Coordination Chemistry and QTAIM Analysis of Homoleptic Dithiocarbamate Complexes, M(S₂CNⁱPr₂)₄ (M = Ti, Zr, Hf, Th, U, Np)

Abstract

In a systematic approach to comparing the molecular structure and bonding in homoleptic transition-metal and actinide complexes, a series of dithiocarbamates, M(SCNPr) (M = Ti, Zr, Hf, Th, U, Np), have been synthesized. These complexes have been characterized through spectroscopic and X-ray crystallographic analysis, and their bonding has been examined using density functional theory calculations. Computational results indicate that the covalent character associated with the M-S bonds shows the trend of Hf < Zr < Th < Ti < U ≈ Np.

Computational analysis of M–O covalency in M(OC6H5)4(M = Ti, Zr, Hf, Ce, Th, U)

“…For example, a recent study of dithiocarbamate complexes, M(S2CN i Pr2)4, featuring a similar metal series to our targets -Ti, Zr, Hf, Th, Np -reports covalency trends based on δ(M,S) which agree with those found here. 9 Note, however, that covalency trends for a given bond can be dependent on ligand environment. For example, in the case of M-Cl bonds, X-ray absorption spectroscopy indicates that U exhibits ca.…”

“…The delocalization index is often used as the defining QTAIM metric for covalency, since it provides a measure of the number of electron pairs exchanged in an interaction. 4,9,[43][44][45] It is derived from the expectation value of the exchange operator over two atomic basins and is irrespective of the nature of the interaction. Please do not adjust margins Please do not adjust margins delocalization elsewhere in the molecule.…”

“…[1][2][3][4] The mixing of metal and ligand orbitals is proportional to the spatial overlap between them and inversely proportional to the difference in their energies. [5][6][7][8][9] Strong mixings can therefore arise when there are small energy differences between metal and ligand orbitals (e.g. in compounds of the so-called minor actinides, americium and curium) but only orbital overlap results in electronic charge accumulation in the internuclear region.…”

Using Redox-Active Ligands to Generate Actinide Ligand Radical Species

“…This study goes well with other studies that highlight a comparison of the bonding in tetravalent transition metals with early actinides, which analyze both structural and computational data. 14,42 Our previous work with the same ligand system where M(DOPO q ) 3 (M = Am, Cf, and Bk) were generated shows that early actinides prefer tetravalency, while the later actinides show trivalency. Additionally, the earlier actinides are reducing enough to generate and stabilize ligand radicals.…”

Synthesis and reactivity of low-valent uranium and neptunium complexes

“…The chemistry of low-valent actinide has been of great interest due to the isolation of actinides in rare divalent oxidation states, [111][112][113][114][115][116] small molecule activation, 133,134 and examining metal-ligand bonding. 149,[163][164][165][166][167][168][169] This is especially true of U(III), a powerful reducing agent. 170 However, when one traverses the actinide series, there is a propensity to favor the trivalent oxidation state, much like their lanthanide counterparts.…”