Synthesis and characterization of bis- and tris-carbonyl Mn(I) and Re(I) PNP pincer complexes

Abstract

A series of neutral bis- and cationic tris-carbonyl complexes of the types cis-[M(κ3P,N,P-PNP)(CO)2Y] and [M(κ3P,N,P-PNP)(CO)3]+ was prepared by reacting [M(CO)5Y] (M = Mn, Re; Y = Cl or Br) with PNP pincer ligands derived from the 2,6-diaminopyridine, 2,6-dihydroxypyridine, and 2,6-lutidine scaffolds. With the most bulky ligand PNPNH-tBu, the cationic square-pyramidal 16e bis-carbonyl complex [Mn(PNPNH-tBu)(CO)2]+ was obtained. In contrast, in the case of rhenium, the 18e complex [Re(PNPNH-tBu)(CO)3]+ was formed. The dissociation of CO was studied by means of DFT calculation revealing in agreement with experimental findings that CO release from [M(κ3P,N,P-PNP)(CO)3]+ is in general endergonic, while for [Mn(κ3P,N,P-PNPNH-tBu)(CO)3]+, this process is thermodynamically favored. X-ray structures of representative complexes are provided.Graphical abstract Electronic supplementary materialThe online version of this article (10.1007/s00706-018-2307-7) contains supplementary material, which is available to authorized users.

Temperature and Solvent Effects on H2 Splitting and Hydricity: Ramifications on CO2 Hydrogenation by a Rhenium Pincer Catalyst

“…The structure of 1 was ascertained through NMR and IR spectroscopy (ν CO 2023, 1923, and 1902 cm –1 ) and a single-crystal X-ray diffraction study (Figure ). The structural metrics and vibrational spectra are similar to related pincer Re carbonyl complexes. − …”

Tricarbonylrhenium(I) Complexes with Tridentate Schiff Bases

“…Although the described complexes with L 3 are the first P,N,P Schiff base complexes with a tricarbonylrhenium(I) unit, there are some amine complexes with a similar coordination pattern. They found interest for potential pharmaceutical applications, [30–32] but also because of their catalytic activity for hydrogen transfer and methylation reactions [33–36] . Due to their flexibility, such tridentate, pincer‐type amine ligands may allow isomerization between the facial and meridional coordination modes and can, thus, activate carbonyl ligands as has been demonstrated for bis[(2‐diisopropylphosphino)ethyl]amine and related ligands after the addition of a base [34,35] .…”

Temperature and Solvent Effects on H2 Splitting and Hydricity: Ramifications on CO2 Hydrogenation by a Rhenium Pincer Catalyst

“…The structural metrics and vibrational spectra are similar to related pincer Re carbonyl complexes. [24][25][26][27][28] Scheme 2. Synthesis of tricarbonyl complex ( tBu POCOP)Re(CO)3 (1).…”