Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing η²-Pyrazolato Ligands:  Development of a New Class of Precursors for Doping Semiconductors

Abstract

Treatment of yttrium metal with bis(pentafluorophenyl)mercury (1.5 equiv), 3,5-di-tert-butylpyrazole (3 equiv), and pyridine (2 equiv) in toluene at ambient temperature for 120 h afforded tris(3,5-di-tert-butylpyrazolato)bis(pyridine)yttrium(III) (33%). In an analogous procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl = methyl or tert-butyl), bis(pentafluorophenyl)mercury, and a neutral nitrogen donor (4-tert-butylpyridine, pyridine, n-butylimidazole, or 3,5-di-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium(III) (88%), tris(3,5-di-tert-butylpyrazolato)bis(n-butylimidazole)erbium(III) (48%), tris(3,5-dimethylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (50%), and tris(3,5-di-tert-butylpyrazolato)(3,5-di-tert-butylpyrazole)erbium(III) (59%), respectively. Treatment of tris(cyclopentadienyl)lutetium(III) or tris(cyclopentadienyl)erbium(III) with 3,5-di-tert-butylpyrazole (3 equiv) and 4-tert-butylpyridine (2 equiv) in toluene at ambient temperature for 24 h afforded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)lutetium(III) (83%) and tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (41%), respectively. The X-ray crystal structures of all new complexes were determined. The X-ray structure analyses revealed seven- and eight-coordinate lanthanide complexes with all-nitrogen coordination spheres and eta(2)-pyrazolato ligands. Molecular orbital calculations were carried out on dichloro(pyrazolato)diammineyttrium(III). The calculations demonstrate that eta(2)-bonding of the pyrazolato ligand is favored over the eta(1)-bonding mode and give insight into the bonding between yttrium and the pyrazolato ligands. Complexes bearing 3,5-di-tert-butylpyrazolato ligands can be obtained in a high state of purity and sublime without decomposition (150 degrees C, 0.1 mmHg). Application of these complexes as source compounds for chemical vapor deposition processes is discussed.

Lanthanide Complexes Coordinated by N‐Substituted (R)‐1,1′‐Binaphthyl‐2,2′‐diamido Ligands in the Catalysis of Enantioselective Intramolecular Hydroamination

“…[32] In the lutetium analogue (1 d (7), 2.263(6), 2.296(7), 2.256(6) ) [33] and pyrazolato [{(Me 3 C) 2 C 3 N 2 } 3 Lu(NC 5 CMe 3 )] (2.294(4), 2.299(4), 2.300(4), 2.371(4) ) complexes. [34] The lanthanide atom in both 1 c and 1 d has a formal coordination number of four, which is very low for these elements. The presence in complexes 1 c, d of the short contacts between the metal atoms and the carbon atoms in the ipso and ortho positions to the amido groups (1 c: 2.770 (4) [35] and [{2,6-(C 6 H 5 ) 2 C 6 H 3 O} 3 Lu] (2.787(8)-3.087(12) ), [36] probably reflects a h Table 1.…”

Erste Pyridylbenzimidazolate der Lanthanide: Synthese, Kristallstruktur und thermischer Abbau von NH4[Ln(N3C12H8)4] mit Ln = Nd, Yb

“…Die Reaktion war ebenfalls bis auf den Metallüberschuß vollständig und ergab neben einigen Hg-Tropfen ein vollständig kristallines, zartgelbes Produkt, welches stark luft-und feuchtigkeitsempfindlich ist. So zeigen sich bei N-Koordinationszahlen von acht bei den Pyrazolaten beispielsweise pseudotrigonal-bipyramidale Koordinationen [2], da die koordinierenden N-Atome direkt benachbart sind. 1).…”

“…Sieht man von Ausnahmen ab [1,2], so führen Synthesen von Koordinationsverbindungen der Lanthanide in Lösung meist nicht zu Verbindungen mit reiner Stickstoff-Koordination. Aufgrund vorwiegend sauerstoffhaltiger Solventien findet sich ungeachtet des chemischen Interesses an den Produkten in der Regel auch Sauerstoff in der Koordinationssphäre der Lanthanide [3].…”

Can Bismuth Replace Mercury in Redox Transmetallation/Protolysis Syntheses from Free Lanthanoid Metals?

“…In a further examination of the prospects of utilizing the commercially available BiPh 3 in RTP reactions, Ce and Ho metals were treated with BiPh 3 and t Bu 2 pzH under ultrasonication, but no reaction was achieved. Besides thf coligands,, Ln/Ph 2 pz complexes have been isolated with dme, [22b, 23] 3,5‐diphenylpyrazole, Ph 3 PO or no coligands, and Ln/ t Bu 2 pz complexes have been isolated with py, Ph 3 PO and no coligands . [La(ttfpz) 3 (thf) 3 ] previously been isolated as a hemitoluene solvate and 21 is known, whilst no trivalent lanthanoid complexes of PhMepz have been reported, though divalent [Yb(PhMepz) 2 (dme) 2 ] is known …”