An isomer-free hexacoordinate bis(acetylacetone)-silicon(IV) complex

Taba, Kalulu M.; Dahlhoff, W. V.

doi:10.1016/0022-328x(85)87058-3

Cited by 8 publications

(15 citation statements)

References 9 publications

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“…For example, the first ionic acetylacetonate (acac) silicon complex, e.g., Si(acac) 3 Cl·HCl, was reported in 1903 . However, only a few neutral hypercoordinate bis(β-diketonate) silicon(IV) complexes, where β-diketonate = acetylacetonate, have been reported to date. − The first complexes of (acac) 2 SiClMe, (acac) 2 SiClPh, and (acac) 2 SiMe 2 were reported to be highly unstable, and the isolation yield of (acac) 2 SiMe 2 was extremely low, only about 10% . The preparation of (acac) 2 SiCl 2 provided a very poor yield as well .…”

Section: Introductionmentioning

confidence: 99%

“…Structural characterization work of these bis(acetylacetonate) silicon(IV) compounds largely depended on indirect techniques, such as elemental analysis, UV, IR, and 29 Si NMR spectroscopic methods. ,− For example, the structures of (acac) 2 SiClMe and (acac) 2 SiClPh were proposed as hexacoordinate complexes and that of (acac) 2 SiMe 2 as tetracoordinate by means of infrared spectroscopy . Contrary to (acac) 2 SiMe 2 , the (acac) 2 SiPh 2 was reported as a trans -hexacoordinate complex on the basis of NMR data . It was concluded that the phenyl group is more favorable for hexacoordination than the methyl group despite the controversy .…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Neutralcis-Hexacoordinate Bis(β-diketonate) Silicon(IV) Complexes

Baum

Rheingold

2004

Inorg. Chem.

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Three new neutral cis-hexacoordinate bis(beta-diketonato) silicon(IV) complexes, (thd)2SiX2, where X = Me (1), tBuO (2), and tAmO (3), and thd = 2,2,6,6-tetramethyl-3,5-heptanedionato, were synthesized in high yield. Single crystal X-ray crystallographic analysis revealed that 1 was monomeric with cis-hexacoordinate octahedral geometry on the silicon and oxygen atoms. Crystal data: empirical formula C24H46O4Si, crystal system monoclinic; space group P2(1)/n; unit cell dimensions a = 10.4195(5) A, b = 19.7297(10) A, c = 13.6496(7) A; beta = 102.6590(10) degrees; Z = 4. Variable temperature NMR confirmed (thd)2SiX2 maintained cis-geometry in solution by observing two distinct methyl proton resonances (of thd) at room temperature or low temperatures. These compounds show potential for use as low temperature silicon oxide CVD precursors for transition metal silicate high kappa gate dielectrics.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Neutralcis-Hexacoordinate Bis(β-diketonate) Silicon(IV) Complexes

Baum

Rheingold

2004

Inorg. Chem.

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“…However, perturbation by deuterium would not lead to an isotope shift as large as 350 ppb, since the difference between zero-point energies of axial and equatorial CH groups is so slight that K in eq 2 must be exceedingly small. If instead the phenyls are trans, as in Ph 2 Si(acac) 2 , 31 then this configuration would be an example of the asymmetric chelate that we seek. It is most unfortunate that a single crystal of Ph 2 GeL 2 could not be obtained.…”

Section: Discussionmentioning

confidence: 99%

“…HL and 1 / 2 equiv of RSiCl 3 were dissolved in CDCl 3 , and the solution was heated to 80 °C for 5 days. The procedure for Ph 2 SiL 2 was adapted from the preparation of Ph 2 Si(acac) 2 . HL and 1 equiv of imidazole were dissolved in C 6 D 6 , 1 / 2 equiv of Ph 2 SiCl 2 was added, and the mixture was filtered to remove imidazole·HCl.…”

Section: Methodsmentioning

confidence: 99%

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Symmetry of Metal Chelates

Perrin

Kim

2000

Inorg. Chem.

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Is a metal chelate symmetric, with the motion of the metal described by a single-well potential, or is it asymmetric, in a double-well potential? For hydrogen, this is the familiar question of the symmetry of a hydrogen bond. The molecular symmetry of MLn complexes (M = Li, Na, K, Al, Pd, Rh, Si, Sn, Ge, Sb, etc.; L is the anion of 3-hydroxy-2-phenylpropenal) in solution is now probed with the method of isotopic perturbation of equilibrium. A statistical mixture of 3-hydroxy-2-phenylpropenal-d0, -1-d, and -1,3-d2 was synthesized and converted to various metal complexes. Some complexes show two aldehydic signals, which means that their ligands are monodentate. For LiL, NaL, and KL, the 13C NMR isotope shifts, delta CH(D) - delta CH(H), for the aldehydic CH groups are small and negative, consistent with L- being a resonance hybrid. They are small and positive for AlL3, PdL2, Rh(CO)2L, SiX3L, SiL3+X-, (CF3)3GeL, SbCl4L, (EtO)4TaL, and (EtO)4NbL. The positive isotope shifts are unusual, but since they are small and temperature independent, they are intrinsic and indicate that these metal chelates are symmetric, as expected. Large positive isotope shifts, up to 400 ppb, are observed for Ph3GeL, Me3GeL, Ph2GeL2, Bu3SnL, and Ph4SbL. However, it is likely that these are monodentate complexes undergoing rapid metal migration, as judged from the X-ray crystal structures of Ph3SnL and Ph4SbL. NMR experiments indicate an intermolecular mechanism for exchange, which may be a biomolecular double metal transfer. It is remarkable that the isotope shifts in these five complexes demonstrate that they are asymmetric structures, even though they appear from other NMR evidence to be symmetric chelates.

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Hypervalent Silicon Compounds

Kost

Kalikhman

2009

Patai's Chemistry of Functional Groups

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Introduction Pentacoordinate Anionic Silicon Compounds Pentacoordinate Neutral Silicon Complexes Cationic Pentacoordinate Complexes Hexacoordinate Ionic Silicon Compounds Neutral Hexacoordinate Silicon Complexes Complexes with Higher Coordination Numbers Addendum

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An isomer-free hexacoordinate bis(acetylacetone)-silicon(IV) complex

Cited by 8 publications

References 9 publications

Synthesis and Characterization of Neutralcis-Hexacoordinate Bis(β-diketonate) Silicon(IV) Complexes

Synthesis and Characterization of Neutralcis-Hexacoordinate Bis(β-diketonate) Silicon(IV) Complexes

Symmetry of Metal Chelates

Hypervalent Silicon Compounds

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