Synthesis, spectroscopy, structure and photophysical properties of dinaphthylmethylarsine complexes of palladium(II) and platinum(II)

Coordination chemistry applied to anti-doping analysis: Cobalt quantification as its diethyldithiocarbamate complex by liquid chromatography coupled to high resolution tandem mass spectrometry

Cobalt was included on the World Anti-Doping Agency Prohibited List in 2015 due to its effect on stimulus of erythropoiesis via stabilization of hypoxia-inducible factor. Although it has proven benefits for performance enhancement, the unavailability of inductively coupled plasma-mass spectrometry on routine of the accredited laboratories is a factor that reduces its applicability in anti-doping analysis. Therefore, an analytical method for quantification of urinary cobalt as its diethyldithiocarbamate complex by liquid chromatography coupled with high-resolution tandem mass spectrometry was developed and validated. Palladium was proposed as internal standard and rhodium as a complexation control. A microwave-assisted acid digestion of the urine samples was essential, not only to eliminate the matrix effect but mainly to avoid the non-specific bond of cobalt to endogenous molecules. A linear method was obtained over the studied range from a negative urine control to a spiked concentration of 25 ng/mL, with an estimated limit of quantification of 2.5 ng/mL, and an adequate combined standard uncertainty of 11.4%. Considering that all reagents are commercially available, the proposed strategy is feasible to be included on routine sample preparation. Monitoring urinary cobalt concentrations globally opens the perspective to support the anti-doping system to define a suitable threshold value and to understand its potential misuse by athletes seeking for performance improvement.

Dithiocarbamate Complexes of Platinum Group Metals: Structural Aspects and Applications

The incorporation of dithiocarbamate ligands in the preparation of metal complexes is largely prompted by the versatility of this molecule. Fascinating coordination chemistry can be obtained from the study of such metal complexes ranging from their preparation, the solid-state properties, solution behavior as well as their applications as bioactive materials and luminescent compounds, to name a few. In this overview, the dithiocarbamate complexes of platinum-group elements form the focus of the discussion. The structural aspects of these complexes will be discussed based upon the intriguing findings obtained from their solid- (crystallographic) and solution-state (NMR) studies. At the end of this review, the applications of platinum-group metal complexes will be discussed.

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

Important applications of the NiII, PdII and PtII complexes [M(Hdmg)2] (H2dmg = dimethylglyoxime) stem from their metal...metal stacked virtually insoluble aggregates. Given the virtual insolubility of the materials, we postulated that the rare reports on dissolved species in solution do not represent monomolecular species but oligomers. We thus studied the structural and spectral properties of the monomolecular entities of these compounds using density functional theory (DFT) and time-dependent DFT computations in dimethyl sulfoxide (DMSO) as a solvent. The molecular geometries, IR and UV-vis spectra, and frontier orbitals properties were computed using LANL2DZ ecp and def2TZVP as basis sets and M06-2X as the functional. The results are compared with the available experimental and other calculated data. The optimised molecular geometries proved the asymmetric character of the two formed O–H…O bonds which connect the two Hdmg‒ ligands in the completely planar molecules. Calculated UV-vis spectra revealed the presence of three absorptions in the range 180 to 350 nm that are red-shifted along the series Ni–Pd–Pt. They were assigned to essentially ligand-centred π−π* transitions in part with metal(d) to ligand(π*) charge transfer (MLCT) contributions. The notorious d‒p transitions dominating the colour and electronics of the compounds in the solid-state and oligomeric stacks are negligible in our monomolecular models strongly supporting the idea that the previously reported spectroscopic observations or biological effects in solutions are not due to monomolecular complexes but rather to oligomeric dissolved species.

Electron belt-to-σ-hole switch of noncovalently bound iodine(i) atoms in dithiocarbamate metal complexes

The nature of metals in the isostructural series of dithiocarbamate complexes affects the electron belt-to-σ-hole switch of noncovalently bound iodine(i) leading to either semicoordination, or halogen bonding.

Experimental and quantum-chemical studies of 1H, 13C and 15N NMR coordination shifts in Au(III), Pd(II) and Pt(II) chloride complexes with picolines

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with picolines, [Au(PIC)Cl(3)], trans-[Pd(PIC)(2)Cl(2)], trans/cis-[Pt(PIC)(2)Cl(2)] and [Pt(PIC)(4)]Cl(2), were performed. After complexation, the (1)H and (13)C signals were shifted to higher frequency, whereas the (15)N ones to lower (by ca 80-110 ppm), with respect to the free ligands. The (15)N shielding phenomenon was enhanced in the series [Au(PIC)Cl(3)] < trans-[Pd(PIC)(2)Cl(2)] < cis-[Pt(PIC)(2)Cl(2)] < trans-[Pt(PIC)(2)Cl(2)]; it increased following the Pd(II) --> Pt(II) replacement, but decreased upon the trans --> cis-transition. Experimental (1)H, (13)C and (15)N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6-31G**//B3LYP/LanL2DZ + 6-31G*.