NH₃and (NH₂)¹⁻as ligands in yttrium metallocene chemistry

Abstract

(C5Me5)2Y(C3H5)(THF) reacts with ammonia in THF to form the first crystallographically-characterized rare-earth metal complex with a terminal (NH2)1- ligand, (C5Me5)2Y(NH2)(THF), 1. Complex 1 can be protonated with [HNEt3][BPh4] to form [(C5Me5)2Y(NH3)(THF)][BPh4], 2. Both complexes were characterized by X-ray crystallography which allowed a comparison of the Y-NH2 bond length, 2.226(2) Å, with an Y-NH3 bond length, 2.476(2) Å, in analogous coordination environments. Reactions of 2 with NaN3 and acetone produced the known complexes [(C5Me5)2YN3]x and [(C5Me5)2Y(OCMe2)2][BPh4], respectively, suggesting that the ammonia moiety in 2 functions as a displaceable solvate like THF.

Lanthanide Amide Complexes Supported by the Bis‐tris(pyrazolyl)borate Ligand Environment

“…The Y−N( μ ‐NH 2 ) distances of 2.351(6) Å and 2.388(7) Å in 4‐Y are longer than the Ln−N(amido) bonds in 2‐Y or 3‐Y , consistent with the dimeric structure. The Y−N( μ ‐NH 2 ) bonds in 4‐Y are also longer than those in the monomeric complex [Y(Cp*) 2 (NH 2 )(THF)] (2.226(2) Å), [8e] but consistent with the clusters [{Y 2 (( η 5 ‐C 9 H 6 SiMe 2 ) 2 N)( μ ‐NH 2 )(THF) 2 } 2 ( μ 3 ‐Cl) 2 ( μ ‐Cl) 2 ] (2.295(4)‐2.390(5) Å), [8b] [{Y(C 5 Me 4 SiMe 3 )} 4 ( μ ‐NH 2 ) 6 ( μ 3 ‐NH 2 )( μ 4 ‐H)] (2.331(11)‐2.380(10) Å, 2.568(11)‐2.603(11) Å), [8d] and the dimeric Dy(III) complex [{Dy(Cp) 2 ( μ ‐NH 2 )} 2 ] (2.353(4), 2.368(4) Å) [8c] …”

“…This broadening of a single pyrazolyl resonance was previously also observed in the dimeric complex [{Y(Tp) 2 ( μ ‐OH)} 2 ] and the monomeric complex [Y(Tp) 2 (OAr)] (OAr=2,6‐ t Bu 2 ‐4‐Me‐phenoxide) and attributed to steric constraints resulting in partially restricted Tp motion [15] . The resonance observed at δ =2.16 ppm in the 1 H NMR spectrum of 4‐Y , is assigned as the amido proton by comparison to the complex [Y(Cp*) 2 (NH 2 )(THF)] ( δ =2.21 ppm) [8e] . However, it is of note that the resonances for amido protons in NH 2 ‐bridged Y(III) clusters do not follow any diagnostic trends [8b,d] .…”

“…The synthesis of molecular parent lanthanide amides, with the exception of cyclopentadienyl ligand‐supported amides, [8] has remained rare. While the homoleptic amide salts [{Ln(NH 2 ) x } n ] ( x =2, 3) and ‘ate’ salts [{KLn(NH 2 ) 3 } n ] have been known since the 1960s, [9] only a handful of crystallographically‐characterised primary lanthanide amides supported by ancillary ligands are known, for example the dimeric amides [{Ln(Cp) 2 ( μ ‐NH 2 )} 2 ] (Cp=C 5 H 5 ) [8c] and the first ever crystallographically‐characterised monomeric terminal amide [Y(Cp*) 2 (NH 2 )(THF)] (Cp*=C 5 Me 5 ) [8e] …”

Pyrrolyl-Bridged Metallocene Complexes: From Synthesis, Electronic Structure, to Single-Molecule Magnetism

“…57 In fact, these types of allyl compounds undergo insertion reactions with substrates such as Me 3 SiCHN 2 and COS. 58 The allyl moiety can also be readily and cleanly displaced through an acidic proton, liberating propene gas as a byproduct. This synthetic strategy was effectively employed to generate both molecules composed of various ancillary ligands such as Cp* 2 Y(NH 2 )(THF), 59 [Cp′ 2 Zr(μ-S)(μ 3 -S)DyCp* 2 ] 2 , 60 [Cp* 2 Dy(μ-CNC 6 H 4 O-κC:κO)] 2 61 and dinuclear complexes in the presence of H 2 . 62,63 The bis(pentamethylcyclopentadienyl) RE pyrrolyl complexes [Cp* 2 RE(μ-pyr)] 2 [RE = Y (1), La (2), and Dy (3)] were synthesized through the protonolysis reaction between the corresponding RE allyl complexes and H-pyrrole.…”

“…The allyl moiety can also be readily and cleanly displaced through an acidic proton, liberating propene gas as a byproduct. This synthetic strategy was effectively employed to generate both molecules composed of various ancillary ligands such as Cp* 2 Y­(NH 2 )­(THF), [Cp′ 2 Zr­(μ-S)­(μ 3 -S)­DyCp* 2 ] 2 , [Cp* 2 Dy­(μ-CNC 6 H 4 O-κC:κO)] 2 and dinuclear complexes in the presence of H 2 . , …”