Synthesis and Characterization of 4‐, 5‐, and 6‐Coordinate Tris(1‐ethyl‐4‐isopropylimidazolyl‐κN)phosphine Cobalt(II) Complexes

Abstract

The synthesis and characterization of [Co(T1Et4iPrIP)X2] {T1Et4iPrIP = tris(1‐ethyl‐4‐isopropylimidazolyl)phosphine; X = OTf– (1), Cl– (2), Br– (3)} and [Co(T1Et4iPrIP)(CH3CN)3](OTf)2 (4) were investigated. In compounds 1 and 4, T1Et4iPrIP binds in a tridentate fashion, whereas 2 and 3 feature bidentate ligation. Compound 1 additionally coordinates two triflate ligands to complete a distorted square pyramidal geometry. Compound 4 also binds three acetonitrile ligands to afford a distorted octahedral geometry. Compounds 2 and 3 exhibit a distorted tetrahedral geometry for which the ligands comprise two imidazole nitrogen atoms and two halides. Bidentate coordination by using a tris(imidazolyl)phosphine ligand is unprecedented. Compounds 2 and 3 can be derived from 1 by the addition of either Cl– or Br– salts, respectively, whereas 4 can be generated by dissolving 1 in acetonitrile. DFT studies indicate that the HOMO–LUMO gaps of all compounds are comparable; however, steric factors stabilize the formation of 2 and 3 over 1 in the presence of halide ligands.

Stepwise N‐Methylation of Ruthenium and Cobalt 5,15‐Diazaporphyrins: Post‐Functionalization of Porphyrinoid Catalysts

“…In the cobalt complexes 5 a ⋅ OTf, 5 b ⋅ OTf, 6 a ⋅ (OTf) 2 , and 6 b ⋅ (OTf) 2 , weak coordination of the triflate(s) to the cobalt center was observed (Figures 1b–1c). The Co−O bond lengths in cobalt complexes 5 a ⋅ OTf, 5 b ⋅ OTf, 6 a ⋅ (OTf) 2 , and 6 b ⋅ (OTf) 2 range from 2.25 to 2.39 Å, which are similar to those in other weakly coordinated Co−OTf complexes (2.022(3)–2.396(4) Å) [35–48] …”

“…(2.022(3)-2.396(4) Å). [35][36][37][38][39][40][41][42][43][44][45][46][47][48] Coordination behavior of the counterions. The coordination behavior of the triflate counterion on the metal center was evaluated in solution.…”

Synthesis, structure and properties of tris(1-ethyl-4-isopropyl-imidazolyl-κN)phosphine copper(II)

“…Steric bulk ( i Pr or t Bu) [18,31,33] was introduced at the 4-position of the imidazole ring to prevent the formation of [Cu(ligand) 2 ] n+ [31]. Tris(imidazol-2-yl)phosphine supported metal complexes using Zn [28,30,32,[34][35][36][37][38][39], Co [38][39][40][41][42][43], Cd [38], Hg [38], Ni [39], Sc [44], and Fe [26,27,29,[45][46][47] have been reported in the literature. Despite their biological relevance, however, only five Cu(II) complexes possessing these ligands have been reported [18,33,38].…”