Coordination Geometry Research Articles

Deciphering electrocatalytic hydrogen production in water through a bioinspired water-stable copper(II) complex adorned with (N2S2)-donor sites.

Electrocatalytic hydrogen production stands as a pivotal cornerstone in ushering the revolutionary era of the hydrogen economy. With a keen focus on emulating the significance of hydrogenase-like active sites in sustainable H2 generation, a meticulously designed and water-stable copper(II) complex, [Cl-Cu-LN2S2]ClO4, featuring the N,S-type ligand, LN2S2 (2,2'-((butane-2,3-diylbis(sulfanediyl))bis(methylene))dipyridine), has been crafted and assessed for its prowess in electrocatalytic H2 production in water, leveraging acetic acid as a proton source. The molecular catalyst, adopting a square pyramidal coordination geometry, undergoes -Cl substitution by H2O during electrochemical conditions yielding [H2O-Cu-LN2S2]2+ as the true catalyst, showcases outstanding activity in electrochemical proton reduction in acidic water, achieving an impressive rate of 241.75 s-1 for hydrogen generation. Controlled potential electrolysis at -1.2 V vs. Ag/AgCl for 1.6 h reveals a high turnover number of 73.06 with a commendable Faradic efficiency of 94.2%. A comprehensive analysis encompassing electrochemical, spectroscopic, and analytical methods reveals an insignificant degradation of the molecular catalyst. However, the post-CPE electrocatalyst, present in the solution domain, signifies the coveted stability and effective activity under the specified electrochemical conditions. The synergy of electrochemical, spectroscopic, and computational studies endorses the proton-electron coupling mediated catalytic pathways, affirming the viability of sustainable hydrogen production.

Two new coordination polymers of Mn(II) and Co(II) based on a tripyridyl derivative ligand: Synthesis, crystal structures and properties

Two coordination polymers, [Mn(cpt)2)]n (C56H36MnN6O6)(1) and [Co(cpt)2)]n (C56H36CoN6O6) (2), have been synthesized under hydrothermal conditions using 4′-(4-(4-carboxyphenyloxy)phenyl)-4,2′:6′,4′-tripyridine (Hcpt) as the ligand. These ploymers have been structurally characterized. The crystal structure analyses of the two synthesized compounds revealed that both Mn(Ⅱ) and Co(Ⅱ) are six-coordinated, exhibiting a distorted octahedral coordination geometry. Additionally, the compounds share an isostructural two-dimensional framework. The various intermolecular interactions within the crystal structures were further examined using Hirshfeld surface analysis. The in vitro antimicrobial assay of the two compounds demonstrated good antibacterial activity against P.aeruginosa and S. aureus. Furthermore, the fluorescence, magnetic properties, and photocatalytic properties were investigated at room temperature.

Heteronuclear cadmium(II)/cobalt(III) cyanide coordination polymers with 1-methylimidazole and 1-ethylimidazole ligands: synthesis, characterization and catalytic activities

Two new heteronuclear Cd(II)/Co(III) compounds, {[Cd(1-meim)3Cd0.5(1-meim)Co(μ-CN)4(CN)2]}n (1) and {[Cd(1-etim)3Cd0.5(1-etim)2Co(μ-CN)3(CN)3]⋅H2O}n (2) (1-meim: 1-methylimidazole, 1-etim = 1-ethylimidazole), have been synthesized and characterized using elemental analysis, FT-IR and Raman spectroscopy, single-crystal X-ray diffraction techniques. The single crystal X-ray study shows that the compound 1 exhibited a 1D double chain structure and is further linked into 3D supramolecular architectures through CH⋅⋅⋅N and π⋅⋅⋅π interactions. Whereas the compound 2 displayed 2D network which is extended into a 3D supramolecular framework by OH⋅⋅⋅N hydrogen bonds and CH∙∙∙π interactions. In 1 and 2, each Co(III) ion is coordinated by six carbon atoms from cyanide ligands, thus showing an octahedral coordination geometry. Cd1 and Cd2 ions exhibited two different geometries, distorted trigonal bipyramidal and octahedral. Furthermore, phase purities, catalytic and thermal properties were investigated.

Novel Nonsymmetrically benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes: Synthesis, crystal structure, DFTstudies and anticancer activities

Due to the success of Ag-NHCs in biological applications, interest in the synthesis and applications of such compounds is increasing rapidly. Therefore, in this study, preparation and structural definition of silver(I)–NHC complexes were accomplished. These complexes were synthesized by combining a metal source, Ag2O, with imidazolium salts in dichloromethane. A comprehensive characterization process was carried out for both the ligands and their resulting complexes. This involved utilizing various analytical techniques, such as elemental analysis, LC-MS, FTIR and NMR spectroscopy. Further, structure of the 3 h complex was determined by X-ray crystallography. A single-crystal of 3 h shows that coordination geometry is a slightly distorted linear coordination geometry around the silver(I) center. Furthermore, our combined experimental and theoretical approach provided insights into the crystal structure, coordination geometry, and intermolecular interactions stabilizing the complex’s lattice. Density functional theory (DFT) optimization revealed its geometry, while time-dependent DFT (TD-DFT) calculations shed light on its optical properties. Furthemore the newly synthesized ligands and silver(I) complexes were evaluated for their in vitro anticancer activity against three human cancer cell lines including hepatocellular carcinoma (HePG2), lung adenocarcinoma (A549) and breast adenocarcinoma (MCF7). Most of the newly synthesized silver(I) complexes exhibited better activity than the ligands, and the results have been compared with Cisplatin as a reference drug.

Improving the Lithography Sensitivity of Atomically Precise Tin-Oxo Nanoclusters via Heterometal Strategy.

Tin-oxo clusters are increasingly recognized as promising materials for nanolithography technology due to their unique properties, yet their structural impacts on lithography performance remain underexplored. This work explores the structural impacts of heterometal strategies on the performance of tin-oxo clusters in nanolithography, focusing on various metal dopants and their coordination geometries. Specifically, SnOC-1(In), SnOC-1(Al), SnOC-1(Fe), and SnOC-2 were synthesized and characterized. These clusters demonstrate excellent solubility, dispersibility, and stability, facilitating the preparation of high-quality films via spin-coating for lithographic applications. Notably, this work innovatively employs nano-infrared (nano-IR), neutron reflectivity (NR), and X-ray reflectivity (XRR) measurements to confirm film homogeneity. Upon electron beam lithography (EBL), all four materials achieve 50 nm line patterns, with SnOC-1(In) demonstrating the highest lithography sensitivity. This enhanced sensitivity is attributed to indium dopants, which possess superior EUV absorption capabilities and unsaturated coordination environments. Further studies on exposure mechanisms indicated that Sn-C bond cleavage generates butyl free radicals, promoting network formations that induce solubility-switching behaviors for lithography. These findings underscore the efficacy of tailored structural design and modulation of cluster materials through heterometal strategies in enhancing lithography performance, offering valuable insights for future material design and applications.

Advanced Electron Microscopy Characterisation of Aluminium-Oxygen Coordination in Catalyst Supports

Performance of alumina-supported catalyst systems are significantly affected by how the tetrahedral (Al-O4) and octahedral (Al-O6) coordination are mixed and blended with each other. Characterisation of aluminium-oxygen coordination is thus important to understand how catalysts interact with alumina at the microscopic level. Here we report the application of two advanced electron microscopy techniques on aluminium-oxygen coordination. The first technique is electron energy loss spectroscopy (EELS) that can reveal detailed electronic structure profile of aluminium valence band to analyse how aluminium is coordinated by oxygen. The second technique is pair distribution function (PDF) based on electron diffraction (ED), employed to measure aluminium-oxygen bond lengths associated with the coordination geometry.

The role of metal-halide bond in the distortions and asymmetric non-covalent interactions in chiral hybrid perovskites

Abstract Hybrid organic–inorganic perovskites have become interesting materials with a set of applications spanning from optoelectronics to energy conversion technologies. Recently, chiral hybrid perovskites encapsulating chiral organic ligands into the inorganic framework, have garnered significant attention for their promising potential in chiroptoelectronics. The generation of chirality and the corresponding chiroptical response are attributed to a chiral bias that arises from the chiral organic ligands extending into the inorganic framework. This was proposed to affect the inorganic geometry, propagating within the whole hybrid perovskite scaffold. Herein, we aim at clarifying the connection between coordination geometries and their distortions in chiral perovskites, by comparing tin and lead 2D perovskites encapsulating chiral methyl benzyl ammonium, S-(MBA+)2PbI4 and S-(MBA+)2SnI4. Ab-initio molecular dynamics simulations based on density functional theory methods were used and disclosed higher degrees of distortion for the tin-based chiral HOIP model, with prominent alteration of the equatorial coordination and evident bending of the equatorial angle. Such geometrical distortions stabilize non-covalent CH-π interaction observed in the tin-based chiral perovskite in which reduced ligand–ligand distances have been found during the dynamics. The substitution of lead with tin ions within the crystallographic coordinates of S-(MBA+)2PbI4 maintains the same degree of distortion observed in S-(MBA+)2SnI4. This result indicates that the central metal strongly influences the overall packing encapsulating the chiral ligands stabilized by non-covalent interactions. The more the central metal is a hard acid, the more the bond with the soft iodide base is weak or viceversa the more the central metal is a soft acid, the more the bond with a hard base is weak. The weakeness of the metal-halide bond increases the distortion and asymmetric non-covalent interactions within the chiral perovskite scaffold.

Improving the Lithography Sensitivity of Atomically Precise Tin‐Oxo Nanoclusters via Heterometal Strategy

Tin‐oxo clusters are increasingly recognized as promising materials for nanolithography technology due to their unique properties, yet their structural impacts on lithography performance remain underexplored. This work explores the structural impacts of heterometal strategies on the performance of tin‐oxo clusters in nanolithography, focusing on various metal dopants and their coordination geometries. Specifically, SnOC‐1(In), SnOC‐1(Al), SnOC‐1(Fe), and SnOC‐2 were synthesized and characterized. These clusters demonstrate excellent solubility, dispersibility, and stability, facilitating the preparation of high‐quality films via spin‐coating for lithographic applications. Notably, this work innovatively employs nano‐infrared (nano‐IR), neutron reflectivity (NR), and X‐ray reflectivity (XRR) measurements to confirm film homogeneity. Upon electron beam lithography (EBL), all four materials achieve 50 nm line patterns, with SnOC‐1(In) demonstrating the highest lithography sensitivity. This enhanced sensitivity is attributed to indium dopants, which possess superior EUV absorption capabilities and unsaturated coordination environments. Further studies on exposure mechanisms indicated that Sn–C bond cleavage generates butyl free radicals, promoting network formations that induce solubility‐switching behaviors for lithography. These findings underscore the efficacy of tailored structural design and modulation of cluster materials through heterometal strategies in enhancing lithography performance, offering valuable insights for future material design and applications.

Linear Algebra :Eigen Value and Eigen Vectors and Their Applications

Abstract: Linear algebra is the branch of mathematics that concerned with the study of vectors,vector spaces(linear spaces), linear maps(linear transformations') and system of linear equations. Linear space is the central theme in modern mathematics that is widely used in both abstract algebra and functional analysis.Linear algebra also has a concrete representation in analytical geometry and in generalized operator theory. It has extensive applications in natural sciences as well as social sciences. Here in this paper we are presenting a study on linear algebra and associated linear equations, also the eigen values and eigen vectors as a subtopic and few applications of it.the work basically focuses n eigen values and eigen vectors their useful properties including some applications of it.

Symmetry-preserving discretizations in Lagrangian cell-centered hydrodynamics

This paper discusses constructing discretizations in Lagrangian cell-centered hydrodynamics (CCH) that preserve cylindrical symmetry on unequal-angle-zoned grids in two-dimensional Cartesian geometry. We achieve this by modifying the nodal solver (Corot and Mercier, 2018) and updating the total and internal energy equations. The method is a unique solution to the challenging problem of ensuring symmetry in vectors. A criterion is established for determining whether or not this symmetry correction should be applied. We prove that both nodal and zonal quantities maintain a symmetry distribution. Numerical illustrations using unequal-angle initial zoning are presented to demonstrate the efficiency of the scheme.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and Computational Studies of Dimeric and Polymeric Cadmium Complexes

In the current investigation, a new dimeric [Cd(DNBA)2(py)2]2 and a polymeric [Cd(DNBA)2(pyz)2]n cadmium complexes have been prepared by the reaction of 3,5-dinitrobenzoic acid (main ligand), nitrogen donor auxiliary ligands (pyridine and pyrazine), and Cd(II) sulphate in aqueous media. The crystal structures of the synthesized compounds were determined by single-crystal X-ray diffraction analysis. The crystal structures were investigated in terms of the coordination geometry, dihedral angles between various rings, and intermolecular interactions. The solid-state assembly was stabilized by various interatomic contacts, explored by Hirshfeld surface analysis. Void analysis was performed to predict the response of crystals to the applied stress. The optimized molecular geometries of the compounds were achieved utilizing the DFT approach along with the B3LYP functional/6-311G(d,p)/LANL2DZ basic set. MEP maps, molecular orbital theory, and quantum chemical parameters for the synthesized compounds were generated using the same level of theory.

Radiochemistry and Complex Formation of the Cyclen-Derived Chelator DOTI-Me with Mn2+, Cu2+, Zn2+, Ga3+, In3+, Tb3+, and Lu3.

In this work, we describe the complex formation and radiochemistry of the cyclen-based chelator DOTI-Me bearing four methylimidazole arms. Radiolabeling properties were evaluated for 52gMn, 64Cu, 68Ga, 111In, 161Tb, and 177Lu, and DOTI-Me showed distinct differences to the structurally related H4DOTA. While radiochemical conversions (RCCs) for 52gMn and 111In were comparable to those of H4DOTA, DOTI-Me was not suited for 68Ga. Conversely, quantitative RCCs were achieved for 64Cu at ambient temperature, while elevated temperatures were required for complexation with H4DOTA. For 161Tb and 177Lu, good but not quantitative RCCs were obtained with DOTI-Me. With the exemption of 68Ga3+, radiolabeled complexes showed high stability in ligand challenge experiments and in human serum. X-ray analysis of the nonradioactive complexes revealed the formation of 8-coordinate Mn2+ and In3+ DOTI-Me complexes. Cu2+ adopted a unique distorted square-pyramidal 2 + 3 with the neutral DOTI-Me ligand and a Jahn-Teller distorted 4 + 2 coordination geometry for the diprotonated H2DOTI-Me2+ cation, respectively. For Zn2+, the complex with HDOTI-Me+ showed a distorted 4 + 3 pentagonal bipyramidal geometry. Summarizing, the ligand DOTI-Me may be an interesting alternative to H4DOTA for 52gMn, 64Cu, 111In, 161Tb, and 177Lu, covering diagnostic as well as therapeutic radionuclides. Further studies of targeted radiopharmaceuticals based on the DOTI-Me scaffold in combination with the set of radiometals presented herein are thus warranted.

Periodic Single-Metal Site Catalysts: Creating Homogeneous and Ordered Atomic-Precision Structures.

Heterogeneous single-metal-site catalysts (SMSCs), often referred to as single-atom catalysts (SACs), demonstrate promising catalytic activity, selectivity, and stability across a wide spectrum of reactions due to their rationally designed microenvironments encompassing coordination geometry, binding ligands, and electronic configurations. However, the inherent disorderliness of SMSCs at both atomic scale and nanoscale poses challenges in deciphering working principles and establishing the correlations between microenvironments and the catalytic performances of SMSCs. The rearrangement of randomly dispersed single metals into homogeneous and atomic-precisely structured periodic single-metal site catalysts (PSMSCs) not only simplifies the chaos in SMSCs systems but also unveils new opportunities for manipulating catalytic performance and gaining profound insights into reaction mechanisms. Moreover, the synergistic effects of adjacent single metals and the integration effects of periodic single-metal arrangement further broaden the industrial application scope of SMSCs. This perspective offers a comprehensive overview of recent advancements and outlines prospective avenues for research in the design and characterizations of PSMSCs, while also acknowledging the formidable challenges encountered and the promising prospects that lie ahead.

Crystal structure and Hirshfeld surface analysis of {2-[bis(pyridin-2-ylmethyl)amino]ethane-1-thiolato}chloridocadmium(II)

The title compound, [Cd(C14H16N3S)Cl] or [CdLCl] (1), where LH = 2-[bis(pyridin-2-ylmethyl)amino]ethane-1-thiol, was prepared and structurally characterized. The Cd2+ complex crystallizes in P21/c with a distorted trigonal–bipyramidal metal coordination geometry. Supramolecular interactions in 1 include parallel offset face-to-face interactions between inversion-related pyridyl rings and potential hydrogen bonds with chlorine or sulfur as the acceptor. Additional cooperative pyridyl–pyridyl interactions with roughly 45° tilt angles and centroid–centroid distances of less than 5.5 Å likely also contribute to the overall solid-state stability. Hirshfeld surface analysis indicates that H...H (51.2%), Cl...H/H...Cl (13.9%), C...H/H...C (12.3%) and S...H/H...S (11.8%) interactions are dominant in the solid state.

Cobalt(II) Complex Constructed from Pyrazinecarboxamide and Aromatic Carboxylic Acid: Synthesis, Single Crystal XRD Along with Computational Study

A cobalt (II) mononuclear complex was synthesized by two-nitrobenzoic acid and pyrazine-two- carboxamide ligands in the presence of sodium bicarbonate and aqueous solution of cobalt acetate tetrahydrate. The synthesized cobalt(II) complex was characterized by single crystal X-rays diffraction. The coordination geometry of the cobalt complex was octahedral with water molecules occupying the axial sites. A lot of intermolecular interactions were in response to stabilize the supramolecular assembly which were inspected by Hirshfeld surface analysis. Enrichment ratios were calculated to find the pair of atoms having the highest propensity to form crystal packing interactions. Void analysis was conducted to forecast how the crystal would respond to applied stress. Interaction energy calculations were carried out using the B3LYP/6-31G(d,p) electron density model to identify which energy types most significantly contributed to the supramolecular assembly. Moreover, the energy data obtained from DFT calculations showed an average level of stability of the molecule. The moderate HOMO-LUMO energy gap suggested reactivity, while a high electrophilicity index indicates a strong tendency for electron-accepting reactions.

STUDY OF THE DESIGN OF RAILWAY TRACKS OF INDUSTRIAL ENTERPRISES WITHIN THE AREAS OF SMOOTH TRACK EXPANSION

The goal. Railway sidings of industrial enterprises are the shippers and receivers of goods, which determine their main nomenclature for transportation by mainline rail transport. The length of railway sidings of industrial enterprises varies widely, from a few hundred meters to hundreds of kilometers, including the length of the siding of PJSC ArcelorMittal Kryvyi Rih exceeding 700 km. The combination of factors such as the presence of technological transportation on the sidings, the development of the industrial enterprises' transportation system over time, and the master plan of the main production facilities leads to the need to apply railway transport design standards for severe and especially severe conditions. This is mainly expressed in reducing the radii of curved track sections to the minimum possible values. When using reinforced concrete sleepers of the Sh6 type, it is possible to arrange a track gauge of 1539 mm in curved sections. But currently, there is no approved design for smooth track widening sections on reinforced concrete sleepers in front of curves with radii of less than 300 meters. There is also a reasonable need to increase the track gauge to at least 1540 mm in curves of such radii. Together with the limited service life of wooden sleepers when they are laid in areas of smooth track widening compared to reinforced concrete sleepers, this necessitates the development of a track structure on reinforced concrete sleepers within the area of smooth track widening. Methods. Methods of scientific analysis and synthesis of the track development structure, methods of analytical geometry. Results. Based on the analysis of the design of intermediate fasteners of the KB50 type, the design of a section of smooth track widening using reinforced concrete sleepers of types Sh1-1 and Sh6 and rails R50 is proposed. The track widening from 1520 to 1545 mm is achieved by developing the order of laying sleepers of different types and turning the KB50 substrates. In this case, the length of the section of smooth track widening from 1520 mm to 1545 mm is 2800 mm, and the actual deviation is 8.9‰. Practical significance. The use of the considered structure within the areas of smooth track widening, provided that the results of trial operation and testing of the established procedure are positive, will reduce the operating costs associated with the current maintenance of industrial enterprises' tracks, the parameter of which correspond to severe and especially severe design conditions.

CONSTRUCTION OF THE RAILWAY TRACK OF UKRAINE AND PROSPECTS FOR THEIR IMPROVEMENT

The goal. The process of improving the design of the railway track requires a detailed study of the history of the development of its structural elements, methods of combination, interconnections and limits of mutual influence. Modern track designs are the result of many years of hard work by scientists and long operational tests. Some designs were inventions at the time, some were breakthrough technologies, some remained just ideas, and some have existed for more than a century. The study of the history of the development of railway track structures and modern existing structures in operation made it possible to identify a promising direction for improvement and further development, taking into account the existing problems on the mainline transport tracks and industrial enterprise tracks. Reinforced concrete sleepers and intermediate fasteners that allow for track gauge adjustment are the railroad track structure that should be improved in the coming years. Improving railroad track design is a continuous process in the development of rail transport. Recently, new track designs have been introduced on Ukrainian railways. As a rule, the problems of track facilities are first considered and technical tasks are formulated. Then, a public discussion is held in the scientific and practical environment and an appropriate development strategy is born. Such a strategy is reviewed and approved at scientific and technical meetings and specialized commissions. This article aims to identify promising areas for improving the track design and solving the problems of installing and operating a continuous track by analyzing existing designs and world experience of railways. Methods. Methods of scientific analysis and synthesis of track development design, methods of analytical geometry. Results. Based on the analysis of the history of the development of the railroad track structure and modern designs, a promising direction of improvement is proposed. A promising railroad track structure is defined as a reinforced concrete sleeper and fasteners capable of forming an adjustable track gauge of up to 1545 mm. At the same time, it is necessary that the new design has sufficient stability of the jointless track plates. Practical significance. The application of the proposed structure within small radius curves, provided that the results of trial operation and testing of the established procedure are positive, will reduce the operating costs associated with the current maintenance of the tracks, expand the scope of laying of the jointless track and use reinforced concrete sleepers in small radius curves at industrial enterprises.

Tensor Network Space-Time Spectral Collocation Method for Time-Dependent Convection-Diffusion-Reaction Equations

Emerging tensor network techniques for solutions of partial differential equations (PDEs), known for their ability to break the curse of dimensionality, deliver new mathematical methods for ultra-fast numerical solutions of high-dimensional problems. Here, we introduce a Tensor Train (TT) Chebyshev spectral collocation method, in both space and time, for the solution of the time-dependent convection-diffusion-reaction (CDR) equation with inhomogeneous boundary conditions, in Cartesian geometry. Previous methods for numerical solution of time-dependent PDEs often used finite difference for time, and a spectral scheme for the spatial dimensions, which led to a slow linear convergence. Spectral collocation space-time methods show exponential convergence; however, for realistic problems they need to solve large four-dimensional systems. We overcome this difficulty by using a TT approach, as its complexity only grows linearly with the number of dimensions. We show that our TT space-time Chebyshev spectral collocation method converges exponentially, when the solution of the CDR is smooth, and demonstrate that it leads to a very high compression of linear operators from terabytes to kilobytes in TT-format, and a speedup of tens of thousands of times when compared to a full-grid space-time spectral method. These advantages allow us to obtain the solutions at much higher resolutions.

Synthesis, structure and optically limiting NLO properties of a distorted cubane-like cluster (µ-Cl)(µ 3-WSe4)(CuPPh3)3

Abstract Treatment of [Et4N]2[WSe4] with three equivalents of CuCl and PPh3 (Ph = phenyl) in a mixed solvent of 25 mL of CH2Cl2 and 5 mL of DMF afforded a distorted cubane-like cluster [(µ-Cl)(µ 3-WSe4)(CuPPh3)3] (1), which has been structurally characterized by single-crystal X-ray diffraction. The coordination geometry of the tungsten center and two copper atoms is tetrahedral, whereas that of the other copper atom is triangular. Regarding the NLO properties, a large optical limiting effect with a threshold of 0.91 J cm−2 was observed with laser pulses of 7 ns at 532 nm.

Chemically Separable Co(II) Spin-State Isomers.

The phenomenon of spin crossover involves coordination complexes with switchable spin states. This spin state change is accompanied by significant geometric changes such that low and high spin forms of a complex are distinct isomers that exist in equilibrium with one another. Typically, spin-state isomers interconvert rapidly and are similar enough in polarity to prevent their independent separation and isolation. We report here the first example, to our knowledge, of cobalt(II) spin-state isomers that can be physically separated. The reaction of Mo2(dpa)4 (dpa = 2,2'-dipyridylamide) with CoBr2 produces a mixture of two heterometallic compounds with a linear, metal-metal-bonded Mo[Formula: see text]Mo-Co chain. The complexes, SC-[BrMo2(dpa)4Co]Br (SC-2) and HS-[BrMo2(dpa)4CoBr] (HS-2), have identical compositions (Mo2Co(dpa)4Br2) but different ground spin states and coordination geometries of the Co(II) ion. In the solid state, SC-2 undergoes incomplete spin crossover from an S = 1/2 state to an S = 3/2 state, and HS-2 has a high spin, S = 3/2, ground state, as confirmed by SQUID magnetometry and EPR spectroscopy. Crystallographic analyses of SC-2 and HS-2 show that SC-2 has an elongated Co-Br distance relative to HS-2 and is best described as the salt [BrMo2(dpa)4Co]Br. This limits SC-2's solubility in nonpolar solvents and allows for the physical separation of the two isomers. Solution studies of SC-2 and HS-2 indicate that SC-2 and HS-2 interconvert slowly relative to the NMR time scale. Additional solution-state EPR and UV-vis absorption measurements demonstrate that the choice of solvent polarity determines the predominant isomer present in solution.