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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(?3 P,N,P-PNP)(CO)2Y] and [M(?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 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(?3 P,N,P-PNP)(CO)3]+ is in general endergonic, while for [Mn(?3 P,N,P-PNPNH-tBu)(CO)3]+, this process is thermodynamically favored. X-ray structures of representative complexes are provided. Graphical abstract:

SUBMITTER: Glatz M

PROVIDER: S-EPMC6320747 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Synthesis and Characterization of Hydrido Carbonyl Molybdenum and Tungsten PNP Pincer Complexes.

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Project description: Not available

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Project description:A series of bis-phosphinite and bis-phosphite PONOP iron complexes were prepared and characterized by NMR and IR spectroscopy. Bis-phosphinite PONOP iron dichloride complexes (RPONOP)FeCl2 (RPONOP = 2,6-(R2PO)2(C5H3N) and R = iPr, tBu) were prepared through complexation of the free ligands with FeCl2 and their solid-state structures were determined. Bis-phosphite PONOP iron complexes (OEtPONOP)Fe(PMe3)2 and (CatPONOP)Fe(PMe3)2 (Cat = catechol) were synthesized through complexation of the free ligands to Fe(PMe3)4. Carbonyl complexes of both bis-phosphinite and bis-phosphite PONOP were prepared and characterized by IR. The monocarbonyl (iPrPONOP)Fe(CO)Cl2 was accessed through exposure of (iPrPONOP)FeCl2 to an atmosphere of CO and the CO stretching frequency was observed at 1969 cm-1. Dicarbonyl complexes (iPrPONOP)Fe(CO)2 and (OEtPONOP)Fe(CO)2 were accessed through reduction of the corresponding chloride complexes with sodium amalgam under a CO atmosphere. Carbonyl stretching frequencies for (iPrPONOP)Fe(CO)2 and (OEtPONOPFe)(CO)2 were observed at 1824 and 1876 cm-1, and at 1871 and 1927 cm-1 respectively. The bis-phosphite PONOP complexes exhibit a less electron rich metal center than the bis-phosphinite PONOP complexes, as would be expected based on the stronger π-acceptor character of these ligands. The electronic properties of the bis-phosphinite PONOP and bis-phosphite PONOP iron complexes are intermediate between previously reported PNP and PDI iron complexes, with the PONOP ligands exhibiting stronger electron donating ability than PDI ligands, but promoting a less electron rich metal center than found in analogous PNP iron complexes.

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Synthesis and Structural Dynamics of Five-Coordinate Rh(III) and Ir(III) PNP and PONOP Pincer Complexes.

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| S-EPMC6549213 | biostudies-literature

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