Ligand Fragmentation Promoted by a Transient Low-Valent Thulium

Abstract

Dipyrrolide dianions were formed by a transient divalent Tm complex via fragmentation of the (Et8-calix[4]tetrapyrrole)[K(DME)]4 ligand during the reaction with TmI2(DME)3.

Homoleptic Rare‐Earth Carbazolates and the Trends of Their E Redox Potentials: Mixed‐Valent Samarium in 1∞[Sm2(Cbz)5](CbzH) (CbzH = carbazole) and Trivalent Thulium, Neodymium and Gadolinium in [Ln2(Cbz)6]

“…The Tm III −N distances range from 220.8(3) to 228.2(3) pm, with the longest distance being found for the linking carbazolate ligands. These distances are in the region expected for the ionic radius of Tm III ,33 but shorter than in [(Et 2 C(C 4 H 3 N) 2 ] 3 Tm][K(Tol)] 3 (233−239 pm) or [(Et 8 ‐calix[4]tetrapyrrole)Tm][K(DME)] [236−238 pm for the Tm III −N(amide) bonds] 34. The Tm−centroid(3)distance to the π‐coordinated phenyl rings in 2 is 244.2(4) pm, with Tm−π(C) bond lengths of 274.9(4)−288.7(3) ppm.…”

Exploring the solid state and solution structural chemistry of the utility amide potassium hexamethyldisilazide (KHMDS)

“…This η 6 -bonding mode of an arene to a metal is a common structural feature in heavy alkali metal organo- metallic complexes and these K⋯arene(centroid) distances are similar to those found in related benzene-or toluene-solvated potassium amide complexes (range, 2.862-3.108 Å). 23,45,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] The K 2 N 2 units in both the non-centrosymmetric 1 and centrosymmetric 2 resemble those of (KHMDS) 2 reported by Tesh and Hanusa. 33 2and 2.800(2) Å for 2, respectively; see Table 1].…”

Multimetallic Cooperative Activation of N2

“…At first glance, this seems in sharp contrast with the much stronger reducing power of divalent Pr and Nd with respect to divalent Sm (−2.75 and −2.95 V, respectively, versus −1.56 V). However, stronger reducing power also destabilizes divalent complexes, thus shortening their lifetime in favor of oxidative disproportionation and attack on either the ligand or the solvent 17. Conversely, it should be reiterated that authentic divalent and dinitrogen‐free Sm complexes can instead be isolated and characterized as long as exposure to N 2 is prevented 18.…”