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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:
Accepted Manuscript
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
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1465421