Treatment of P(X)(X′)Cl with KC₈ gave the crystalline diphosphine [P(X)X′]₂ (1) which dissociated reversibly into the phosphinyl radical ˙P(X)X′ (2), a plausible intermediate in the reaction of 1 with [Cr(CO)₆], [Co(NO)(CO)₃] or P₄, yielding [Cr{P(X)X′}₂(CO)₃] (3), [Co{P(X)X′}(CO)₃] (4), or 1,4-P₄[P(X)X′]₂ (5); the P(X)X′ substituent is pyramidal at P in 5 but planar in 4 [X = N(SiMe₃)₂, X′ = NPrⁱ ₂].

Treatment of PCl[N(SiMe₃)₂](NPrⁱ ₂) (1) with potassium–graphite in thf afforded the colourless, crystalline diphosphine {P[N(SiMe₃)₂](NPrⁱ ₂)}₂ (2) in good yield. Sublimation of 2in vacuo yielded the yellow phosphinyl radical P[N(SiMe₃)₂](NPrⁱ ₂) (3), which upon cooling reverted to 2; the latter in C₆D₆ at 298 K was a mixture of rac and meso diastereoisomers. The yellow, crystalline phosphenium salt {P[N(SiMe₃)₂](NPrⁱ ₂)}[AlCl₄] (4) was obtained from 1 and ½Al₂Cl₆ in CH₂Cl₂. By single-crystal X-ray diffraction (XRD) the structures of the known compound 1 and of 2 and 4 were determined. The structure of the radical 3, formed by the thermal homolytic dissociation of the diphosphine 2, was determined in the gas phase by electron diffraction (GED), utilising data from UMP2/6-31+G* ab initio calculations. The model of the molecule in the GED structure analysis was described by a set of internal coordinates and an initial set of Cartesian coordinates from ab initio calculations, facilitating the structure analysis. The experimental data were found to be consistent with the presence of a single conformer of the radical in the gas phase. The computed standard homolytic dissociation enthalpy of the P–P bond in the corresponding diphosphine 2, corrected for BSSE, 54 kJ mol⁻¹, is substantially reduced compared to the dissociation enthalpy of tetramethyldiphosphine by the reorganisation energies of the fragments that form upon dissociation. The intrinsic energy content of the P–P bond in the diphosphine 2 was estimated to be 286 kJ mol⁻¹, in agreement with the results of previous work on a series of crowded diphosphines.

In this study, a series of fourteen ring-substituted 8-hydroxyquinoline derivatives were prepared. The synthesis procedures are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four mycobacterial strains and against eight fungal strains. Several compounds showed biological activity comparable with or higher than the standards isoniazid or fluconazole. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed.

Treatment of the β-diketimine HL with successively LiBuⁿ and PCl₂Ph gave the first C–centered monodentate β-diketiminate PCl(Ph)L 1; with C₈K 1 underwent reductive dechlorination yielding 2, a novel N–P^III–P^III–CC heterocycle.