Characterization of a Reactive Rh2 Nitrenoid by Crystalline Matrix Isolation

Here we report the first X-ray crystal structure of a reactive Rh₂ nitrenoid, enabled by N₂ elimination from an organic azide ligand within a single-crystal matrix. The resulting high-resolution data set demonstrates a long Rh–N bond, consistent with a triplet electronic structure. The demonstration of facile access to reactive metal nitrenoids within a crystalline matrix provides a platform for structural characterization of the elusive transient species at the heart of C–H functionalization.

Characterization of a Reactive Rh2 Nitrenoid by Crystalline Matrix Isolation

Here we report the first X-ray crystal structure of a reactive Rh₂ nitrenoid, enabled by N₂ elimination from an organic azide ligand within a single-crystal matrix. The resulting high-resolution data set demonstrates a long Rh–N bond, consistent with a triplet electronic structure. The demonstration of facile access to reactive metal nitrenoids within a crystalline matrix provides a platform for structural characterization of the elusive transient species at the heart of C–H functionalization.

Organic chelate-free and azido-rich metal clusters and coordination polymers from the use of Me3SiN3: a new synthetic route to complexes with beautiful structures and diverse magnetic properties

A new synthetic route to structurally novel and magnetically interesting 3d-metal azido clusters and coordination polymers is presented; the key reagent for the preparation of solely azido-bridged molecule-based species is the organic azide precursor Me3SiN3.

Crystal structures of two PCN pincer iridium complexes and one PCP pincer carbodiphosphorane iridium intermediate: substitution of one phosphine moiety of a carbodiphosphorane by an organic azide

The structure of [Ir{(4-Cl-C6H4N3)C(dppm)-κ3 P,C,N}(dppm-κ2 P,P′)]Cl·1.5CH2Cl2·0.5C7H8 (C57H48Cl2IrN3P4·1.5CH2Cl2·0.5C7H8) (2), dppm = bis(diphenylphosphino)methane {systematic name: [7-(4-chlorophenyl)-1,1,3,3-tetraphenyl-5,6,7-triaza-κN 7-1,3λ4-diphospha-κP 1-hepta-4,6-dien-4-yl][methylenebis(diphenylphosphine)-κ2 P,P′]iridium(I) chloride–dichloromethane–toluene (2/3/1)}, resulting from the reaction of [IrClH{C(dppm)2-κ3 P,C,P)(MeCN)]Cl (1a) with 1-azido-4-chlorobenzene, shows a monocationic five-coordinate IrI complex with a distorted trigonal–bipyramidal geometry. In 2, the iridium centre is coordinated by the neutral triazeneylidenephosphorane (4-Cl-C6H4N3)C(dppm) acting as a PCN pincer ligand, and a chelating dppm unit. The structure of the coordination compound [IrCl(CN)H(C(dppm)2-κ3 P,C,P)]·CH3CN, (C52H45ClIrNP4·CH3CN) (1b) [systematic name: chloridocyanidohydrido(1,1,3,3,5,5,7,7-octaphenyl-1,3λ5,5λ4,7-tetraphospha-κ2 P 1,P 7-hept-3-en-4-yl)iridium(III) acetonitrile monosolvate], prepared from 1a and KCN, reveals an octahedral IrIII central atom with a meridional PCP pincer carbodiphosphorane (CDP) ligand; the chloride ligand is located trans to the central carbon of the CDP functionality while the hydrido and cyanido ligands are situated trans to each other. The chiral coordination compound [Ir(CN)((4-Cl-C6H4N3)CH(CH(P(Ph)2)2)-κ3 P,C,N)(dppm-κ2 P,P′)]·2CH3OH, (C58H48ClIrN4P4·2CH3OH) (3) (systematic name: {4-[3-(4-chlorophenyl)triazenido-κN 3]-1,1,3,3-tetraphenyl-1,3λ5-diphospha-κP 1-but-2-en-4-yl}cyanido[methylenebis(diphenylphosphine)-κ2 P,P′]iridium(III) methanol disolvate), formed via prolonged reaction of 1-azido-4-chlorobenzene with 1b, features a six-coordinate IrIII central atom. The iridium centre is coordinated by the dianionic facial PCN pincer ligand [(4-Cl-C6H4N3)CH(CH(P(Ph2)2)2)], a cyanido ligand trans to the central carbon of the PCN pincer ligand and a chelating dppm unit. Complex 2 exhibits a 2:1 positional disorder of the Cl− anion. The CH2Cl2 and C7H8 solvent molecules show occupational disorder, with the toluene molecule exhibiting additional 1:1 positional disorder with some nearly overlying carbon atoms.

Synthesis and reactivity of actinide phosphorano-stabilized carbene and phosphido complexes

Nuclear power plants have been operated in the United States for over 60 years, generating over 800 terawatt-hours of energy per year. However, there is still no reliable process to recycle the spent nuclear fuel. This dissertation looks at the formation of actinide-ligand multiple bonds, which may give us insights into how to improve the process of separation of actinides from the spent nuclear fuels contaminated with lanthanides. This is because lanthanides cannot participate in multiple bonding and a difference in coordination chemistry between actinides and lanthanides is important in separation methods. This dissertation contains two parts, both of which involve using phosphorus to create new actinide complexes. Chapters 1 and 2 outline the use of phosphorano-stabilized carbene complexes to make short actinide-carbon bonds. In fact, these complexes exhibit the shortest uranium and thorium-carbon bonds reported in the literature. Chapter 3 revolves around investigating the synthesis, characterization, and reactivity of actinide phosphido (monoanionic phosphine) complexes. In this regard, I have synthesized the first trivalent uranium phosphido complex, (C5Me5)2U[P(SiMe3)(2,4,6- Me3C6H2)](THF). The investigation of its reactivity revealed that the complex is capable of 4-electron reduction chemistry. For example, the reaction of (C5Me5)2U[P(SiMe3)(2,4,6-Me3C6H2)](THF) with azidotrimethylsilane, N3SiMe3, produces a U(VI) complex. Three electrons are from the metal center, U(III) to U(VI), and one electron is from reductive coupling of the phosphido ligand. The phosphido chemistry can also be extended to tetravalent uranium and thorium. Chapter 4 outlines the synthesis of thorium phosphido complexes which exhibit an unusual absorption in the visible region which we contributed to a ligand to metal charge transfer. Just by varying the ligand design, we were able to manipulate the HOMO/LUMO gap, which results in an absorption in a different part of the visible region. Appendix A summaries the synthesis of copper(I) complexes with bulky terphenyl ligands. The steric properties of the complex center can be tuned by changing the substituent on the terphenyl. By carefully controlling the steric properties, different coordinating environments around the metal center can be achieved. Finally, Appendix B describes the reactivity of U(IV) phosphido complexes with organic azide and tert-butyl isocyanide.