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

Abstract

Abstract

A series of neutral bis- and cationic tris-carbonyl complexes of the types cis-[M(κ ³ P,N,P-PNP)(CO) ₂Y] and [M(κ ³ P,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 PNP ^NH- tBu, the cationic square-pyramidal 16e bis-carbonyl complex [Mn(PNP ^NH- tBu)(CO) ₂] ⁺ was obtained. In contrast, in the case of rhenium, the 18e complex [Re(PNP ^NH- 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(κ ³ P,N,P-PNP)(CO) ₃] ⁺ is in general endergonic, while for [Mn(κ ³ P,N,P-PNP ^NH- tBu)(CO) ₃] ⁺, this process is thermodynamically favored. X-ray structures of representative complexes are provided.

Graphical abstract

Electronic supplementary material

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