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A New Series of Homoleptic, Paramagnetic Organochromium Derivatives: Synthesis, Characterization, and Study of Their Magnetic Properties
Author(s) -
Alonso Pablo J.,
Forniés Juan,
GarcíaMonforte María Angeles,
Martín Antonio,
Menjón Babil,
Rillo Conrado
Publication year - 2002
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 - 10.1002/1521-3765(20020902)8:17<4056::aid-chem4056>3.0.co;2-q
Subject(s) - homoleptic , chemistry , crystallography , octahedron , denticity , electron paramagnetic resonance , paramagnetism , yield (engineering) , crystal structure , center (category theory) , stereochemistry , materials science , nuclear magnetic resonance , organic chemistry , metallurgy , metal , physics , quantum mechanics
The synthesis and characterization of the triad of organochromium derivatives [Cr(C 6 Cl 5 ) 4 ] n − ( n =0, 1, 2) are described. By treating [CrCl 3 (thf) 3 ] with LiC 6 Cl 5 in 1:5 molar ratio, the salt [Li(thf) 4 ][Cr III (C 6 Cl 5 ) 4 ] ( 1 ) was obtained as a violet solid in 57 % yield. Oxidation of 1 with [N(4‐BrC 6 H 4 ) 3 ][SbCl 6 ] yielded the neutral complex [Cr IV (C 6 Cl 5 ) 4 ] ( 2 ) as a brown solid in 71 % yield. The arylation of [CrCl 2 (thf)] with LiC 6 Cl 5 under similar conditions as above gave [{Li(thf) 3 } 2 ( μ ‐Cl)] 2 [Cr II (C 6 Cl 5 ) 4 ] ( 3 ) as an extremely air‐ and water‐sensitive red solid in 47 % yield. The crystal and molecular structures of 1 and 3 have been established by X‐ray diffraction methods. Complex 3 contains the unusual cation [{Li(thf) 3 } 2 ( μ ‐Cl)] + with an almost linear Li‐Cl‐Li unit (174.2(6)°). All four C 6 Cl 5 groups are σ‐bonded to the Cr II center, which is located in a square‐planar environment. The local geometry around the Cr III center in 1 is, in turn, pseudo‐octahedral, since two of the C 6 Cl 5 groups act as standard σ‐bonded monodentate ligands, while the other two act as small‐bite didentate ligands coordinated through both the ipso ‐C and one of the ortho ‐Cl atoms. Compounds 1 – 3 are paramagnetic with maximum spin multiplicity each (EPR and magnetization measurements).