Premium
Synthesis and Characterization of Methyltrioxorhenium(VII) Immobilized in Bipyridyl‐Functionalized Mesoporous Silica
Author(s) -
Nunes Carla D.,
Pillinger Martyn,
Valente Anabela A.,
Gonçalves Isabel S.,
Rocha João,
Ferreira Paula,
Kühn Fritz E.
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200205)2002:5<1100::aid-ejic1100>3.0.co;2-b
Subject(s) - chemistry , rhenium , adduct , x ray absorption fine structure , mesoporous material , mesoporous silica , bipyridine , alkyl , magic angle spinning , raman spectroscopy , mcm 41 , molecule , infrared spectroscopy , x ray absorption spectroscopy , inorganic chemistry , crystallography , polymer chemistry , nuclear magnetic resonance spectroscopy , adsorption , spectroscopy , molecular sieve , absorption spectroscopy , organic chemistry , catalysis , crystal structure , physics , quantum mechanics , optics
Methyltrioxorhenium(VII) (MTO) has been immobilized in the mesoporous silica MCM‐41 functionalized with pendant bipyridyl (bpy) groups of the type 4‐[(−O) 3 Si(CH 2 ) 4 ]‐4′‐CH 3 ‐2,2′‐bipyridine. Powder X‐ray diffraction and N 2 adsorption‐desorption studies confirm that the regular hexagonal symmetry of the host is retained during the grafting reaction and that the channels remain accessible. Solid‐state magic angle spinning NMR spectroscopy ( 29 Si, 13 C) was also used to monitor the coupling reactions. The formation of a tethered Lewis base adduct of the type CH 3 ReO 3 ·bpy is confirmed by IR, Raman, and X‐ray absorption fine structure (XAFS) spectroscopy. The XAFS results do, however, indicate that not all rhenium ions are present in this form, and this agrees with elemental analysis which gives an Re/N ratio of 1:1.1 (0.55 mmol Re g −1 ). It is likely that the excess rhenium atoms are present as uncoordinated MTO molecules assembled in the MCM channels. The model complexes (4‐alkyl4′‐methyl‐2,2′‐bipyridine)(methyl)trioxorhenium (alkyl = methyl, n ‐butyl) were also prepared and characterized. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)