Design and synthesis of versatile ligand precursors based on phosphonium ylides for palladalactam formation and catalytic investigation.

A new series of ligand precursors designed for the synthesis of palladalactams has been developed. These precursors are easily accessible through a one-step reaction involving 2-chloro-N-phenylacetamide and a wide choice of various monophosphines, offering tunable electronic and steric properties within the ligand framework. The stability of both ligand precursors and resulting palladalactams in ambient air enhances their practical applicability. A newly synthesized palladalactam, featuring an electron-donating triethylphosphine moiety on the anionic phosphonium ylide ligand scaffold exhibited promising catalytic activities in the Mizoroki-Heck coupling reaction between aryl chlorides and alkenes. Theoretical calculations further affirmed that the ligand system in the complex is the most electron-donating, forming the strongest Pd-C bond compared to other complexes with alternative phosphine moieties.

One-step synthesis of isocoumarins and 3-benzylidenephthalides via ligandless Pd-catalyzed oxidative coupling of benzoic acids and vinylarenes.

A straightforward synthetic method for the preparation of isocoumarins and 3-benzylidenephthalides via C-H olefination and oxidative coupling of readily available benzoic acids and vinylarenes was developed. The directing effect of the substituents on the benzoic acid allows for the synthesis of both types of lactone in pure form.

1-(10-Bromo-anthracen-9-yl)-1H-imidazole.

In the title mol-ecule, C17H11BrN2, the planes of the anthracene ring system [maximum deviation from the mean plane = 0.036 (3) Å] and the imidazole ring form a dihedral angle of 85.14 (14)°. In the crystal, weak C-H⋯N and C-H⋯Br hydrogen bonds link the mol-ecules into double chains propagating along [01-1]. In addition, π-π stacking inter-actions between pairs of benzene rings are observed, with centroid-centroid distances of 3.7968 (17) and 3.8496 (16) Å.

Nitron-derivative-based palladium carbene complexes: structural characterization, theoretical calculations, and catalytic applications in the Mizoroki-Heck coupling reaction.

New palladium(0) and palladium(ii) complexes with N-heterocyclic carbene (NHC) ligands derived from nitron and its derivatives were synthesized. The structures of most of these complexes were established by single-crystal X-ray diffraction studies. Among the new complexes, the palladium complex with a monodentate NHC ligand derived from nitron demonstrated the highest efficacy as a catalyst precursor in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes. Theoretical calculations provide valuable insights into the electronic parameters of both the ligands and the palladium complexes, highlighting the significance of a robust Pd-C bond and the π-accepting property of the NHC ligand in achieving enhanced catalytic activity. Notably, catalyst activation occurred much more rapidly with the preformed palladium(0) complex compared to its palladium(ii) counterpart.

Pd(0)-catalyzed decarboxylative coupling and tandem C-H arylation/decarboxylation for the synthesis of heteroaromatic biaryls.

An effective Pd(0) carbene complex was successfully employed in the decarboxylative coupling of the heteroaromatic carboxylic acids (imidazo[1,2-a]pyridine and isoxazole) with aryl halides. For carboxyindoles, either decarboxylative coupling or tandem C-H arylation and decarboxylation occurred, leading to the formation of C2-monoarylated indoles.

An order-disorder phase transition in the structure of C60·4benzene.

A reversible, broad, order-disorder phase transition in the structure of C(60)·4benzene has been observed to take place with an inflection point at 134 K. In the low-temperature structure fullerene disorder is removed, although the average atomic displacement parameters differ for the two C(60) molecules in the asymmetric unit. Some benzene disorder persists, even at 13 K.

1,3-Bis(2-anilino-2-oxoeth-yl)-1H-imidazol-3-ium chloride dimethyl-formamide monosolvate.

In the imidazolium cation of the title compound, C19H19N4O2(+)·Cl(-)·C3H7NO, the dihedral angles between the imidazole ring and the phenyl rings are 85.86 (4) and 70.26 (5)°. In the crystal, N-H⋯Cl hydrogen bonds link the imdiazo-lium cations and chloride anions into zigzag chains along [110] and together with C-H⋯Cl and C-H⋯O hydrogen bonds, which involve also the dimethyl-formamide solvent mol-ecule, form a two-dimensional network extending across the ab plane.

N,N'-Bis[(1H-imidazol-1-yl)meth-yl]-2,2'-(disulfanedi-yl)dianiline.

The symmetrical title compound, C(20)H(20)N(6)S(2), contains a disulfide bond of 2.0884 (6) Å. The C-S-S-C torsion angle is -59.57 (7)°. In the crystal, classical N-H⋯N and non-classical C-H⋯N hydrogen bonds link the compounds into chains along the a axis.

N-[2-(Methyl-sulfan-yl)phen-yl]-2-sulfanylbenzamide.

In the title compound, C(14)H(13)NOS(2), the S atom with the methyl group is involved in an intra-molecular hydrogen bond with the amido H atom. In the crystal, the sulfanyl H atoms form inter-molecular hydrogen bonds with the O atoms, connecting the mol-ecules into zigzag chains along the c axis. The two aromatic rings exhibit a small interplanar angle of 16.03 (9)°.

1,3-Bis(2-anilino-2-oxoeth-yl)-1H-imidazol-3-ium chloride.

In the cation of the title salt, C(19)H(19)N(4)O(2) (+)·Cl(-), the dihedral angles between the imidazole ring and the phenyl rings are 70.39 (8) and 86.26 (9)°. The chloride anion inter-acts with the cation through an N-H⋯Cl hydrogen bond. In the crystal, classical N-H⋯O hydrogen bonds link the cations into chains parallel to the b axis. Non-classical C-H⋯Cl and C-H⋯O hydrogen bonds further connect the chains into a three-dimensional network.

Nickel(II) complexes containing tridentate ONCi ligands (i = abnormal N-heterocyclic carbene donors) and their catalytic application in Suzuki-Miyaura coupling reaction.

New nickel complexes with tridentate phenoxy-amidate-aNHC donor groups were synthesized from the reactions between nickel acetate and imidazolium ligand precursors in net pyridine. An unusual degradation pathway was observed, leading to imidazole derivatives occupying the fourth coordination sites in these square planar complexes. A new imidazole-coordinated nickel complex was found to be efficient in catalyzing Suzuki-Miyaura cross-coupling with aryl chlorides under 3 mol% of catalyst loading. The catalytic activities were superior to those of its reported normal NHC counterpart. Instead of the common procedure of using additional phosphine, the addition of IMes·HCl significantly enhances the product yields of the catalytic reaction.

Direct arylation reaction catalyzed by a PEPPSI-type palladium complex with an amido-functionalized triazole-based mesoionic carbene ligand.

Ligand precursors for amido/amidate-functionalized triazole-based MIC ligands were synthesized. An initial theoretical calculation confirmed that triazole-based MIC ligands were promising ligands in terms of their σ-donating and π-acidic properties. Based on these ligand precursors, three different types of palladium complexes were successfully obtained, namely (1) a PEPPSI-type MIC complex, (2) a complex containing both a bidentate ligand of a MIC and an amidate donor and a mondentate NHC derived from nitron, and (3) a complex featuring a tridentate ligand of a MIC, an amidate, and a phenoxy donor. The structures of all these complexes were established by single-crystal X-ray diffraction studies. Imidazole derivatives are important heterocycles with enormous medicinal value. The catalytic activities of these new palladium complexes in the green direct C-H arylation of imidazoles with aryl halides were investigated and compared to those delivered from palladium complexes with IMes and triazole-based normal NHC ligands. Among the new complexes, the PEPPSI-type palladium complex with the monodentate triazole-based MIC ligand was found to be a very promising precatalyst which was capable of utilizing electron-deficient aryl chlorides as coupling partners in the reaction.

trans-Bis[1-(2-anilino-2-oxoeth-yl)-3-benzyl-1H-imidazol-2-yl]palladium(II) methanol disolvate.

In the title compound, [Pd(C(18)H(16)N(3)O)(2)]·2CH(3)OH, the Pd(II) atom is located on a crystallographic inversion center. It has a square-planar coordination geometry, with the two bidentate ligands coordinated in a trans fashion via the carbene C atom and the amido N atoms. The methanol solvent mol-ecules form O-H⋯O hydrogen bonds with the complex. Additional non-classical inter-molecular C-H⋯O hydrogen bonds link the complexes into a two-dimensional network parallel to (001).

1,3-Bis(2-anilino-2-oxoeth-yl)-1H-imidazol-3-ium chloride acetonitrile monosolvate.

In the title compound, C(19)H(19)N(4)O(2) (+)·Cl(-)·C(2)H(3)N, the dihedral angle between the two phenyl rings is 69.57 (8)° while the dihedral angles between the imidazole ring and the phenyl rings are 70.61 (7) and 82.11 (7)°. In the crystal, N-H⋯Cl, C-H⋯O, C-H⋯Cl and C-H⋯N hydrogen bonds link the imidazolium cations, chloride anions and acetonitrile solvent mol-ecules into a two-dimensional hydrogen-bonded network parallel to (001); an intra-molecular C-H⋯O hydrogen bond is also observed.

3,3'-Bis(3-meth-oxy-benz-yl)-1,1'-(ethane-1,2-diyl)-diimidazolium dibromide dihydrate.

In the title compound, C(24)H(28)N(4)O(2) (2+)·2Br(-)·2H(2)O, the diimid-azo-lium cation is located on an inversion center. The imidazole and the benzene rings make a dihedral angle of 68.08 (04)°. In the crystal, O-H⋯Br, C-H⋯O and C-H⋯Br hydrogen bonds link the diimidazolium cations, the bromide anions and the water mol-ecules into a two-dimensional network.

3,3'-Dibenzyl-1,1'-ethyl-enediimidazolium dibromide.

In the title compound, C(22)H(24)N(4) (2+)·2Br(-), the imidazolium dication is located on a crystallographic inversion center. The imidazole and benzene rings make a dihedral angle of 73.1 (9)°. In the crystal, non-classical inter-molecular C-H⋯Br hydrogen bonds link the ion pairs into a two-dimensional network.

Azido-(benzoyl-acetonato-κO,O')[1-phenyl-3-(2-pyridylmethyl-imino)but-1-en-1-olato-κN,N',O]cobalt(III).

In the title complex, [Co(C(16)H(15)N(2)O)(C(10)H(9)O(2))(N(3))], the Co(II) atom adopts an octa-hedral coordination geometry by a tridentate Schiff base, a bidentate benzoyl-acetonate and an azide ligand. The imine N atom of the tridentate ligand is trans to the benzoyl O atom of the bidentate ligand and the azide ligand is trans to the acetyl O atom of the bidentate ligand. Non-classical intra-molecular C(ar-yl)-H⋯O hydrogen bonds are present in the structure.

Bis{N'-[1-(2-pyrid-yl)ethyl-idene-κN]benzohydrazidato-κN',O}nickel(II).

In the title complex, [Ni(C(14)H(12)N(3)O)(2)], the Ni(II) atom lies at the centre of a distorted octahedron formed by two tridentate hydrazone ligands. Inter-molecular hydrogen bonds of the type C-H⋯X (X = N, O) link the complexes into a two-dimensional network.

Di-µ-azido-bis-({N'-[1-(2-pyrid-yl-κN)ethyl-idene]acetohydrazidato-κN',O}dicopper(II)).

The dimeric title compound, [Cu(2)(C(9)H(10)N(3)O)(2)(N(3))(2)], is located on a crystallographic inversion center. The Cu atom is coordinated by a tridentate anionic hydrazone ligand and two bridging azide ligands in a distorted square-pyramidal coordination geometry. The non-bonding Cu⋯Cu distance is 3.238 (1) Å. Non-classical inter-molecular C-H⋯N hydrogen bonds link the dimers into chains along the c axis.

Dichlorido{N'-[1-(2-pyridin-2-yl)ethyl-idene]acetohydrazide-κN',O}copper(II).

In the title compound, [CuCl(2)(C(9)H(11)N(3)O)], the Cu(II) atom is in a distorted square-pyramidal CuCl(2)N(2)O coordination geometry. The tridentate acetohydrazide ligand chelates in a meridional fashion. The chloride ligand in the axial position forms a long Cu-Cl distance of 2.4892 (9) Å. In contrast, the Cu-Cl distance from the equatorial chloride ligand is much shorter [2.2110 (7) Å]. Inter-molecular N-H⋯Cl and C-H⋯Cl hydrogen bonds link the complexes into a three-dimensional network.