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Title: Insertion, protonolysis and photolysis reactivity of a thorium monoalkyl amidinate complex

The reactivity of the thorium monoalkyl complex Th(CH 2SiMe 3)(BIMA) 3[ 1, BIMA = MeC(NiPr) 2] with various small molecules is described. While steric congestion prohibits the insertion of N,N'-diisopropylcarbodiimide into the Th-C bond in 1, the first thorium tetrakis(amidinate) complex, Th(BIMA) 4 ( 2), is synthesized via an alternative salt metathesis route. Insertion of p-tolyl azide leads to the triazenido complex Th[(p-tolyl)NNN(CH 2SiMe 3)-κ 2 N 1,2] (BIMA) 3( 3), which then undergoes thermal decomposition to the amido species Th[(p-tolyl)N(SiMe 3)](BIMA) 3 ( 4). The reaction of 1 with 2,6-dimethylphenylisocyanide results in the thorium iminoacyl complex Th[η 2-(CN)-2,6-Me 2-C 6H 3(CH 2SiMe 3)](BIMA) 3 ( 5), while the reaction with isoelectronic CO leads to the products Th[OC(CH 2)SiMe 3](BIMA) 3 ( 6) and Th[OC(NiPr)C(CH 2SiMe 3)(C(Me)N( iPr))O-κ 2O,O'](BIMA) 2 ( 7), the latter being the result of CO coupling and insertion into an amidinate ligand. Protonolysis is achieved with several substrates, producing amido ( 9), aryloxide ( 10), phosphido ( 11a,b), acetylide ( 12), and cationic ( 13) complexes. Ligand exchange with 9-borabicyclo[3.3.1]nonane (9-BBN) results in formation of the thorium borohydride complex (BIMA) 3Th(μ-H) 2[B(C 8H 14)] ( 14). Complex 1 also reacts under photolytic conditions to eliminate SiMemore » 4 and produce Th(BIMA) 2(BIMA*) [ 15, BIMA* = ( iPr)NC(CH 2)N( iPr)], featuring a rare example of a dianionic amidinate ligand. Complexes 2, 3, 5, 6, 11a, and 12-15 were characterized by 1H and 13C{ 1H} NMR spectroscopy, FTIR, EA, melting point and X-ray crystallography. All other complexes were identified by one or more of these spectroscopic techniques.A tris-amidinate thorium monoalkyl complex facilitates new small molecule reactivity and eliminates SiMe 4 under photolytic conditions to generate a mixed amidinate dimer.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Published Article
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 9; Journal Issue: 10; Related Information: © 2018 The Royal Society of Chemistry.; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1421572
Alternate Identifier(s):
OSTI ID: 1465421

Settineri, Nicholas S., and Arnold, John. Insertion, protonolysis and photolysis reactivity of a thorium monoalkyl amidinate complex. United States: N. p., Web. doi:10.1039/c7sc05328b.
Settineri, Nicholas S., & Arnold, John. Insertion, protonolysis and photolysis reactivity of a thorium monoalkyl amidinate complex. United States. doi:10.1039/c7sc05328b.
Settineri, Nicholas S., and Arnold, John. 2018. "Insertion, protonolysis and photolysis reactivity of a thorium monoalkyl amidinate complex". United States. doi:10.1039/c7sc05328b.
@article{osti_1421572,
title = {Insertion, protonolysis and photolysis reactivity of a thorium monoalkyl amidinate complex},
author = {Settineri, Nicholas S. and Arnold, John},
abstractNote = {The reactivity of the thorium monoalkyl complex Th(CH2SiMe3)(BIMA)3[1, BIMA = MeC(NiPr)2] with various small molecules is described. While steric congestion prohibits the insertion of N,N'-diisopropylcarbodiimide into the Th-C bond in 1, the first thorium tetrakis(amidinate) complex, Th(BIMA)4 (2), is synthesized via an alternative salt metathesis route. Insertion of p-tolyl azide leads to the triazenido complex Th[(p-tolyl)NNN(CH2SiMe3)-κ2 N1,2] (BIMA)3(3), which then undergoes thermal decomposition to the amido species Th[(p-tolyl)N(SiMe3)](BIMA)3 (4). The reaction of 1 with 2,6-dimethylphenylisocyanide results in the thorium iminoacyl complex Th[η2-(CN)-2,6-Me2-C6H3(CH2SiMe3)](BIMA)3 (5), while the reaction with isoelectronic CO leads to the products Th[OC(CH2)SiMe3](BIMA)3 (6) and Th[OC(NiPr)C(CH2SiMe3)(C(Me)N(iPr))O-κ2O,O'](BIMA)2 (7), the latter being the result of CO coupling and insertion into an amidinate ligand. Protonolysis is achieved with several substrates, producing amido (9), aryloxide (10), phosphido (11a,b), acetylide (12), and cationic (13) complexes. Ligand exchange with 9-borabicyclo[3.3.1]nonane (9-BBN) results in formation of the thorium borohydride complex (BIMA)3Th(μ-H)2[B(C8H14)] (14). Complex 1 also reacts under photolytic conditions to eliminate SiMe4 and produce Th(BIMA)2(BIMA*) [15, BIMA* = (iPr)NC(CH2)N(iPr)], featuring a rare example of a dianionic amidinate ligand. Complexes 2, 3, 5, 6, 11a, and 12-15 were characterized by 1H and 13C{1H} NMR spectroscopy, FTIR, EA, melting point and X-ray crystallography. All other complexes were identified by one or more of these spectroscopic techniques.A tris-amidinate thorium monoalkyl complex facilitates new small molecule reactivity and eliminates SiMe4 under photolytic conditions to generate a mixed amidinate dimer.},
doi = {10.1039/c7sc05328b},
journal = {Chemical Science},
number = 10,
volume = 9,
place = {United States},
year = {2018},
month = {2}
}