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The in situ electrophilic fluorination of phosphanes with commercially available bench-stable N-fluorobenzenesulfonimide (NFSI), followed by subsequent methylation of the [N(PhSO2)2]− anion with MeOTf yields a family of electrophilic fluorophosphonium cations as triflate salts. Most of these fluorophosphonium triflate salts are remarkably Lewis acidic and form isolable adducts in stoichiometric reactions with suitable donors such as N,N-dimethylformamide (DMF). Furthermore, their catalytic capabilities were tested in the transformation of formamides into N-sulfonyl formamidines in the reaction with Na[N(SO2Ph)2] and the proposed mechanism is validated by DFT calculations.

Structural investigations of three actinide(IV) 4-phosphoryl 1H-pyrazol-5-olate complexes (An = Th(IV), U(IV), Np(IV)) and their cerium(IV) analogue display the same metal coordination in the solid state. The mononuclear complexes show the metal centre in a square antiprismatic coordination geometry composed by the two O-donor atoms of four deprotonated ligands. Detailed solid state analysis of the U(IV) complex shows that dependent on the solvent used altered arrangements are observable, resulting in a change in the coordination polyhedron of the U(IV) metal centre to bi-capped trigonal prismatic. Further, single crystal analyses of the La(III) and Ce(III) complexes show that the ligand can also act as a neutral ligand by protonation of the pyrazolyl moiety. All complexes were comprehensively characterized by NMR, IR and Raman spectroscopy. A single resonance in each of the 31P NMR spectra for the La(III), Ce(III), Ce(IV), Th(IV) and Np(IV) complex indicates the formation of highly symmetric complex species in solution. Extended X-ray absorption fine structure (EXAFS) investigations provide evidence for the same local structure of the U(IV) and Np(IV) complex in toluene solution, confirming the observations made in the solid state.

Triphosphanes R′2PP(R)PR′2 (9a,c: R = Py; 9b R = BTz), 1,3-diphenyl-2-pyridyl-triphospholane 9d and pentaphospholanes (RP)5 (13: R = Py; 18: R = BTz) are obtained in high yield of up to 98% from the reaction of dipyrazolylphosphanes RPpyr2 (5: R = Py; 6: R = BTz; pyr = 1,3-dimethylpyrazolyl) and the respective secondary phosphane (R′2PH, R′ = Cy (9a,b), tBu (9c); PhPH(CH2)2PHPh (9d)). The formation of derivatives 9a–d proceeds via a condensation reaction while the formation of 13 and 18 can only be explained by a selective scrambling reaction. We realized that the reaction outcome is strongly solvent dependent as outlined by the controlled scrambling reaction pathway towards pentaphospholane 13. In our further investigations to apply these compounds as ligands we first confined ourselves to the coordination chemistry of triphosphane 9a with respect to coinage metal salts and discussed the observation of different syn- and anti-isomeric metal complexes based on NMR and X-ray analyses as well as quantum chemical calculations. Methylation reactions of 9a with MeOTf yield triphosphan-1-ium Cy2MePP(Py)PCy2+ (10+) and triphosphane-1,3-diium Cy2MePP(Py)PMeCy22+ (112+) cations as triflate salts. Salt 11[OTf]2 reacts with pentaphospholane 13 in an unprecedented chain growth reaction to give the tetraphosphane-1,4-diium triflate salt Cy2MePP(Py)P(Py)PMeCy22+ (19[OTf]2) via a P–P/P–P bond metathesis reaction. The latter salt is unstable in solution and rearranges via a rare [1,2]-migration of the Cy2MeP-group followed by the elimination of the triphosph-2-en-1-ium cation [Cy2MePPPMeCy2]+ (20+) to yield a novel 1,4,2-diazaphospholium salt (21[OTf]).

The impact of the strongly electron donating carbodiphosphorane moiety in the series of tri(phosphonio)methanide dications as triflate salts [(Ph3P)2CP(X)Ph2][OTf]2 (X = H, Me, CN, NCS, OH, Cl, OTf, F) deriving from [(Ph3P)2CPPh2][OTf] (19[OTf]) is presented. The influence of the introduced substituents X on the electronic structures of these dications is investigated by means of detailed NBO analysis, NMR spectroscopy and X-ray analysis.

The reaction of imidazoliumyl-substituted P((III)) cations of type [L((R,Me))PCl2](+) (3a,b(+); L(R,Me) = imidazolium-2-yl a: R = Me; b: R = iPr) with (Me3Si)2S leads to the formation of tetra-cationic, eight-membered phosphorus sulfur heterocycles [L((R,Me))PS]4(4+) (9a,b(4+)), which can be explained by the tetramerization of the intermediately formed cationic phosphorus monosulfide [L((R,Me))PS](+) (8a,b(+)). The P4S4 ring adopts a crown conformation as observed for cyclo-S8. The Lewis base DMAP (4-dimethylaminopyridine) initiates a deoligomerization- and dismutation reaction of 9a,b(4+) to give P((I)) centered cation [L((R,Me))2P](+) (12a,b(+)) and phosphorus disulfide [(DMAP)2PS2](+) (14(+)).