Pushing redox potentials to highly positive values using inert fluorobenzenes and weakly coordinating anions.

While the development of weakly coordinating anions (WCAs) received much attention, the progress on weakly coordinating and inert solvents almost stagnated. Here we study the effect of strategic F-substitution on the solvent properties of fluorobenzenes C6FxH6-x (xFB, x = 1-5). Asymmetric fluorination leads to dielectric constants as high as 22.1 for 3FB that exceeds acetone (20.7). Combined with the WCAs [Al(ORF)4]- or [(FRO)3Al-F-Al(ORF)3]- (RF = C(CF3)3), the xFB solvents push the potentials of Ag+ and NO+ ions to +1.50/+1.52 V vs. Fc+/Fc. The xFB/WCA-system has electrochemical xFB stability windows that exceed 5 V for all xFBs with positive upper limits between +1.82 V (1FB) and +2.67 V (5FB) vs. Fc+/Fc. High-level ab initio calculations with inclusion of solvation energies show that these high potentials result from weak interactions of the ions with solvent and counterion. To access the available positive xFB potential range with stable reagents, the innocent deelectronator salts [anthraceneF]+∙[WCA]- and [phenanthreneF]+∙[WCA]- with potentials of +1.47 and +1.89 V vs. Fc+/Fc are introduced.

Reaction Mechanisms of High-Rate Copper Electrochemical Machining in Nitrate Electrolytes.

The high-rate electrochemical dissolution of copper in nitrate electrolytes is investigated primarily via polarization curves, while varying parameters such as the electrolyte flow velocity, the electrolyte resistance, the anode geometry, and the temperature. This study focuses on the re-rise in current at high voltages after the limiting current plateau. As a result of the studies, a change in the complexation mechanism from hydration to "solvo-nitration" is proposed, which requires an additional potential drop within the electrochemical double layer.

Synthesis and Characterization of a Copper Dinitrogen Complex Supported by a Weakly Coordinating Anion.

We report the synthesis and full characterization of the copper dinitrogen complex [(η1-N2)Cu{Al(ORF)4}] 2 (RF=C(CF3)3) prepared by a cascade metathesis reaction of Ag[Al(ORF)4] with CuI-excess in iso-perfluorohexane (i-pfh) under N2 atmosphere. Title compound 2 features an extraordinarily high N2 stretching frequency at 2313/2314 cm-1 (IR/Raman) and was characterized by single-crystal and powder X-ray diffractometry. Quantum chemical charge displacement analysis based on natural orbitals of chemical valence (CD-NOCV) indicates that the copper-dinitrogen interaction is still governed by weak π-backdonation, but is significantly reduced compared to all literature-known transition metal dinitrogen complexes.

Utilizing the Perfluoronaphthalene Radical Cation as a Selective Deelectronator to Access a Variety of Strongly Oxidizing Reactive Cations.

A selective deelectronation reagent with very high potential of +2.00 (solution)/+2.41 V (solid-state) vs. Fc+/0 and based on a room temperature stable perfluoronaphthalene (naphthaleneF) radical cation salt was developed and applied. The solid-state deelectronation of commercial naphthaleneF with [NO]+[F{Al(ORF)3}2]- generates [naphthaleneF]+⋅[F{Al(ORF)3}2]- (ORF=OC(CF3)3) in gram scale. Thermochemical analysis unravels the solid-state deelectronation potential of the starting [NO]+-reagent to be +2.34 V vs. Fc+/0 with [F{Al(ORF)3}2]- counterion, but only +1.14 V vs. Fc+/0 with the small [SbF6]- ion. Selective reactions demonstrate the selectivity of [naphthaleneF]+⋅ for deelectronation of a multitude of organ(ometall)ic molecules and elements in solution: providing the molecular structures of the acene dications [tetracene]2+, [pentacene]2+ or spectroscopic evidence for the carbonyl complex of the ferrocene dication [Fc(CO)]2+, the [P9]+ cation from white phosphorus, the solvent-free copper(I) salt starting from copper metal and the dicationic Fe(IV)-scorpionate complex [Fe(sc)2]2+.

On the Synthesis and Structure of 'Naked' Ga(I) and In(I) Salts and the Surprising Stability of Simple Ga(I) and In(I) Salts in the Coordinating Solvents Ether and Acetonitrile.

In this work, we present the solid-state structures of solvent-free Ga[pf] and In[pf] salts ([pf]-=[Al(ORF)4]-; RF=C(CF3)3), which are very rare examples of salts with truly 'naked' metal cations. Both salts may serve as starting materials for subvalent gallium and indium chemistry with very weakly coordinating ligands providing the freedom of choice for solvents and ligands for the future. On the other hand, we report and rationalize the formation and isolation of [M(OEt2)2][pf] and [M(MeCN)2][pf] (M=Ga, In), underlining the surprising stability of these subvalent group 13 M+ ions against disproportionation. Unexpectedly, dicoordinate and carbene analogous [M(L)2]+ ions with the [pf]- counterion are stable in L=acetonitrile and diethyl ether at room temperature, opening up possible applications for example in organic synthesis and catalysis.

Gold carbonyl cations and beyond: homoleptic gold(I) complexes with P4 and P4S3 and the half-sandwich cation [Au(C6H6)(CO)].

Oxidation of Au0 with the synergistic Ag+/0.5 I2 system in the commercial organic solvent 1,2,3,4-tetrafluorobenzene led to the perfluoroalkoxyaluminate salt of the [Au(CO)2]+ cation known from superacid chemistry. This [Au(CO)2]+ salt proved to be an excellent 'naked' Au+-synthon yielding complex salts with [Au(η2-P4)2]+, [Au(η1-P4S3)2]+ and half-sandwich [Au(η2-C6H6)(CO)]+ cation.

From the Iron Pentacarbonyl Cation to Heteroleptic η6-arene Carbonyls and bis-η6-arene Cations.

Partial ligand substitution at the iron pentacarbonyl radical cation generates novel half-sandwich complexes of the type [Fe(η6-arene)(CO)2]⋅+ (arene=1,3,5-tri-tert-butylbenzene, 1,3,5-trimethylbenzene, benzene and fluorobenzene). Of those, the bulkier 1,3,5-tri-tert-butylbenzene (mes*) derivative [Fe(mes*)(CO)2]⋅+ was fully characterized by XRD analysis, IR, NMR, cw-EPR, Mössbauer spectroscopy and cyclic voltammetry as the [Al(ORF)4]- (RF=C(CF3)3) salt. Chemical electronation, i. e., the single electron reduction, with decamethylferrocene generates neutral [Fe(mes*)(CO)2], whereas further deelectronation under CO-pressure leads to a dicationic three-legged [Fe(mes*)(CO)3]2+ salt with [Al(ORF)4]- counterion. The full substitution of the carbonyl ligands in [Fe(CO)5]⋅+[Al(ORF)4]- mainly resulted in disproportionation reactions, giving solid Fe(0) and the dicationic bis-arene salts [Fe(η6-arene)2]2+([Al(ORF)4]-)2 (arene=1,3,5-trimethylbenzene, benzene and fluorobenzene). Only by employing the very large fluoride bridged anion [F-{Al(ORF)3}2]-, it was possible to isolate an open shell bis-arene cation salt [Fe(C6H6)2]⋅+[F-{Al(ORF)3}2]-. The highly reactive cation was characterized by XRD analysis, cw-EPR, Mössbauer spectroscopy and cyclic voltammetry. The disproportionation of [Fe(C6H6)2]⋅+ salts to give solid Fe(0) and [Fe(C6H6)2]2+ salts was analyzed by a suitable cycle, revealing that the thermodynamic driving force for the disproportionation is a function of the size of the anion used and the polarity of the solvent.

Continuous Anhydrous Synthesis of Oxymethylene Dimethyl Ethers by Reaction of Dimethyl Ether with Molecular Formaldehyde.

A novel gaseous synthesis route to oxymethylene dimethyl ethers (OMEn, n = 3-5) starting from CO2 and green H2 by using molecular formaldehyde (FA) and dimethyl ether (DME) is presented. The anhydrous reaction runs in a pressure free, gaseous, and continuous reaction setup. Hetero-geneous cata-lysts including zeolites and ion exchange resins (IER) are investigated, if they catalyze this reaction. While IER is almost inactive, zeolites with a 3D pore structure and an acidity exceeding ρm,H+ (NH3,ads ) = 250 µmol·gcat.-1 proved to be catalytically active. DME conversions of up to 2.76 mol-% are observed. The observed product gas stream compositions confirm thermo-dynamic considerations with back reactions / OMEn decomposition occurring as part of the equilibria under the investigated reaction conditions (90…180 °C). However, feed gas ratio variations (FA:DME = 1:2 to 1:9.5) highlighted the possibility to shift the product selectivity in favor of OMEn and suppress FA disproportionation to methyl formate. FA trimerization to trioxane is almost completely suppressed by running the reaction at 120 °C. The results presented here provide an important and unprecedented contribution to understand the complex reaction network in the OMEn synthesis reaction necessary to establish an energy efficient sustainable OMEn production process.

Synthesis and Characterization of a Stable Nickelocenium Dication Salt.

We report the synthesis and characterization of the nickelocenium cations [NiCp2 ]⋅+ and [NiCp2 ]2+ as their [F-{Al(ORF )3 }2 ]- (Cp = C5 H5 ; RF =C(CF3 )3 ) salts. Diamagnetic [NiCp2 ]2+ represents the first example for the isolation of an unsubstituted parent metallocene dication. Both salts were generated by reacting neutral NiCp2 with [NO]+ [F-{Al(ORF )3 }2 ]- in 1,2,3,4-tetrafluorobenzene (4FB). The salts were characterized by single crystal X-ray diffraction (XRD), indicating shorter metal-ligand bond lengths for the higher charged salt. Powder XRD shows the salts to be phase pure, cyclic voltammetry in 4FB gave quasi reversible redox waves at -0.44 (0→1) and +1.17 V (1→2) vs Fc/Fc+ . The 1 H NMR of [NiCp2 ]2+ is a singlet at 8.6 ppm, whereas paramagnetic [NiCp2 ]⋅+ is significantly shifted upfield to -103.1 ppm.

The Best of Both Worlds: Combining the Power of MICs and WCAs To Generate Stable and Crystalline CrI -Tetracarbonyl Complexes with π-Accepting Ligands.

Invited for the cover of this issue are Biprajit Sarkar and co-workers at the University of Stuttgart and University of Freiburg. In the image, the solar flare represents the non-innocence (fluorine-specific interactions) of the counterion, and the black hole at the metal center illustrates the oxidation/electron deficiency of the Cr-center, while the electron "gets lost" in the space (oxidation agent). Read the full text of the article at 10.1002/chem.202301205.

Homoleptic Transition Metal Carbonyl Cations: Synthetic Approaches, Characterization and Follow-Up Chemistry.

ConspectusCarbon monoxide, CO, is one of the most important ligands in organometallic chemistry. It is an excellent π-acceptor and a moderate σ-donor. Therefore, most of the known transition metal carbonyls (TMCs) exhibit a zerovalent or even negative metal oxidation state (OS) of up to -4. However, given the right conditions, the carbonyl ligand also forms homoleptic cationic complexes with one or more transition metal atoms, the transition metal carbonyl cations (TMCCs), known with an OS of up to +3. Despite their long-standing history upon discovery of the first [M(CO)6]+ examples (M = Mn, Tc, Re) by E. O. Fischer in 1962 as well as their very fundamental nature, it took until the 1990s for the scope to be widened by Aubke, Strauss and Willner. Yet, many potential TMCC entries known from gas-phase mass spectrometry work remained unknown on preparative grounds. This is due to their high reactivity, which puts scientists to new challenges and encourages the development of suitable solvents, anions and oxidants, to cope with the demands of these fundamental salts─later referred to as pseudo-gas-phase conditions and innocent deelectronators and solvents.Hence, the utilization of extremely weakly coordinating perfluorinated alkoxyaluminates [Al(ORF)4]- and [F{Al(ORF)3}2]- (ORF = -OC(CF3)3) in combination with the polar but non- or weakly coordinating innocent solvents 1,2-difluorobenzene (oDFB) and 1,2,3,4-tetrafluorobenzene (TFB) yielded the first TMCC salts containing heptacoordinate [M(CO)7]+ (M = Nb, Ta) as well as paramagnetic [M(CO)6]+· (M = Cr, Mo, W) or [Ni(CO)4]+·. However, the use of typical inorganic oxidants Ag+, [NO]+ and Ag+/0.5 I2 regularly led to unwanted side reactions. For example, the Lewis acidic silver(I) cations form Lewis pairs with various Lewis basic TMCs yielding partly clustered [Agx{TMC}y]x+ complex salts, while nitrosonium cations may substitute for carbonyl ligands, forming [M(CO)x-1(NO)]+ complexes. The synergistic oxidizing reagent Ag+/0.5 X2 can add halonium ions X+ to the TMCs (X = Cl, Br, I). This prevented the synthesis of univalent group 8 TMCC salts. Yet, the application of radical cation salts of perfluorinated arenes as innocent deelectronators finally yielded salts of [Fe(CO)5]+· and [M3(CO)14]2+ (M = Ru, Os).TMCC salts are excellent starting materials, and the reaction of [Co(CO)5]+ and [Ni(CO)4]+· with benzene led to the previously unknown bis(benzene) sandwich complexes [Co(benzene)2]+ and [Ni(benzene)2]+·. Under the right conditions, even the very weakly bound oDFB-complex salts with [M(oDFB)2]+ (M = Co, Ni) cations form, useful as naked metal(I) synthons and for small-molecule activation.

Structures, Bonding Analyses and Reactivity of a Dicationic Digallene and Diindene Mimicking trans-bent Ditetrylenes.

The reaction of bisdicyclohexylphosphinoethane (dcpe) and the subvalent MI sources [MI (PhF)2 ][pf] (M=Ga+ , In+ ; [pf]- =[Al(ORF )4 ]- ; RF =C(CF3 )3 ) yielded the salts [{M(dcpe)}2 ][pf]2 , containing the first dicationic, trans-bent digallene and diindene structures reported so far. The non-classical MI ⇆MI double bonds are surprisingly short and display a ditetrylene-like structure. The bonding situation was extensively analyzed by quantum chemical calculations, QTAIM (Quantum Theory of Atoms in Molecules) and EDA-NOCV (Energy Decomposition Analysis with the combination of Natural Orbitals for Chemical Valence) analyses and is compared to that in the isoelectronic and isostructural, but neutral digermenes and distannenes. The dissolved [{Ga(dcpe)}2 ]2+ ([pf]- )2 readily reacts with 1-hexene, cyclooctyne, diphenyldisulfide, diphenylphosphine and under mild conditions at room temperature. This reactivity is analyzed and rationalized.

Activation of the GaI Cation for Bond Activation: from Oxidative Additions into C-Cl and H-P Bonds to Reversible Insertion into P4.

Although the discovery of the GaI complex salt [Ga(PhF)2-3 ][Al(ORF )4 ] (RF =C(CF3 )3 , PhF=C6 H5 F) invoked the preparation of a diverse library of cationic Ga(I) coordination complexes and clusters, studies on small molecule activation with low-valent GaI cations are scarce. Herein, a first experimental study on the reactivity of a monomeric Ga(I) cation activated with a pyridine-diimine pincer ligand (in [Ga(PDIdipp )][Al(ORF )4 ]) towards small-molecules is reported. First controlled oxidative additions of the GaI cation into C-Cl, H-P and P-P bonds are presented. Moreover, the [4+1]cycloaddition to butadienes was achieved. Intriguingly, the isolated, blue insertion product into the P-P bond of P4 allows for the quantitative release of the P4 molecule upon reaction with AlEt3 and butadienes. Reversible P4 insertion of main-group metals has previously been reported for Ge and Sn, respectively. The experimental study is supported by high-level computational analysis of the in-part reversible oxidative additions at the DLPNO-CCSD(T)/def2-TZVPP//PBEh-3c/def2-mSVP level of theory with COSMO-RS solvation in 1,2-difluorobenzene.

Surface Modification of ITO with N-Heterocyclic Carbene Precursors Results in Electron Selective Contacts in Organic Photovoltaic Devices.

Surface modification of indium tin oxide (ITO) electrodes with organic molecules is known to tune their work function which results in higher charge carrier selectivity in corresponding organic electronic devices and hence influences the performance of organic solar cells. In recent years, N-heterocyclic carbenes (NHCs) have also been proven to be capable to modify the work function of metals and semimetals compared to the unfunctionalized surface via the formation of strong covalent bonds. In this report, we have designed and performed the modification of the ITO surface with NHC by using the zwitterionic bench stable IPr-CO2 as the NHC precursor, applied via spin coating. Upon modification, the work function of ITO electrodes was reduced significantly which resulted in electron selective contacts in corresponding organic photovoltaic devices. In addition, various characterization techniques and analytical methods are used to elucidate the nature of the bound species and the corresponding binding mechanism of the material to the ITO surface.

[Ni(CO)4 ]+ as NiI Synthon: Synthesis and Characterization of NiI Half-Sandwich and Sandwich Cations.

The stable, easily accessible salt [Ni(CO)4 ]+ [F{Al(ORF )3 }2 ]- (RF =C(CF3 )3 ) was used as a NiI synthon to generate the novel half-sandwich complexes [Ni(arene)(CO)2 ]+ (arene=C6 H6 , o-dfb=1,2-F2 C6 H4 ). By irreversible removal of CO from the equilibrium, even the rather endergonic reaction to a [Ni(o-dfb)2 ]+ salt was successful (Δr G°(solv) =+78 kJ mol-1 ). The latter displays an unprecedented slipped η3 ,η3 -sandwich structure and is the ultimate synthon to NiI -chemistry.

From CO2 to DME: Enhancement through Heteropoly Acids from a Catalyst Screening and Stability Study.

The direct synthesis of dimethyl ether (DME) via CO2 hydrogenation in a single step was studied using an improved class of bifunctional catalysts in a fixed bed reactor (T R: 210-270 °C; 40 bar; gas hourly space velocity (GHSV) 19,800 NL kgcat -1 h-1; ratio CO2/H2/N2 3:9:2). The competitive bifunctional catalysts tested in here consist of a surface-basic copper/zinc oxide/zirconia (CZZ) methanol-producing part and a variable surface-acidic methanol dehydration part and were tested in overall 45 combinations. As dehydration catalysts, zeolites (ferrierite and ß-zeolite), alumina, or zirconia were tested alone as well as with a coating of Keggin-type heteropoly acids (HPAs), i.e., silicotungstic or phosphotungstic acid. Two different mixing methods to generate bifunctional catalysts were tested: (i) a single-grain method with intensive intra-particular contact between CZZ and the dehydration catalyst generated by mixing in an agate mortar and (ii) a dual-grain approach relying on physical mixing with low contact. The influence of the catalyst mixing method and HPA loading on catalyst activity and stability was investigated. From these results, a selection of best-performing bifunctional catalysts was investigated in extended measurements (time on stream: 160 h/7 days, T R: 250 and 270 °C; 40 bar; GHSV 19,800 NL kgcat -1 h-1; ratio CO2/H2/N2 3:9:2). Silicotungstic acid-coated bifunctional catalysts showed the highest resilience toward deactivation caused by single-grain preparation and during catalysis. Overall, HPA-coated catalysts showed higher activity and resilience toward deactivation than uncoated counterparts. Dual-grain preparation showed superior performance over single grain. Furthermore, silicotungstic acid coatings with 1 KU nm-2 (Keggin unit per surface area of carrier) on Al2O3 and ZrO2 as carrier materials showed competitive high activity and stability in extended 7-day measurements compared to pure CZZ. Therefore, HPA coating is found to be a well-suited addition to the CO2-to-DME catalyst toolbox.

The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions.

We have devised the unified redox scale Eabs H2O , which is valid for all solvents. The necessary single ion Gibbs transfer energy between two different solvents, which only can be determined with extra-thermodynamic assumptions so far, must clearly satisfy two essential conditions: First, the sum of the independent cation and anion values must give the Gibbs transfer energy of the salt they form. The latter is an observable and measurable without extra-thermodynamic assumptions. Second, the values must be consistent for different solvent combinations. With this work, potentiometric measurements on silver ions and on chloride ions show that both conditions are fulfilled using a salt bridge filled with the ionic liquid [N2225 ][NTf2 ]: if compared to the values resulting from known pKL values, the silver and chloride single ion magnitudes combine within a uncertainty of 1.5 kJ mol-1 to the directly measurable transfer magnitudes of the salt AgCl from water to the solvents acetonitrile, propylene carbonate, dimethylformamide, ethanol, and methanol. The resulting values are used to further develop the consistent unified redox potential scale Eabs H2O that now allows to assess and compare redox potentials in and over six different solvents. We elaborate on its implications.

The Best of Both Worlds: Combining the Power of MICs and WCAs To Generate Stable and Crystalline CrI -Tetracarbonyl Complexes with π-Accepting Ligands.

Here we present stable and crystalline chromium(I) tetracarbonyl complexes with pyridyl-MIC (MIC=mesoionic carbene) ligands and weakly coordinating anions (WCA=[Al(ORF )4 ]- , RF =C(CF3 )3 and BArF =[B(ArF )4 ]- , ArF =3,5-(CF3 )2 C6 H3 ). The complexes were fully characterized via crystallographic, spectroscopic and theoretical methods. The influence of counter anions on the IR and EPR spectroscopic properties of the CrI complexes was investigated, and the electronic innocence versus non-innocence of WCAs was probed. These are the first examples of stable and crystalline [Cr(CO)4 ]+ complexes with a chelating π - ${\pi -}$ accepting ligand, and the data presented here are of relevance for both the photochemical and the electrochemical properties of these classes of compounds.

Isolation, Structural and Physical Characterization as well as Reactivity of Persistent Acenium Radical Cation Salts.

The unsubstituted acenium radical cations (ARCs) are extremely sensitive and were hitherto only studied in situ, i. e. in the gas phase, as dilute solutions in strong acids or by matrix isolation spectroscopy at about 10 K. In this study, room temperature stable ARC salts with the weakly coordinating anion [F{Al(ORF )3 }2 ]- (ORF =-OC(CF3 )3 ) supported by the weakly coordinating solvent 1,2,3,4-tetrafluorobenzene (TFB) were prepared and structurally, electrochemically and spectroscopically characterized. Reaction of the neutral acenes with Ag+ [F{Al(ORF )3 }2 ]- led, non-innocent,[54] to intermediate [Ag2 (acene)2 ]2+ complexes, which decompose over time to Ag0 and the corresponding (impure) ARC salts. By contrast, direct deelectronation with the recently developed innocent[54] deelectronator radical cation salt [anthraceneHal ]+⋅ [F{Al(ORF )3 }2 ]- led to phase-pure products [acene]+⋅ [F{Al(ORF )3 }2 ]- (anthraceneHal =9,10-dichlorooctafluoroanthracene; acene=anthra-, tetra-, pentacene). For the first time, a homogenous set of spectroscopic data on analytically pure ARC salts was obtained. In addition, cyclovoltammetric measurements of the acenes connected the potentials in solution with those in the gas-phase. Hence, the data complement the existing isolated gas-phase, strong acid or matrix isolation studies. A first entry to follow-up chemistry of the acenium radical cations as ligand forming oxidizers was demonstrated by reaction with 1 / 2 ${{ 1/2 }}$ Co2 (CO)8 giving [Co(anthracene)(CO)2 ]+ .

Coordination versus Insertion: On the Interaction of 5 d-Transition Metal Carbonyl Clusters with Silver(I).

The title silver(I) complex salts [Ag{Re2 (CO)10 }{Re(CO)5 }2 ]+ [Al(ORF )4 ]- (AgRe4 ; ORF =-OC(CF3 )3 ) and [Ag{Ir4 (CO)12 }2 ]+ [Al(ORF )4 ]- (AgIr8 ) form upon reaction of Ag+ [Al(ORF )4 ]- and the transition metal carbonyls (TMCs) Re2 (CO)10 and Ir4 (CO)12 respectively. The solid-state structure of the AgRe4 cluster shows an unexpected asymmetric coordination motif, wherein the silver(I) cation has inserted into the Re-Re bond of one Re2 (CO)10 moiety, while the other dirhenium carbonyl coordinates only over one metal atom towards the silver(I) cation. The AgIr8 cluster is formed by the edge-on coordination of two Ir4 tetrahedra and the silver cation in a D2 symmetric fashion with a torsion angle of 46.5°. QTAIM analysis shows bond paths between the silver atom and the nearby metal atoms in all cases, whereas only the non-inserted Re2 (CO)10 moiety shows additional bond paths between the carbonyl ligands and the silver cation. In addition, the insertion of the Ag+ cation into the Re-Re bond in Re2 (CO)10 removes the bond path between the two rhenium atoms. The EDA-NOCV analysis suggests an increase of the interaction energy between the silver(I) cation and the respective metal carbonyls from the metal centered transition metal carbonyl (TMC) donors W(CO)6