Synthesis and characterization of iron complexes based on bis-phosphinite PONOP and bis-phosphite PONOP pincer ligands
摘要:
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 ((PONOP)-P-R = 2,6-(R2PO)(2)(C5H3N) and R = Tr, tBu) were prepared through complexation of the free ligands with FeCl2 and their solid-state structures were determined. Bis-phosphite PONOP iron complexes (c1E1PONOP)Fe(PMe3)2 and (ca1PONOP)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 ((PONOPFe)-P-OEt(CO)(2) was accessed through exposure of (111`PONOP)FeCl2 to an atmosphere of CO and the CO stretching frequency was observed at 1969 cm -1. Dicarbonyl complexes ((PONOP)-P-iPr)Fe(C0)2 and ((PONOPFe)-P-OEt(CO)(2) were accessed through reduction of the corresponding chloride complexes with sodium amalgam under a CO atmosphere. Carbonyl stretching frequencies for (RIPONOP)Fe(C0)2 and ( E1PONOPFe)(C0)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 pi-acceptor character of these ligands. The electronic properties of the bisphosphinite 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. (c) 2014 Elsevier BY. All rights reserved.
Disclosed are methods and compositions for regulating the melanin content of mammalian melanocytes; regulating pigmentation in mammalian skin, hair, wool or fur; treating or preventing various skin and proliferative disorders; by administration of various compounds, including alcohols, diols and/or triols and their analogues.
Disclosed are methods and compositions for regulating the melanin content of mammalian melanocytes; regulating pigmentation in mammalian skin, hair, wool or fur; treating or preventing various skin and proliferative disorders; by administration of various compounds, including alcohols, diols and/or triols and their analogues.