Disilyl complexes of zirconium, hafnium, and tantalum. Their synthesis, characterization, and exchanges with silyl anions

He Qiu, Hu Cai, Jaime B. Woods, Zhongzhi Wu, Tianniu Chen, Xianghua Yu, Zi Ling Xue

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Cyclopentadienyl-free disilyl amide complexes [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2 as [Li(THF) 4] + salts), K(18-crown-6) 3/2{(Me 2N) 3M[(Me 3Si) 2Si-(CH 2) 2-Si(SiMe 3) 2]} (M = Zr, 3; Hf, 4), (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5), (Me 2N) 3Ta(SiBu tPh 2) 2 (6), and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) have been prepared. The structures of 1-4 have been determined by X-ray single-crystal diffraction. The two -Si(SiMe 3) 3 - ligands in (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5) were replaced sequentially by the -SiBu tPh 2 - anions to give (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) and (Me 2N) 3Ta(SiBu tPh 2) 2 (6). The silyl ligand in (Me 2N) 3Zr-Si(SiMe 3) 3 was found to undergo a reversible exchange with SiBu tPh 2 -, probably through a disilyl intermediate, to reach the following equilibrium: (Me 2N) 3ZrSi(SiMe 3) 3 + SiBu tPh 2 - (Me 2N) 3ZrSiBu tPh 2 + Si(SiMe 3) 3-with ΔH° = 4.6(0.5) kcal/mol and ΔS° = -7(2) eu. A similar exchange involving [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2) was observed: (Me 2N) 3ZrSiBu tPh 2 + SiBu tPh 2 - ⇌ 1 with the estimated free energy of activation ΔG‡ = 14.1(0.5) kcal/mol. (Me 2N) 3Ta(SiBu tPh 2) 2 (6) and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) are thermally unstable. Kinetic studies give the activation parameters of the decomposition of 7: ΔH‡ = 22.8(1.3) kcal/mol and ΔS‡ = -3(5) eu.

Original languageEnglish (US)
Pages (from-to)4190-4197
Number of pages8
JournalOrganometallics
Volume24
Issue number17
DOIs
StatePublished - Aug 15 2005

Fingerprint

Hafnium
Tantalum
hafnium
tantalum
Anions
Ion exchange
Chemical activation
activation
anions
Ligands
ligands
synthesis
Amides
amides
Free energy
Salts
Diffraction
free energy
Single crystals
methylidyne

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

Disilyl complexes of zirconium, hafnium, and tantalum. Their synthesis, characterization, and exchanges with silyl anions. / Qiu, He; Cai, Hu; Woods, Jaime B.; Wu, Zhongzhi; Chen, Tianniu; Yu, Xianghua; Xue, Zi Ling.

In: Organometallics, Vol. 24, No. 17, 15.08.2005, p. 4190-4197.

Research output: Contribution to journalArticle

Qiu, He ; Cai, Hu ; Woods, Jaime B. ; Wu, Zhongzhi ; Chen, Tianniu ; Yu, Xianghua ; Xue, Zi Ling. / Disilyl complexes of zirconium, hafnium, and tantalum. Their synthesis, characterization, and exchanges with silyl anions. In: Organometallics. 2005 ; Vol. 24, No. 17. pp. 4190-4197.
@article{e1e87823def54d28a281c72b4f1e28eb,
title = "Disilyl complexes of zirconium, hafnium, and tantalum. Their synthesis, characterization, and exchanges with silyl anions",
abstract = "Cyclopentadienyl-free disilyl amide complexes [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2 as [Li(THF) 4] + salts), K(18-crown-6) 3/2{(Me 2N) 3M[(Me 3Si) 2Si-(CH 2) 2-Si(SiMe 3) 2]} (M = Zr, 3; Hf, 4), (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5), (Me 2N) 3Ta(SiBu tPh 2) 2 (6), and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) have been prepared. The structures of 1-4 have been determined by X-ray single-crystal diffraction. The two -Si(SiMe 3) 3 - ligands in (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5) were replaced sequentially by the -SiBu tPh 2 - anions to give (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) and (Me 2N) 3Ta(SiBu tPh 2) 2 (6). The silyl ligand in (Me 2N) 3Zr-Si(SiMe 3) 3 was found to undergo a reversible exchange with SiBu tPh 2 -, probably through a disilyl intermediate, to reach the following equilibrium: (Me 2N) 3ZrSi(SiMe 3) 3 + SiBu tPh 2 - (Me 2N) 3ZrSiBu tPh 2 + Si(SiMe 3) 3-with ΔH° = 4.6(0.5) kcal/mol and ΔS° = -7(2) eu. A similar exchange involving [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2) was observed: (Me 2N) 3ZrSiBu tPh 2 + SiBu tPh 2 - ⇌ 1 with the estimated free energy of activation ΔG‡ = 14.1(0.5) kcal/mol. (Me 2N) 3Ta(SiBu tPh 2) 2 (6) and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) are thermally unstable. Kinetic studies give the activation parameters of the decomposition of 7: ΔH‡ = 22.8(1.3) kcal/mol and ΔS‡ = -3(5) eu.",
author = "He Qiu and Hu Cai and Woods, {Jaime B.} and Zhongzhi Wu and Tianniu Chen and Xianghua Yu and Xue, {Zi Ling}",
year = "2005",
month = "8",
day = "15",
doi = "10.1021/om050302f",
language = "English (US)",
volume = "24",
pages = "4190--4197",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "17",

}

TY - JOUR

T1 - Disilyl complexes of zirconium, hafnium, and tantalum. Their synthesis, characterization, and exchanges with silyl anions

AU - Qiu, He

AU - Cai, Hu

AU - Woods, Jaime B.

AU - Wu, Zhongzhi

AU - Chen, Tianniu

AU - Yu, Xianghua

AU - Xue, Zi Ling

PY - 2005/8/15

Y1 - 2005/8/15

N2 - Cyclopentadienyl-free disilyl amide complexes [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2 as [Li(THF) 4] + salts), K(18-crown-6) 3/2{(Me 2N) 3M[(Me 3Si) 2Si-(CH 2) 2-Si(SiMe 3) 2]} (M = Zr, 3; Hf, 4), (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5), (Me 2N) 3Ta(SiBu tPh 2) 2 (6), and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) have been prepared. The structures of 1-4 have been determined by X-ray single-crystal diffraction. The two -Si(SiMe 3) 3 - ligands in (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5) were replaced sequentially by the -SiBu tPh 2 - anions to give (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) and (Me 2N) 3Ta(SiBu tPh 2) 2 (6). The silyl ligand in (Me 2N) 3Zr-Si(SiMe 3) 3 was found to undergo a reversible exchange with SiBu tPh 2 -, probably through a disilyl intermediate, to reach the following equilibrium: (Me 2N) 3ZrSi(SiMe 3) 3 + SiBu tPh 2 - (Me 2N) 3ZrSiBu tPh 2 + Si(SiMe 3) 3-with ΔH° = 4.6(0.5) kcal/mol and ΔS° = -7(2) eu. A similar exchange involving [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2) was observed: (Me 2N) 3ZrSiBu tPh 2 + SiBu tPh 2 - ⇌ 1 with the estimated free energy of activation ΔG‡ = 14.1(0.5) kcal/mol. (Me 2N) 3Ta(SiBu tPh 2) 2 (6) and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) are thermally unstable. Kinetic studies give the activation parameters of the decomposition of 7: ΔH‡ = 22.8(1.3) kcal/mol and ΔS‡ = -3(5) eu.

AB - Cyclopentadienyl-free disilyl amide complexes [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2 as [Li(THF) 4] + salts), K(18-crown-6) 3/2{(Me 2N) 3M[(Me 3Si) 2Si-(CH 2) 2-Si(SiMe 3) 2]} (M = Zr, 3; Hf, 4), (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5), (Me 2N) 3Ta(SiBu tPh 2) 2 (6), and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) have been prepared. The structures of 1-4 have been determined by X-ray single-crystal diffraction. The two -Si(SiMe 3) 3 - ligands in (Me 2N) 3Ta[Si(SiMe 3) 3] 2 (5) were replaced sequentially by the -SiBu tPh 2 - anions to give (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) and (Me 2N) 3Ta(SiBu tPh 2) 2 (6). The silyl ligand in (Me 2N) 3Zr-Si(SiMe 3) 3 was found to undergo a reversible exchange with SiBu tPh 2 -, probably through a disilyl intermediate, to reach the following equilibrium: (Me 2N) 3ZrSi(SiMe 3) 3 + SiBu tPh 2 - (Me 2N) 3ZrSiBu tPh 2 + Si(SiMe 3) 3-with ΔH° = 4.6(0.5) kcal/mol and ΔS° = -7(2) eu. A similar exchange involving [(Me 2N) 3M(SiBu tPh 2) 2] - (M = Zr, 1; Hf, 2) was observed: (Me 2N) 3ZrSiBu tPh 2 + SiBu tPh 2 - ⇌ 1 with the estimated free energy of activation ΔG‡ = 14.1(0.5) kcal/mol. (Me 2N) 3Ta(SiBu tPh 2) 2 (6) and (Me 2N) 3Ta(SiBu tPh 2)[Si(SiMe 3) 3] (7) are thermally unstable. Kinetic studies give the activation parameters of the decomposition of 7: ΔH‡ = 22.8(1.3) kcal/mol and ΔS‡ = -3(5) eu.

UR - http://www.scopus.com/inward/record.url?scp=23844447348&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=23844447348&partnerID=8YFLogxK

U2 - 10.1021/om050302f

DO - 10.1021/om050302f

M3 - Article

VL - 24

SP - 4190

EP - 4197

JO - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 17

ER -