European Journal of Inorganic Chemistry

Cobaltoceniumselenolate is an unusual, highly air-sensitive, mesoionic compound containing a very soft anionic selenium donor atom. Here we explore its coordination chemistry with Au(I) metal centers and show that its hetero- and homoleptic gold complexes are highly colored, air-stable compounds, which were characterized by 1 H/13 C/31 P/77 Se NMR, IR, UV-Vis, HR-MS and single crystal XRD. Cytotoxicity of these polar, water-soluble complexes was studied against various standard cancer cell lines (A549MDA-MB-231, HT-29) revealing good anticancer activity of all three complexes...

A series of gold(I) complexes with the general formula [Au( L2 )( L' )] ( L2 =4-phenyl- N -(prop-2-yn-1-yl)quinazoline-2-carboxamide, L' =PPh3 (triphenylphosphine), 1 ; TPA (1,3,5-triaza-7-phosphaadamantane), 2 , and Me2 -imy (1,3-dimethylimidazol-2-ylidene), 3 ) were synthesized and fully characterized by spectroscopic methods. The alkynyl ligand L2 belongs to the quinazoline carboxamide class of ligands that are known to bind to the translocator protein (TSPO) at the outer mitochondrial membrane. 1 and 2 exert cytotoxic effects in bladder cancer cells with IC50 values in the low micromolar range...

Reaction between the platinum(IV) azido complex trans,trans , trans -[Pt(py)2 (N3 )2 (OH)2 ] ( 1 ) and 1,4-diphenyl-2-butyne-1,4-dione 2 in MeCN produces the intermediate peroxide-bridged dimeric platinum(IV) azido triazolato species ( 5 ), which has been characterised by X-ray crystallography. However, if the reaction between 1 and 2 is conducted in MeOH it results in decomposition. Over time in MeCN, dimer ( 5 ) converts into mononuclear complexes trans,trans , trans -[Pt(py)2 (N3 )(triazole)(OH)2 ] ( 3 a / 3 b ), which are in dynamic exchange...

DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-based chelates that give only a single isomer in solution when complexed with lanthanide (Ln3+ ) ions is of value for studying protein dynamics and interactions via NMR. Herein, we have investigated the geometries, energetics, and electrostatic potentials of Lu complexed with DOTA ( 1 ), ring methylated M4DOTA ( 2 ), and arm methylated R -DOTMA ( 3 ) and S -DOTMA ( 4 ), as well as, both ring and arm methylated 4 S -4 S -M4DOTMA ( 5) and 4 S -4 R -M4DOTMA ( 6 ) at the level of M06-L/6-31+G(d)-SDD, to elucidate the origin of the isomer stability...

The synthesis and organometallic chemistry of rhodium(I) complex [Rh(CNC-Me)(SOMe2 )][BArF 4 ], featuring NHC-based pincer and labile dimethyl sulfoxide ligands, is reported. This complex reacts with biphenylene and chlorobenzene to afford products resulting from selective C-C and C-Cl bond activation, [Rh(CNC-Me)(2,2'-biphenyl)(OSMe2 )][BArF 4 ] and [Rh(CNC-Me)(Ph)Cl(OSMe2 )][BArF 4 ], respectively. A detailed DFT-based computational analysis indicates that C-H bond oxidative addition of these substrates is kinetically competitive, but in all cases endergonic: contrasting the large thermodynamic driving force calculated for insertion of the metal into the C-C and C-Cl bonds, respectively...

The R , R and S , S enantiomers of N , N '-bis(1-phenylpropyl)-2,6-pyridinedicarboxamide, L(Et) , react with Ln3+ ions (Ln = La, Eu, Gd, and Tb) to give stable [Ln(( R , R )- and ( S , S )- L(Et ))3 ]3+ in anhydrous acetonitrile solution, as evidenced by various spectroscopic measurements, including NMR and luminescence titrations. In addition to the characteristic Eu3+ and Tb3+ luminescence bands, the steady-state and time-resolved luminescence spectra of the aforementioned complexes show the residual ligand-centered emission of the 1 ππ* to 3 ππ* states, indicating an incomplete intersystem crossing (ISC) transfer from the 1 ππ* to 3 ππ* and ligand-to-Ln3+ energy transfer, respectively...

We present a computational study on tetrapnictide dianions Pn 4 2- (Pn = P, As, Sb, Bi), using density functional theory (DFT), coupled-cluster [DLPNO-CCSD(T)] and complete active space self-consistent field (CASSCF) methods. Environmental effects such as solvation and coordination of counterions are included. The calculations reveal that out of three isomers (square-planar, butterfly and capped-triangle), the square planar isomers are generally the most stable. The counterion (Li+ and Mg2+ ) used in the calculations have a substantial effect on the relative stabilities...

Redox reactions, substitutions, and metalations are reported for the iron carbido sulfide [Fe6 C(CO)14 (S)]2- ([ 1 ]2- ). Dianion [ 1 ]2- oxidized to [Fe6 C(CO)16 (S)]0 ([ 2 ]0 ) upon treatment with of [Fe(C5 H5 )2 ]BF4 or HBF4 (H2 formation) under an atmosphere of CO. Reaction of [ 2 ]0 with t BuNC gave [Fe6 C(S)(CO)13 ( t BuNC)5 ], consisting of Fe5 C(CO)13 and [Fe( t BuNC)5 ]2+ subunits linked by a μ3 -S2- . The Fe7 CS cluster [Fe7 C(CO)17 (S)]2- formed upon treatment of (Ph4 P)2 [ 1 ] with Fe(benzylideneacetone)(CO)3 ...

In recent decades, the chemistry of stable silylenes (R2 Si:) has evolved significantly. The first major development in this chemistry was the isolation of a silicocene which is stabilized by the Cp* (Cp* = η5 -C5 Me5 ) ligand in 1986 and subsequently the isolation of a first N -heterocyclic silylene (NHSi:) in 1994. Since the groundbreaking discoveries, a large number of isolable cyclic silylenes and higher coordinated silylenes, i.e. Si(II) compounds with coordination number greater than two, have been prepared and the properties investigated...

A set of novel, easily synthesized aluminum complexes, Al[κ2 - N , N- 2-(methylamino)pyridine]2 R (R = Et, i Bu) are reported. When subjected to 1 atm of CO2 pressure, each hemilabile pyridine arm dissociates and facilitates cooperative activation of the CO2 substrate reminiscent of a Frustrated Lewis Pair. This reaction has limited precedent for Al/N based Lewis Pair systems, and this is the first system readily shown to sequester multiple equivalents of CO2 per aluminum center. The ethyl variant then reacts further, inserting a third equivalent of CO2 into the aluminum alkyl to generate an aluminum carboxylate...

This minireview aims to cover the developments over the past two decades in the chemistry of sulfonium salts. Specifically, insight is provided into the synthetic strategies available for the preparation of these compounds, the different reactivity patterns that are expected depending on their structural features or the reaction conditions applied, and the diversity of organic scaffolds that can thereby be synthesized. Additionally, the pros and cons derived from the use of sulfonium salts are presented and critically compared, when possible, in relation to reagents not based on sulfur but depicting similar reactivity...

We report catalytic silylation of dinitrogen to tris(trimethylsilyl)amine by a series of trinuclear first row transition metal complexes (M = Cr, Mn, Fe, Co, Ni) housed in our tris(β-diketiminate) cyclophane ( L 3- ). Yields are expectedly dependent on metal ion type ranging from 14 to 199 equiv NH4 + /complex after protonolysis for the Mn to Co congeners, respectively. For the series of complexes, the number of turnovers trend observed is Co > Fe > Cr > Ni > Mn, consistent with prior reports of greater efficacy of Co over Fe in other ligand systems for this reaction...

Nitrogen (N2 ) fixation to produce bio-available ammonia (NH3 ) is essential to all life but is a challenging transformation to catalyse owing to the chemical inertness of N2 . Transition metals can, however, bind N2 and activate it for functionalization. Significant opportunities remain in developing robust and efficient transition metal catalysts for the N2 reduction reaction (N2 RR). One opportunity to target in catalyst design concerns the stabilization of transition metal diazenido species (M-NNH) that result from the first N2 functionalization step...

The splitting of N2 into well-defined terminal nitride complexes is a key reaction for nitrogen fixation at ambient conditions. In continuation of our previous work on rhenium pincer mediated N2 splitting, nitrogen activation and cleavage upon (electro)chemical reduction of [ReCl2 ( L 2)] { L 2 = N(CHCHP t Bu2 )2 - } is reported. The electrochemical characterization of [ReCl2 ( L 2)] and comparison with our previously reported platform [ReCl2 ( L 1)] { L 1 = N(CH2 CH2 P t Bu2 )2 - } provides mechanistic insight to rationalize the dependence of nitride yield on the reductant...

Complexes of copper and 1,10-phenanthroline have been utilized for organic transformations over the last 50 years. In many cases these systems are impacted by reaction conditions and perform best under an inert atmosphere. Here we explore the role the 1,10-phenanthroline ligand plays on the electronic structure and redox properties of copper coordination complexes, and what benefit related ligands may provide to enhance copper-based coupling reactions. Copper(II) triflate complexes bearing 1,10-phenanthroline (phen), ([Cu(phen)2 (OTf)]OTf, 1 ) and oxidized derivatives of phen including [Cu(edhp)2 ](OTf)2 ( 2 ), [Cu(pdo)2 ](OTf)2 ( 3 ), [Cu(dafo)2 ](OTf)2 ( 4 ) were prepared and characterized...

The good performance of N-heterocyclic carbenes (NHCs), in terms of versatility and selectivity, has called the attention of experimentalists and theoreticians attempting to understand their electronic properties. Analyses of the Au(I)-C bond in [(NHC)AuL]+/0 (L stands for a neutral or negatively charged ligand), through the Dewar-Chatt-Duncanson model and the charge displacement function, have revealed that NHC is not purely a σ -donor but may have a significant π-acceptor character. It turns out, however, that only the σ -donation bonding component strongly correlates with one specific component of the chemical shielding tensor...

We report the synthesis, characterisation and cytotoxicity of six cyclometalated rhodium(III) complexes [CpX Rh(C^N)Z]0/+ , in which CpX = Cp*, Cpph , or Cpbiph , C^N = benzo[h]quinoline, and Z = chloride or pyridine. Three x-ray crystal structures showing the expected "piano-stool" configurations have been determined. The chlorido complexes hydrolysed faster in aqueous solution, also reacted preferentially with 9-ethyl guanine or glutathione compared to their pyridine analogues. The 1-biphenyl-2,3,4,5,-tetramethylcyclopentadienyl complex [Cpbiph Rh(benzo[h]quinoline)Cl] ( 3a ) was the most efficient catalyst in coenzyme reduced nicotinamide adenine dinucleotide (NADH) oxidation to NAD+ and induced an elevated level of reactive oxygen species (ROS) in A549 human lung cancer cells...

Bistable spin crossover complexes such as [Fe{HB(pz)3 }2 ] (pzH = pyrazole) show promise for sensor applications and electrically-controlled data storage units, but exploiting their potential hinges on their integration into a functional environment. We here present a system enabling such covalent post-functionalization steps in both symmetric and asymmetric patterns, based on the amine-functionalized complex [Fe{HB(4-NH2 pz)(pz)2 }2 ], obtained by reduction of the nitro analogue. The building block aspects of [Fe{HB(4-NH2 pz)(pz)2 }2 ] are showcased by its transformation into amide, imine and azo derivatives, which are structurally and magnetically characterized...

For the first time, the tetrahedral diphosphorus complex [Cp2 W2 (CO)4 (µ,η2 :η2 -P2 )] (Cp = C5 H5 ) ( 3 ) is used as a connecter in supramolecular chemistry. The treatment of 3 with CuI halides leads to the formation of the new one-dimensional (1D) linear polymers [Cu(µ-X){Cp2 W2 (CO)4 (µ,η2 :η2 :η1 :η1 -P2 )}] n {X = Cl ( 4 ), Br ( 5 ), I ( 6 )}. The coordination polymers (CPs) 4 - 6 are almost insoluble in organic solvents, thus, their 31 P MAS-NMR spectra were recorded and found to be remarkably influenced by their solid-state structures...

Metal carbonyls are commonly employed probes for quantifying the donor properties of monodentate ligands. With a view to extending this methodology to mer -tridentate "pincer" ligands, the spectroscopic properties [ν(CO), δ 13C , 1 J RhC ] of rhodium(I) and rhodium(III) carbonyl complexes of the form [Rh(pincer)(CO)][BArF 4 ] and [Rh(pincer)Cl2 (CO)][BArF 4 ] have been critically analysed for four pyridyl-based pincer ligands, with two flanking oxazoline (NNN), phosphine (PNP), or N-heterocyclic carbene (CNC) donors...