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Compared to their C1-symmetric counterparts, planar chiral C2-symmetric metallocenyl P,N-ligands are efficient chiral ligands for Pd-catalyzed asymmetric allylic aminations, providing a number of amination products with high enantioselectivities. A non-C2-symmetric ferrocenyl P,N-ligand (a by-product obtained during the synthesis of the above C2-symmetric species) was also found to be an efficient ligand for asymmetric allylic aminations. A mixed ligand system consisting of both C2- and non-C2-symmetric ferrocene complexes was examined and showed high catalytic activity with the amination products being obtained with excellent enantioselectivities.

Trans-[Re6S8(CN)2(OH)4] 4- as mixed Cs/K salt is prepared by ligand exchange of a boiling aqueous K4 [Re6S8(OH)6]·8H2O solution in presence of excess KCN followed by addition of CsOH.

The analogous mechanisms leading to the related performance of Pd(dba)2 and Pd2(dba)3, respectively, in catalyzing C—N and C—S coupling reactions are demonstrated with the aid of mixed ligand catalytic systems.

Transition-metal-catalyzed cross-coupling reactions have fundamentally revolutionized organic synthesis, empowering the otherwise difficult to achieve products with rapid and convenient accesses alongside excellent yields. Within these reactions, ligands often play a critical role in specifically and effectively advocating the corresponding catalysis. Consequently, a myriad of ligands have been created and applied to make a fine tuning of electronic and steric effect of catalysts, remarkably promoting catalytic efficiency and applicability. The "mixed-ligand" concept has recently emerged; by combining and capitalizing on the superiority of each individual ligand already available, an expedient way can be achieved to reach a larger extent of catalytic diversity and efficacy. Given the availability of a wealth of ligands, it is reasonable to have great expectations for the original application of mixed-ligand catalytic systems and their important value in organic synthesis.

For the first time a mixed-ligand system, which can also activate C—Cl bonds in heteroaryl rings for C—S bond formation, is used in the title reaction.

The selective amination of aryl chlorides with anilines for the preparation of diarylamines is catalyzed by a mixed ligand catalytic system of Pd/PPh3/salicylaldimine.

Title ligand (I) is readily prepared and its structure is determined by computational and crystallographic studies to be similar to that of the known chiral crown complex Rh2((S)-PTTL)4.

The newly synthesized compounds are tested for their anticancer activity against the drug-resistant pancreatic cancer MiaPaCa-2 cells.

K10.5H0.5 [Np(BW11O39)(W5O18)] ·15H2O is hydrothermally synthesized from a mixture of Np(C2O4)2, K8BW11O39H, and H2O (sealed glass ampule, 150 °C, 2 d).

Orange red crystals of CuI8(imi)4(bpy)6 (H2O) [AsV2WV2W VI16O62]·2H2O (imi: imidazole; bpy: 4,4′-bipyridine) are hydrothermally synthesized from a mixture of Cu(OAc)2, As2O3, WO3, bpy, imi, and H2O (autoclave, 160 °C, 4 d, 25% yield).

It is found that the systems shown efficiently promote the reactions aryl iodides, bromides, and chlorides.

Five-, six-, and seven-membered endocyclic enol ethers are prepared in good to excellent yield by the title reaction.

The catalyst (no details given) can be successfully used for the regeneration of aldehydes and ketones.

A modified sol-gel process has been developed for the production of thin films of PbTiO3. The new route uses the mixed ligand complex titanium diisopropoxide bis(acetylacetonate), Ti(OC3H7)2(CH3COCHCOCH3)2, in place of titanium tetraisopropoxide, Ti(OC3H7)4. For base-catalyzed conditions, the maximum thickness of crack-free PbTiO3 films after one high-temperature firing cycle is 1 μm. This value represents a twofold increase in thickness over that obtained using existing sol-gel routes based on Ti(OC3H7)4.

In the absence of added solvent, B 4 Cl 4 and BBr 3 , present in a 1:5 mole ratio, generated B 4 BrCl 3 in approximately 13% yield after 800 h at 95 o C. Repeated exposure of B 4 Cl 4 to fresh aliquots of BBr 3 and pentane at 95 o C did ultimately (2200 h) form B 4 Br 4 and the mixed ligand species B 4 Br 3 Cl, B 4 Br 2 Cl 2 , and B 4 BrCl 3 , but the quantities provided were small

Asymmetric hydrogenation of (E)-4-phenyl-3-buten-2-one by use of [Ir(binap)(cod)]BF4 and o-di-methylaminophenyldiphenylphosphine afforded (E)-4-phenyl-3-buten-2-ol in 97% chemoselectivity and in 65% enantiomeric excess. A mixed ligand iridium dihydride complex containing both BINAP and the aminophosphine ligand has been shown to be the catalytically active species.

An efficient ruthenium catalysed asymmetric hydrosilylation of ketones has been developed using high-throughput, parallel screening to optimise ligand combinations.

The mixed ligand system 10 mol % NiCl2(dppp) with 5 mol % dppf was discovered to be an extremely efficient catalyst for the neopentylglycolborylation of a diversity of electron-rich and electron-deficient aryl chlorides. Optimization showed that 5 mol % catalyst with 10% dppf was even more efficient. These results highlight the complexity of the relationship between catalyst and coligand in Ni catalysis and the benefit of combinations of mixed ligand in catalyst design.

This work details the development of ruthenium(II) catalysts for the enantioselective alkylation of chiral racemic secondary phosphines. The reactions proceed through the intermediacy of nucleophilic phosphido species, which have low barriers to pyramidal inversion; this allows for a dynamic kinetic asymmetric alkylation. The initially discovered [((R)-iPr-PHOX)2Ru(H)][BPh4] (6) catalyst was found to be effective in the reaction with benzylic chlorides; moreover, the alkylation displayed an unusual temperature dependence. However, the limited scope of alkylation of 6 motivated further studies which led to the development of two complementary chiral mixed ligand Ru(II) catalysts of type [L1L2Ru(H)]+. These catalysts were derived from a combination of one chiral and one achiral ligand, where a synergistic interaction of the two ligands creates an effective asymmetric environment around the ruthenium center. The (R)-MeO-BiPHEP/dmpe (dmpe = 1,2-bis(dimethylphosphino)ethane) catalyst (10) was found to be effec...

Hydroxamic acids are an important class of chelators of hard metal ions such as Fe(III), which have found applications in therapeutic, diagnostic, and separation chemistry. Hence, methods for their preparation and incorporation into various matrices are important. A new strategy for the preparation of hydroxamic acids that uses readily available N-benzyloxy carbamic acid ethyl ester, 1, has been developed. N-Alkylation of 1 occurs readily to give N-alkyl-N-benzyloxy carbamates, 2, which react with a variety of stabilized carbon nucleophiles to give functionalized protected hydroxamic acids, 3, in good to excellent yields. The O-protected hydroxamate intermediates 3 can be further alkylated with halides to access a variety of potential metal binding hosts. The usefulness of this methodology has been demonstrated by the synthesis of a novel trihydroxamic acid 6, mixed ligand systems 9 and 12, and the macrocyclic dihydroxamic acid 16.

A catalytic aldehyde olefination reaction has been discovered. A Cu(II) complex (5 mol %) derived from a salen-quinine mixed ligand catalyzed the reaction between aldehydes and two molecules of acetyl chloride to produce trans C–C double bonds exclusively. The new catalytic aldehyde alkenation reaction presumably goes through a C-3 acylated β-lactone intermediate that loses one molecule of CO 2 .

Selected Fe and Ru systems, whose photochemical behaviour is sensitive to numerous parameters, are presented. These systems, containing multiple species in equilibrium, are versatile enough to be adapted to special tasks and may also be used to model the phenomena and mechanisms occurring in nature. The role of various parameters is analysed and principal emphasis is given to the ligand sphere influence on the nature of the excited state and thereby on the photochemical mode. This is crucial in the case of Fe(II) complexes of the type [Fe(CN)5L]n−, whereas in the carbolyl–cyclopentadienyl complexes, represented by [cpRu(CO)2]2, the nature of the excited state is of less importance than for pentacyanoferrates(II). The photochemistry of the carbonyl–cyclopentadienyl complexes is more susceptible to the impact of the medium and the role of the secondary processes is more significant.

Reactions of (R2C2B4H4)Fe(η6-C8H10) complexes with Na+R′2C2B4H−5 salts (R = C2H5, n-C4H9, CH2C6H5; R′ = CH3, C2H5, n-C4H9, CH2C6H5) at 150°C in the absence of solvent gave products of the general formula R2R′2C4B8H8, accompanied in each case by R4C4B8H8 carboranes. 11B, 1H, and 13C NMR Studies of the R2R′2C4B8H8 clusters indicated that each consists of two isomers consistent with the “open” and “closed” geometries identified in earlier work on R4C4B8H8 clusters, and that the isomer ratios do not change over time in solution at room temperature.

We report the results concerning the absorption spectra, luminescence spectra and luminescence lifetimes of the complexes [(η 5 -Me 5 C 5 )Ir(bpy)Cl]Cl ( 1 ), [(η 5 -Me 5 C 5 )Ir(phen)Cl]Cl ( 2 ), [(η 5 -Me 5 C 5 )Ir(bpy)H]BPh 4 ( 3 ) and [(η 5 -Me 5 C 5 )Ir(phen)H]BPh 4 ( 4 ) (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline and η 5 -Me 5 C 5 = pentamethylcyclopentadienyl = Cp*). For all complexes examined the low energy absorption band is assigned to metal-to-ligand charge-transfer transitions involving the diimine ligands. For the hydrido complexes 2 and 4 the luminescence observed both at 77 K and at room temperature is assigned to metal-to-ligand charge-transfer transitions involving the diimine ligands. The chloride complexes 1 and 3 were not found to emit.

Conductivity measurements are performed on solutions of the mixed ligand complexes (I) in dichloroethane and DMF.

The interaction of potassium tetrachloropalladate(II) with theophylline in a 1:1 molar ratio resulted in the formation of the monotheophylline (K[Pd(ThH)Cl3]) or monotheophyllinato ([Pd(Th)Cl]2) complexes, depending on the solvent and the acidity conditions. In the first complex, theophylline coordinates to Pd(II) as a neutral molecule through its N9 atom, while in the second as a monoanion through both its N7 and O6 atoms. Both complexes react with nucleosides, giving the complexes [Pd(Nucl)(ThH)Cl2] and [Pd(Nucl)(Th)Cl], respectively. Those complexes with one N(1)H ionizable imino-proton undergo deprotonation and two new series of mixed ligand complexes, [Pd(Nucl − H+)(ThH)Cl] and [Pd(Nucl − H+(Th)] are formed. In the mixed ligand complexes, theophylline maintains its coordination modes. The nucleosides, on the other hand, exhibit their usual coordination sites; i.e. in the nondeprotonated complexes they coordinate only through their N7 atoms, while in the deprotonated they act as bidentate through both their N7 and O6 atoms. All complexes were characterized with elemental analyses, conductivity measurements and various spectroscopic techniques.