Syntheses, Structures, and DFT Calculations of Phosphenium Phosphite Complexes of Molybdenum: Preference of Nonbridging Form to Bridging Form of a Donor Group

Ylide-stabilized phosphenium cations: Impact of the substitution pattern on the coordination chemistry

Although N‐heterocyclic phosphenium (NHP) cations have received considerable research interest due to their application in organocatalysis, including asymmetric synthesis, phosphenium cations with other substitution patterns have hardly been explored. Herein, the preparation of a series of ylide‐substituted cations of type [YPR]⁺ (with Y=Ph₃PC(Ph), R=Ph, Cy or Y) and their structural and coordination properties are reported. Although the diylide‐substituted cation forms spontaneous from the chlorophosphine precursor, the monoylidylphosphenium ions required the addition of a halide‐abstraction reagent. The molecular structures of the cations reflected the different degrees of electron donation from the ylide to the phosphorus center depending on the second substituent. Molecular orbital analysis confirmed the stronger donor properties of the ylide systems compared to NHPs with the mono‐ylide substituted cations featuring a more pronounced electrophilicity. This was mirrored by the reaction of the cations towards gold chloride, in which only the diylide‐substituted cation [Y₂P]⁺ formed the expected LAuCl]⁺ complex, while the monoylide‐substituted compounds reacted to the chlorophosphine ligands by transfer of the chloride from gold to the phosphorus center. These results demonstrate the tunability of ylide‐functionalized phosphorus cations, which should allow for further applications in coordination chemistry in the future.

Mol-ecular structure of fac-[Mo(CO)3(DMSO)3]

The title compound, tri-carbonyl-tris-(dimethyl sulfoxide)-molybdenum, [Mo(C2H6OS)3(CO)3] or fac-[Mo(CO)3(DMSO)3], crystallizes in the triclinic space group P with two mol-ecules in the unit cell. The geometry around the central molybdenum is slightly distorted octa-hedral and the facial isomer is found exclusively. The packing within the crystal is stabilized by three-dimensional non-classical inter-molecular hydrogen-bonding contacts between individual methyl substituents of di-methyl sulfoxide and the oxygen atoms of either another di-methyl sulfoxide or a carbonyl ligand on adjacent complex mol-ecules. The observed bond lengths in the carbonyl ligands and between carbonyl carbon atoms and molybdenum are correlated to the observed FT-IR bands for the carbonyl stretches and compared to respective metrical parameters of related complexes.

N-heterocyclic phosphenium and phosphido nickel complexes supported by a pincer ligand framework

A tridentate ligand framework containing a central N-heterocyclic phosphenium cation (NHP⁺) has been coordinated to nickel. Among the compounds reported is a series of [(PPP)Ni]₂^0/+/2+ dimers in three different redox states.

Phosphinite-Ni(0) mediated formation of a phosphide-Ni(II)-OCOOMe species via uncommon metal-ligand cooperation

Reversible transformations are observed between a phosphide-nickel(II) alkoxide and a phosphinite-nickel(0) species via a P-O bond formation coupled with a 2-e(-) redox change at the nickel center. In the forward reaction, the nickel(0) dinitrogen species (PP(OMe)P)Ni(N2) (2) and {(PP(OMe)P)Ni}2(μ-N2) (3) were formed from the reaction of (PPP)NiCl (1) with a methoxy anion. In the backward reaction, a (PPP)Ni(II) moiety was regenerated from the CO2 reaction of 3 with the concomitant formation of a methyl carbonate ligand in (PPP)Ni(OCOOMe) (7). Thus, unanticipated metal-ligand cooperation involving a phosphide based ligand is reported.