1501.59(4), c = 1421.43(4) pm, β = 98.9798(9)°}.     

Calcium Thiolates and Selenolates: Synthesis and Structures

The synthesis and structural characterization of a family of calcium thiolates and selenolates is described. In the solid state the compounds adopt either contact pairs, as observed in Ca(THF)₄(SMes*)₂ ( 1 ), (Mes* 2,4,6‐tBu₃C₆H₂), and Ca(THF)₄(SeMes*)₂, ( 2 ), or separated ions as shown in [Ca(18‐crown‐6)(HMPA)₂][SeMes*]₂ ( 3 ). The two different ion association modes are induced by addition of specific donors. The compounds were prepared by metalation involving the reaction of elemental calcium dissolved in dry liquid ammonia with either HSMes* or Mes*SeSeMes*. All compounds were characterized by X‐ray crystallography, NMR and IR spectroscopy.     

Crystal Structures and Chemical Properties of Dimesitylcadmium and Dimesitylmercury

Mesityllithium was used to synthesize dimesitylcadmium and dimesitylmercury from CdCl₂ and HgCl₂, respectively. X‐ray‐crystallographic data show that the group 12 metal compounds M[Mes]₂ (M = Zn, Cd, Hg) are isomorphous (monoclinic, P2₁/n). The asymmetric unit of M[Mes]₂ (M = Zn, Cd, Hg) consists of one mesityl group bonded to the metal atom, which is related to the second substituent by an inversion center. In addition we have investigated the reaction of BBr₃ with M[Mes]₂ (M = Cd, Hg) for our understanding of the reactivity of donor‐free group 12 mesityl compounds. The reaction of M[Mes]₂ (M = Cd, Hg) with an excess of BBr₃ produces MesBBr₂. UV‐induced conversion of Hg[Mes]₂ in benzene yielded quantitatively mesitylene and mercury whereas irradiation of a chloroform solution of Hg[Mes]₂ for 1290 min (λ_max = 510 nm) gave mesitylene, Hg[Mes]Cl, and HgCl₂ in a ratio of 6:4:1. Slow concentration of the reaction solution led to the deposition of X‐ray quality crystals of the addition compound of two Hg[Mes]Cl molecules and HgCl₂ (monoclinic space group P2₁/n).     

离子液体[C2mim][GaCl4]的溶解热研究

在干燥氩气氛下, 用等摩尔的高纯无水GaCl3和[C2mim][Cl](氯化1-甲基-3-乙基咪唑)直接搅拌混合, 制备了淡黄色透明的的离子液体[C2mim][GaCl4] (1-ethyl-3-methylimidazolium chlorogallate) . 在298.15 K下, 利用具有恒温环境的溶解反应热量计, 测定了这种离子液体的不同浓度摩尔溶解焓 . 针对[C2mim][GaCl4]溶解于水后即分解的特点, 在Pitzer电解质溶液理论基础上, 提出了确定这种离子液体标准摩尔溶解焓的新方法, 得到了[C2mim][GaCl4]在水中的标准摩尔溶解焓, ＝－132 kJ•mol－1, 以及Pitzer焓参数组合: ＝－0.1373076和 ＝0.3484209. 借助热力学循环和Glasser离子液体晶格能理论, 用Ga3＋, Cl－和[C2mim]—的离子水化焓数据以及本文得到的[C2mim][GaCl4]标准摩尔溶解焓, 估算了配离子4Cl－(g)解离成Ga3＋(g)和4Cl－(g)的解离焓ΔHdis([GaCl4]-)≈5855 kJ•mol－1. 这个结果揭示了离子液体[C2mim][GaCl4]的标准摩尔溶解焓绝对值并不很大的原因, 即是很大的离子水化焓被很大的[GaCl4]－(g)的解离焓相互抵消了.     

{(MesGa)3[GaP(H)Mes](PMes)4}, Ein phosphorsubstituiertes Ga?P-Heterocuban

{(MesGa)₃[GaP(H)Mes](PMes)₄}, a Phosphorus-substituted Ga? P-Heterocubane A mixture of MesGaCl₂/GaCl₃ (ratio 3:1) reacts with 5 equivalents of MesPLi₂ in THF at ?78°C to the title compound {(MesGa)₃[GaP(H)Mes](PMes)₄} ( 1 ) by use of the “dilution principle”. 1 can be obtained in 30% yield. Recrystallization of 1 from DME and toluene, respectively, gives 1 · 0.5 DME and 1 · toluene. 1 was characterized by NMR-, IR-, and MS-techniques. According to the X-ray structure determination of 1 · toluene, 1 has a heterocubane structure, one corner of which is substituted with an P(H)Mes group.     

Dimerization of Dimethyl 2‐(Naphthalen‐1‐yl)cyclopropane‐1,1‐dicarboxylate in the Presence of GaCl3 to [3+2], [3+3], [3+4], and Spiroannulation Products

In the presence of a catalytic amount of GaCl₃, dimethyl 2‐(naphthalen‐1‐yl)cyclopropane‐1,1‐dicarboxylate 5 undergoes selective [3+2]‐annulation‐type dimerization to give a polysubstituted cyclopentane containing two naphthalenyl substituents in the vicinal position (Scheme 2). Treatment of the same cyclopropane with an equimolar amount of GaCl₃?THF results in dimerization with electrophilic attack on each of the benzene rings to give [3+3] and [3+4] annulation products. The latter represent a new type of dimerization of donor? acceptor cyclopropanes. Finally, under conditions of double catalysis with GaCl₃, 3,3,5,5‐tetrasubstituted 4,5‐dihydropyrazole, this cyclopropane‐dicarboxylate undergoes stereospecific dimerization as a result of electrophilic ipso‐attack to give a tetracyclic pentaleno[6a,1‐a]naphthalene derivative (Scheme 5). Possible reaction mechanisms are proposed.