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Complexes cis‐[Pd(ArF)2(NCMe)2] (A) and cis‐[Pd(ArF)2(THF)2] (B) (ArF=C6F3H2) are fast general precursors easy to prepare, store and handle, which allow in situ synthesis of tailor‐made [Pd(Ar)(X)(L)] catalysts for chosen Ar‐Nu couplings, provided that the L ligand (in this case PR2(2‐biaryl)) induces (ArF)2 coupling. This fluorinated byproduct is inert in the reaction conditions, and no other byproduct is expected because the Ar and X groups are the same in the catalyst, the intermediates and the products. The application of A or B in catalysis (e. g. with 1% catalyst) consists of a first step (formation of 1% tailor‐made catalyst) where 100 ArX+1 A (or B)+1 L in THF gives a solution with 99 ArX+1 [Pd(Ar)(X)(L)]+(ArF)2. The only other byproduct is THF or NCMe. In the second step, addition of the nucleophile, 100 Q(Nu), triggers and completes the catalytic cycle yielding 100 Ar‐Nu+100 Q(X)+1 [Pd0(L)]. The 100% yield is theoretical, but the tested catalysis (Ar‐Me Negishi coupling, C6F5‐alkynyl Stille coupling and Ar‐naphthyl Suzuki coupling) using A as precursor, SPhos as ligand, and 1000:1 reagents:catalyst ratio, afford 95–99% yield. In contrast, aryl‐amination requires 1000:5 ratio to give 96% yield (or 1000:50 for 99% yield) because PhNH2 eventually displaces the SPhos from Pd and blocks the catalyst. As a bonus, the presence of F in the precursors facilitates stepwise 19F NMR monitoring of the formation of [Pd(Ar)(X)(L)] with different phosphines, facilitating analysis of weaknesses or strengths of each of them to produce the catalyst, and helps in the choice of the most convenient one for the case. The in situ catalyst formation is ideal for serial two‐step catalysis with different phosphines or different nucleophiles. [ABSTRACT FROM AUTHOR]

Complexes trans-[PdX2L2] (X = Cl and Br), where L is 1-(PR2),2-(CH＝CH–C(O)Ph)-C6F4 (R = Ph, Cy, and iPr), display phosphorescent emission in the solid state, whereas due to their substantially lower lifetimes, the free ligands exhibit fluorescent behaviour. Alternatively, structurally identical derivatives with halide replaced by CN− or Pd replaced by Pt are non-emissive. DFT calculations explain this diverse behaviour, showing that the hybridization of orbitals of the MX2 moiety with those of the chalcone fragment of ligands is significant only for the LUMO of the emissive compounds. In other words, in our complexes, only MLMCT processes (LM = Metal-perturbed Ligand-centered orbital) lead to observable luminescence. [ABSTRACT FROM AUTHOR]

19F NMR monitoring shows that heating trans-[AuIIIRf2I2]− solutions (Rf = C6F3Cl2-3,5) leads to formation of cis-[AuRf2I2]−, [AuRf3I]− and [AuRfI3]−via kinetic competition between isomerization and Rf/I scrambling. The system evolution is driven by the easy Rf–I reductive elimination from [AuRfI3]− (forming also [AuI2]−), which is faster than any of the Rf–Rf couplings from the coexisting species, hindering the commonly desired and thermodynamically preferred C–C coupling. A kinetic model where I− dissociation triggers both isomerization and transmetalation steps is proposed, which fits well the experimental data. DFT calculations support that the lower bond strength of AuIII–I compared to other halides produces a pathway switch that makes C–I coupling kinetically preferred. Consequently, it is better avoided in reactions looking for C–C coupling. [ABSTRACT FROM AUTHOR]

RhI complexes [Rh(L)4](A) (A− = Cl−, BF4−, [Au(CN)2]−) with conventional arylisocyanides (p-MeC6H4(NC), LA; p-MeOC6H4(NC), LB; 3,5-(OMe)2C6H3(NC), LC) or with the alkoxy-functionalized triphenylene-arylisocyanides TPh(OC12H25)5(O(CH2)6OC6H4(NC)-p) (LD1) and TPh(OC12H25)5(O(CH2)6OC6H2Me2(NC)-p) (LD2), have been prepared and their self-assembly, aggregation, optical, redox, mesogenic and conducting properties investigated. Intermolecular π–π stacking, RhI⋯RhI, and RhI⋯AuI interactions rule the crystal packing and aggregation in solution for the complexes with LA, LB, and LC. For the RhI complexes with the alkoxy-functionalized-triphenylene isocyanides LD1 and LD2 mesogenic behaviour is induced, giving rise to multicolumnar mesophases in broad temperature ranges (ca. 70–160 °C). Detailed analysis (POM, DSC, SAXS/WAXS and GIWAXS) of the columnar mesophases has allowed us to propose precise packing models that explain the diverse supramolecular arrangements found in the nanostructured condensed phases. Columnar alignments predominantly with Rh⋯Rh interactions (or Rh⋯Au, only for LD2 in specific conditions) are observed, depending on the aligning conditions. The hole mobility in the columnar mesophases of the complexes with Rh⋯Rh interactions are ∼1 cm2 V−1 s−1, that is up to four orders of magnitude higher than those reported for columnar mesophases of organic triphenylene derivatives, and increases one order of magnitude further in the mesophases containing the [Au(CN)2]− counteranion. [ABSTRACT FROM AUTHOR]

A new system based on dinuclear gold complexes with biphenyl isocyanides which shows luminescence properties and also liquid crystal behavior is reported. All the gold(I) derivatives except the phenylisonitrilegold(I) derivative [[mu]-(1,4-CN-[C.sub.6][H.sub.4]-NC)[{Au([C.sub.6][F.sub.4]O[C.sub.6][H.sub.17]}.sub.2] display liquid crystal behavior giving rise to a nematic mesophase.

This study reports new mesomorphic benzylethylammonium salts containing a 2,3,6,7,10-pentakis(dodecyloxy)-11-(hexyloxy)triphenylene unit and Cl− or [MCl4]2− (M = Cu, Ni, Co, Mn) as counterions. They show a rich columnar polymesomorphism, characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and small- and wide-angle X-ray scattering (S/WAXS). All the compounds self-organize into multisegregated structures in the solid state and in the mesophases, with the alternation within large superlattices of triphenylene-containing columns and benzylammonium chloride or tetrachorometallate fragments. Interestingly, the nickel derivative displays a continuous and reversible thermochromic behavior in the range of 50–80 °C. Magnetic measurements and UV-Vis data at different temperatures, support changes in the coordination sphere of the Ni(II) atom from octahedral to tetrahedral. Furthermore, these systems form stable and homogeneous Langmuir films at the air–water interface. These films have been successfully transferred onto solid substrates giving rise to nanostructured LB films with a clearly defined bilayer structure in which each layer consists of molecular columns aligned along the surface. [ABSTRACT FROM AUTHOR]

Research has been conducted on binuclear mesogenic copper(I) isocyanide complexes with a tetrahedral core. The preparation of these complexes and the relationship between the thermal behavior of these complexes and their molecular structure are described.

The platinum amides exhibit planar arylamido moieties and hindered rotation around the N-aryl and Pt-N bonds. Data indicate that the rotation about the Pt-N bond is unfavorable due to steric congestion with the planar amide.

Research has been conducted on the rhodium(I) complexes. The synthesis and structures of these complexes with the ligands PePy (sub)n are discussed.

The process of interconversion of the syn and anti-rotational isomers of cis-(Pd(2-C6BrF4)2(tht)2)(tht = tetrahydrothiophene) was studied by 19F NMR magnetization transfer experiments. The first-order syn-to-anti atropisomerization rate constant k(sub ab) decreased with the addition of tht until it reached an asymptotic value (1.414 + O.012s-1 at 299.1 K). This behavior revealed a dual mechanism involving two competitive pathways.

An efficient Pd/Cu bimetallic cross-coupling catalysis of fluoroaryl halides and fluoroarenes is reported. In situ generation of the Cu nucleophile by rate determining C–H activation of highly fluorinated aryls (≥4 F atoms) leads to high cross-coupling selectivity with little formation of homocoupling products. [ABSTRACT FROM AUTHOR]

Chiral gold(I) isocyanide complexes [Au(p-C6F4OR1)(p-CNC6H4(O2CC6H4OR2)] with R1, R2 or both being (R)-2-octyl, display an interesting and unprecedented response to mechanical or thermal stress. For all the complexes, heating leads to formation of Sm mesophases identified by POM, DSC, and X-ray diffraction studies. On the other hand, grinding produces soft materials which are eventually identified also as Sm metastable mesophases formed at temperatures much below the melting point. Intriguingly, only some of these mesophases (those with the tertiary carbon in the isocyanide ligand) display a strong green luminescence. The X-ray analysis supports that the melting of the crystals, either by mechanical or by thermal stress, produces a transition from regular Sm-like molecular arrangement in the solids to interdigitated-Sm arrangement in the mesophases. The molecular slippage producing this interdigitation is conditioned by the position of the bulky tertiary carbon in the molecule, which allows or impedes formation of the Au⋯Au interactions that give rise to luminescence. [ABSTRACT FROM AUTHOR]

The chemical process involving palladium-catalyzed cross-coupling of organotin reagents with organic electrophiles (Stille reaction) has become a favored technique in contemporary organic synthesis primarily because of the benefits of using trialkylorganotin species. The Still reaction technique is critically evaluated with regard to certain inconsistencies and a plausible correction mechanism is proposed.

Four complexes of [Pd(C6F5)2(SPPynPh3-n)] are synthesized. Three of the complexes exhibit slow equilibrium of the N,N- and N,S- isomers. Intramolecular substitution process in two N,S- isomers is found to take place by a turnstyle mechanism in a square-pyramidal intermediate. This mechanism is favored over the more common Berry pseudorotation in a trigonal-bipyramidal intermediate.

The ligands P(CH2CH2Py)Ph2 (PN), P(CH2-CH2Py)2Ph (PN2) and P(CH2CH2Py)3 (PN3) act as bidentate P,N-chelating ligands in a number of neutral palladium(II) complexes of the type [PdRCl(PNn)] prepared with these ligands. For neutral complexes, the base-catalyzed addition of P-H bonds to 2-vinylpyridine offers an easy way to prepare (2-pyridylethyl)phosphines PNn. These react with dimers [Pd2-(mu-Cl)2(R)2(tht)2] to generate the neutral complexes [PdCl(R)(PNn0)]. For cationic complexes, the position previously occupied by the halide must be filled by the second Py group.

Mono- and dinuclear(perhalophenyl)gold(I) complexes such as [AuR(C=N)(C6H4)2(OCnH2n=1-p)] and [mu-4,4'(C6F4C4F4){AuC=N(C6H4)m-OC6H2n+1}2 (m=1,2) were characterized as thermotropic liquid crystals. The mononuclear derivatives exhibited a nematic phase when the isocyanides have a short tail and smectic A phases when the isocyanide have an intermediate tail. On the other hand, the dinuclear(perhalophgenyl)gold(I) complexes exhibited an intermediate tail.

The reaction between molybdenum(O) carbonyl complexes, (Mo(CO)6) or (Mo(CO)4)(NBD), where NBD is norbornadiene, with PPy3 or ZPPy3, where Z is O,S ClAu, C6F5Au and Py is 2-pyridyl, yields complexes with ligands that act as tridentate N-donors. The crystal structure of fac-(Mo(CO)3(SPPhPy2-S,N2)) suggests an octahedral coordination at molybdenum with trigonal elongation. The synthesis of these tricarbonyl complexes yields many tetracarbonyl complexes as intermediates.

An analysis of the reactions of 1,4-pentadiene and 3-methyl-1,4-pentadiene with [Pd(C6F5)Br(CH3CN)2] at low temperature revealed that these yield two types of eta1-eta2-pentenylpalladium derivatives, following insertion of one double bond into the Pd-C6F5 bond. These are the 4.5-membered palladacycles [Pd2(mu-Br)2(5-Pf-3-R-1,2,4-eta1-eta2-pentenyl)2] (Pf = C6F5; R = H, Me) and the 5.5-membered metallacycles [Pd2(mu-Br)2(5-Pf-3-R-1,2,5-eta1-eta2-pentenyl)2] (R = H, Me). Two competitive processes are involved in evolution to give eta3-allyls, namely, Pd migration and cyclopropane formation from 4.5-membered eta1-eta2-palladacycles and reopening.

The preparation of the palladium dipicolinate complex (Pd dipic NCME), where H2dipic = pyridine-2,6-dicarboxylic acid, is described. The scheme involves the reaction of Pd(acac)2 or (Pd OAc sub 2)3 with H2dipic in acetonitrile. The dipicolinate anion showed two modes of coordination depending on the fourth ligand. These were as a pincer ligand O,N,O-bonded to the same palladium in mononuclear complexes and as an O,N-chelate N,O'-bridging ligand in dinuclear complexes.

The reaction of the dihydrido-olefin complex OsH2(eta2-CH2=CHEt)(CO)(P(super i)Pr3)2 with H2SiPh2 produced OsF3(SiHPh2)(CO)(P(super i)Pr3)2. The complex also reacted with H2GePh2, H2GePh3, and HGEt3 to form trihydrido-germyl derivatives, and with HSnPh3 and HSn(super n)Bu3 to form trihydrido-stannyl derivatives. The orientation of the ligand around the osmium atom was similar in all three products with the resulting structure described as a severely damaged pentagonal bipyramid. All compounds were fluxional in solution with the hydrido ligands exchanging positions.

Highly selective cross-couplings to polyfluorinated assymmetric biaryls, including the symmetric biaryl C6F5–C6F5, are achieved at relatively low temperature (80 °C) and in short times using [MCl2(PhPEWO-F)] catalysts (M = Ni, Pd; PhPEWO-F = 1-(PPh2), 2-(CH＝CH–C(O)Ph)–C6F4), ArFI, and Zn(C6F5)2 as example of highly fluorinated nucleophile. [ABSTRACT FROM AUTHOR]

Palladium complex (Pd(pdtc))2 with the tridentate ligand pdtc is prepared and this complex is used to prepare neutral and anionic complexes. X-ray studies show pdtc dianionic ligand as tridentate ligand producing strain free metal chelation. The fourth coordination site can be occupied by other ligands to form monomers and dimers.

The chemical and electrochemical behavior of tetranuclear compounds formed from the double oxidative coupling of the complex (Pd-ortho-C6H4-single bond- C Me -double bond-N-single bond-NPh L)2, where L = P(OMe)3, were studied. It was found that the coupling reactions can yield meso or rac diastereomers of (Pd4)0. The (Pd4)n+ system was generated only when the applied potential was more than 0.5 V and a solution with (PD4)4+ was produced at this same condition. This indicates that intermediates in a higher oxidation state are involved in the formation of (Pd4)2+ by chemical oxidation.

A study was done on covalent soaps to determine the mesogenic behavior of silver thiolates with layered structures. It was shown that primary silver thiolate compounds with R substituents extending perpendicular to the central slab of Ag and S atoms behave as thermotropic liquid crystals. The thiolates show successively lamellar, cubic and micellar mesophases with heat. The micellar phase was shown to be a hexagonal columnar mesophase while the lamellar and cubic phases were found to decrease with increasing length of R.

The almost quantitative synthesis of homologous luminescent fluorophosphoranes, by SNAr cyclization of (2′-F,2-(PR2)biaryl) phosphines made from easily accessible reagents, is reported and the DFT cyclization mechanism and alternative pathways to complete this isomerization are studied and discussed. [ABSTRACT FROM AUTHOR]

Aryl rearrangements triggered by Cl− extraction from trans-[AuIII(Rf)2Cl2]− (Rf = C6F3Cl2-3,5), led quickly to a mixture of [Au(Rf)3(solv)], cis-[Au(Rf)2Cl(solv)] and [Au(Rf)Cl2(solv)] (solv = OEt2, OH2). 19F NMR and X-ray diffraction studies led us to identify the species present in solution and the role of the solvent in their formation, while DFT calculations confirm the thermodynamic basis of their evolution. Very different Rf–Rf coupling rates are found from (μ-Cl)2[cis-Au(Rf)2]2 or cis-[Au(Rf)2ClL] species (L = OEt2, NCMe, Cl−) depending on the coordination strength of the ligand or solvent in the fourth position. [ABSTRACT FROM AUTHOR]

The isomerization process involved in the uncatalyzed dissociation of bis(pentafluorophenyl)bis(tetrahydrothiophene) was studied. The results showed no evidence that the dissociation step was indicative of the rate. Isomerization was demonstrated to affect the rate, as deduced from the observed establishment of preequilibrium, and the regulation of the distribution of unsaturated species. However, the topomerization step represents the biggest activation obstacle in the process.

The perylene derivative 2-(3-perylenyl)-4-methylpyridine (HPerPy) was prepared and used to synthesize [Ag(HPerPy)(PPh3)(OClO3)], with the perylene ligand bonded to the metal centre only by the pyridine nitrogen. The treatment of HPerPy with [Pd(OAc)2] in methanol or acetic acid led to acetate bridged dimers (μ-OOCCH3)2[Pd(PerPy)]2, six-membered or five-membered cycled at the perylenyl fragment. Substitution reactions afforded mononuclear compounds [Pd(PerPy)(acac)] (six-member or five-member cycled) and [Pd(PerPy)(S2COMe)] (six-member or five-member cycled). The reaction of HPerPy with a platinum(II) fragment led to a five-membered cyclometallated Pt(II) complex [Pt(PerPy)(acac)]. The oxidative addition with MeI gave the corresponding cyclometallated Pt(IV) compound [Pt(PerPy)(acac)MeI]. X-ray single crystal studies of compounds [Ag(HPerPy)(PPh3)(OClO3)], (μ-OOCCH3)2[Pd(PerPy)]2-five-membered, [Pd(PerPy)(acac)]-six-membered, [Pd(PerPy)(S2COMe)]-five-membered, [Pt(PerPy)(acac)]-five-membered, and [Pt(PerPy)(acac)MeI]-five-membered confirmed the proposed structures. The UV-Vis spectra show one intense absorption with vibronic coupling in the visible region with maxima in the range of 448–519 nm. DFT calculations were carried out for the absorption spectra of the HPerPy molecule and representative complexes [M(PerPy)(acac)] (M: Pd, Pt; five and six-membered isomers) and [Pt(PerPy)(acac)MeI], showing that the lowest energy most intense transition in the complexes corresponds to the HOMO → LUMO transition in the perylene moiety, although affected by the metallacycle size and the metal nature. All the compounds are fluorescent in solution, due to the perylene fragment. The emission spectra display maxima in the range of 468–549 nm, with quantum yields from 1.1 to 82%. The attenuation of the intensity of fluorescence by the presence of heavy atoms and the formation of metallacycles has been experimentally determined and sequenced. [ABSTRACT FROM AUTHOR]