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Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands
Author(s) -
Zhang Cungen,
Rheinwald Gerd,
Lozan Vasile,
Wu Biao,
Lassahn PaulGerhard,
Lang Heinrich,
Janiak Christoph
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200206)628:6<1259::aid-zaac1259>3.0.co;2-q
Subject(s) - chemistry , schiff base , moiety , crystal structure , imidazole , octahedron , stereochemistry , molecule , methanol , molybdenum , crystallography , stacking , medicinal chemistry , inorganic chemistry , organic chemistry
Four new molybdenum complexes [Mo VI O 2 (L 1 )(Him)] ( 1 ), [Mo VI O 2 (L 1 )(3‐MepzH] ( 2 ), [Mo VI O 2 (L 2 )(3‐MepzH)] ( 3 ), and [(Mo VI O 2 ) 2 (μ‐L 3 )(MeOH) 2 ] ( 4 ) were synthesized and characterized by IR, NMR, ESI‐MS, and single‐crystal structure analysis [H 2 L 1 = 2‐(salicylideneamino)‐2‐methyl‐1‐propanol, H 2 L 2 = 2‐(3‐methoxysalicylideneamino)‐2‐methyl‐1‐propanol, H 4 L 3 = 1, 7‐bis(salicylidene)dihydrazide malonic acid, Him = imidazole and 3‐MepzH = 3‐methylpyrazole]. In all four structures the molybdenum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di‐ or tetraanion (L 1, 2 ) 2— /(L 3 ) 4— and one oxo group occupying the sites of the equatorial plane. The other oxo group and the azole or methanol molecule occupy the apical sites. In 1—3 two centrosymmetrically related molecules form a hydrogen‐bonded pair through the (azole)N‐H···O(alkoxo) interaction. Additional crystal packing appears to be controlled mostly by π stacking between the aromatic rings of the salicyl moiety. ESI‐MS investigations reveal that the integrity of complexes 1—4 is largely retained in methanol solution. At the same time evidence is provided that di‐ to tetranuclear oligomers of formula [{Mo VI O 2 (L)} x ] and [{Mo VI O 2 (L)} x (3‐MepzH)] with L = L 1 , L 2 , x = 2, 3, 4 are present simultaneously with 2 and 3 in methanol solution, respectively the tetranuclear species [{(Mo VI O 2 ) 2 (L 3 )} 2 ] with 4 .