The oligomerisation of olefins catalysed by transition metal complexes has been extensively studied and is well documented in the literature. However, despite numerous reports of highly efficient catalytic systems, the oligomerisation of polar olefins remains a significant challenge due to competing side reactions that lead to catalyst deactivation. The development of new, well-defined catalytic systems with precisely tuned structural and electronic properties capable of promoting these transformations therefore remains an important goal in modern coordination chemistry. In this work, four nickel(II) and vanadium(IV) complexes bearing ligands based on 2,2 ' bipyridine and its derivatives were synthesised and comprehensively characterised. Two of the complexes represent new compounds not previously reported. The synthesised complexes were evaluated as precatalysts in the oligomerisation of ethylene, norbornene, prop-2-en-1-ol, and 2-chloroprop-2-en-1-ol. All systems exhibited good catalytic performance, leading to the formation of oligomeric products. Structural modifications of the bipyridine ligands enabled an assessment of the influence of steric and electronic effects on catalytic activity as well as on the thermal properties of the resulting oligomers. This study expands the library of structurally welldefined transition metal catalysts and demonstrates the potential of nickel and vanadium bipyridine complexes in the still poorly understood oligomerisation of polar olefins, highlighting promising directions for the further development of this class of catalytic systems.

Two novel rhodium(III) and rhodium(IV) coordination compounds incorporating dipicolinate anion, 1,10-phenanthroline, and 2-phenylpyridine are presented. The crystal structure of the compounds was confirmed by single-crystal X-ray diffraction (XRD). Their physicochemical properties were investigated by potentiometric and conductometric titrations. Stability constants were determined using Hyperquad fitting analyses. In addition, the newly synthesized complexes were used as precatalysts for the polymerization of ethylene and the copolymerization of ethylene with α-olefins and methyl acrylate. Moderate catalytic activities of up to 3.13 × 105 gPE molRh-1 h-1 were achieved. The addition of comonomers reduces the catalytic activity but allows for control over the copolymer's microstructure and properties. These results establish clear structure-activity relationships in the (co)polymerization of olefins process.

Vanadium-based catalysts represent an attractive alternative to group IV systems in olefin polymerization; however, their broader implementation remains limited by a persistent trade-off between catalytic activity, stability, and solubility. These limitations originate from the uncontrolled reduction of the metal center and poorly defined ionic environments during activation with aluminum alkyls. Here, we introduce an ion-pairing precatalyst architecture composed exclusively of organic cations paired with anionic dioxovanadium(V) complexes chelated by polycarboxylate ligands, offering a novel strategy for control at the precatalyst design stage. This ion-pairing strategy enables straightforward, one-step access to well-defined dioxovanadium(V) precatalysts under mild conditions, while simultaneously enhancing their solubility in non-polar media and enabling tunable activation kinetics. As a result, high catalytic activities (up to 4.66 & times; 104 kgPE molV-1 h-1), controlled polymer molecular weights (up to 5.5 & times; 105 g mol-1), narrow dispersities (Mw/Mn approximate to 2), and significant 1-octene incorporation (up to 5.8 mol%) are achieved. Comparative catalytic, spectroscopic, and computational studies suggest that ion pairing may decouple key performance parameters-such as catalyst lifetime and propagation behavior-from the identity of the final active species. These findings demonstrate the potential of ion-pairing precatalyst design as a promising strategy for tuning the performance of vanadium-based olefin polymerization catalysts.

The structure of the catalyst plays a crucial role in determining its catalytic properties in the oligomerization process. Hence, even a slight modification can significantly reduce or increase catalytic activity, as well as completely change the properties of the resulting products. In this study, we report on the synthesis and comprehensive structural characterization of two coordination complexes containing cobalt(II) and oxovanadium(V) ions with 1,10-phenanthroline as the coordinating ligand. Detailed structural insights obtained from single-crystal X-ray diffraction and spectroscopic analyses enabled the use of these complexes as precatalysts in olefin oligomerization and co-oligomerization. Based on the results obtained, the catalytic activity of the complexes used was determined and the physicochemical properties of the resulting oligomeric products were examined in detail. The results of the study provided valuable information on the influence of catalyst structure on catalytic activity and the properties of the oligomers obtained. They also provide insight into the potential use of transition metal ions in the synthesis of olefin oligomerization catalysts.

A universal and flexible model fully describing photoreaction kinetics in dithienylethene (DTE) systems is presented. The proposed method enables reliable determination of photocyclization and photocycloreversion quantum yields at various conditions. Most importantly, it is applicable to a broad range of photoswitch concentrations and accounts for competitive reactions, such as annulation of the closed form. By employing both analytical and numerical solutions to the kinetic equations, we achieve consistent results: the numerical method ensures high accuracy in quantum yield determination, while the analytical method allows for the prediction of DTE photoreaction behavior. The robustness of the model was validated across four distinct DTE photoswitches under varying concentrations, solvents, excitation wavelengths conditions, demonstrating its broad applicability and reliability.

A comprehensive insight into ultrafast dynamics of photo-switchable materials is desired for efficient control of material properties through light excitation. Here, we study a polycrystalline spin crossover thin film as a prototypical example and reveal the sequential photo-switching dynamics, from local molecular rearrangement to global lattice deformation. On the earliest femtosecond timescale, the local molecular structural rearrangement occurs within a constant unit-cell volume through a two-step process, involving initial Fe-ligand bond elongation followed by ligand rotation. The highly-oriented structure of the nanocrystalline films and the experimental geometry enables resolving the full anisotropic lattice structural dynamics in and out of the sample plane separately. While both molecular switching and lattice heating influence lattice volume, they exert varying degrees of impact at disparate time scales following photoexcitation. This study highlights the opportunities provided by Mega-electron-volt electron and X-ray free electron laser to advance the understanding of ultrafast dynamics of photo-switchable materials.

The challenge of ever-increasing greenhouse gas emissions correlates with intensive research into the development of new CO2 sorbents. The research aimed to propose a new generation of porous polymer sorbents that contribute to decarbonization. Among all oligomers and (co)polymers, the 3-buten-2-ol oligomer showed the highest CO2 sorption properties (0.82 mmol g-1). The heat of adsorption of CO2 by oligo(3-buten-2-ol) was equal to 8.51 kJ mol-1. Polyolefins and polar oligomers were synthesized using a new, innovative, and highly active oxovanadium(IV) precatalyst. An easy, one-step method for the synthesis of cis/trans-[VO(acac)2(3-ppy)] provides a unique coordination compound containing two molecules that are reciprocal geometric isomers with a spatial arrangement of acetylacetonate ligands (cis and trans). The complex shows very active catalytic properties in the polymerization reactions of olefins (83,400 kgPE molV-1 h-1) and polar monomers, for example, 2-propen-1-ol (1060 kg molV-1 h-1). A physicochemical study was also conducted to determine the stability constant of the complex formation, log β1210 = 27.82.

As an element, cobalt has a very interesting coordination chemistry and great potential to participate in the formation of a variety of complex compounds, that play a significant role in the synthesis of catalytic systems. In the present work, a new cobalt(II) complex compound with an unusual and rare structure, not previously described in the literature, was synthesized. This complex has two 2,2 '-bipyridyl ligands, a water molecule and, most interestingly, a sulfate(VI) anion in the Co(II) coordination sphere. Its use and catalytic properties were studied in the oligomerization of selected olefins, where it acted as a precatalyst. The achieved catalytic activity values were rather high (<100 g mmol(-1) h(-1) & sdot; bar(-1)), except for the oligomerization process of 2,3-dibromo-2-propen-1-ol using MAO. The obtained oligomers were subjected to structural (FT-IR, SEM, MALDI-TOF-MS) and thermal (TG, DSC) analysis, and the results allowed to characterize their physicochemical properties. The conducted process allowed to determine the effect of the applied activator on the catalytic activity, as well as the structural and thermal properties of the obtained oligomers. In addition, the specific surface area and sorption properties of the oligomerization products were studied, and one of them showed very high CO2 sorption values (<1.6 mmol g(-1)).

This study fills an important gap in the use of group V cation complexes - Nb(V), Ta(V), V(IV) - as versatile catalysts that can be used both in the polymerisation of olefins and in the synthesis of MMA-based materials that exhibit temperature-responsive properties and self-healing capabilities. This area has so far remained insufficiently explored. The work shows clear structure-property relationships of the materials and highlights their potential for green applications. This work introduces newly developed crystalline coordination compounds of Nb(V), Ta(V), and V(IV), synthesized with ligands such as 2-phenylpyridine, 4-phenylpyridine, and dimethylformamide (DMF). These complexes were explored as catalysts in both ethylene polymerization and its copolymerization with 1-octene, in addition to their role in forming temperature-responsive, self-healing materials based on methyl methacrylate (MMA). The catalysts demonstrated notable versatility, effectively enabling the synthesis of traditional polyolefins as well as advanced MMA-derived polymers with adaptive features. Rheological and mechanical testing showed that both the choice of catalyst and the concentration of MMA significantly impacted key material properties, including viscosity, shear stress, hardness, and healing capability. Particularly impressive were the V(IV)-based catalysts, which enabled rapid self-healing. For instance, the V-PE-50MMA composition achieved full structural recovery within just 15 minutes at 35 °C. Microscopic analysis revealed a transformation in material structure-from dense to porous forms-as MMA content increased, which was linked to stronger molecular interactions.

High-pressure structural, spectroscopic and theoretical investigations towards understanding piezochromism of square-planar rhodium( i ) dicarbonyl complexes exhibiting metallophilic interactions in a crystal are reported.

Catalysts based on nickel(II) ions, due to their high reactivity and easiness of ligand modification, are among the most widely used catalytic systems in the world, with applications in a variety of catalytic processes. Herein, research that leads to the synthesis of new nickel(II) complex compounds containing nicotinic and isonicotinic acid ligands is presented. Their catalytic properties have been studied in oligomerization processes of olefins and isocyanides and the obtained oligomers are subjected to qualitative and quantitative analysis to determine their physicochemical properties. The catalytic activity values achieved in the oligomerization of olefins only in a few cases reach above 100 g mmol-1 h-1 bar-1. However, the newly obtained catalytic systems show very high (99%) and moderate (36%) efficiency in the oligomerization of cyclohexyl isocyanide. The conducted studies provide knowledge about the influence of modification of the main ligand and reaction conditions on the values of catalytic activity, process yields, as well as physicochemical properties of the obtained oligomers. Furthermore, it is possible to determine which of the processes carried out using the newly synthesized catalytic systems achieve better results and in which process they should be further used and developed.

Light-induced structural changes in crystals of a luminescent silver(I) complex were evaluated at 100 K via time-resolved laser-pump/X-ray-probe Laue diffraction. Based on theoretical modelling, they are attributed to the S0 → S1 LLCT electronic transition. Low-temperature photoluminescence spectroscopy revealed 2-ns-lived emission followed by phosphorescence. Above 200 K, the system becomes majorly TADF-emissive.

Two square-planar nitrite nickel-(II) photoswitches were designed and synthesized, referred to as Ni-4d and the related oxime Ni-4d'. In the ground-state single crystals of both compounds, the nitro form (Ni-N-(O)2) is the dominant one. For the two systems, it was possible to generate and detect both endo-nitrito and exo-nitrito linkage isomers using 530 nm light-emitting diode (LED) light at 100 K. Over time, the endo-nitrito form takes over, and almost 100% conversion can be achieved, as confirmed by photocrystallographic and infrared (IR) spectroscopic experiments. The stability of this isomer is similar for both systems, which is confirmed by the experimentally determined decay temperature (T d) values. Furthermore, when 660 nm LED light is applied at 90 K, the exo-nitrito form can be generated up to about 25% population with no admixture of the endo-nitrito isomer for Ni-4d. Based on the kinetic parameters, the exo-nitrito isomer is slightly less stable for Ni-4d'. In this work, we report for the first time the experimental evidence of the earlier theoretically predicted nitro-to-endo-nitrito mechanism via the exo-nitrito form for square-planar nickel-(II) nitrite coordination compounds in the solid state.

Isocyanides, due to the divalent carbon atom present in their structure, are among the most reactive groups of compounds in organic chemistry. Unfortunately, although according to the literature they do not have acute toxicity, they have a very unpleasant odor that makes it difficult to collaborate with them. However, despite the properties mentioned, reactions of isocyanides often lead to a variety of functional materials. In this article, we present a modified method for obtaining isocyanide-based polymers that significantly reduce the release of their hazardous vapors into the environment. For the study, a series of nickel(II) metal ion complex compounds containing organic ligands (e.g., 2,2'-bipyridyl, 1,10-phenanthroline, and diglycolate anion) were synthesized and used as catalysts in the oligomerization reaction of cyclohexyl isocyanide. The obtained oligomers were subjected to quantitative and qualitative physicochemical analyses (FT-IR, MALDI-TOF-MS, TGA/DSC, and DSC), which confirmed their structure and thermal properties. Reaction yields ranged from moderate (8-52%) to extremely high (94%) for a single catalyst. The synthesized catalytic systems are new, previously undescribed isocyanide oligomerization catalysts, which successfully led to the synthesis of poly(cyclohexyl isocyanide) and allowed us to obtain materials that can be used to produce many useful polymeric materials.

Two analogous photoswitchable square-planar nitrite coordination compounds of NiII and PdII with the (N,N,O)-donor (1-phenyl-3-(2'-picolylimino)prop-2-en-1-one) ancillary ligand, Ni-1a and Pd-1a, are reported. The samples were thoroughly characterized (photo)crystallographically, spectroscopically, and computationally. Ni-1a crystallizes in the P1 space group with one molecule comprising the asymmetric unit, whereas Pd-1a tends to form polymorphic (Pd-1a and Pd-1a ') and solvatomorphic (with dichloromethane: Pd-1a-DCM and with chloroform: Pd-1a-CHCl 3 ) crystal structures. In the Ni-1a crystal structure, the nitro binding mode is dominant; however, some traces of the endo-nitrito isomer are detected, whereas for the palladium derivative, purely the nitro form is observed for all the crystal forms in the 100-290 K temperature range. Ni-1a, Pd-1a, and Pd-1a-DCM are efficient photoswitches working between 100 and 200 K, with conversions as high as 80-100% upon 470-530 nm light-emitting diode irradiation. At 200 K and above, the decrease in population of the photogenerated product is observed. Under continuous light irradiation, some notable population of the endo-nitrito isomer can be generated and crystallograhically detected also at higher temperatures (up to around 240 K). In the case of Ni-1a, the endo-nitrito form is generated faster, and its decay is slower at 200 K and at higher temperatures than for Pd-1a. It should also be noted that for Pd-1a, only one symmetry-independent molecule is photoswitchable. In turn, the Pd-1a ' and Pd-1a-CHCl 3 systems appeared nonphotoactive. Such behavior can be explained by the energetic factors, nitrite group orientation, and the shape of the reaction cavity. Interestingly, a strong linear correlation between the MM distance in the crystal structures of the examined photoswitches and the population of the endo-nitrito form is noted.