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Structure and Reactivity of Homoleptic Samarium( II ) and Thulium( II ) Phospholyl Complexes
Author(s) -
Turcitu Daniela,
Nief François,
Ricard Louis
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305107
Subject(s) - chemistry , homoleptic , diethyl ether , samarium , medicinal chemistry , reactivity (psychology) , inorganic chemistry , yield (engineering) , steric effects , stereochemistry , organic chemistry , medicine , materials science , alternative medicine , pathology , metal , metallurgy
Potassium 2,5‐di‐ tert ‐butyl‐3,4‐dimethylphospholide K(dtp) ( 9 ) was synthesised in 45 % yield from commercially available starting materials by using zirconacyclopentadiene chemistry. Reaction of the K salt of this bulky anion and of the previously described potassium 2,5‐bis(trimethylsilyl)‐3,4‐dimethylphospholide K(dsp) ( 8 ) with SmI 2 in diethyl ether afforded the homoleptic samarium( II ) complexes 7 and 6 , respectively, whose solid‐state structures, [{Sm(dtp) 2 } 2 ] ( 7 a ) and [{Sm(dsp) 2 } 2 ] ( 6 a ), are dimeric owing to coordination of the phosphorus lone pairs to samarium, as shown by X‐ray crystallography. Reaction of 8 with TmI 2 in diethyl ether afforded [Tm(dsp) 2 (Et 2 O)], which could not be desolvated without decomposition. In contrast, the coordinated ether group of the solvate [Tm(dtp) 2 (Et 2 O)], obtained from 9 and TmI 2 , could easily be removed by evaporation of the solvent and extraction with pentane at room temperature, and the monomer [Tm(dtp) 2 ] ( 5 ) could be isolated and was characterised by X‐ray crystallography. Presumably, steric crowding in 5 is too high for dimerisation to occur. Compound 5 , the first Tm II homoleptic sandwich complex, is remarkably stable at room temperature in solution and did not noticeably react with nitrogen, in sharp contrast with other thulium( II ) species. As expected, 5, 6 and 7 all reacted with azobenzene to give the trivalent complexes [Tm(dtp) 2 (N 2 Ph 2 )] ( 13 ), [Sm(dsp) 2 (N 2 Ph 2 )], ( 14 ) and [Sm(dtp) 2 (N 2 Ph 2 )] ( 15 ), respectively; 13 and 14 were characterised by X‐ray crystallography. Complex 5 immediately reacted with triphenylphosphane sulfide at room temperature to give [{Tm(dtp) 2 } 2 ( μ ‐S)] ( 16 ), which was characterised by X‐ray crystallography, whereas samarium( II ) complexes 6 and 7 did not noticeably react with Ph 3 PS over 24 h under the same conditions.