Novel insertion of dimethylsilanone into an Yb–N bond and molecular structure of the insertion product [{Yb(η2-C3N2HMe2-3,5)(µ-η1:η2-OSiMe2C3N2HMe2-3,5)(η-C5H4Me)}2]
Abstract:When 5)2(C5H4Me)l (C3N2H2Me2-3,5 = 3,5-dimethylpyrazole) is recrystallized by slow diffusion of hexane into a thf solution which contains a small amount of dimethylsilicone grease, it is converted into to the unexpected complex [{Yb(rl2-C3N2HMe2-3,5)(~-rll:y2-OSiMe2C3N2HMe2-3,5)(r-CgHqMe)}2l indicating a novel Me2Si0 insertion react ion.
“…Figure B) originates from trace silicone [(H 3 C) 2 SiO] n concentrations in the THF reaction mixture with the surplus oxygen removed at the sodium metal mirror surface. This is consistent with the previous literature assumptions. − 2 Total-reflection X-ray fluorescence spectra of the reaction solution containing 9,9-dimethylsilafluorene (- - -), of THF dried over Na (···), and of THF dried over molecular sieves () (the circle insert shows Si peaks).…”
supporting
confidence: 91%
“…An extensive literature search reveals that the inclusion of one , and up to seven (H 3 C) 2 SiO subunits into organometallic compounds under reductive conditions has been repeatedly reported, yielding, for example, an ytterbium pyrazole compound, the hexameric lithium dimethylnaphthylsilanolate, or an indium complex containing a K[OSi(CH 3 ) 2 ] 7 solvated cation − the silicon content has been assumed to result from the easily ether-soluble dimethylsiloxane grease used to seal the glass fittings. …”
Sodium metal mirror reduction of biphenylene in aprotic THF solution containing [2.2.1]cryptand yields as a structurally characterized product the 9,9dimethylsilafluorene radical anion salt containing a (H 3 C) 2 Si expanded cyclobutadiene ring. In addition, the Si content can be detected by total reflection X-ray (TXRF) analysis. When the use of any silicon grease was avoided for all glass fittings, the solvent-separated biphenylene radical anion contact pair crystallized from an aprotic diglyme solution.
“…Figure B) originates from trace silicone [(H 3 C) 2 SiO] n concentrations in the THF reaction mixture with the surplus oxygen removed at the sodium metal mirror surface. This is consistent with the previous literature assumptions. − 2 Total-reflection X-ray fluorescence spectra of the reaction solution containing 9,9-dimethylsilafluorene (- - -), of THF dried over Na (···), and of THF dried over molecular sieves () (the circle insert shows Si peaks).…”
supporting
confidence: 91%
“…An extensive literature search reveals that the inclusion of one , and up to seven (H 3 C) 2 SiO subunits into organometallic compounds under reductive conditions has been repeatedly reported, yielding, for example, an ytterbium pyrazole compound, the hexameric lithium dimethylnaphthylsilanolate, or an indium complex containing a K[OSi(CH 3 ) 2 ] 7 solvated cation − the silicon content has been assumed to result from the easily ether-soluble dimethylsiloxane grease used to seal the glass fittings. …”
Sodium metal mirror reduction of biphenylene in aprotic THF solution containing [2.2.1]cryptand yields as a structurally characterized product the 9,9dimethylsilafluorene radical anion salt containing a (H 3 C) 2 Si expanded cyclobutadiene ring. In addition, the Si content can be detected by total reflection X-ray (TXRF) analysis. When the use of any silicon grease was avoided for all glass fittings, the solvent-separated biphenylene radical anion contact pair crystallized from an aprotic diglyme solution.
“…For example, the latter feature is responsible for isonitrile insertion into Ln−N bonds and it explains the key steps in the catalytic hydroamination/cyclization of aminoolefins . Very recently, the proximity of silicon- and nitrogen-containing moieties even allowed the unprecedented insertion reaction of a dimethylsilicone into a Ln−N(amide) bond . Readily available and routinely employed compounds Ln[N(SiMe 3 ) 2 ] 3 were chosen to evaluate the reaction of 1 .…”
The synthesis and X-ray crystal structures of
Y[N(SiHMe2)2]3(carbene)
x
(carbene = 1,3-dimethylimidazolin-2-ylidene, x = 1, 2) are described.
The donor capability of the strongly
nucleophilic carbene ligand is expressed in both the displacement of
two THF ligands by
one carbene ligand in precursor compound
Y[N(SiHMe2)2]3(THF)2
and by the addition of a
second carbene ligand to yield the preferred (3 + 2) trigonal
bipyramidal coordination
geometry. In particular, the structural data reveal that the
carbene ligands affect the
coordination mode of the bis(dimethylsilyl)amide
counterligands by forcing them to form
close β-Si−H(silylamide)−yttrium agostic contacts. According
to Pearson's terminology such
carbene ligands have to be classified as hard donor ligands.
“…However, the preparations of 4 and 8 demonstrate the utility of this methodology. Interestingly, a previous study reported that only two cyclopentadienyl ligands were replaced upon treatment of tris(cyclopentadienyl)lanthanide(III) complexes with pyrazoles. , …”
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.
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