Search for: All records

Lanthanide triflates have been used to incorporate Nd^IIIand Sm^IIIions into the 2.2.2‐cryptand ligand (crypt) to explore their reductive chemistry. The Ln(OTf)₃complexes (Ln=Nd, Sm; OTf=SO₃CF₃) react with crypt in THF to form the THF‐soluble complexes [Ln^III(crypt)(OTf)₂][OTf] with two triflates bound to the metal encapsulated in the crypt. Reduction of these Ln^III‐in‐crypt complexes using KC₈in THF forms the neutral Ln^II‐in‐crypt triflate complexes [Ln^II(crypt)(OTf)₂]. DFT calculations on [Nd^II(crypt)]²⁺], the first Nd^IIcryptand complex, assign a 4f⁴electron configuration to this ion.

 

The combination of a boron Lewis acid and a decamethylsamarocene, specifically 9,10-Me 2 -9,10-diboraanthracene with (C 5 Me 5 ) 2 Sm II (THF) 2 , in toluene leads to cooperative reductive capture of N 2 . The product crystallizes as the salt, [(C 5 Me 5 ) 2 Sm III (THF) 2 ][(C 5 Me 5 ) 2 Sm III (η 2 -N 2 B 2 C 14 H 14 )], 1, which formally is comprised of an (NN) 2− moiety sandwiched between a [(C 5 Me 5 ) 2 Sm III ] 1+ metallocene cation and the diboraanthracene ditopic Lewis acid. 

The reduction potentials (reported vs. Fc + /Fc) for a series of Cp′ 3 Ln complexes (Cp′ = C 5 H 4 SiMe 3 , Ln = lanthanide) were determined via electrochemistry in THF with [ n Bu 4 N][BPh 4 ] as the supporting electrolyte. The Ln( iii )/Ln( ii ) reduction potentials for Ln = Eu, Yb, Sm, and Tm (−1.07 to −2.83 V) follow the expected trend for stability of 4f 7 , 4f 14 , 4f 6 , and 4f 13 Ln( ii ) ions, respectively. The reduction potentials for Ln = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, that form 4f n 5d 1 Ln( ii ) ions ( n = 2–14), fall in a narrow range of −2.95 V to −3.14 V. Only cathodic events were observed for La and Ce at −3.36 V and −3.43 V, respectively. The reduction potentials of the Ln( ii ) compounds [K(2.2.2-cryptand)][Cp′ 3 Ln] (Ln = Pr, Sm, Eu) match those of the Cp′ 3 Ln complexes. The reduction potentials of nine (C 5 Me 4 H) 3 Ln complexes were also studied and found to be 0.05–0.24 V more negative than those of the Cp′ 3 Ln compounds.