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DFT computation indicates the presence of solution equilibria with very low barriers when diiodine interacts with the square‐planar platinum(II) pincer complex Pt(NCN)I (NCN=[2,6‐bis{(dimethylamino)methyl}phenyl‐N,C,N]−) in dichloromethane. Species present include square‐planar Pt(NCN)(η1‐I3) and square‐pyramidal Pt(NCN)I(η1‐I2) interconverted via a triangular transition state with I2 bridging a Pt−I bond, and interaction of diiodine at the para‐position of the arene ring interconverted with Pt(NCN)I(η1‐I2) via a transition state with diiodine bridging the Cortho‐ and Cmeta‐positions. Similar facile intramolecular rearrangements occur for a model system with a molar ratio of 1 : 2 for Pt : I2, exhibiting species such as Pt(NCN)(η1‐I3)(η1‐I2) and mobility of diiodine over the (pincer)PtI plane. [ABSTRACT FROM AUTHOR]

Multistage mass spectrometry (MSn) experiments were used to explore extrusion-insertion (ExIn) reactions of the palladium complex [(phen)Pd(O2CPh)]+ (phen, 1,10-phenanthroline). Under collision-induced dissociation (CID) conditions, the organopalladium cation [(phen)Pd (Ph)]+ was formed via decarboxylation and was found to react with phenylmethylketene to yield the enolate [(phen)Pd(CPhMeC(O)Ph)]+ via an insertion reaction. A further stage of CID revealed that the enolate fragments via loss of styrene to form the acyl complex [(phen)Pd (C(O)Ph)]+. Formation of both the coordinated enolate and acyl anions is supported by density functional theory (DFT) calculations. Attempts to develop a palladium-mediated one-pot synthesis of ketones from 2,6-dimethoxybenzoic acid as the key substrate and the ketene substrates R¹R²"C"O (R¹ = Ph, R² = Me; R¹ = R² = Ph) proved challenging owing to low yields and side product formation. [ABSTRACT FROM AUTHOR]

Multistage mass spectrometry experiments, isotope labelling and DFT calculations were used to explore whether selective decarbonylation of formic acid could be mediated by molybdate anions [(MoO3)x(OH)]− (x = 1 and 2) via a formal catalytic cycle involving two steps. In step 1, both molybdate anions undergo gas-phase ion-molecule reactions (IMR) with formic acid to produce the coordinated formates [(MoO3)x(O2CH)]− and H2O. In step 2, both coordinated formates [(MoO3)x(O2CH)]− undergo decarbonylation under collision-induced dissociation (CID) conditions to reform the molybdate anions [(MoO3)x(OH)]− (x = 1 and 2), thus closing a formal catalytic cycle. In the case of [MoO3(O2CH)]− an additional decarboxylation channel also occurs to yield [MoO3(H)]−, which is unreactive towards formic acid. The reaction between [Mo18O3(18OH)]− and formic acid gives rise to [Mo18O3(O2CH)]− highlighting that ligand substitution occurs without 18O/16O exchange between the coordinated 18OH ligand and HC16O2H. The reaction between [(MoO3)x(OD)]− (x = 1 and 2) and DCO2H initially produces [(MoO3)x(OH)]− (x = 1 and 2), indicating that D/H exchange occurs. DFT calculations were carried out to investigate the reaction mechanisms and energetics associated with both steps of the formal catalytic cycle and to better understand the competition between decarbonylation and decarboxylation, which is crucial in developing a selective catalyst. The CO and CO2 loss channels from the monomolybdate anion [MoO3(O2CH)]− have similar barrier heights which is in agreement with experimental results where both fragmentation channels are observed. In contrast, the dimolybdate anion is more selective, since the decarbonylation pathway of [(MoO3)2(O2CH)]− is both kinetically and thermodynamically favoured, which agrees with experimental observations where the CO loss channel is solely observed. [ABSTRACT FROM AUTHOR]

A near thermal two-step catalytic cycle for the selective release of hydrogen from formic acid by mononuclear cuprate anions was revealed using multistage mass spectrometry experiments, deuterium labelling and DFT calculations. In gas-phase ion-molecule reactions, mononuclear copper hydride anions [(L)Cu(H)]− (where L = H−, O2CH−, BH4− and CN−) were found to react with formic acid (HCO2H) to yield [(L)Cu(O2CH)]− and H2. The copper formate anions [(L)Cu(O2CH)]− can decarboxylate via collision-induced dissociation (CID) to reform the copper hydride [(L)Cu(H)]−, thereby closing the two-step catalytic cycle. Analogous labelling experiments with d1-formic acid (DCO2H) reveal that the decarboxylation process also occurs spontaneously. A kinetic study was carried out to provide further insights into the species involved in this reaction. Energetics from density functional theory (DFT) calculations show that the key decarboxylation step can occur without CID, thus in support of experimental observations. [ABSTRACT FROM AUTHOR]

The gas-phase extrusion–insertion (ExIn) reactions of the palladium complexes [(phen) n Pd(O2SC6H5)]+ (phen = 1,10-phenanthroline, n = 1 or 2), were investigated in the gas phase by multistage mass spectrometry (MS n ) experiments consisting of electrospray ionisation and a linear ion trap combined with density functional theory (DFT) calculations. Desulfination of palladium sulfinate cations under collision-induced dissociation (CID) generates the organopalladium intermediates [(phen) n Pd(C6H5)]+. Of these two organometallic cations, only [(phen)Pd(C6H5)]+ reacts with phenyl isocyanate via insertion to yield [(phen)Pd(NPhC(O)C6H5)]+. The formation of a coordinated amidate anion is supported by DFT calculations. In exploring this reactivity in the solution phase, we found that heating a mixture of benzenesulfinic acid, phenylisocyanate and palladium trifluoroacetate under a range of different conditions (ligand free versus with ligand, different solvents, addition of acid or base) failed to lead to the formation N -phenyl-benzamide in all cases. Instead, biphenyl was formed and could be isolated in a yield of 46%. DFT calculations using a solvent continuum reveal that the barrier associated with the insertion reaction lies above the competing sequential reactions of desulfination of a second phenyl sulfinate followed by reductive elimination of biphenyl. While gas-phase studies suggest that both palladium-mediated extrusion–insertion (ExIn) and condensation reactions operate for the generation of a N -phenyl-benzamide anion from the phenylsulfinate anion, a double desulfinative biaryl homocoupling reaction is favoured in the solution phase. [ABSTRACT FROM AUTHOR]

The gas-phase extrusion–insertion (ExIn) reactions of a silver complex [(BPS)Ag(O2CC6H5)]2− ([BPS]2− = 4,7-diphenyl-1,10-phenanthroline-disulfonate), generated via electrospray ionisation was investigated by Multistage Mass Spectrometry (MS n ) experiments in a linear ion trap combined with density functional theory (DFT) calculations. Extrusion of carbon dioxide under collision-induced dissociation (CID) generates the organosilver intermediate [(BPS)Ag(C6H5)]2−, which subsequently reacts with phenyl isocyanate via insertion to yield [(BPS)Ag(NPhC(O)C6H5)]2−. Further CID of the product ion resulted in the formation of [(BPS)Ag(C6H5)]2−, [(BPS)Ag]− and C6H5C(O)NPh−. The formation of a coordinated amidate anion is supported by DFT calculations. Heating a mixture of benzoic acid, phenyl isocyanate, silver carbonate (5 mol%) and phenanthroline (20 mol%) in DMSO and heating by microwave irradiation led to the formation N -phenyl-benzamide in an isolated yield of 89%. The yield decreased to 74% without the addition of phenanthroline, while replacing silver carbonate with sodium carbonate gave an isolated yield of 84%, suggesting that the ExIn reaction may not operate in solution. This was confirmed using benzoic acid with a 13C-isotopic-label at the carboxylate carbon as the starting material, which, under microwave heating in the presence of phenyl isocyanate, silver carbonate (5 mol%) and phenanthroline (20 mol%) gave N -phenyl-benzamide with retention of the 13C isotopic label based on GC-MS experiments under electron ionisation (EI) conditions. DFT calculations using a solvent continuum reveal that the barriers associated with the pathway involving direct attack by the non-coordinated benzoate are below the ExIn pathways for the coordinated silver benzoate. While gas-phase studies suggest that both silver-mediated extrusion-insertion (ExIn) and base-mediated condensation reactions operate for the generation of N -phenyl-benzamide anion from the benzoate anion, the condensation reaction is favoured in the solution phase. [ABSTRACT FROM AUTHOR]

The synthesis of benzofurans by the reaction of the palladium(II) complex Pd{1-C6H4-2-OCH(CO2Et)-C,C}(bipy) (bipy = 2,2′-bipyridine) with hypervalent iodine(III) reagents [Ph(CH＝CHR)I]+ has been examined by Density Functional Theory. Results highlight the role of oxidative alkenylation to form PdIV intermediates and the role of initial adduct formation in this process, an annulation process facilitated by PdII, and the role of 'chain-walking' at PdII centres to allow formation of the lowest energy product. Computation (R = Me) allows assignment of an initially formed adduct with a 'PdII → IIII' interaction at −50 °C, and, after oxidative alkenylation of PdII and reductive elimination from a PdIV centre via Ar⋯Alkenyl coupling, formation of a second intermediate with a structure consistent with NMR detection (R = n-hexyl) at −30 °C is obtained. This PdII complex, containing a coordinated alkene group in Pd{1-(RHCγ＝Cβ)C6H4-2-OCαH(CO2Et)-η2-Cα＝Cβ,C}(bipy), undergoes a 5-exo-trig annulation by forming a Cα–Cβ bond to give a complex with a bicyclic carbon skeleton suitable for subsequent formation of benzofurans. A series of facile rearrangements including chain-walking results in formation of a lowest energy complex of three feasible hydrido(alkene)palladium(II) species, leading to decomposition and release of the observed benzofuran isomer isolated under synthesis conditions. The computational study allows reinterpretation of the NMR data reported previously, in particular the determination of barriers in the reaction pathway allowing assignment of structure for key intermediates. [ABSTRACT FROM AUTHOR]

Gas-phase ion-ion reactions between tris-1,10-phenantholine metal dications, [(phen)3M]2+ (where M = Ni and Mg), and the tetraphenylborate anion yield the ion-pairs {[(phen)3M]2+[BPh4]−}+. The ion-pairs undergo transmetalation upon loss of a phen ligand to give the organometallic complexes [(phen)2M(Ph)]+. DFT calculations, used to determine the energy barriers for the transmetalation reactions and the hydrolysis reactions, are entirely consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Density functional theory computation indicates that bridge splitting of [PtIIR2(μ‐SEt2)]2 proceeds by partial dissociation to form R2Pta(μ‐SEt2)PtbR2(SEt2), followed by coordination of N‐donor bromoarenes (L‐Br) at Pta leading to release of PtbR2(SEt2), which reacts with a second molecule of L‐Br, providing two molecules of PtR2(SEt2)(L‐Br‐N). For R=4‐tolyl (Tol), L‐Br=2,6‐(pzCH2)2C6H3Br (pz=pyrazol‐1‐yl) and 2,6‐(Me2NCH2)2C6H3Br, subsequent oxidative addition assisted by intramolecular N‐donor coordination via PtIITol2(L‐N,Br) and reductive elimination from PtIV intermediates gives mer‐PtII(L‐N,C,N)Br and Tol2. The strong σ‐donor influence of Tol groups results in subtle differences in oxidative addition mechanisms when compared with related aryl halide oxidative addition to palladium(II) centres. For R=Me and L‐Br=2,6‐(pzCH2)2C6H3Br, a stable PtIV product, fac‐PtIVMe2{2,6‐(pzCH2)2C6H3‐N,C,N)Br is predicted, as reported experimentally, acting as a model for undetected and unstable PtIVTol2{L‐N,C,N}Br undergoing facile Tol2 reductive elimination. The mechanisms reported herein enable the synthesis of PtII pincer reagents with applications in materials and bio‐organometallic chemistry. [ABSTRACT FROM AUTHOR]

Palladium(II) boronates are recognized as fundamental pre‐transmetalation intermediates in Suzuki–Miyaura cross‐couplings. While these typically transient species have been detected and studied spectroscopically, it is conspicuous that they have never been isolated since this important reaction was discovered over forty years ago. This study reports the synthesis of a family of unprecedented arylpalladium(II) boronates that are, by design, kinetically stable at ambient temperature, both in solution and in the solid state. These properties enabled unambiguous crystallographic confirmation of their structure for the first time and their chemical competence in a Suzuki–Miyaura reaction was demonstrated. [ABSTRACT FROM AUTHOR]

Palladium(II) boronates are recognized as fundamental pre‐transmetalation intermediates in Suzuki–Miyaura cross‐couplings. While these typically transient species have been detected and studied spectroscopically, it is conspicuous that they have never been isolated since this important reaction was discovered over forty years ago. This study reports the synthesis of a family of unprecedented arylpalladium(II) boronates that are, by design, kinetically stable at ambient temperature, both in solution and in the solid state. These properties enabled unambiguous crystallographic confirmation of their structure for the first time and their chemical competence in a Suzuki–Miyaura reaction was demonstrated. [ABSTRACT FROM AUTHOR]

Electrospray ionization‐mass spectrometry (ESI‐MS) of mixtures of AgBF4 or AgNO3 with the capping ligand bis(diphenylarsino)methane ((Ph2As)2CH2 = dpam) in a solution of acetonitrile revealed the formation of the following cations: [Ag(CH3CN)(dpam)]+, [Ag(dpam)2]+, [Ag2(Cl)(dpam)2]+, and [Ag3(Cl)2(dpam)3]+. Addition of NaBH4 to these solutions results in the formation of the cluster cations [Ag2(BH4)(dpam)2]+, [Ag2(BH4)(dpam)3]+, [Ag3(H)(BH4)(dpam)3]+, [Ag3(BH4)2(dpam)3]+, [Ag3(H)(Cl)(dpam)3]+, and [Ag3(I)(BH4)(dpam)3]+, as established by ESI‐MS. Use of NaBD4 confirmed that borohydride is the source of the hydride in these clusters. An Orbitrap Fusion LUMOS mass spectrometer was used to explore the gas‐phase unimolecular chemistry of selected clusters via multistage mass spectrometry (MSn) experiments employing low‐energy collision‐induced dissociation (CID) and high‐energy collision‐induced dissociation (HCD) experiments. The borohydride containing clusters fragment via two competing pathways: (i) ligand loss and (ii) B–H bond activation involving BH3 loss. Density functional theory (DFT) calculations were used to calculate the energetics of the optimized structures for all precursor ions, fragment ions, and neutrals and to estimate the reaction endothermicities. Generally, there is reasonable agreement between the most abundant product ion formed and the predicted endothermicity of the associated reaction channel. The DFT calculations predicted that the novel dimer [Ag2(BH4)(dpam)2]+ has a paddlewheel structure in which the dpam and BH4− ligands bridge both silver centers. [ABSTRACT FROM AUTHOR]

The gas‐phase extrusion–insertion reactions of the copper complex [bathophenanthroline (Bphen)CuI(O2CC6H5)]2−, generated via electrospray ionization, was studied in a linear ion trap mass spectrometer with the combination of collision‐induced dissociation (CID) and ion‐molecule reaction (IMR) events. Multistage mass spectrometry (MSn) experiments and density functional theory (DFT) demonstrated that extrusion of carbon dioxide from [(Bphen)Cu(O2CC6H5)]2− (CID) gives the organometallic intermediate [(Bphen)Cu(C6H5)]2−, which subsequently reacts with carbon disulfide (IMR) via insertion to yield [(Bphen)Cu (SC(S)C6H5)]2−. The fragmentation of the product ion resulted in the formation of [Bphen]2−, [(Bphen)Cu]− and C6H5CS2− under CID conditions. The formation of the latter two charge separation products thus provides evidence of C–C bond formation in the IMR step. Although analogous studies with isocyanate, which is isoelectronic with CS2, showed a poor reactivity in the gas phase, the mechanistic understanding obtained from these model studies encourages future development of a solution phase protocol for the synthesis of amides from carboxylic acids and isocyanates mediated by copper(I) complexes. [ABSTRACT FROM AUTHOR]

The gas-phase unimolecular reactions of the silver(I) complex [Ag(PhBF3)2]−, formed via electrospray ionisation mass spectrometry of solutions containing the phenyltrifluoroborate salt and AgNO3, are examined. Upon collision induced dissociation (CID) three major reaction channels were observed for [Ag(PhBF3)2]−: Ph− group transfer via a transmetalation reaction to yield [PhAg(PhBF3)]−; F− transfer to produce [FAg(PhBF3)]−; and release of PhBF3−. The anionic silver product complexes of these reactions, [LAg(PhBF3)]− (where L = Ph and F), were then mass-selected and subjected to a further stage of CID. [PhAg(PhBF3)]− undergoes a Ph− group transfer via transmetalation to yield [Ph2Ag]− with loss of BF3. [FAg(PhBF3)]− solely fragments via loss of BF4−, a reaction that involves Ph− group transfer from B to Ag in conjunction with F− transfer from Ag to B. Density functional theory (DFT) calculations on the various competing pathways reveal that: (i) the overall endothermicities govern the experimentally observed product ion abundances; (ii) the Ph− group and F− transfer reactions proceed via late transition states; and (iii) formation of BF4− from [FAg(PhBF3)]− is a multistep reaction in which Ph− group transfer from B to Ag proceeds first to produce a [FAgPh(BF3)]− complex in which the BF3 moiety is initially weakly bound to the ipso-carbon of the phenyl group and then migrates across the linear [FAgPh]− moiety from C to Ag to F yielding [PhAg(BF4)]−, which can then dissociate via loss of PhAg. [ABSTRACT FROM AUTHOR]

Density Functional Theory studies of square‐planar PtII pincer structures, (4‐Z‐NCN)PtCl ([4‐Z‐NCN]−=[4‐Z‐2,6‐(Me2NCH2)2C6H2‐N,C,N]−, Z=H, NO2, CF3, CO2H, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2, NMe2), enable characterisation of mesomerism for the pincer‐Pt interaction. Relationships between Hammett σp substituent parameters of Z and DFT data obtained from NBO6 and AOMix computation are used to probe the interaction of the 5dyz orbital of platinum with π‐orbitals of the arene ring. Analogous computation for 2,6‐(Me2CH2)2C6H3Z (Z=H, CF3, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2) and (4‐H‐NCN)PtZ allows an estimation of the relative substituent effects of "(CH2NMe2)2PtZ" on π‐delocalisation in the pincer system. [ABSTRACT FROM AUTHOR]

Using fatty acids as renewable sources of biofuels requires deoxygenation. While a number of promising catalysts have been developed to achieve this, their operating mechanisms are poorly understood. Here, model molecular systems are studied in the gas phase using mass spectrometry experiments and DFT calculations. The coordinated metal complexes [(phen)M(O2CR)]+ (where phen=1,10‐phenanthroline; M=Ni or Pd; R=CnH2n+1, n≥2) are formed via electrospray ionization. Their collision‐induced dissociation (CID) initiates deoxygenation via loss of CO2 and [C,H2,O2]. The CID spectrum of the stearate complexes (R=C17H35) also shows a series of cations [(phen)M(R')]+ (where R' < C17) separated by 14 Da (CH2) corresponding to losses of C2H4‐C16H32 (cracking products). Sequential CID of [(phen)M(R')]+ ultimately leads to [(phen)M(H)]+ and [(phen)M(CH3)]+, both of which react with volatile carboxylic acids, RCO2H, (acetic, propionic, and butyric) to reform the coordinated carboxylate complexes [(phen)M(O2CR)]+. In contrast, cracking products with longer carbon chains, [(phen)M(R)]+ (R>C2), were unreactive towards these carboxylic acids. DFT calculations are consistent with these results and reveal that the approach of the carboxylic acid to the "free" coordination site is blocked by agostic interactions for R > CH3. [ABSTRACT FROM AUTHOR]

The oxidant diphenyldiselenide reacts with MIIMe2(bipy) (bipy = 2,2′-bipyridine) to form a pre-equilibrium involving weak adducts, from which [MMe2(bipy)]2·Ph2Se2 undergoes rate-limiting dissociation of phenylselenide preceded by the oxidative addition step to obtain [Me2(bipy)M-MMe2(bipy)(SePh)]+. Coordination of PhSe− gives the neutral MIII–MIII bonded dimers [MMe2(bipy)(SePh)]2. The dimers fragment in the presence of light to give radicals [MIIIMe2(bipy)(SePh)]˙. After reorientation in the solvent cage, the radicals interact to form triplet adducts [MIIIMe2(bipy)(SePh)·(bipy)MIIIMe2(SePh)]˙˙ with π-stacked 'SePh·bipy', followed by transformation via a Minimum Energy Crossing Point allowing [SePh]˙ transfer to give MIIMe2(bipy) and MIVMe2(bipy)(SePh)2. The regenerated MII reagent reacts with Ph2Se2 through the above sequence, allowing completion of reaction to give the MIV product only. The reaction of PtMe2(bipy) with diphenyldisulfide has been studied in an analogous manner to assist with interpretation of DFT results for reactions of diphenyldiselenide. In short, this study shows that photochemical cleavage of metal–metal bonds (Pd, Pt) via excitation to an M–M antibonding orbital facilates disproportionation of the MIII–MIII complex to MII and MIV complexes. [ABSTRACT FROM AUTHOR]

Electrospray ionisation of the ligated group 10 metal complexes [(phen)M(O2CCH3)2] (M = Ni, Pd, Pt) generates the cations [(phen)M(O2CCH3)]+, whose gas-phase chemistry was studied using multistage mass spectrometry experiments in an ion trap mass spectrometer with the combination of collision-induced dissociation (CID) and ion-molecule reactions (IMR). A new catalytic cycle has been discovered. In step 1, decarboxylation of [(phen)M(O2CCH3)]+ under CID conditions generates the organometallic cations [(phen)M(CH3)]+, which react with acetone to generate the [(phen)M(CH3)(OC(CH3)2)]+ adducts in competition with formation of the coordinated enolate for M = Pt (step 2). For M = Ni and Pd, the adducts regenerate [(phen)M(CH3)]+ upon CID. In the case of M = Pt, loss of methane is favored over loss of acetone and results in the formation of the enolate complex, [(phen)Pt(OC(CH2)CH3)]+. Upon further CID, both methane and CO loss can be observed resulting in the formation of the ketenyl and ethyl complexes [(phen)Pt(OCCH)]+ and [(phen)Pt(CH2CH3)]+ (step 3), respectively. In step 4, CID of [(phen)Pt(CH2CH3)]+ results in a beta-hydride elimination reaction to yield the hydride complex, [(phen)Pt(H)]+, which reacts with acetic acid to regenerate the acetate complex [(phen)Pt(O2CCH3)]+ and H2 in step 5. Thus, the catalytic cycle is formally closed, which corresponds to the decomposition of acetone and acetic acid into methane, CO, CO2, ethene and H2. All except the last step of the catalytic cycle are modelled using DFT calculations with optimizations of structures at the M06/SDD 6-31G(d) level of theory. [ABSTRACT FROM AUTHOR]

Electrospray ionisation mass spectrometry (ESI-MS) was used to monitor the reaction of AgBF4, bis(diphenylphosphino)amine (dppa = (Ph2P)2NH = LPh) and NaBH4 in acetonitrile and thereby direct the synthesis of the silver nanocluster [Ag3(μ3-H)(μ3-BH4)LPh3](BF4), 3b·BF4, formed via reaction of AgBF4, bis(diphenylphosphino)amine (dppa = (Ph2P)2NH = LPh) and NaBH4 in acetonitrile. The X-ray structure of 3b·BF4 highlights that the cation adopts a planar trinuclear Ag3 geometry surrounded by three dppa ligands and coordinated on the bottom face by a μ3-hydride and on the top face by a μ3-BH4. The solution phase structure of 3b·BF4 was characterised by multinuclear NMR and DOSY NMR, which showed that the borohydride anion remains bound in the [Ag3(μ3-H)(μ3-BH4)LPh3]+ cluster cation in solution. ESI-MS and in situ1H and HSQC NMR spectroscopy reveals that 3b·BF4 reacts with CS2 in solution at the BH4 site to yield [Ag3(H)(S2CH)LPh3]+, 4b, which has to date eluded structural characterisation via X-ray crystallography due to lack of formation of suitable crystals. The gas-phase ion chemistry of [Ag3(H)(S2CH)LPh3]+ was examined under multistage mass spectrometry conditions using collision-induced dissociation (CID) and compared to that of the previously examined copper analogue, [Cu3(H)(S2CH)LPh3]+. While both cluster cations fragment via ligand loss, the CID spectra of the resultant [M3(H)(S2CH)LPh2]+ are different. Unlike [Cu3(H)(S2CH)LPh2]+, which solely undergoes loss of thioformaldehyde to give [Cu3(S)LPh2]+, [Ag3(H)(S2CH)LPh2]+ gives a richer CID spectrum with fragmentation channels that include ligand loss, CH2S loss and reductive elimination of dithioformic acid. DFT calculations exploring rearrangement and fragmentation of the model systems [M3(H)(S2CH)LMe2]+ ((Me2P)2NH = dmpa = LMe) were used to suggest plausible mechanisms and examine the energetics of the three competing channels: ligand loss, CH2S loss and reductive elimination of dithioformic acid. [ABSTRACT FROM AUTHOR]

A PtIV prodrug needs to be reduced to PtII by a biomolecule in order to show efficacy. Among biomolecules, those containing an l-Cys residue have the highest potential to be involved in reduction. Tautomerisation from HSCH2CH(NH3+)CO2− to the unusual zwitterion form −SCH2CH(NH3+)CO2H is the prerequisite for l-Cys to become a potent reductant at a low pH. [ABSTRACT FROM AUTHOR]

A new decarbonylation reaction is observed for [(K2-acetate)Pd(K2-diphosphine)]+ complexes. Gas-phase IR experiments identify the product as [CH3Pd(OP(Ph2)CH2PPh2)]+. DFT calculations uncovered a plausible mechanism involving O atom abstraction by the diphosphine ligand within the coordination sphere to yield the acetyl complex, [CH3COPd(OP(Ph2)CH2PPh2)]+, which then undergoes decarbonylation. [ABSTRACT FROM AUTHOR]

The mechanism for the [PtIICl4]2−-catalysed reaction of Ph2IIII(TFA) (TFA = trifluoroacetate) with naphthalene (NapH) to give β-phenylation over α-phenylation of naphthalene has been examined by computational methods. In support of the mechanism proposed by Sanford based on experimental evidence, reaction commences by oxidative phenyl transfer from [Ph2I]+ to [PtIICl4]2−, giving trans-[PhPtIVCl4(TFA)]2−. Transformation to cis-[PhPtIVCl3(TFA)]− leads to reaction with NapH at the β-position in an inner-sphere Concerted Metalation Deprotonation (CMD) manner to give cis-[Ph(Nap)PtIVCl3]− and trifluoroacetic acid. Reductive elimination yields β-PhNap, and coordination of chloride regenerates [PtIICl4]2− for subsequent catalytic cycles. The selectivity for β-phenylation over α-phenylation is attributable to steric factors in the CMD PtIV transition state containing a higher coordination number than that occurring for related reactions in PdII catalysis that gives α-phenylation. [ABSTRACT FROM AUTHOR]

The copper nanocluster [Cu3(μ3-H)(μ3-BH4)LPh3](BF4), 1a·BF4 (LPh = (PPh2)2NH = dppa), can potentially react with substrates at either the coordinated hydride or borohydride sites. Reaction of 1a·BF4 with CS2 has given rise to [Cu3(μ3-H)(μ2,μ1-S2CH)LPh3](BF4), (2a·BF4), which was structurally characterised using electrospray ionisation (ESI) with high-resolution mass spectrometry (HRMS), X-ray crystallography, NMR, IR and UV-Vis spectroscopy. The copper(i) atoms adopt a planar trinuclear Cu3 geometry coordinated on the bottom face by a μ3-hydride, on the top face by a μ2,μ1-dithioformate and surrounded by three bridging LPh ligands. Reaction of 1a·BF4 with elemental sulfur gives the known cluster [Cu4(LPh-H + 2S)3](BF4), (3·BF4), which was structurally characterised via X-ray crystallography. ESI-MS of 2a·BF4 produces [Cu3(H)(S2CH)LPh3]+ and its gas-phase ion chemistry was examined under multistage mass spectrometry conditions using collision-induced dissociation (CID). The primary product, [Cu3(H)(S2CH)LPh2]+, formed via ligand loss, undergoes further fragmentation via loss of thioformaldehyde to give [Cu3(S)LPh2]+. DFT calculations exploring rearrangement and fragmentation of the model system [Cu3(H)(S2CH)LMe2]+ (LMe = (PMe2)2NH = dmpa) provide a feasible mechanism. Thus, coupling of the coordinated hydride with the dithioformate ligands gives [Cu3(S2CH2)LMe2]+, which then undergoes CH2S extrusion via C–S bond cleavage to give [Cu3(S)LMe2]+. [ABSTRACT FROM AUTHOR]

A new palladium mediated “one pot” synthesis of thioamides from aromatic carboxylic acids (ArCO2H + RNCS → ArC(S)NHR + CO2) was discovered by gas-phase experiments and theoretical studies. Palladium-mediated decarboxylation of aromatic carboxylic acids followed by addition of substituted isothiocyanates leads to the corresponding thioamide derivatives. [ABSTRACT FROM AUTHOR]

This report describes a computational study of C(sp3)–OR bond formation from PdIV complexes of general structure PdIV(CH2CMe2-o-C6H4-C,C′)(F)(OR)(bpy-N,N′) (bpy = 2,2′-bipyridine). Dissociation of −OR from the different octahedral PdIV starting materials results in a common square-pyramidal PdIV cation. An SN2-type attack by −OR (−OR = phenoxide, acetate, difluoroacetate, and nitrate) then leads to C(sp3)–OR bond formation. In contrast, when −OR = triflate, concerted C(sp3)–C(sp2) bond-forming reductive elimination takes place, and the calculations indicate this outcome is the result of thermodynamic rather than kinetic control. The energy requirements for the dissociation and SN2 steps with different −OR follow opposing trends. The SN2 transition states exhibit “Pd…C…O” angles in a tight range of 151.5 to 153.0°, resulting from steric interactions between the oxygen atom and the gem-dimethyl group of the ligand. Conformational effects for various OR ligands and isomerisation of the complexes were also examined as components of the solution dynamics in these systems. In all cases, the trends observed computationally agree with those observed experimentally. [ABSTRACT FROM AUTHOR]

Synchrotron data have been used to determine the structures of the yellow polymorph of dichlorido(2,2′-bipyridine)platinum(ii) (1), and diiodido(2,2′-bipyridine)palladium(ii) (2), allowing a detailed comparison of the crystal chemistry of [MX2(bipy)] (M = Pd, Pt; X = Cl, Br, I), which exhibit polymorphism involving nine structures distributed over five space groups. Complex 1 crystallizes in space group Pbca (a = 18.2540(7), b = 15.6970(7), c = 7.3560(6) Å), and 2 in space group C2/c (a = 17.149(1), b = 9.8050(8), c = 7.548(1) Å, β = 110.72(1) °). [ABSTRACT FROM AUTHOR]

This perspective focuses on the higher oxidation state (iii, iv) organometallic chemistry of palladium involving a range of strong oxidants, with consideration of platinum chemistry where it is informative for the evaluation of structure and mechanism. Particular emphasis is placed on hypervalent iodine reagents, halogens and related oxidants of intense current interest in organic synthesis, together with linkages in concepts between this chemistry and recent advances in studies of diaryl disulfides, diaryl diselenides, and diaryl peroxides as oxidants. [ABSTRACT FROM AUTHOR]

Aryl halides, bridge splitting, coordination modes, oxidative addition, pincer complexes, platinum, reductive elimination Keywords: aryl halides; bridge splitting; coordination modes; oxidative addition; pincer complexes; platinum; reductive elimination EN aryl halides bridge splitting coordination modes oxidative addition pincer complexes platinum reductive elimination 15275 15275 1 11/09/21 20211105 NES 211105 B Density functional theory b studies of bridge-splitting of [Pt SP II sp R SB 2 sb (SEt SB 2 sb )] SB 2 sb (R = 4-tolyl) by bromoarenes containing nitrogen donor groups, subsequent intramolecular coordination assisted oxidative addition, and reductive elimination elucidate the mechanism for formation of I mer i -Pt SP II sp (N,C,N)Br pincers via Pt SP IV sp , where the pincers have applications in fundamental and applied chemistry. Cover Feature: Computational Study of Bridge Splitting, Aryl Halide Oxidative Addition to PtII, and Reductive Elimination from PtIV: Route to Pincer-PtII Reagents with Chemical and Biological Applications (Chem. Eur. J. 62/2021). [Extracted from the article]

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The first of the title compounds, [Fe(C9H10N4O)3]Cl2·5.SH2O, is the first structurally characterized homoleptic tris[bis(imidazol-2-yl) ketone]-metal complex to be structurally defined. In the second of the title compounds, [FeCl2(C9H10N4O)2], a pair of monodentate donors supplants one of the bidentate ligands. In the third complex, [Fe2Cl4(C9H10N4O)2]·2CH3OH, a centrosymmetric binuclear compound with a pair of bridging chloride ligands, the introduction of a third chloro ligand results in five-coordination about each of the metal atoms; the environments of the latter are square pyramidal, with a chloro ligand at the apex and the two bidentate arrays about the base of the pyramid. [ABSTRACT FROM AUTHOR]