Investigation of iron–ammine and amido complexes within a C3-symmetrical phosphinic amido tripodal ligand. Issue 32 (2nd August 2021)

• Record Type: Journal Article
• Authors: Sun, Chen; Oswald, Victoria F.; Hill, Ethan A.; Ziller, Joseph W.; Borovik, A. S.
• Is Part Of: Dalton transactions. Volume 50:Issue 32(2021)
• Page Start: 11197
• Page End: 11205
• Publication Date: 2021-08-02
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt01032h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A symmetry match was achieved between an Fe III synthon with phosphinic amido group and ammonia to achieve an Fe III –NH3 complex with three intramolecular hydrogen bonds. Abstract : The primary and secondary coordination spheres can have large regulatory effects on the properties of metal complexes. To examine their influences on the properties of monomeric Fe complexes, the tripodal ligand containing phosphinic amido groups, N, N ′, N ′′-[nitrilotris(ethane-2, 1-diyl)]tris( P, P -diphenylphosphinic amido) ([poat] 3− ), was used to prepare [Fe II/III poat] −/0 complexes. The Fe II complex was four-coordinate with 4 N-atom donors comprising the primary coordination sphere. The Fe III complex was six-coordinate with two additional ligands coming from coordination of O-atom donors on two of the phosphinic amido groups in [poat] 3− . In the crystalline phase, each complex was part of a cluster containing potassium ions in which K⋯OP interactions served to connect two metal complexes. The [Fe II/III poat] −/0 complexes bound an NH3 molecule to form trigonal bipyramidal structures that also formed three intramolecular hydrogen bonds between the ammine ligand and the OP units of [poat] 3− . The relatively negative one-electron redox potential of −1.21 V vs. [Fe III/II Cp2 ] +/0 is attributed to the phosphinic amido group of the [poat] 3− ligand. Attempts to form the Fe III –amido complex via deprotonation were not conclusive but isolation of [Fe III poat(NHtol)] − using the p -toluidine anion was successful, allowing for the full characterization of this complex.