In:
Dalton Transactions, Royal Society of Chemistry (RSC), Vol. 51, No. 37 ( 2022), p. 14345-14351
Abstract:
Titanium( iii ) and titanium( iv ) formate complexes supported by the sterically encumbering tris(phenolato)amine ligand (H 3 (O 3 N) = tris(4,6-di- tert -butyl-2-hydroxybenzyl)amine) are described. Salt metathesis of the chlorido precursor [(O 3 N)TiCl] (1-Cl) with sodium formate in a 2 : 1 ratio in THF gave a dimer of sodium dititanium triformate units with 12-membered ring [Na{(O 3 N)Ti} 2 (μ-OCHO-η O :η O ′) 3 ] 2 (3-Na) when crystallized from acetonitrile. Complex 3-Na was also prepared by reacting the previously reported terminal formate complex [(O 3 N)Ti(OCHO)] (2) with excess sodium formate. Salt metathesis of 1-Cl with potassium formate gave a tetratitanium cluster of the composition [K 3 {(O 3 N)Ti} 4 (OCHO) 7 ] (3-K) which can be also obtained by treating 2 with potassium formate. In 3-K both Ti and K centers are six-coordinate. The titanium( iii ) complexes [(O 3 N)Ti(L)] (4-L, L = THF, THP, Et 2 O) and solvent free dimeric [(O 3 N)Ti] 2 (5) were synthesized by reduction of 1-Cl with sodium sand or magnesium in THF, THP, Et 2 O, and n -pentane, respectively. The tert -butyl formate adduct of titanium( iii )-[(O 3 N)Ti( t BuOCHO)] (6) was isolated by reacting 4-L or 5 with tert -butyl formate. Complex 6 is thermolabile and slowly decomposed in solution to produce a formate-bridged mixed-valence titanium( iii )/titanium( iv ) complex [{(O 3 N)Ti} 2 (μ-OCHO-η O :η O ′)] (7) which further decomposed to a mixture containing 2, [(O 3 N)Ti(OH)] and [(O 3 N)Ti–O–Ti(O 3 N)]. All new complexes were isolated in moderate to good yields and fully characterized by elemental analysis, 1 H and 13 C NMR spectroscopy, and single crystal X-ray diffraction analysis. For the titanium( iii ) complexes solution magnetic moments were measured by the Evans method and EPR spectra recorded as toluene glass at 77 K.
Type of Medium:
Online Resource
ISSN:
1477-9226
,
1477-9234
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
1472887-4
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