Deprotonation of a Hydridoborate Anion

The first deprotonation of a borohydride anion was achieved by treatment of [BH(CN)₃]⁻ with strong non‐nucleophilic bases, which resulted in the formation of alkali‐metal salts of the tricyanoborate dianion B(CN)₃²⁻ in up to 97 % yield and 99.5 % purity. [BH(CN)₃]⁻ is less acidic than (Me₃Si)₂NH but a stronger acid than i Pr₂NH. Less sterically hindered, more nucleophilic bases such as PhLi and MeLi mostly attack a CN group under formation of imine dianions [RC(N)B(CN)₃]²⁻, which can be hydrolyzed to ketones of the [RC(O)B(CN)₃]⁻ type. The boron‐centered nucleophile B(CN)₃²⁻ reacts with CO₂ and CN⁺ reagents to give salts of the [B(CN)₃CO₂]²⁻ dianion and the tetracyanoborate anion [B(CN)₄]⁻, respectively, in excellent yields.     

The Sulfur Rich Fluorothiophosphate Dianions [S5P2F2]2− and [S3PF]2− : Cluster and Chelation Control of P-S Heterolysis

The sulfur rich difluoropentathiodiphosphate dianion [S₅P₂F₂]²⁻, from fluoride addition to P₄S₁₀, has a somewhat checkered history and proves to be the main product of the reaction in acetonitrile. Its optimized synthesis, and structural characterization, as either a tetraphenylphosphonium or a tetrapropylammonium salt, [NⁿPr₄]₂[S₅P₂F₂] allows for the first coordination chemistry for this dianion. Reactions of [S₅P₂F₂]²⁻ with d¹⁰ metal ions of zinc(II), and cadmium(II), and d⁹ copper(II) resulted in a surprising diverse array of binding modes and structural motifs. In addition to the simple bis-chelate coordination of [S₅P₂F₂]²⁻ with zinc, cleavage of the P−S bond resulted in complexes with the unusual [S₃PF]²⁻ fluorotrithiophosphate dianion. This was observed in two cluster complexes: a trinuclear cadmium complex with mixed [S₅P₂F₂]²⁻/[S₃PF]²⁻ ligands, [Cd₃(S₅P₂F₂)₃(S₃PF)₂]⁴⁻ as well as an octanuclear copper cluster, [Cu₈(S₃PF)₆]⁴⁻ which form rapidly at room temperature. These new metal/sulfur/ligand clusters are of relevance to understanding multimetal binding to metallothionines, and to potential capping strategies for the condensed nanoparticulate cadmium chalcogenide semiconductors CdS and CdSe.     

Syntheses,Structures, and Electronic Properties of Mono- and Bimetallic Thiolato Complexes Containing Unusual Coordination Modes of Thiolato Ligands

Synthesis, bonding and chemistry of mono- and bimetallic complexes supported by chelating thiolato ligands have been established. Treatment of [Cp*VCl₂]₃ ( 1 ) with [LiBH₄ ⋅ THF] followed by the addition of ethane-1,2-dithiol led to the formation of an EPR active bimetallic vanadium thiolato complex [(Cp*V){μ-(SCH₂CH₂S)-κ²S,S′)₂{V(SCH₂CH₂S-SH)}] ( 2 ). In complex 2 , two ethane-1,2-dithiolato ligands are symmetrically coordinated to two vanadium atoms through μ-S atoms. Interestingly, when similar reactions were carried out with heavier group 5 metal precursors, such as [Cp*NbCl₄] ( 3 a ), it afforded monometallic thiolato complex [Cp*Nb(SCH₂CH₂S)(SCH₂CH₂S−CH₂S)] ( 4 a ). On the other hand, the Ta-analogue [Cp*TaCl₄] ( 3 b ) yielded thiolato species [Cp*Ta(SCH₂CH₂S)(SCH₂CH₂S−CH₂S)] ( 4 b ) and [Cp*Ta(SCH₂CH₂S) (SCH₂CH₂S−S)] ( 5 ). In complexes 4 a and 4 b , one ethane-1,2-dithiolato and one trithiolato ligand are coordinated to Nb and Ta centers, respectively. Whereas, in complex 5 , one ethane-1,2-dithiolato and one 2-disulfanylethanethiolato is coordinated to the Ta center. Moreover, the photolytic reaction of 5 with [Mo(CO)₅ ⋅ THF] yielded heterobimetallic thiolato complex [(Cp*Ta){μ-(SCH₂CH₂S)-κ²S,S′}{μ-(SCH₂CH₂S−CH₂(CH₃)S)κ²S′′ : κ¹S-′′′′ : κ¹S′′′′′}{Mo(CO)₃}] ( 6 ). All the complexes have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies. Further, computational analyses were performed to provide an insight into the bonding of these complexes.     

Reactivity of α-germyl nitriles with acetonitrile: Synthesis, structures, and generation of Ph3Ge[NHC(CH3)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine from Ph3GeCH2CN

The formation of 3-aminocrotononitrile and 4-amino-2,6-dimethylaminopyrimidine has been observed during the course of the hydrogermolysis reaction between a germanium amide and a germanium hydride, either as the free amines or bound to germanium as ligands consisting of their conjugate bases. These species arise from the dimerization or trimerization of acetonitrile, and have only been detected when germanium amides having substantial steric bulk at the germanium center are employed in the reaction. The isolation of germanium-bound 3-aminocrotononitrile compounds suggests that α-germyl nitrile species R₃GeCH₂CN that result from the reaction of the germanium amides R₃GeNMe₂ with CH₃CN solvent also can further react with CH₃CN to generate the 3-aminocrotononitrile and 4-amido-2,6-dimethylaminopyrimidine species. The two germanes Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine have been prepared and structurally characterized, and the conversion of Ph₃GeCH₂CN to Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethylamino-4-(triphenylgermylamino)pyrimidine as well as the conversion of Ph₃Ge[NHC(CH₃)CHCN] to 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine in acetonitrile solvent has been observed using ¹H NMR spectroscopy.     

The Hexacyanodiborane(6) Dianion [B2(CN)6]2−

Diborane(6) dianions with substituents that are bonded to boron via carbon are very reactive and therefore only a few examples are known. Diborane(6) derivatives are the simplest catenated boron compounds with an electron‐precise B–B σ‐bond that are of fundamental interest and of relevance for material applications. The homoleptic hexacyanodiborane(6) dianion [B₂(CN)₆]²⁻ that is chemically very robust is reported. The dianion is air‐stable and resistant against boiling water and anhydrous hydrogen fluoride. Its salts are thermally highly stable, for example, decomposition of (H₃O)₂[B₂(CN)₆] starts at 200 °C. The [B₂(CN)₆]²⁻ dianion is readily accessible starting from 1) B(CN)₃²⁻ and an oxidant, 2) [BF(CN)₃]⁻ and a reductant, or 3) by the reaction of B(CN)₃²⁻ with [BHal(CN)₃]⁻ (Hal=F, Br). The latter reaction was found to proceed via a triply negatively charged transition state according to an S_N2 mechanism.     

Crystal structure of a cyanide-bridged heptanuclear manganese(III)–chromium(III) complex with a ground state S = 21/2

K₃[Cr(CN)₆] reacts with the mononuclear Mn^III complex Mn(salen)ClO₄ · 2H₂O [salen: N,N-ethylenebis(salicylideneiminato)dianion] to give a bimetallic heptanuclear complex cation salt [Cr{(CN)Mn(salen · H₂O)}₆][Cr(CN)₆]6H₂O. In the complex anion, [Cr{(CN)Mn(salen · H₂O)}₆]³⁺, six Mn^III ions coordinate to a Cr^III center via cyano bridges, forming a spherical species with 3 symmetry. A study of magnetic properties shows the presence of antiferromagnetic interaction through the cyanide bridge between Cr^III (S = 3/2) and Mn^III (S = 4/2) and results in a ground state S = 21/2.     

Kinetics,mechanism, and stereochemistry of Diels-Alder reactions of CN-substituted ethenes with cyclohexa-1, 3-diene in the gas phase

The kinetics of the Diels-Alder additions of CH₂ = CHCN, CH₂ = C(CH₃) CN, and cis- and trans-CH₃CH = CHCN to cyclohexa-1, 3-diene have been studied in the gas phase. The stereochemistry of these reactions is discussed. In terms of a biradical mechanism, a minimum value of 4.1 ± 0.8 kcal mol^?1 for the stabilizing effect of a CN group vis-à-vis a methyl group is shown to fit the experimental activation energies.     

Ligand‐Centred Reactivity of Bis(picolyl)amine Iridium: Sequential Deprotonation,Oxidation and Oxygenation of a “Non‐Innocent” Ligand

Treatment of [Ir(bpa)(cod)]⁺ complex [ 1 ]⁺ with a strong base (e.g., tBuO^?) led to unexpected double deprotonation to form the anionic [Ir(bpa?2H)(cod)]^? species [ 3 ]^?, via the mono‐deprotonated neutral amido complex [Ir(bpa?H)(cod)] as an isolable intermediate. A certain degree of aromaticity of the obtained metal–chelate ring may explain the favourable double deprotonation. The rhodium analogue [ 4 ]^? was prepared in situ. The new species [M(bpa?2H)(cod)]^? (M=Rh, Ir) are best described as two‐electron reduced analogues of the cationic imine complexes [M^I(cod)(Py‐CH₂‐N?CH‐Py)]⁺. One‐electron oxidation of [ 3 ]^? and [ 4 ]^? produced the ligand radical complexes [ 3 ]^. and [ 4 ]^.. Oxygenation of [ 3 ]^? with O₂ gave the neutral carboxamido complex [Ir(cod)(py‐CH₂‐N‐CO‐py)] via the ligand radical complex [ 3 ]^. as a detectable intermediate.     

Cyclization of N-alkyldithiocarbamates in alkaline media,a counter example of well-known chemistry – an experimental and theoretical study

In strong alkaline media, the reaction of 2-(tert-butylamino)ethanol (3: R?=?Bu^t) with CS₂ at 0°C produced a cyclic dithiocarbamate, 3-tert-butylthiazolidine-2-thione (1: R?=?Bu^t), rather than alkaline metal or ammonium salts of [S₂CN(Bu^t)CH₂CH₂OH]^?. This is in contrast to isolation of stable alkaline metal or ammonium salts of [S₂CN(R)CH₂CH₂OH]^? (R?=?Me, Et, Pr, or CH₂CH₂OH) obtained in analogous reactions. The use of Ni(OAc)₂, both as a source of Ni(II) and a weaker base, in a one-pot reaction with (3: R?=?Bu^t) and CS₂, successfully gave the first reported metal complex of [S₂CN(Bu^t)CH₂CH₂OH]^?, namely [Ni{S₂CN(Bu^t)CH₂CH₂OH}₂] (2: R?=?Bu^t). Compounds 1 and 2 have been fully characterized by infrared and NMR spectroscopies, and by X-ray crystallography. DFT calculations on the cyclization and stabilities of [S₂CN(R)CH₂CH₂OH]^? (R?=?Pr and Bu^t) have been carried out.     

Novel species in the electrochemical reduction of a metalmetal bond bridged by a bidentate fluorophosphine

The purple bridged bimetallic complex [CH₃N(PF₂)₂]₃Co₂(CO)₂ undergoes successive chemically and electrochemically reversible one-electron reductions to the corresponding green radical anion and pale-yellow dianion. The radical anion is relatively unreactive towards oxygen and methyl iodide. The dianion is not only reactive towards oxygen and methyl iodide but also captures small positively charged species (e.g. Li⁺ and H⁺) with significant alteration of its chemical properties.     

P−P Condensation and P−N/P−P Bond Metathesis: Facile Synthesis of Cationic Tri- and Tetraphosphanes

[L_C^RP((PhP)₂C₂H₄)][OTf] ( 4 a,b [OTf]) and [L_C^iPrP(PPh₂)₂][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl-substituted dipyrazolylphosphane triflate salts [L_C^RP(pyr)₂][OTf] ( 3 a,b [OTf]; a : R=Me, b =iPr; L_C^R=1,3-dialkyl-4,5-dimethylimidazol-2-yl; pyr=3,5-dimethylpyrazol-1-yl) with the secondary phosphanes PhP(H)C₂H₄P(H)Ph) and Ph₂PH. A stepwise double P−N/P−P bond metathesis to catena-tetraphosphane-2,3-diium triflate salt [(Ph₂P)₂(L_C^MeP)₂][OTf]₂ ( 7 a [OTf]₂) is observed when reacting 3 a [OTf] with diphosphane P₂Ph₄. The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH₃CN)₄]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph₂PPL_C^iPr)Au}₄][OTf]₄ ( 9 [OTf]₄) was unexpectedly formed as a result of a chloride-induced P−P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [( 5 b )M(CH₃CN)₃][OTf]₂ (M=Cu, Ag) ( 10 [OTf]₂, 11 [OTf]₂).     

Electrochemistry of coordination compounds: Part XIX. Electrochemical study of some cationic hydrido-complexes of iron(II)

The Electrochemical behaviour of a series of cationic hydrido-complexes of Fe(II) of general formula trans-[FeH(L)(DPE)₂] (BPh₄)(L=N₂, C₂H₅N, C₆H₅CN, CH₂CHCN, CH₃CN, P(OCH₃)₃, P(OC₂H₅)₃, CO; DPE=1,2- bis(diphenylphosphino)ethane) has been investigated in 1,2-dimethoxyethane at the platinum electrode. The reduction of these d⁶ complexes has been found to proceed by an ECE mechanism in which a one-electron transfer, generating a transient d⁷ species, is followed by the fast loss of one of the neutral ligands and a further one-electron reduction of the pentacoordinated intermediates to the final d⁸ anionic hydrides. The reduced species are stabilized considerably at low temperature. The ligands, L, are divided into two groups according to their bonding properties, with particular references to their ability to act as π- acceptors. Weak π-bonders (N₂, C₂H₅N, C₆H₅CN, CH₂CHCN, CH₃CN) are lost in the chemical step interposed between the two charge-transfer processes, whereas strong π-accepting ligands (CO and P(OR)₃) favour dissocia tion of one end of a diphosphine.     

Elucidating the Mechanism of Simultaneous Activation of CH4 and CO2 Mediated by Single Group 10 Metal Anions in Gas Phase

Quantum chemistry calculations predict that besides the reported single metal anion Pt⁻, Ni⁻ can also mediate the co-conversion of CO₂ and CH₄ to form [CH₃−M(CO₂)−H]^– complex, followed by transformation to C−C coupling product [H₃CCOO−M−H]⁻ ( A ), hydrogenation products [H₃C−M−OCOH]⁻ ( B ) and [H₃C−M−COOH]⁻. For Pd⁻, a fourth product channel leading to PdCO₂⁻…CH₄ becomes more competitive. For Ni⁻, the feed order must be CO₂ first, as the weaker donor-acceptor interaction between Ni⁻ and CH₄ increases the C−H activation barrier, which is reduced by [Ni−CO₂]⁻. For Ni⁻/Pt⁻, the highly exothermic products A and B are similarly stable with submerged barrier that favors B . The smaller barrier difference between A and B for Ni⁻ suggests the C−C coupling product is more competitive in the presence of Ni⁻ than Pt⁻. The charge redistribution from M⁻ is the driving force for product B channel. This study adds our understanding of single atomic anions to activate CH₄ and CO₂ simultaneously.     

Substituting group induced structural transformation from 1D zigzag chain to 2D grid network in cyano-bridged dimetallic complexes derived from Mn(Schiff-base) and [Cr(CN)5NO]: Synthesis, crystal structure and magnetic properties

Two cyano-bridged dimetallic complexes derived from Mn^III(Schiff-base) and [Cr^I(CN)₅NO]³⁻, [Mn(3-CH₃)salen]₃[Cr(CN)₅NO]·2.5H₂O (1) and [Mn(5-CH₃)salen]₆[Cr(CN)₅NO]₂·2CH₃OH·16H₂O (2) [salen = N,N′-ethylenebis (salicylideneiminato)dianion] were synthesized and characterized. The reaction conditions of the two complexes are identical. The substituting group (CH₃-) in the salen-type ligands gives different assembly styles for the two complexes, 1D zigzag chain for 1 while 2D grid network for 2. The magnetic investigation indicates the dominant antiferromagnetic interactions between the Mn(III) and Cr(I) mediated by the CN bridge. Due to the weak interchain antiferromagnetic interactions, no magnetic ordering phase was observed in complex 1. Interestingly, complex 2 showed the long range ferrimagnetic magnetic ordering with T_c = 9 K, in contrast to 1. Furthermore, the hysteresis loop confirms the nature of complex 2 as soft ferrimagnet.     

Redox,spectroscopic, photo-induced ligand exchange,and DNA interaction studies of a new Ru(II)Pt(II) bimetallic complex

A new bimetallic complex, [Ru(biq)₂(dpp)PtCl₂](PF₆)₂ (where biq = 2,2′-biquinoline and dpp = 2,3-bis(2-pyridyl)pyrazine), containing a cis-PtCl₂ moiety coupled to a sterically strained Ru(II)-based chromophore was designed, synthesized, and investigated with respect to its spectroscopic, redox, photo-induced ligand exchange, and DNA-interaction properties. The electrochemistry of the designed complex was found to be consistent with the bridging coordination of the dpp ligand and formation of the bimetallic complex. The complex displays intense ligand-based π → π* transitions in the UV region and metal-to-ligand charge-transfer transitions (MLCT) in the visible region. The loss of bridging coordination of the dpp ligand and formation of complexes, [Ru(biq)₂(CH₃CN)₂]²⁺ and [Pt(dpp)(CH₃CN)₂]²⁺ was observed when an acetonitrile solution of the metal complex was irradiated with visible light (λ_irr ≥ 550 nm). The designed complex displays covalent binding with DNA in dark through the cis-PtCl₂ moiety, as confirmed by agarose gel electrophoresis. Upon photoirradiation, the complex dissociates into two DNA-binding moieties and displays covalent binding through: (i) a cis-PtL₂ subunit of [Ptdpp(L)₂]²⁺ and (ii) open coordination sites of the ruthenium of [Ru(biq)₂(L)₂]²⁺ (L = solvent). The designed complex represents the first Ru(II)Pt(II) complex that undergoes photo-induced ligand exchange and displays multifunctional interactions with DNA upon photoirradiation.     

An iron(III) complex salt containing pyrazole as both ligand and counter‐ion: bis(1H‐pyrazol‐2‐ium) pentacyanido(1H‐pyrazole‐κN2)ferrate(III)

The title compound, (C₃H₅N₂)₂[Fe(CN)₅(C₃H₄N₂)], is composed of a mononuclear [Fe(CN)₅(pyrazole)]²⁻ dianion and two 1H‐pyrazol‐2‐ium cations. A three‐dimensional supramolecular network is formed through a rich scheme of N—H...N hydrogen bonds and C—H...π interactions among the cations and anions.     

Preparation and Structural Characterization of [CpRu(1,10-phenanthroline)(CH3CN)][X] and Precursor Complexes (X=PF6, BArF,TRISPHAT-N)

Cationic [Ru(η⁵-C₅H₅)(CH₃CN)₃]⁺ complex, tris(acetonitrile)(cyclopentadienyl)ruthenium(II), gives rise to a very rich organometallic chemistry. Combined with diimine ligands, and 1,10-phenanthroline in particular, this system efficiently catalyzes diazo decomposition processes to generate metal-carbenes which undergo a series of original transformations in the presence of Lewis basic substrates. Herein, syntheses and characterizations of [CpRu(Phen)(L)] complexes with (large) lipophilic non-coordinating (PF₆⁻ and BAr_F⁻) and coordinating TRISPHAT-N⁻ anions are reported. Complex [CpRu(η⁶-naphthalene)][BAr_F] ( [1][BAr_F] ) is readily accessible, in high yield, by direct counterion exchange between [1][PF₆] and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr_F) salts. Ligand exchange of [1][BAr_F] in acetonitrile generated stable [Ru(η⁵-C₅H₅)(CH₃CN)₃][BAr_F] ( [2][BAr_F] ) complex in high yield. Then, the desired [CpRu(Phen)(CH₃CN)] ( [3] ) complexes were obtained from either the [1] or [2] complex in the presence of the 1,10-phenanthroline as ligand. For characterization and comparison purposes, the anionic hemilabile ligand TRISPHAT−N (TTN) was introduced on the ruthenium center, from the complex [3][PF₆] , to quantitatively generate the desired complex [CpRu(Phen)(TTN)] ( [4] ) by displacement of the remaining acetonitrile ligand and of the PF₆⁻ anion. Solid state structures of complexes [1][BAr_F] , [2][BAr_F] , [3][BAr_F] , [3][PF₆] and [4] were determined by X-ray diffraction studies and are discussed herein.     

The question of tautomerism of alkylnitrile and isonitrile radical cations

The isomeric pairs [CH₃CN]^+˙ and [CH₂CNH]^+˙ and [CH₃NC]^+˙ and [CH₂NCH]^+˙ have been established as stable, noninterconverting structures. The conclusion derives from studies of collision induced decomposition spectra. The same conclusion pertains for the ions [CH₃CH₂CN]^+˙ and [CH₃CHCNH]^+˙, and for [NCCH₂CH₂CN]^+˙, [HNCCHCH₂CN]^+˙ and [HNCCHCHCNH]^+˙. The energy barrier of a [1,3]-hydrogen shift, a possible isomerization mechanism, is determined to be at least 163 kJ mol^?1 for the [CH₃CN]^+˙ and [CH₂CNH]^+˙ pair, and the barrier may be as high as 318 kJ mol^?1. The C₃H₅N and C₄H₄N₂ radical cations decompose before they can be activated with 318 kJ mol^?1 of internal energy.     

Cationic rhodium(I) and iridium(I,III) complexes of cinnamonitrile and their catalytic activities

Summary Reactions of cinnamonitrile (trans-PhCH=CHCN) with [M(ClO₄)(CO)(PPh₃)₂] (M=Rh or Ir) produce hydrogenation oftrans-PhCH=CHCN to PhCH₂CH₂CN at 100°C under 3 atm of hydrogen.     

Gold(I) and Palladium(II) Complexes Containing the Functionalized Ylides Triarylphosphonium Cyanomethylide or 2-Cyanoethylide (R3P=CHR′, R′=CN,CH2CN)

The coordination properties of ylides R₃P=CHCN and R₃P=CHCH₂CN were studied. Ylide R₃P=CHCN reacts with [AuCl(tht)] (molar ratio 1 : 1, tht=tetrahydrothiophene) to give [AuCl{CH(PPh₃)CN}] ( 1 ). Dinuclear complexes [(AuL)₂{μ-C(PR₃)CN}]ClO₄⋅nH₂O (n=1, L=PPh₃, R=Ph ( 2a ) or Tol (=4-MeC₆H₄) ( 2b ); n=0, R=Tol, L=P(pmp)₃ ( 2c ; pmp=4-MeOC₆H₄ or AsPh₃ ( 2d )) are the products of reactions between phosphonium salts (R₃PCH₂CN)ClO₄ (R=Ph or Tol) and [Au(acac)L] (molar ratio 1 : 3, L=PPh₃ or P(pmp)₃; acacH=acetylacetone). The reaction of [Au(acac)PPh₃] with (Ph₃PCH₂CH₂CN)ClO₄ (Au/P 2 – 5) gives the mononuclear complex [Au{CH(PPh₃)CH₂CN}(PPh₃)]ClO₄⋅0.5 H₂O ( 3 ). Complexes 2b or 2c react with [Au(acetone)L]ClO₄ (molar ratio 1 : 1, L=PPh₃ or P(pmp)₃), prepared in situ from [AuCl(L)] and AgClO₄ in acetone, to give the corresponding trinuclear derivatives [(AuL)₂{μ₃-{C(PTol₃)CN}(AuL)}](ClO₄)₂ (L=PPh₃ ( 4a ) or P(pmp)₃ ( 4b )]. We attempted unsuccessfully to prepare single crystals of 4a or 4b or of the triflate salt [{Au(PPh₃)}₂{μ₃-{C(PTol₃)CN}(AuPPh₃)}](TfO)₂⋅H₂O ( 4a′ ), obtained by reacting 4a with 2 equiv. of KCF₃SO₃. In complexes 2 and 4 , two new types of coordination of the ylides R₃P=CHCN are present. Attempts to coordinate three AuL groups to the N-atom of (R₃PCCN)⁻ induced by aurophilicity (see A and B ) were unsuccessful. The reaction between PdCl₂ and R₃P=CHCN (molar ratio 1 : 2) gives trans-[PdCl₂{CH(PTol₃)CN}₂] ( 5 ).