Crystal structures of seven mixed-valence gold compounds of the form [( P)Au][Au ] ( = -butyl or isopropyl, = S or Se, and = Cl or Br).

During our studies of the oxidation of gold(I) complexes of tri-alkyl-phosphane chalcogenides, general formula PAu, ( = -butyl or isopropyl, = S or Se, = Cl or Br) with PhICl or elemental bromine, we have isolated a set of seven mixed-valence by-products, the bis-(tri-alkyl-phosphane chalcogenido)gold(I) tetra-halogenidoaurates(III) [( P)Au][Au ]. These corres-pond to the addition of one halogen atom per gold atom of the Au precursor. Com-pound , bis-(triiso-propyl-phosphane sulfide)-gold(I) tetra-chlorido-aur-ate(III), [Au(CHPS)][AuCl] or [( PrPS)Au][AuCl], crystallizes in space group 2/ with = 4; the gold(I) atoms of the two cations lie on twofold rotation axes, and the gold(III) atoms of the two anions lie on inversion centres.

Gold(i) and gold(iii) carbene complexes from the marine betaine norzooanemonin: inhibition of thioredoxin reductase, antiproliferative and antimicrobial activity.

The natural marine betaine norzooanemonin (1,3-dimethylimidazolim-4-carboxylate) and its methyl and ethyl esters were used as ligand precursors to prepare a systematic series (12 members) of neutral monocarbene gold(i/iii) and cationic dicarbene gold(i/iii) complexes. The complexes were evaluated as inhibitors of bacterial thioredoxin reductase and for their antiproliferative and antimicrobial activities. While gold complexes with the parent norzooanemonin scaffold resulted in overall poor performance, the more lipophilic esters proved to be highly bioactive agents, related to their higher cellular uptake.

Crystal structures of fourteen halochalcogenylphos-pho-nium tetra-halogenidoaurates(III).

The structures of fourteen halochalcogenyl-phospho-nium tetra-halogen-ido-aurates(III), phosphane chalcogenide derivatives with general formula [ P][Au ] ( = -butyl; = isopropyl; = 0 to 3; = S or Se; = Cl or Br) are presented. The eight possible chlorido derivatives are: , = 3, = S; , = 2, = S; , = 1, = S; , = 0, = S; , = 3, = Se; , = 2, = Se; , = 1, = Se; and , = 0, = Se, and the corresponding bromido derivatives are - in the same order. Structures were obtained for all compounds except for the tri--butyl derivatives and .

Crystal structures of ten phosphane chalcogenide complexes of gold(III) chloride and bromide.

The structures of ten phosphane chalcogenide complexes of gold(III) halides, with general formula PAu ( = -butyl; = -propyl; = 0 to 3; = S or Se; = Cl or Br) are presented. The eight possible chlorido derivatives are: , = 3, = S; , = 2, = S; , = 1, = S; , = 0, = S; , = 3, = Se; , = 2, = Se; , = 1, = Se; and , = 0, = Se, and the corresponding bromido derivatives are - in the same order. Structures were obtained for , (and a second polymorph ), (and its deutero-chloro-form monosolvate ), (as its di-chloro-methane monosolvate), , (as its deutero-chloro-form monosolvate , in which the solvent mol-ecule is disordered over two positions), , , and .

Crystal structures of sixteen phosphane chalcogenide complexes of gold(I) chloride, bromide and iodide.

The structures of 16 phosphane chalcogenide complexes of gold(I) halides, with the general formula PAu ( = -butyl; = isopropyl; = 0 to 3; = S or Se; = Cl, Br or I), are presented. The eight possible chlorido derivatives are: , = 3, = S; , = 2, = S; , = 1, = S; , = 0, = S; , = 3, = Se; , = 2, = Se; , = 1, = Se; and , = 0, = Se, and the corresponding bromido derivatives are - in the same order. However, and were badly disordered and was not obtained.

Synthesis of N-heterocyclic carbene gold(I) complexes from the marine betaine 1,3-dimethylimidazolium-4-carboxylate.

The marine natural product norzooanemonin (1,3-dimethylimidazolium-4-carboxylate) has been used to prepare a series of carboxyl- or carboxylate-functionalized N-heterocyclic carbene (NHC) gold(I) complexes from [(MeS)AuCl] in the presence of potassium carbonate. The potential of the resulting mono- and dicarbene complexes to act as cytotoxic or antibacterial drugs was investigated.

Synthesis of Stable Potassium Phosphinophosphides and Reaction with Organosilyl Halides and Chlorophosphanes.

The synthesis of sterically demanding 2,6-bis(2,4,6-trimethylphenyl)phenyl (Ter)-stabilized and H-substituted diphosphanes TerHP-PR (-) via conversion of the phosphide TerPHK () with secondary chlorophosphanes ClPR (-, where R = Pr, Ph, and Bu, respectively) is described. The diphosphanes - were deprotonated using KH in tetrahydrofuran, selectively yielding the potassium phosphinophosphides K[TerP-PR] (-). These phosphinophosphides are stable in solution as well as in the solid state and can be further functionalized via salt-metathesis reactions.

N-Heterocyclic Carbene-Phosphinidenide Complexes as Hydroboration Catalysts.

The reactions of the N-heterocyclic carbene-phosphinidene adducts (NHC)PSiMe and (NHC)PH with the dinuclear ruthenium and osmium complexes [(η--cymene)MCl] (M = Ru, Os) afforded the half-sandwich complexes [(η--cymene){(NHC)P}MCl] and [(η--cymene){(NHC)PH}MCl] with two- and three-legged piano-stool geometries, respectively (NHC = IDipp, IMes; IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene). The complexes were initially tested as precatalysts for the hydroboration of benzonitrile, and the most active species, the ruthenium complex [(η--cymene){(IMes)P}RuCl], was further used for the efficient hydroboration of a wide range (ca. 50 substrates) of nitriles, carboxylic esters, and carboxamides in neat pinacolborane (HBpin) under comparatively mild reaction conditions (60-80 °C, 3-5 mol % catalyst loading).

Palladium(0) complexes of diferrocenylmercury diphosphines: synthesis, X-ray structure analyses, catalytic isomerization, and C-Cl bond activation.

Palladium(0) phosphine complexes are of great importance as catalysts in numerous bond formation reactions that involve oxidative addition of substrates. Highly active catalysts with labile ligands are of particular interest but can be challenging to isolate and structurally characterize. We investigate here the synthesis and chemical reactivity of Pd complexes that contain geometrically adaptable diferrocenylmercury-bridged diphosphine chelate ligands (L) in combination with a labile dibenzylideneacetone (dba) ligand.

Isoselective Polymerization of rac-Lactide by Aluminum Complexes of N-Heterocyclic Carbene-Phosphinidene Adducts.

The N-heterocyclic carbene-phosphinidene adducts (NHC)PH were reacted with AlMe in toluene to afford the monoaluminum complexes [{(IDipp)PH}AlMe ] and [{(IMes)PH}AlMe ] (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene). In contrast, the dialuminum complex [{( IMes)PH}(AlMe ) ] was obtained for IMes=1,3-bis(2,4,6-trimethylphenyl)-4,5-dimethylimidazolin-2-ylidene. These complexes served as initiators for the efficient ring-opening polymerization of rac-lactide in toluene at 60 °C.

N-Heterocyclic Carbene Analogues of Nucleophilic Phosphinidene Transition Metal Complexes.

Chloride abstraction from the complexes [(η -p-cymene){(IDipp)P}MCl] (2 a, M=Ru; 2 b, M=Os) and [(η -C Me ){(IDipp)P}IrCl] (3 b, IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr ) in the presence of trimethylphosphine (PMe ), 1,3,4,5-tetramethylimidazolin-2-ylidene ( IMe) or carbon monoxide (CO) afforded the complexes [(η -p-cymene){(IDipp)P}M(PMe )]BAr ] (4 a, M=Ru; 4 b, M=Os), [(η -p-cymene){(IDipp)P}Os( IMe)]BAr ] (5) and [(η -C Me ){(IDipp)P}IrL][BAr ] (6, L=PMe ; 7, L= IMe; 8, L=CO). These cationic N-heterocyclic carbene-phosphinidene complexes feature very similar structural and spectroscopic properties as prototypic nucleophilic arylphosphinidene complexes such as low-field P NMR resonances and short metal-phosphorus double bonds. Density functional theory (DFT) calculations reveal that the metal-phosphorus bond can be described in terms of an interaction between a triplet [(IDipp)P] cation and a triplet metal complex fragment ligand with highly covalent σ- and π-contributions.

Pogo-Stick Iron and Cobalt Complexes: Synthesis, Structures, and Magnetic Properties.

The synthesis, structures, and magnetic properties of monomeric half-sandwich iron and cobalt imidazolin-2-iminato complexes have been comprehensively investigated. Salt metathesis reactions of [Cp'M(μ-I)] (, M = Fe, Co; Cp' = η-1,2,4-tri--butylcyclopentadienyl) with [ImNLi] (ImN = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-iminato) furnishes the terminal half-sandwich compounds [Cp'M(NIm)] (, M = Fe, Co), which can be regarded as models for elusive half-sandwich iron and cobalt imido complexes. X-ray diffraction analysis confirmed the structure motif of a one-legged piano stool.

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1'-diacetylenic ferrocenes.

Novel alkyne-bridged ferrocenophanes [fc{CO(CH) C≡}] (: = 2; : = 3) were synthesized from the corresponding terminal diacetylenic ferrocenes [fc{CO(CH) C≡CH}] (: = 2; : = 3) through ring-closing alkyne metathesis (RCAM) utilizing the highly effective molybdenum catalyst [MesC≡Mo{OC(CF)CH}] (; Mes = 2,4,6-trimethylphenyl). The metathesis reaction occurs in short time with high yields whilst giving full conversion of the terminal alkynes. Furthermore, the solvent-dependant reactivity of towards Ag(SbF) is investigated, leading to oxidation and formation of the ferrocenium hexafluoroantimonate in dichloromethane, whereas the silver(I) coordination polymer was isolated from THF solution.

Isolation of Carbene-Stabilized Arsenic Monophosphide [AsP] and its Radical Cation [AsP] and Dication [AsP].

Arsenic monophosphide (AsP) species supported by two different N-heterocyclic carbenes were prepared by reaction of (IDipp)PSiMe (1) (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with (IMes)AsCl (2) (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) to afford the dichloride [(IMes)As(Cl)P(IDipp)]Cl (3), which upon reduction with KC furnished heteroleptic [(IMes)AsP(IDipp)] (4). The corresponding mono- and dications [(IMes)AsP(IDipp)][PF ], [5]PF , and [(IMes)AsP(IDipp)][GaCl ] [6][GaCl ] , respectively, were prepared by one-electron oxidation of 4 with ferrocenium hexafluorophosphate, [Fc]PF or by chloride abstraction from 3 with two equivalents of GaCl , respectively. Compounds 4-6 represent rare examples of heterodiatiomic interpnictogen compounds, and X-ray crystal structure determinations together with density functional theory (DFT) calculations reveal a consecutive shortening of the As-P bond lengths and increasing bond order, in agreement with the presence of an arsenic-phosphorus single bond in 4 and a double bond in 6 .

Pentamethylcyclopentadienyl ruthenium "pogo stick" complexes with nitrogen donor ligands.

The half-sandwich 1,3-bis(trimethylsilyl)allyl and bis(trimethylsilyl)amido ruthenium complexes [(η5-C5Me5)RuX] (X = η3-C3H3(SiMe3)2, 1; X = N(SiMe3)2, 2) were prepared by reaction of tetranuclear [(η5-C5Me5)RuCl]4 with four equivalents of K[C3H3(SiMe3)2] or Na[N(SiMe3)2]. Complexes 1 and 2 are formally 16- and 14-electron complexes, respectively, and exhibit γ-agostic C-HRu interactions in the solid state, which were further investigated by density functional theory (DFT) calculations and quantum theory of atoms in molecules (QTAIM) analysis. The acid-base reaction of the amido complex 2 with 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (ImDippNH) afforded the imidazolin-2-iminato complex [(η5-C5Me5)Ru(NImDipp)] (4); 4 was also obtained from the reaction of [(η5-C5Me5)RuCl]4 with the lithium reagent [(ImDippN)Li]2.

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex.

The molybdenum and tungsten complexes M(OR) (, M = Mo, R = C(CF)Me; , M = W, R = OC(CF)Me) were synthesized as bimetallic congeners of the highly active alkyne metathesis catalysts [MesC≡M{OC(CF) Me }] (, M = Mo, = 2; , M = W, = 1; Mes = 2,4,6-trimethylphenyl). The corresponding benzylidyne complex [PhC≡W{OC(CF)Me}] ( ) was prepared by cleaving the W≡W bond in with 1-phenyl-1-propyne. The catalytic alkyne metathesis activity of these metal complexes was determined in the self-metathesis, ring-closing alkyne metathesis and cross-metathesis of internal and terminal alkynes, revealing an almost equally high metathesis activity for the bimetallic tungsten complex and the alkylidyne complex .

Unraveling the Mechanism of 1,3-Diyne Cross-Metathesis Catalyzed by Silanolate-Supported Tungsten Alkylidyne Complexes.

The benzylidyne complex [PhC≡W{OSi(OtBu) } ] (1) catalyzed the cross-metathesis between 1,4-bis(trimethylsilyl)-1,3-butadiyne (2) and symmetrical 1,3-diynes (3) efficiently, which gave access to TMS-capped 1,3-diynes RC≡C-C≡CSiMe (4). Diyne cross-metathesis (DYCM) studies with C-labeled diyne PhC≡ C- C≡CPh (3*) revealed that this reaction proceeds through reversible carbon-carbon triple-bond cleavage and formation according to the conventional mechanism of alkyne metathesis. The reaction between 1 and 3* afforded the 3-phenylpropynylidyne complex PhC≡ C- C≡W{OSi(OtBu) } ] (5*), indicating that alkynylalkylidyne complexes are likely to act as catalytically active species.

A modular approach to carbene-stabilized diphosphorus species.

Heteroleptic N-heterocyclic dicarbene-diphosphorus species were prepared by reaction of the carbene-phosphinidene adduct (IPr)PSiMe (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with the carbene-phosphorus trichloride adduct (IMes)PCl (2, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene), which furnished the dichloride [(IPr)PPCl(IMes)]Cl (3). Reduction of 3 with potassium graphite (KC) afforded [(IPr)PP(IMes)] (4). The corresponding radical cation [(IPr)PP(IMes)]˙ (5˙) is isolated as [5]PF by reaction of 4 with ferrocenium hexafluorophosphate, whereas complexes containing the corresponding dication [(IPr)PP(IMes)] (6) can be isolated as the gallate and borate salts [6](GaCl) and [6](BAr) by chloride abstraction from 3 with GaCl or sodium tetrakis[bis(3,5-trifluoromethyl)phenyl]borate (NaBAr), respectively.

Molecular and Silica-Supported Molybdenum Alkyne Metathesis Catalysts: Influence of Electronics and Dynamics on Activity Revealed by Kinetics, Solid-State NMR, and Chemical Shift Analysis.

Molybdenum-based molecular alkylidyne complexes of the type [MesC≡Mo{OC(CH)(CF)}] (MoF, x = 0; MoF, x = 1; MoF, x = 2; MoF, x = 3; Mes = 2,4,6-trimethylphenyl) and their silica-supported analogues are prepared and characterized at the molecular level, in particular by solid-state NMR, and their alkyne metathesis catalytic activity is evaluated. The C NMR chemical shift of the alkylidyne carbon increases with increasing number of fluorine atoms on the alkoxide ligands for both molecular and supported catalysts but with more shielded values for the supported complexes. The activity of these catalysts increases in the order MoF < MoF < MoF before sharply decreasing for MoF, with a similar effect for the supported systems (MoF ≈ MoF < MoF < MoF).

N-Heterocyclic carbene-stabilised arsinidene (AsH).

N-Heterocyclic carbene adducts of the parent arsinidene (AsH) were prepared by two different synthetic routes, either by reaction of As(SiMe) with 2,2-difluoroimidazolines followed by desilylation or by reaction of [Na(dioxane)][AsCO] with imidazolium chlorides.

N-Heterocyclic Carbene-Phosphinidene Complexes of the Coinage Metals.

Coinage metal complexes of the N-heterocyclic carbene-phosphinidene adduct IPr⋅PPh (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were prepared by its reaction with CuCl, AgCl, and [(Me2 S)AuCl], which afforded the monometallic complexes [(IPr⋅PPh)MCl] (M=Cu, Ag, Au). The reaction with two equivalents of the metal halides gave bimetallic [(IPr⋅PPh)(MCl)2 ] (M=Cu, Au); the corresponding disilver complex could not be isolated. [(IPr⋅PPh)(CuOTf)2 ] was prepared by reaction with copper(I) trifluoromethanesulfonate.

N-heterocyclic carbene-phosphinidyne transition metal complexes.

The N-heterocyclic carbene-phosphinidene adduct IPrPSiMe3 is introduced as a synthon for the preparation of terminal carbene-phosphinidyne transition metal complexes of the type [(IPrP)MLn ] (MLn =(η(6) -p-cymene)RuCl) and (η(5) -C5 Me5 )RhCl). Their spectroscopic and structural characteristics, namely low-field (31) P NMR chemical shifts and short metal-phosphorus bonds, show their similarity with arylphosphinidene complexes. The formally mononegative IPrP ligand is also capable of bridging two or three metal atoms as demonstrated by the preparation of bi- and trimetallic RuAu, RhAu, Rh2 , and Rh2 Au complexes.