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The reaction of [BrRe(CO)₄]₂ with 2-(diphenylphosphino)pyridine (PN) and 6-(diphenylphosphino)-2-formylpyridine (PON) was investigated. The reactions were regiospecific and exclusively produced the phosphorus-coordinated products, BrRe(CO)₄(κᵖ-PN) and BrRe(CO)₄(κᴾ-PON). The kinetics for the chelate ring closure (κᴾ→ κᴾᴺ) in BrRe(CO)₄(κᴾ-PN) were confirmed to occur by dissociative CO loss. The reaction of [BrRe(CO)₄]₂ with 2-(diphenylphosphino)pyridine (PN) was modeled computationally by DFT calculations. The preferred reaction pathway for the substitution reaction was determined to occur by direct attack of the pnictogen donor on the dimer and formation of the κᴺ isomer as the kinetic substitution product occurs. The κᴺ kinetic product then rapidly isomerizes to the κᴾ thermodynamic product by way of a reversible ligand dissociation. Treatment of the tetrahedral cluster H₂Ru₃(CO)₃(μ₃-S) (1) with 2-(diphenylphosphino)thioanisole (PS) furnishes the cluster H₂Ru₃(CO)₇(κ²-PS)(μ₃-S) (2). Cluster 2, which exhibits a chelated thiophosphine ligand (κ²-PS), exists as a pair of diastereomers with Keq = 1.55 at 298 K that differ in their disposition of ligands at the Ru(CO)(κ²-PS) center. The PS ligand occupies the equatorial sites (Peq, Seq) in the kinetic isomer and axial and equatorial sites (Pax, Seq) in the thermodynamically favored species. The reversible first-order kinetics to equilibrium have been measured experimentally by NMR spectroscopy and HPLC over the temperature range 293-323 K. The substitution reaction involving 1 and the isomerization of the PS ligand in 2 were investigated by DFT calculations. The computational results support a phosphine-induced expansion of the cluster polyhedron that is triggered by the associative addition of the PS donor to 1. The observed isomerization of the PS ligand in 2 is best explained by a tripodal rotation of the CO and PS groups at the Ru(CO)(κ²-PS) center that is preceded by a regiospecific migration of one of the edge-bridging hydrides to the non-hydride-bridged Ru-Ru bond in 2. The chiral clusters 1,2-Ru₃(μ-H)₂(μ₃-S)(CO)₇(μ-1p1,2p2-POP) (A) and 1,2-Ru₃(μ-H)₂(μ₃-S)(CO)₇(μ-1p2,2p1-POP) (B) were formed were formed from reaction of Ru₃(μ-H)₂(μ₃-S)(CO)₉ with 1-diphenylphosphino-2-[2-(diphenylphosphino)ethoxy]benzene (POP). Chiral clusters A and B were fully characterized by IR and NMR spectroscopy. Additionally, the molecular structure of A was solved by X-ray crystallography. Chiral cluster A was resolved into its enantiomers by preparative HPLC with a chiral column. The enantiomers were characterized by electronic circular dichroism (ECD) spectroscopy and their absolute stereochemical configuration was determined by X-ray crystallography.

<p>Solid-state (SS) luminescent materials are an important class of materials in a myriad of technological applications including light-emitting devices (LEDs) and displays, SS lasers, sensors, imaging agents, etc. Unfortunately, the design of efficient SS emitters is often plagued by sensitivity to environment/matrix (e.g. aggregation-induced quenching, AIQ), competing non-radiative relaxation pathways, and complicated emission mechanisms that are difficult to systematically study and tune. Copper-based systems have been proven to be good candidates for SS emissive materials due to their low-cost, high synthetic variation and well-defined features. Examples of copper-cluster systems, specifically, have been shown to be highly stable, exhibit high photoluminescent quantum yields (ΦPL), and are often relatively insensitive to environmental changes. However, many of these systems are complicated in nature, and often evoke additional relaxation pathways. To mitigate these issues, tetranuclear Cu(I)-pyrazolate complexes have been made which exhibit high ΦPL, matrix insensitivity and proceed through one major radiative emission pathway: cluster-centered based phosphorescence (3CC). The pyrazoles are highly tunable, and by increasing the size of the ligand substituents (H, F, Cl/Me/Br), a rigidochromic effect is observed, causing a significant blue-shift in their photoluminescence, making these viable materials for organic LEDs (OLEDs), especially in the deep-blue region. Furthermore, by increasing the chain length of the ligand substituent (e.g., Me → Et), another material which exhibits stimuli-responsive luminochromism in response to solvent vapor or heat can be achieved. This material exhibits blue ↔ green rigidochromic luminescence in response to stimuli via isomerization of the ethyl units from exo ↔ endo resulting in additional steric effects that effectively prevent rigidification of the Cu4 cluster. This additional phenomenon opens the door for further exploration of Cu(I)-pyrazolate complexes for stimuli-responsive luminescent materials (SRLMs) applications.</p>

<p dir="ltr">Nanoparticles have seen immense development in the past several decades due to their intriguing physicochemical properties. The modern chemist is interested not only in methods of synthesizing nanoparticles with tunable properties but also in the chemistry that nanoparticles can drive. While several methods exist to synthesize nanoparticles, it is often advantageous to put nanoparticles on a variety of conductive substrates for multiple applications (such as energy storage and conversion). Despite enjoying over 200 years of development, the electrodeposition of nanoparticles suffers from a lack of control over nanoparticle size and morphology. Understanding that structure-function studies are imperative to understand the chemistry of nanoparticles, new methods are necessary to electrodeposit a variety of nanoparticles with control over macro-morphology but also microstructure. When a nanodroplet full of a metal salt precursor is incident on the electrode biased sufficiently negative to drive electroplating, nanoparticles form at a shocking rate (on the order of microseconds to milliseconds). We start with the general nuts-and-bolts of the experiment (nanodroplet formation and methods for electrodeposition). The deposition of new nanomaterials often requires one to develop new methods of measurement, and we detail new measurement tools for quantifying nanoparticle porosity and nanopore tortuosity within single nanodroplets. Owing to the small size of the nanodroplets and fast mass transfer, the use of nanodroplets also allows the electrodeposition of high entropy alloy nanoparticles at room temperature. Electrodeposition in aqueous nanodroplets can also be combined with stochastic electrochemistry for a variety of interesting studies. We detail the quantification of the growth kinetics of single nanoparticles in single aqueous nanodroplets. Nanodroplets can also be used as tiny reactors to trap only a few molecules, and the reactivity of those molecules can be electrochemically probed and evaluated with time. Overall, this burgeoning synthetic tool is providing unexpected avenues of tunability of metal nanoparticles on conductive substrates. Moreover, there is little understanding of how ion transfer can affect the fundamental of nanoparticle synthesis with nanodroplet-mediated electrodeposition. This thesis details different experiments performed to study the role of ion transfer during the nucleation and growth of nanoparticles.</p>

In recent years there is an increasing awareness of the importance of chiral phosphorus ligands in transition metal organometallic chemistry because of the utility of such complexes in homogeneous catalytic reactions. This thesis deals with synthetic, spectroscopic and X-ray crystallographic studies on ruthenium complexes of chiral and achiral P-N-P type ligands, known as "diphosphazanes", with emphasis on ruthenium carbonyl clusters. Several ruthenium carbonyl clusters have been synthesized and characterized by elemental analyses, ER and NMR (lH, nC and 3lP) spectroscopic data. In several instances, the molecular structures of the clusters have been confirmed by single crystal X-ray diffraction studies. Chapter 1 provides a brief overview of various types of chiral phosphorus ligands and general synthetic routes to diphosphazanes. A brief review of the transition metal chemistry of diphosphazanes and diphosphazane chalcogenides (published since 1994) is presented A review of the literature on the carbonyl clusters of the group-8 transition metals (Fe, Ru, Os) bearing mono- and diphosphines is also included in this chapter The scope and aim of the present investigation is outlined at the end of this chapter. Chapter 2 provides the results obtained in the present investigation and a detailed discussion of the spectroscopic and crystallographic data. The essential feature of the work is summarized at the end of the chapter. Chapter 3 gives a detailed account of the experimental procedure for the synthesis of the compounds and spectroscopic and analytical measurements. The experimental details of X-ray structure determination are also given in this chapter. To save space, the coordinates of the H-atoms and the calculated and observed structure factor tables are not included. In some cases, reference to CCDC deposition number is included. The references of the literature are compiled at the end of the thesis and are indicated in the text by appropriate numbers appearing as superscripts. The compounds synthesized in the present study are represented by bold Arabic numerals and are listed in Appendix I. The abbreviations employed in the thesis conform to those generally used in Chemical Abstracts.