Unusual selective reactivity of the rare-earth metal complexes bearing a ligand with multiple functionalities

Rare-Earth Metal Complexes Supported by 1,3-Functionalized Indolyl-Based Ligands for Efficient Hydrosilylation of Alkenes

“…In complex 5 , the bond lengths of Dy(1)–C(1) and Dy(1)–C(2) are 2.788(6) and 2.709(6) Å, respectively, which is similar to that found in complex trans -[{μ-η 2 :η 1 :η 1 -3-( t BuNCH­(CH 2 SiMe 3 ))-Ind)­RE­(thf)­(CH 2 SiMe 3 )] 2 (Dy(1)–C(2) = 2.745(3), Dy(1)–C(3) = 2.775(3) Å), and the bond length of RE(1)–C(1)#1 is 2.527(6) Å, indicating that the 2-indolyl carbanion and C3 of the indolyl ring bonded with two rare-earth metals in a novel μ-η 2 :η 1 mode which is different from that η 2 bonded with central metal ions through C3 and C8 carbons of the indolyl ring in [{μ-η 2 :η 1 :η 1 -3-( t BuNCH­(CH 2 SiMe 3 ))­Ind)­RE­(thf)-(CH 2 SiMe 3 )] 2 . The bond length of Dy(1)–C(1) is longer than that found in the dinuclear complex {[μ-η 3 :η 1 :η 1 -3-(2,4,6-Me 3 C 6 H 2 NCH 2 )­C 8 H 4 N]­Dy­(CH 2 SiMe 3 )­(THF)} 2 [Dy–C sp 2 = 2.659(3) Å] after deduction of the influence of the coordination number, indicating the steric hindrance of the substituents on the indolyl ring . The C(14)–N(2) bond length (1.485(5) Å) in 6 was longer than that of CN double bond (1.29 Å), but is compared with the length of the typical C–N single bond (1.47 Å).The distance is similar to that found in complex {[μ-η 2 :η 1 :η 1 -3-(2- t BuC 6 H 4 NCH)­(CH 2 SiMe 3 )­C 8 H 5 N]­Dy­(CH 2 SiMe 3 )­(THF)} 2 (C–N = 1.489(9) Å), indicating that the imino group (−CHN) inserts into the Dy–CH 2 SiMe 3 bond to become an amido group [−(CH 2 SiMe 3 )­CH–N­( t BuC 6 H 4 )].…”

“…Although various pincer organometallic complexes have been synthesized and exhibited good homogeneous catalytic properties, pincer ligands based on electron-rich indolyl backbone and their metal complexes for the catalytic hydrosilylation of olefins have rarely been reported . Our previous works indicated that different functionalized indolyl ligands displayed different reactivities with RE­(CH 2 SiMe 3 ) 3 (THF) 2 including CN insertion into RE-C σ bond producing rare-earth complexes with novel hapticities, the sp 2 C–H activation affording 2-indolyl carbanion σ-bonded to rare-earth metal center, 1,1-alkyl and 1,1-H­(D) migratory insertion through the transformation of the sp 2 carbanion to the electrophilic carbene, and some of the resulting complexes exhibited a high activity and selectivity in catalyzing the isoprene polymerization. , As our continuous interest in development of rare-earth metal complexes bearing functionalized indolyl-based ligands as efficient catalysts for small molecule transformation, herein, we will report the rare-earth metal complexes bearing the [NCN]/[OCN] pincer ligands based on the indolyl frame incorporating two different chelation side arms and their catalytic application toward the hydrosilylation of olefins.…”

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

“…Single crystal X-ray analysis shows that the structures of complexes 1b−1e are similar; all of them are deformed 1 show that the bond lengths of RE− C(1), RE−C(26), and RE−C (30) in complexes 1a−1e increase with the increase in the radii of central metal ions, which is consistent with the lanthanide contraction. 35 The bond lengths of the RE−C(1) can be compared with those in the previously reported rare-earth monoalkyl complexes 21 and the NCO pincer rare-earth dialkyl complexes 34 The bond lengths of the RE−C(1), RE−N(3), RE−C(26), and RE−C (30) (THF) x (x = 1, RE = Y; x = 0, RE = Yb, Er, Dy), 34 which may be due to the combined steric hindrance of the coordinated tetrahydrofuran and different ionic radii.…”

“…11−18 Chiral pincer metal complexes are used in asymmetric catalytic reactions. 19 Rare-earth metal pincer complexes have been demonstrated to exhibit excellent performance in the activation of small molecules like H 2 , CO, and silanes, 20,21 the catalytic conversion of unsaturated organic substrates, 22−24 the and regioselective and stereoselective catalytic polymerization of conjugated dienes. 25 Although the fundamental skeletons of pincer ligands are diverse, most of them are either fixed or nonfixed structures with central symmetry.…”

“…Transition metal complexes with pincer ligands have been successfully utilized to catalyze a wide variety of transformations. − Chiral pincer metal complexes are used in asymmetric catalytic reactions . Rare-earth metal pincer complexes have been demonstrated to exhibit excellent performance in the activation of small molecules like H 2 , CO, and silanes, , the catalytic conversion of unsaturated organic substrates, − the and regioselective and stereoselective catalytic polymerization of conjugated dienes …”