Phosphinylidene compounds R(1)R(2)P(O)H are important functionalities in organophosphorus chemistry and display prototropic tautomerism. Quantifying the tautomerization rate is paramount to understanding these compounds' tautomerization behavior, which may impact their reactivities in various reactions. We report a combined theoretical and experimental study of the initial tautomerization rate of a range of phosphinylidene compounds. Initial tautomerization rates are found to decrease in the order H3PO2 > Ph2P(O)H > (PhO)2P(O)H > PhP(O) (OAlk)H > AlkP(O)(OAlk)H ≈ (AlkO)2P(O)H, where "Alk" denotes an alkyl substituent. The combination of computational investigations with experimental validation establishes a quantitative measure for the reactivity of various phosphorus compounds, as well as an accurate predictive tool.

Collision cross-section (CCS) measurements obtained from ion mobility spectrometry-mass spectrometry (IMS-MS) analyses often provide useful information concerning a protein’s size and shape and can be complemented by modeling procedures. However, there have been some concerns about the extent to which certain proteins maintain a native-like conformation during the gas-phase analysis, especially proteins with dynamic or extended regions. Here we have measured the CCSs of a range of biomolecules including non-globular proteins and RNAs of different sequence, size, and stability. Using traveling wave IMS-MS, we show that for the proteins studied, the measured CCS deviates significantly from predicted CCS values based upon currently available structures. The results presented indicate that these proteins collapse to different extents varying on their elongated structures upon transition into the gas-phase. Comparing two RNAs of similar mass but different solution structures, we show that these biomolecules may also be susceptible to gas-phase compaction. Together, the results suggest that caution is needed when predicting structural models based on CCS data for RNAs as well as proteins with non-globular folds. Graphical Abstractᅟ Electronic supplementary materialThe online version of this article (doi:10.1007/s13361-017-1689-9) contains supplementary material, which is available to authorized users.

We herein showcase the ability of NHC‐coordinated dinuclear NiI–NiI complexes to override fundamental reactivity limits of mononuclear (NHC)Ni0 catalysts in cross‐couplings. This is demonstrated with the development of a chemoselective trifluoromethylselenolation of aryl iodides catalyzed by a NiI dimer. A novel SeCF3‐bridged NiI dimer was isolated and shown to selectively react with Ar−I bonds. Our computational and experimental reactivity data suggest dinuclear NiI catalysis to be operative. The corresponding Ni0 species, on the other hand, suffers from preferred reaction with the product, ArSeCF3, over productive cross‐coupling and is hence inactive.

H-Phosphinates react with alkenes and alkynes using catalytic manganese(II) acetate. Under stoichiometric conditions with manganeseA C H T U N G T R E N N U N G (III) acetate or with catalytic manganese(II) acetate + excess manganese(II) oxide various reactions like arylation or cyclization through radical oxidative arylation can take place. Whereas the chemistry of manganese is already well developed for the functionalization of H-phosphonates, the present methodology provides an unprecedented access to functionalized phosphinates in acceptable to good yields.

The room-temperature hydrophosphinylation of unactivated monosubstituted alkenes using phosphinates (ROP(O)H2) and catalytic NiCl2 in the presence of dppe is described. The method is competitive with prior palladium-catalyzed reactions and uses a much cheaper catalyst and simple conditions. The scope of the reaction is quite broad in terms of unactivated terminal olefins, proceeds at room temperature, often avoids chromatographic purification, and allows one-pot conversion to various organophosphorus compounds.