Iron(I)-Based Carbonyl Complexes with Bridging Thiolate Ligands as Light-Triggered CO Releasing Molecules (photoCORMs)

A series of thiolate ligands were used to synthesize diiron(I) hexacarbonyl bis(thiolates) for structural studies. Conversion of the corresponding thiols with triiron(0) dodecacarbonyl yields complexes of the type [{(CO)₃Fe(μ-SR)}₂] [R = C₆H₅ ( 1 ), C₆H₄-4-CH₃ ( 2 ), C₆H₄-4-F ( 3 ), C₆F₅ ( 4 ), C₆H₄-4-CF₃ ( 5 ), C₆H₂-2,4,6-(CH₃)₃ ( 6 ), CH₂–C₆H₄-4-Cl ( 7 )]. These complexes were isolated and fully characterized, including X-ray crystal structures of complexes 2 – 7 . The bridging thiolate ligands mainly influence the Fe–CO bond which is trans-positioned to the second iron(I) center. In solution, the anti-isomer with one axially and one equatorially oriented thiolate is the major species; severe steric strain induced by mesityl groups only allows the formation of syn-endo-isomeric molecules of 7 . Furthermore, light-induced CO release at solid material at the three representative complexes 1 , 3 , and 6 verify suitability as photoCORMs.     

Di­chloro­[N,N,N′,N′-tetrakis(2-pyridyl­methyl)­benzene-1,4-di­amine]­iron(II)

In the title complex, [FeCl₂(C₃₀H₂₈N₆)], the Fe atom is five-coordinated by two terminal chloride ligands and one end of the bis-tridentate ligand. The complexes display intermolecular C—H⃛π, π-stacking and C—H⃛X (X = N, Cl) interactions.     

(Aminocarbene)(Divinyltetramethyldisiloxane)Iron(0) Compounds: A Class of Low‐Coordinate Iron(0) Reagents

The combined use of aminocarbene and divinyltetramethyldisiloxane (dvtms) as supporting ligands enables the access of unprecedented low‐coordinate iron(0) alkene compounds [L_nFe(η²:η²‐dvtms)] (L=N‐heterocyclic carbene (NHC) or cyclic (alkyl)(amino)carbene (CAAC), n=1 or 2) from the reactions of FeCl₂ with alkali‐metal reducing agents, free aminocarbene ligands, and dvtms. The iron(0) species deliver their {L_nFe⁰} fragments to perform redox reactions with Ph₂SiH₂, S₈, Se, and DippN₃, furnishing novel aminocarbene‐supported iron(IV) silylene, all‐ferrous iron–sulfur/selenium cubanes, and bis(imido)iron(IV) compounds. These conversions demonstrate the potential synthetic utility of the carbene‐supported iron(0) complexes as a valuable class of low‐coordinate iron(0) reagents.     

Synthesis and coordination chemistry of the PPN ligand 2‐[bis(diisopropylphosphanyl)methyl]‐6‐methylpyridine

The synthesis and crystal structure of the multidentate PPN ligand 2‐[bis(diisopropylphosphanyl)methyl]‐6‐methylpyridine (L ), C₁₉H₃₅NP₂, are described. In the isostructural tetrahedral Fe and Co complexes of type LM Cl₂ (M = Fe, Co), namely {2‐[bis(diisopropylphosphanyl)methyl]‐6‐methylpyridine‐κ²P ,N }dichloridoiron(II), [FeCl₂(C₁₉H₃₅NP₂)], and {2‐[bis(diisopropylphosphanyl)methyl]‐6‐methylpyridine‐κ²P ,N }dichloridocobalt(II), [CoCl₂(C₁₉H₃₅NP₂)], the ligand adopts a bidentate P ,N‐coordination, whereas in the case of the octahedral Mn complex {2‐[bis(diisopropylphosphanyl)methyl]‐6‐methylpyridine‐κ²P ,P ′}bromidotricarbonylmanganese(I), [MnBr(C₁₉H₃₅NP₂)(CO)₃], the ligand coordinates via both P atoms to the metal centre.     

Chemical Bonding in Homoleptic Carbonyl Cations [M{Fe(CO)5}2]+ (M=Cu,Ag, Au)

Syntheses of the copper and gold complexes [Cu{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] containing the homoleptic carbonyl cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Au) are reported. Structural data of the rare, trimetallic Cu₂Fe, Ag₂Fe and Au₂Fe complexes [Cu{Fe(CO)₅}₂][SbF₆], [Ag{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] are also given. The silver and gold cations [M{Fe(CO)₅}₂]⁺ (M=Ag, Au) possess a nearly linear Fe-M-Fe’ moiety but the Fe-Cu-Fe’ in [Cu{Fe(CO)₅}₂][SbF₆] exhibits a significant bending angle of 147° due to the strong interaction with the [SbF₆]⁻ anion. The Fe(CO)₅ ligands adopt a distorted square-pyramidal geometry in the cations [M{Fe(CO)₅}₂]⁺, with the basal CO groups inclined towards M. The geometry optimization with DFT methods of the cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Ag, Au) gives equilibrium structures with linear Fe-M-Fe’ fragments and D₂ symmetry for the copper and silver cations and D_4d symmetry for the gold cation. There is nearly free rotation of the Fe(CO)₅ ligands around the Fe-M-Fe’ axis. The calculated bond dissociation energies for the loss of both Fe(CO)₅ ligands from the cations [M{Fe(CO)₅}₂]⁺ show the order M=Au (D_e=137.2 kcal mol⁻¹)>Cu (D_e=109.0 kcal mol⁻¹)>Ag (D_e=92.4 kcal mol⁻¹). The QTAIM analysis shows bond paths and bond critical points for the M−Fe linkage but not between M and the CO ligands. The EDA-NOCV calculations suggest that the [Fe(CO)₅]→M⁺←[Fe(CO)₅] donation is significantly stronger than the [Fe(CO)₅]←M⁺→[Fe(CO)₅] backdonation. Inspection of the pairwise orbital interactions identifies four contributions for the charge donation of the Fe(CO)₅ ligands into the vacant (n)s and (n)p AOs of M⁺ and five components for the backdonation from the occupied (n-1)d AOs of M⁺ into vacant ligand orbitals.     

Syntheses and Molecular Structures of [(thf)4Li] [{(thf)Li}M(C4H8)3] (M = Zr,Hf) and Their Solution Behavior

The reaction of MCl₄(thf)₂ (M = Zr, Hf) with 1,4-dilitiobutane in diethyl ether at –25 °C or at 0 °C with a molar ratio of 1 : 3 yields the homoleptic “ate” complexes [(thf)₄Li] [{(thf)Li}M(C₄H₈)₃] 1 - Zr (M = Zr) and 1 - Hf (M = Hf). The crystalline compounds form ion lattices with solvent-separated [(thf)₄Li]⁺ cations and [{(thf)Li}M(C₄H₈)₃]^– anions. The NMR spectra at –20 °C show magnetic equivalence of the M–CH₂ and of the β-CH₂ groups of the butane-1,4-diide ligands on the NMR time scale. Analogous reactions of MCl₄(thf)₂ with 1,4-dilithiobutane with a molar ratio of 1 : 2 proceed unclear. However, single crystals of [Li(thf)₄] [HfCl₅(thf)] ( 2 ) can be isolated with the hafnium atom in a distorted octahedral coordination sphere of five chloro and one thf ligand. NMR spectra allow to elucidate the time-dependent degradation of 1-Hf and 1-Zr in THF and toluene at 25 °C via THF cleavage. Addition of tmeda to a solution of 1-Zr allows the isolation of intermediately formed [{(tmeda)Li}₂Zr(nBu)₂(C₄H₈)₂] ( 3 ).     

Octanuclear Palladacycles with B(3)–H Bond Activation of o-Carborane†

Herein, we describe the synthesis of a carborane-supported octanuclear palladacycle complex, Pd₈(o-C₂B₁₀H₁₀CS₂CH₃)₄Cl₄(CH₃CN)₄ (complex 1 ), with B(3)–H activations on o-carborane ligand. The substitution reaction of 1 has been explored, and three of its substituted complexes Pd₈(o-C₂B₁₀H₁₀CS₂CH₃)₄Cl₄(L)₄ (L = ^tBuNC, 2 ; L = C₅H₅N, 3 ; L = C₄H₈S, 4 ) have been synthesized. The m- and p-carborane disubstituted ligands m- and p-C₂B₁₀H₁₀(CS₂CH₃)₂ (ligands 5 and 6 ) as well as their B—H activated carborane complexes [m-C₂B₁₀H₉(CS₂CH₃)₂PdCl] ( 7 ) and [p-C₂B₁₀H₈(CS₂CH₃)₂][PdCl(^tBuNC)]₂ ( 8 ) have also been synthesized by the similar method. All of these complexes have been characterized, including X-ray single crystal diffraction, NMR spectroscopy, IR spectroscopy and elemental analysis methods.      

A mixed‐valence iron complex of the antitumour drug 6‐mercaptopurine: tris(6‐mercaptopurine)iron(II) tetrachloroferrate(III) chloride

Single crystals of the title complex, tris(1,6‐di­hydro‐9H‐purine‐6‐thione‐N⁷,S)­iron(II) tetra­chloro­ferrate(III) chloride, [Fe(C₅H₄N₄S)₃][FeCl₄]Cl, were grown on the surface of solid 6‐mercaptopurine monohydrate pellets in a solution of iron(III) chloride. The solution of the hexagonal structure required the application of twin refinement techniques. All the component ions lie on threefold rotation axes. The complex contains distorted octahedral [Fe(C₅H₄N₄S)₃]²⁺ cations with three N7/S6‐chelating neutral 6‐mercaptopurine ligands, tetrahedral [FeCl₄]^? anions with a mean Fe—Cl distance of 2.189 (1) Å, and free chloride ions.     

Crystal structures of two (5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) complexes

Reported in this contribution are the synthesis and crystal structures of two new Fe^III complexes of 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane (HMC), namely, dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) chloride, [FeCl₂(C₁₆H₃₆N₄)]Cl or cis‐[FeCl₂(rac‐HMC)]Cl ( 1 ), and dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) tetrachloridoferrate, [FeCl₂(C₁₆H₃₆N₄)][FeCl₄] or trans‐[FeCl₂(meso‐HMC)][FeCl₄] ( 2 ). Single‐crystal X‐ray diffraction studies revealed that both 1 and 2 adopt a pseudo‐octahedral geometry, where the macrocycles adopt folded and planar geometries, respectively. The chloride ligands in 1 are cis to each other, while those in 2 have a trans configuration. The relevant bond angles in 1 deviate substantially from an ideal octahedral coordination geometry, with the angles between the cis substituents varying from 81.55 (5) to 107.56 (4)°, and those between the trans‐ligating atoms varying from 157.76 (8) to 170.88 (3)°. In contrast, 2 adopts a less strained configuration, in which the N—Fe—N angles vary from 84.61 (8) to 95.39 (8)° and the N—Fe—Cl angles vary from 86.02 (5) to 93.98 (5)°.     

Tetradentate asymmetric Schiff bases and their Ni(II) and Fe(III) complexes

Three asymmetric Schiff-base tetradentate diimines H₂L¹, H₂L², and H₂L³ [(2-OH)C₆H₄N=CHC₆H₄2-N=CHC₆H₃(2-OH)(5-X), X?=?H, CH₃, Cl respectively] have been synthesized by a two step process. The reaction of 2-hydroxy aniline with 2-nitro-benzaldehyde in EtOH gave the starting Schiff base, 2-hydroxy-N-(2-nitrobenzylidene)aniline (SB-NO₂), which was reduced into the amino derivative (SB-NH₂) in solution. Reacting SB-NH₂ with 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-5-chlorobenzaldehyde gave the three new ligands H₂L¹, H₂L², and H₂L³ respectively. Their dimeric, binuclear metal complexes with Ni(II) and Fe(III) have also been synthesized. The ligands and their complexes were characterized by elemental analyses, LC–MS, IR, electronic, ¹H and ¹³C-NMR spectra, TGA, conductivity and magnetic measurements. All of the spectroscopic, analytical and other data indicate octahedral geometry M₂L₂(H₂O)X₂ (M: Ni,Co;X: Cl or H₂O), except for NiL² which is monomeric. Antimicrobial activities of the ligands and the complexes were evaluated against five bacteria. While the ligands and the Ni complexes are inactive towards Pseudomonas aeruginosa and Staphylococcus aureus, Fe complexes are active; only Fe complexes are inactive against Escherichia coli. All of the compounds have antimicrobial activities against Bacillus subtilis, and Yersinia enterecolitica.     

Kinetic investigations of the Oxidative Addition Reactions of Simple Molecules with Carbon-Carbon Multiple Bonds to {Ir(CO)XL2}-type complexes

The kinetics of the addition reactions of tetracyanoethylene (TCNE), dimethyl maleate (DMM), diethyl maleate (DEM), maleicanhydride (MA), acetylenedicarboxylic acid (ADCA) and dimethyl acetylenedicarboxylate (DMADC) to complexes of the type trans-{Ir(CO)XL₂} (X = Cl, Br, I; L = P(C₆H₅)₃, P(p-CH₃C₆H₄)₃, P(p-CH₃OC₆H₄)₃, P(OC₆H₅)₃) in various solvents were investigated employing stopped-flow techniques. The kinetics were found to obey a second order/first order rate law for a reversible process. The rate constants obtained are discussed in terms of a Lewis acid-base model.     

Synthesis,Characterization and Crystal Structure of Novel Mixed Bridged Trinuclear Oxo‐Centered Iron(III), Chromium(III) Complexes Containing Terminal Unsaturated Carboxylato and Acrylic Acid Dimer Anion Ligands

Three new oxo‐centered trinuclear mixed‐bridged carboxylate complexes with terminal unsaturated ligands ([M₂M′(μ₃‐O)(μ‐O₂C₃H₃)₅(μ‐O₄C₆H₇)(O₂C₃H₃) (H₂O)₂]·2H₂O [M = Fe, M′ = Fe ( 1 ); M = Fe, M′ = Cr ( 2 ); M = Cr, M′ = Fe ( 3 )]) have been synthesized and characterized by means of elemental analyses, IR spectra and crystal structure analyses. The compounds crystallize isotypically in the orthorhombic space group type Pbcn with a = 24.622(3) Å, b = 16.304(2) Å, c = 17.491(2) Å, V = 7021.5(15) ų ( 1 ), a = 24.708(5) Å, b = 16.290(2) Å, c = 17.394(2) Å, V = 7001.0(18) ų ( 2 ), a = 24.611(4) Å, b = 16.300(3) Å, c = 17.359(3) Å, V = 6964(2) ų ( 3 ), and Z = 8. The infrared spectra show resolved bands arising from ν_asym(OCO) and ν_sym(OCO) vibrations of monodentate and bridging carboxylate ligands along with those of ν_asym(M₂M′O) vibrations in the complexes.     

Darstellung und Struktur von Tetraethylcyclotetraarsoxan-Komplexen von Kupfer(I)-Halogeniden

Preparation and Structure of Tetraethylcyclotetraarsoxane Complexes of Copper(I) Halides The polymeric complexes [Cu₄Cl₄{cyclo-(C₂H₅AsO)₄}₃]_n ( 1 ), [Cu₃Br₃{cyclo-(C₂H₅AsO)₄}₂]_n ( 2 ) and [Cu₆I₆{cyclo-(C₂H₅AsO)₄}₃]_n ( 3 ) were prepared by the reaction of (C₂H₅AsO)_n and CuX (X = Cl, Br, I) in acetonitrile and characterised by X-ray analysis. All three complexes contain only tetramers (C₂H₅AsO)₄ as ligands, in which the As₄O₄ ring systems coordinate between two and four Cu-atoms. In each case one As₄O₄ ring with a crown-shaped conformation is observed, which coordinates either four (in 1 ) or three (in 2 and 3 ) axially sited Cu-atoms. In addition there are further (C₂H₅AsO)₄ ligands, which display either a boat-chair- (in 1 ) or a twist-chair-conformation (in 1–3 ). The individual building units are connected to one another via Cu? X? Cu bridges (in 2 and 3 ) and/or centrosymmetric As₄O₄ ring systems (in 1–3 ) into chain ( 1 ) or layer structures ( 2 und 3 ).     

Zweikernige silylenverbrückte Cyclopentadienylrhodiumbis(ethen)-Komplexe,photochemische Reaktion mit Benzolderivaten und selektiver Einschluß von Methylcyclopentan in das Kristallgitter von [Me2Si{3-But-C5H3Rh(C2H4)2}2]

Dinuclear Silylene Bridged Cyclopentadienylrhodiumbis(ethene) Complexes, Photochemical Reaction with Benzene Derivatives, and Selective Inclusion of Methylcyclopentane into the Crystal Lattice of [Me₂Si{3-Bu^t-C₅H₃Rh(C₂H₄)₂}₂] By reaction of [{(C₂H₄)₂RhCl}₂] with Na₂[Me₂Si(C₅H₄)₂] or with Li₂[Me₂Si(3-Bu^t-C₅H₃)₂] in THF the dinuclear silylene bridged complexes [Me₂Si{C₅H₄Rh(C₂H₄)₂}₂] 1 and [Me₂Si{3-Bu^t-C₅H₃Rh(C₂H₄)₂}₂] 2 , respectively, were synthesized. Due to the asymmetric substitution of the five-membered rings and their hindered rotation around the Si? C axes, 2 is formed as three isomers. The X-ray structure analysis of 2 obtained from hexane reveals the selective inclusion of methylcyclopentane, the content of which in the solvent is about 17%, into the crystal lattice. UV irradiation of 1 in hexane in the presence of benzene causes elimination of the ethene ligands yielding the μ-η³:η³ benzene complex [Me₂Si(C₅H₄Rh₂)₂C₆H₆] which cannot be separated from unreacted 1 . However, separation is possible in case of the hexamethylbenzene compound 4 analogous with 3 .     

Disubstituted diphenyldithiophosphates of cadmium: synthesis,characterization, and single-crystal X-ray structure

A series of new disubstituted diphenyldithiophosphate complexes of cadmium [{(ArO)₂PS₂}₂Cd] (9–12) have been isolated in aqueous media while their donor stabilized adducts [{(ArO)₂PS₂}₂Cd·2C₅H₅N] (13–16) [(Ar = 2,4-(CH₃)₂C₆H₃, 2,5-(CH₃)₂C₆H₃, 3,4-(CH₃)₂C₆H₃ and 3,5-(CH₃)₂C₆H₃)] have been isolated in chloroform. These newly synthesized complexes were characterized by elemental analyses, IR and NMR (¹H, ¹³C and ³¹P) spectroscopic analyses. The dithiophosphate ligands are coordinated bidentate to the cadmium ion via the two thiolate sulfurs. The compounds [{(3,5-CH₃)₂C₆H₃O}₂PS₂HNEt₃] (4) and [{(3,5-CH₃)₂C₆H₃O}₂PS₂]₂Cd(NC₅H₅)₂ (16) crystallize in the monoclinic system with space group P2₁/c. Single-crystal X-ray analysis of 4 reveals that phosphorus of the anion is tetrahedrally bonded to two S and two O atoms. The structure is stabilized by cation–anion N–H?S intermolecular hydrogen bond interactions. In 16, two diphenyldithiophosphate ions are bidentate with both sulfurs coordinated to cadmium. Each forms a four-membered chelate ring in the equatorial plane. Two pyridines are axially coordinated to cadmium leading to octahedral geometry. The thermal properties of this complex have also been examined by combined DTA/DTG thermal analyses.     

The Coordination Chemistry of Iron with the 1,4‐Bis(2‐pyridyl‐methyl)piperazine Ligand

The behaviour of Fe^II and Fe^III ions in combination with the potential ligand 1,4‐bis(2‐pyridyl‐methyl)piperazine (BPMP) under anhydrous conditions has been investigated. BPMP has been reacted with FeCl₂, FeCl₃ and [Fe(OTf)₂(MeCN)₂]. This led to the isolation of four new complexes, which were fully characterized and structurally investigated by single crystal X‐ray diffraction. It turned out that in the presence of chloride co‐ligands Fe^III favours the tetradentate coordination mode of BPMP with the piperazine unit in a boat configuration, like for instance in [BPMP(Cl)Fe(μ‐O)FeCl₃] or [BPMP‐FeCl₂][FeCl₄], ( 1 ). However, the employment of FeCl₂ leads to the formation of a coordination polymer [BPMP‐FeCl₂]_n, ( 2 ), containing the piperazine ring in a chair configuration binding to two iron centres each. 2 can only be dissolved in very polar solvents like dmf which is capable of breaking up the polymeric structure under formation of [Cl₂(dmf)Fe(μ‐BPMP‐1κ²N,N:2κ²N,N))Fe(dmf)Cl₂]·2 dmf, ( 3 ). In contrast, using [Fe(OTf)₂(MeCN)₂] instead of FeCl₂ as the starting material leads to a mononuclear Fe^II complex with BPMP bound in the desirable tetradentate fashion: [BPMP‐Fe(OTf)₂], ( 4 ). Unlike other complexes with tetradentate N/py ligands the two residual ligands in 4 are bound almost trans to each other with the potential to adopt a cis orientation under oxidising conditions, and it will be interesting to exploit its catalytic properties in future.     

Functionalised Tris(pyrazolyl)methane Ligands and Re(CO)3 Complexes Thereof

The synthesis of new tripodal nitrogen ligands derived from tris(pyrazolyl)methane (Tpm^R, R = H, tBu, Ph in 3‐position) is described. After deprotonation of the parent tris(pyrazolyl)methane Tpm^R, the carbanion reacts readily with ethylene oxide to yield the 3,3,3‐tris(3′‐substituted pyrazolyl)propanol ligands[(3‐Rpz)₃CCH₂CH₂OH, R = H, tBu, Ph, 1a – c ]. These ligands can be easily derivatised at the alcohol function. Microwave‐assisted reactions of these ligands and [Re(CO)₅Br] yields the complex [( 1a )Re(CO)₃]Br ( 4 ) in the case of ligand 1a , whereas in the case of the substituted ligands 1b and 1c degradation was observed. The degradation products are identified as [(Hpz^R)₂Re(CO)₃Br] [R = tBu ( 7b ), Ph ( 7c )]. These complexes were also prepared directly from [Re(CO)₅Br] and the corresponding pyrazoles by microwave‐assisted synthesis. The Re(CO)₃ complexes 4 and [( 1a )Re(CO)₃]OTf ( 5 ) are water‐soluble. The structures of 5· H₂O and [{(pz)₃CCH₂CH₃}Re(CO)₃]OTf · 1.5H₂O · ¹/₂CH₃CN ( 6· 1.5H₂O · ¹/₂CH₃CN) as well as the structure of 7b have been elucidated by X‐ray crystallography.     

Darstellung und NMR-spektroskopische Untersuchung eines hexakoordinierten p-Tolylo-tantal(V)-Komplexes: [(p-CH3C6H4)5 Ta(p-CH3C6H4)Li · O(C2H5)2]

Preparation and N.M.R.-spectroscopie Investigation of a Hexacoordinated p-Tolylotantalum(V) Complex: [(p-CH₃C₆H₄)₅Ta(p-CH₃C₆H₄)Li · O(C₂H₅)₂] Reaction of tantalum(V) bromide with an etheral solution of p-tolyllithium in the molar ratio 1:5 leads to precipitation of a yellow complex of the brutto formula LiTaTol₆ · Ae[Tol = p-CH₃C₆H₄^?; Ae = (C₂H₅)₂O]. The ¹H and ¹³C n.m.r. spectra are discussed.     

Synthesis and characterization of heteroleptic iron(II) thiolate complexes with weak iron-arene interactions

Selective preparation and characterization of a series of heteroleptic thiolate complexes of iron(II) are described. The compounds were synthesized by treatment of iron bis-amide Fe{N(SiMe₃)₂}₂ (1) with 1 equiv. of terphenyl thiols HS(2,6-(aryl)₂C₆H₃) followed by addition of another equivalent of different thiol. An amide-thiolate intermediate [{(Me₃Si)₂N}Fe]₂(μ-SDpp)₂ (2; Dpp = 2,6-Ph₂C₆H₃) was isolated from the 1:1 reaction of 1 and HSDpp. The X-ray crystal structures of all new thiolate complexes have been determined. The compounds crystallize as monomers or dimers, dependent on the substituents. They consist of distorted tetrahedral or trigonal-planar iron centers with weak interactions between the aromatic rings of thiolate ligands, where the Fe-C(arene) contact is 2.272(2) Å at shortest. The stronger iron-arene interaction appears to induce more pyramidalized geometry at the iron center.     

Efficient Blue Phosphorescence in Gold(I)-Acetylide Functionalized Coinage Metal Bis(amidinate) Complexes

The synthesis of linear symmetric ethynyl- and acetylide-amidinates of the coinage metals is presented. Starting with the desilylation of the complexes [{Me₃SiC≡CC(NDipp)₂}₂M₂] (Dipp=2,6-diisopropylphenyl) (M=Cu, Au) it is demonstrated that this compound class is suitable to serve as a versatile metalloligand. Deprotonation with n-butyllithium and subsequent salt metathesis reactions yield symmetric tetranuclear gold(I) acetylide complexes of the form [{(PPh₃)AuC≡CC(NDipp)₂}₂M₂] (M=Cu, Au). The corresponding Ag complex [{(PPh₃)AuC≡CC(NDipp)₂}₂Ag₂] was obtained by a different route via metal rearrangement. All compounds show bright blue or blue-green microsecond long phosphorescence in the solid state, hence their photophysical properties were thoroughly investigated in a temperature range of 20–295 K. Emission quantum yields of up to 41 % at room temperature were determined. Furthermore, similar emissions with quantum yields of 15 % were observed for the two most brightly luminescent complexes in thf solution.