Structural Dichotomy in Six-Coordinate d⁰ Complexes: Trigonal Prismatic (ᵗBu₃SiC≡C)₆Ta⁻ and Octahedral (ᵗBu₃SiC≡C)₆M²⁻ (M = Zr, Hf)

Description:

Article discussing structural dichotomy in six-coordinate d⁰ complexes and trigonal prismatic (ᵗBu₃SiC≡C)₆Ta⁻ and octahedral (ᵗBu₃SiC≡C)₆M²⁻ (M ≡ Zr, Hf).

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Creation Date: September 19, 1998
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UNT College of Arts and Sciences
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UNT Scholarly Works
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Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, D.C.]
Date(s):
  • Creation: September 19, 1998
Description:

Article discussing structural dichotomy in six-coordinate d⁰ complexes and trigonal prismatic (ᵗBu₃SiC≡C)₆Ta⁻ and octahedral (ᵗBu₃SiC≡C)₆M²⁻ (M ≡ Zr, Hf).

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Department: Chemistry
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Reprinted with permission from the Journal of the American Chemical Society. Copyright 1998 American Chemical Society.

Note:

Abstract: Utilization of the bulky acetylide, ᵗBu₃SiC≡C⁻, enabled the synthesis of several early metal polyacetylides. Addition of NaC≡CH to ᵗBu₃SiBr in dimethyl sulfoxide afforded ᵗBu₃SiC≡CH, which was deprotonated to yield ᵗBu₃SiC≡CLi. Treatment of ZrCl₄, HfCl₄, adn TaCl₅ with varying amounts of ᵗBu₃SiC≡CLi gave {(THF)₂Li(ᵗBu₃SiC≡C)₂}Zr(C≡CSiᵗBu₃)₃(THF) (1; THF = tetrahydrofuran), {Et₂O)Li(ᵗBu₃SiC≡C)₂}Hf(C≡CSiᵗBu₃)₃(OEt₂) (2), {Li(ᵗBu₃SiC≡C)₃}₂M(M = Zr, 6; Hf, 7), and {Li(ᵗBu₃SiC≡C)₃}Ta(C≡CSiᵗBu₃)₃ (3). Metathesis of 3 with KOTf generated KTa(C≡CSiᵗBu₃)₆ (4) and cation sequestration of 4 with crypt 2.2.2 provided [K(crypt 2.2.2)][Ta(C≡CSiᵗBu₃)₆](5). Single-crystal X-ray structural studies determined the structures (core symmetry) of 1 (Oh), 2, (Oh), 3 (D₃), 5 (D₃), 6 (Oh), and 7 (Oh). The D₃h to D₃ twist in 3 and 5 has a steric origin, and the counterion position appears inconsequential. Origins of the structural preferences illustrated by the dichotomous twisted trigonal prismatic and octahedral cores of the d⁰ hexaacetylides 5 and 6 were probed through density functional (ADF) and effective core potential (GAMESS) calculations. The structural difference results from a lessening electronic preference for the trigonal prism-primarily a greater HOMO/LUMO gap-upon moving from Ta to Zr, minor steric factors, and increased interligand repulsions in the dianion (VSEPR).

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13 p.

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Subject(s):
Keyword(s): metal polyacetylides | d⁰ hexaacetylides | structural dichotomy
Source: Journal of the American Chemical Society, 1998, Washington DC: American Chemical Society, pp. 10067-10079
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UNT College of Arts and Sciences
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UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja9802899
  • ARK: ark:/67531/metadc107797
Resource Type: Article
Format: Text
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Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 120
Issue: 39
Page Start: 10067
Page End: 10079
Peer Reviewed: Yes