The dinitrogen complex [{Cp*Ru(L)}(2)(mu-N-2)]-[BPh4](2) (L = bis(3-methylimidazol-2-ylidene) reacts with dichloro-methane at room temperature, furnishing the diene derivative [Ru(eta(4), kappa(1)-Cl-C5Me5CH2Cl)Cl(L)][BPh4] as result of CH2Cl2 oxidative addition and subsequent migration of the chloromethyl group into the Cp* ring. Mechanistic insight provided by DFT computations indicate that while the cleavage of the C-Cl bond is not thermodynamically favored, the subsequent migration step is largely exergonic and thus provides the driving force for the formation of the observed product.

The complex [Cp*RuCl(COD)] reacts with LH2Cl2 (L = bis(3-methylimidazol-2-ylidene)) and LiBun in tetrahydrofuran at 65 degrees C furnishing the bis-carbene derivative [Cp*RuCl(L)] (2). This compound reacts with NaBPh4 in MeOH under dinitrogen to yield the labile dinitrogen-bridged complex [{Cp*Ru(L)}(2)(mu-N-2)][BPh4](2) (4). The dinitrogen ligand in 4 is readily replaced by a series of donor molecules leading to the corresponding cationic complexes [Cp*Ru(X)(L)][BPh4] (X = MeCN 3, H-2 6, C2H4 8a, CH2CHCOOMe 8b, CHPh 9). Attempts to recrystallize 4 from MeNO2/EtOH solutions led to the isolation of the nitrosyl derivative [Cp*Ru(NO)(L)][BPh4](2) (5), which was structurally characterized. The allenylidene complex [Cp*Ru=C=C=CPh2 (L)][BPh4] (10) was also obtained, and it was prepared by reaction of 2 with HC CC(OH)Ph-2 and NaBPh4 in MeOH at 60 degrees C. Complexes 3, 4, and 6 are efficient catalyst precursors for the transfer hydrogenation of a broad range of ketones. The dihydrogen complex 6 has proven particularly effective, reaching TOF values up to 455 h(-1) at catalyst loadings of 0.1% mol, with a high functional group tolerance on the reduction of a broad scope of aryl and aliphatic ketones to yield the corresponding alcohols.

A series of new cationic Rn‐substituted‐indenyl nickel(II) complexes containing arsine or stibine ligands were synthesized in moderate to very high yields by the protonation of the corresponding bis(indenyl) nickel derivatives [Ni(η‐Rn‐Ind)2] with HBF4, in the presence of 2 equiv. of AsPh3 or SbPh3 donor ligands. These complexes, with the general formula [Ni(η‐Rn‐Ind)(EPh3)2]BF4 (E = As, Sb), were structurally characterized by NMR spectroscopy and X‐ray diffraction, and subsequently tested as single‐component catalysts for the oligomerization of styrene, leading to the formation of very low molecular weight head‐to‐tail oligomers (typically consisting of dimers, trimers and tetramers). The new 1‐ or 2‐monosubstituted‐indenyl NiII catalyst precursors exhibit extremely high catalytic activities, considerably higher than those observed for the symmetrical unsubstituted‐ and the 1,3‐disubstituted‐indenyl nickel analogues (i.e. monosubstituted >> non‐substituted > 1,3‐disubstituted), their reactivity pattern showing similarities with that of the corresponding allyl derivatives. A simpler and more straightforward experimental procedure for the high yield preparation of [NiBr2(DME)], an important nickel starting material, which was used in the preparation of the bis(indenyl) nickel precursors of this work, is also described.

A variety of Ni II complexes with a wide range of electronic and steric properties, bearing picolylimidazolidene ligands ( a – g ) and Cp (Cp = η 5 ‐C 5 H 5 ; 2a – f ) or Cp* (Cp* = η 5 ‐C 5 Me 5 ; 3a , c , g ) groups, have been synthesised and characterised by using NMR spectroscopy and single‐crystal X‐ray crystallography. The complexes have been used as precatalysts for a wide range of catalytic transformations, which most likely involve a Ni 0 /Ni II catalytic cycle. In particular, the new well‐defined 2a , 2c , 3a and 3c complexes have demonstrated great efficiency and versatility towards Suzuki–Miyaura coupling reactions, hydroamination of activated olefins and C–S cross‐coupling reactions of aryl halides and thiols under mild conditions.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The complex [TpRuCl(COD)] reacts with L center dot Ag2Cl2 (L = bis(3-methylimidazol-2-ylidene)) in dichloroethane at 120 degrees C for a period of 20 h, furnishing the bis(carbene) derivative [TpRuCl(L)] (1). This compound reacts with NaBAr4' in FPh under dinitrogen to yield the cationic dinitrogen complexes [TpRu(N-2)(L)][BAr4'] (2') and [{TPRu(L)/(mu-N-2)][BAr4'](2) (2). The terminal dinitrogen complex 2' is labile and spontaneously converts into 2, which was structurally characterized. The reaction of 2 with CO is slow and affords [TpRu(CO)(L)][BAr'4] (3). The kinetics of the substitution of coordinated dinitrogen in 2 by CD3CN has been studied. The value of 25 +/- 4 kcal mol(-1) determined for Delta G(298)(double dagger) for the substitution reaction is consistent with the observation that the dinitrogen ligand is strongly bound to ruthenium in 2. Complex 1 reacts with propargyl alcohols HC equivalent to CC(OH)RR' (RR' = Me-2, (CH2)(5), MePh, HPh) and NaBPh4 in MeOH at 50-60 degrees C, yielding the corresponding gamma-methoxyvinylidene complexes [TpRu=C=CHC(OMe)RR'(L)][BPh4] (RR' = Me-2 (4a), (CH2)(5) (4b), MePh (4c), HPh (4d)). The reaction of 1 with HC equivalent to CCH2OH under the same conditions led to the gamma-hydroxyvinylidene derivative [TpRu=C=CHCH2OH(L)][BPh4] (5), whereas the reaction with HC equivalent to CC(OH)Ph-2 resulted in the formation of the deep purple allenylidene complex [TpRu=C=CCPh2(L)][BPh4] (6). A series of N- and S-donor molecules such as pyrazole, piperidine, 2-pyridinethiol, and 1,3-benzenedithiol add to the C-alpha atom of the allenylidene ligand in 6 to yield the corresponding diphenylvinylcarbene species [TpRu=C(X)CH=CPh2(L)][BPh4] (X = C3H3N2 (7), N(CH2)(4)CH2 (8), SC5H4N (9), SC6H4SH (10)), of which compound 7 was structurally characterized. The reaction of 6 with KOBut in acetone produced the neutral sigma-alkynyl derivative [TpRuCE equivalent to CC(CH2COCH3)Ph-2(L)] (11), resulting from the addition of acetone enolate to the C-gamma of the allenylidene ligand.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

New indenyl nickel(ii) complexes bearing arsine or stibine ligands synthesised by a new methodology exhibit very high catalytic activities for the oligomerisation of styrene.

An atom-economical, more environmentally friendly alternative method of synthesis of the versatile complex [TpRuCl(COD)] (1) (Tp = hydrotris(pyrazol-1-yl)borate; COD = 1,5-cyclooctadiene) has been developed. Instead of starting from [RuHCl(COD)(NH2NMe2)3]+, 1 can be conveniently prepared by reaction of the derivative trans-[RuCl2(COD)(Me2NCH2CH2NHMe)] (2) with KTp in acetone at 55 °C. Compound 2, which has been structurally characterized by X-ray crystallography, results from an unexpected diamine dealkylation process which takes place in the course of the reaction of [{RuCl2(COD)}n] with tmeda (tmeda = Me2NCH2CH2NMe2) in toluene at 80 °C. This process had been overlooked in the literature, as compound 2 had been misidentified as cis-[RuCl2(COD)(tmeda)], and suggests that amine dealkylation might occur more commonly than previously anticipated.

In contrast with [TpRu(κ2P,N-iPr2PNHPy)Cl] (1a, Tp = trispyrazolylborate), [TpRu(κ2P,N-iPr2PSPy)Cl] (1b) reacts with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF4) in fluorobenzene under nitrogen to afford the dinuclear complex [{TpRu(κ2P,N-iPr2PSPy)}2(μ-Cl)][BArF4] (1b′). Through diverse synthetic strategies, a series of neutral acetylides [TpRu(C≡CR)(κ2P,N-iPr2PXHPy)] [X = NH; R = Ph (2a), SiMe3 (2b); X = S; R = Ph (2c), p-C6H4Br (2d), COOMe (2e)], cationic vinylidene complexes [TpRu(=C=CHR)(κ2P,N-iPr2PNHPy)]+ [X = NH; R = Ph (3a), SiMe3 (3b); X = S; R = Ph (3c), p-C6H4Br (3d)] and [TpRu(=C=CH2)(κ2P,N-iPr2PNHPy)]+ (3e), and a cationic η2-alkyne complex [TpRu(η2-HC≡CCOOMe)(κ2P,N-iPr2PSPy)][BArF4] have been efficiently synthesized from 1a and 1b. The methoxy(methyl)carbene complexes [TpRu{=C(OMe)CH3}(κ2P,N-iPr2PXPy)][BPh4] [X = NH (5a), S (5b)] were isolated from the reactions of 1a and 1b with acetylene gas in the presence of NaBArF4 in methanol. The deprotonation of the cationic vinylidenes derived from 1b with KtBuO affords the corresponding neutral acetylide complexes, which undergo facile protonation with CF3SO3H to reproduce the cationic vinylidenes quantitatively.

Weak noncovalent interactions are the basic forces in crystal engineering. Polymorphism in flexible molecules is very common, leading to the development of the crystals of same organic compounds with different medicinal and material properties. Crystallization of 2,2'-{[1,2-phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6-dimethylnicotinonitrile) by evaporation at room temperature from ethyl acetate and hexane and from methanol and ethyl acetate gave stable polymorphs 4a and 4b, respectively, while in acetic acid, it gave metastable polymorph 4c. The polymorphic behavior of the compound has been visualized through single-crystal X-ray and Hirshfeld analysis. These polymorphs are tested for anti-inflammatory activity via the complete Freund's adjuvant-induced rat paw model, and compounds have exhibited moderate activities. Studies of docking in the catalytic site of cyclooxygenase-2 were used to identify potential anti-inflammatory lead compounds. These results suggest that the supramolecular aggregate structure, which is formed in solution, influences the solid state structure and the biological activity obtained upon crystallization.

Flexible dimers 1, 2, and 3 of “pyrazole” derivatives linked with propylene spacer are synthesized and conformational stability in solid, solution, and gaseous states is studied through single crystal X-ray diffraction, 2D NOESY ,and DFT, respectively. The folded conformation of compound 2 is stable in all three states and X-ray diffraction evince that molecule is intramolecularly stacked in reverse face-to-face manner. TEM image of compound 2 exhibits rigid hollow nanospikes with high tendency to form agglomerates.

The tetraphenylborate salts of the cationic vinylidene complexes (Cp*Ru=C=CHR((Pr2PNHPy)-Pr-i)](+) (R = p-C6H4CF3 (1a-BPh4), Ph (1b-BPh4), p-C6H4CH3 (1c-BPh4), p-C6H4Br (1d-BPh4), Bu-t (1e-BPh4), H (1f-BPh4)) have been protonated using an excess of HBF4 center dot OEt2 in CD2Cl2, furnishing the dicationic carbyne complexes [Cp*Ru CCH2R((Pr2PNHPy)-Pr-i)](2+) (R = p-C6H4CF3 (2a), Ph (2b), p-C6H4CH3 (2c), p-C6H4Br (2d), Bu-t (2e), H (21)), which were characterized in solution at low temperature by NMR spectroscopy. The corresponding reaction of the chloride salts 1a-Cl, 1b-Cl, 1c-Cl, and 1d-Cl followed a different pathway, instead affording the novel alkene complexes [Cp*RuCl(kappa(1)(N),eta(2)(C,C)-C5H4N-(NHPPr2CH)-Pr-i=CHR)][BF4] (3a-d). In these species, the entering proton is located at the alpha-carbon atom of the former vinylidene ligand, which also forms a P C bond with the phosphorus atom of the (Pr2PNHPy)-Pr-i ligand. To shed light on the reaction mechanism, DFT calculations have been performed by considering several protonation sites. The computational results suggest metal protonation followed by insertion. The coordination of chloride to ruthenium leads to alkenyl species which can undergo a P C coupling to yield the corresponding alkene complexes. The noncoordinating nature of [BPh4](-) does not allow the stabilization of the unsaturated species coming from the insertion step, thus preventing this alternative pathway.

Weak noncovalent interactions are the basic forces in crystal engineering. Polymorphism in flexible molecules is very common, leading to the development of the crystals of same organic compounds with different medicinal and material properties. Crystallization of 2,2′-{[1,2-phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6-dimethylnicotinonitrile) by evaporation at room temperature from ethyl acetate and hexane and from methanol and ethyl acetate gave stable polymorphs 4a and 4b, respectively, while in acetic acid, it gave metastable polymorph 4c. The polymorphic behavior of the compound has been visualized through single-crystal X-ray and Hirshfeld analysis. These polymorphs are tested for anti-inflammatory activity via the complete Freund's adjuvant-induced rat paw model, and compounds have exhibited moderate activities. Studies of docking in the catalytic site of cyclooxygenase-2 were used to identify potential anti-inflammatory lead compounds. These results suggest that the supramolecular aggregate structure, which is formed in solution, influences the solid state structure and the biological activity obtained upon crystallization.

When studying the activation of 3-arylpropiolates by [TpRu(picolyl-(R)I)Cl]/NaBAr(F)4 (picolyl-(Me)I = 3-methyl-1-(2-picolyl)imidazol-2-ylidene (1); picolyl-(Me)BI = 3-methyl-1-(2-picolyl)benzoimidazol-2-ylidene (2)) a migratory insertion of the NHC into a ruthenium-carbon bond and an unprecedented C-N bond activation of the chelating picolyl-NHC ligand take place to give the new ruthenium metallacycles [TpRu(κ(3)-C,N,N'-═C(Ph)-C(CH2Py)(CO2Me)((Me)I)][BAr(F)4] 3a and 4a and [TpRu(κ(3)-C,N,N'-═C(4-CF3Ph)-C(CH2Py)(CO2Me)((Me)I)][BAr(F)4] 3b and 4b. X-ray crystal structures of 3a and 3b are reported, and a mechanistic pathway is proposed. In contrast, activation of internal alkynones by a mixture of [TpRu(picolyl-(Me)I)Cl] complex (1) and NaBAr(F)4 led to isolation and characterization of the corresponding disubstituted vinylidene complexes. Also, structures of [TpRu(picolyl-(Me)I)(═CC(COR)(Ph)][BAr(F)4] (R = Me (6a); Ph (6b)) are reported.

Two conformational polymorphs of novel 2-[2-(3-cyano-4,6-dimethyl-2-oxo-2H-pyridin-1-yl)-ethoxy]-4,6-dimethyl nicotinonitrile have been developed. The crystal structure of both polymorphs (1a and 1b) seems to be stabilized by weak interactions. A difference was observed in the packing of both polymorphs. Polymorph 1b has a better binding affinity with the cyclooxygenase (COX-2) receptor than the standard (Nimesulide).

The complex [Cp*RuCl((i)Pr2PNHPy)] (1) reacts with 1-alkynes HC≡CR (R = COOMe, C6H4CF3) in dichloromethane furnishing the corresponding vinylidene complexes [Cp*Ru═C═CHR((i)Pr2PNHPy)]Cl (R = COOMe (2a-Cl), C6H4CF3 (2b-Cl)), whereas reaction of 1 with NaBPh4 in MeOH followed by addition of HC≡CR (R = COOMe, C6H4CF3) yields the metastable π-alkyne complexes [Cp*Ru(η(2)-HC≡CR)((i)Pr2PNHPy)][BPh4] (R = COOMe (3a-BPh4), C6H4CF3 (3b-BPh4)). The transformation of 3a-BPh4/3b-BPh4 into their respective vinylidene isomers in dichloromethane is very slow and requires hours to its completion. However, this process is accelerated by addition of LiCl in methanol solution. Reaction of 1 with HC≡CR (R = COOMe, C6H4CF3) in MeOH goes through the intermediacy of the π-alkyne complexes [Cp*Ru(η(2)-HC≡CR)((i)Pr2PNHPy)]Cl (R = COOMe (3a-Cl), C6H4CF3 (3b-Cl)), which rearrange to vinylidenes in minutes, i.e., much faster than their counterparts containing the [BPh4](-) anion. The kinetics of these isomerizations has been studied in solution by NMR. With the help of DFT studies, these observations have been interpreted in terms of chloride- and methanol-assisted hydrogen migrations. Calculations suggest participation of a hydrido-alkynyl intermediate in the process, in which the hydrogen atom can be transferred from the metal to the β-carbon by means of species with weak basic character acting as proton shuttles.