Dioxomolybdenum complex

Serrette, A.G. and Swager, TM. (1994) Polar Superstructures Stabilized by Polymeric Oxometal Units Columnar Liquid Crystals Based on Tapered Dioxomolybdenum Complexes. Angewandte Chemie (International Edition in English), 33, 2342-2345. 

Chiral dioxomolybdenum complexes were synthesized from (25,4R)-4-hydroxyproline and connected to the surface of USY zeolite by covalent bonding (2 in Fig. 7.4). 

In the presence of the dioxomolybdenum complex M0O2 (dipic) (HMPA) (dipic = pyridine-2,6-dicarboxylate, HMPA = hexamethylphosphoramide), 2-methylhex-2-ene and phenylhydroxylamine produce the amine 194 in 52% yield other alkenes react analogously199. 

Scheme 2 Direct grafting of dioxomolybdenum complexes Mo02X2(THF)2 onto MCM-41 and MCM-48...

Scheme 12 Dioxomolybdenum complexes 1-3 tested in several imidazolium-based RTILs for olefin epoxidation...

TBHP and the molybdenum catalysts are soluble in imidazohiun-based RTlLs. The system becomes biphasic when the olefinic substrate is added. In all cases, the TOFs of the catalytic reactions are considerably lower with the ionic solvent than when performed without the ionic solvent (data reported in Table 9). This slower catalytic reaction may be due to dilution effects and phase transfer problems, especially with the olefin, which is quite insoluble in the RTIL. The conversion appears to be strongly temperature-dependent, as decreasing the temperature from 55 °C to 35 °C reduces the conversion by ca. 50% (entries 7 and 8, Table 9). With the dioxomolybdenum complexes 1 and 2, the epoxidation reaction proceeds with 100% selectivity (Table 9), whereas some diol is formed with the catalyst 3. 

Hydroxumie acids. Oxidation of N-trimethylsilylamtdes (I, prepared by the reaction of a secondary amide with hexamethyldisilazane) with the MoOvMMPT complex in methylene chloride at room temperature for several hours np to several days affords dioxomolybdenum complexes (2) in moderate yields (15-40%). The free hydroxamic acids (3) are Hbcrated by treatment of (2) with ethylenediaminetetraacetic acid (EDTA). 

Z. Petrovski, S. S. Braga, A. M. Santos, S. S. Rodrigues, 1. S. Goncalves, M. I illinger, F. E. Kiihn, C. C. Romao, Synthesis and characterization of the inclusion compound of a ferrocenyldiimine dioxomolybdenum complex with heptakis-2,3,6-tri-O-methyl-p-cyclodextrrn, Inorg. Chim. Acta 358 (2005) 981. 

Swager has described a series of dioxomolybdenum complexes based upon non-mesomorphic substituted pyridinediyl-2,6-dimethanolato ligands [181]. For decy-loxy chains and above, the complexes display disordered hexagonal columnar phases as identified by X-ray diffraction studies. Variable-temperature infrared studies looking at the oxomolybdenum symmetric and asymmetric frequencies show that there are weak interactions within the mesophase compared to the isotropic state and that the strongest interactions are seen in the solid state. These interactions are proposed to help stabilize the columnar mesophase observed (Figure 97). 

Figure 97 Schematic of the proposed arrangement of dioxomolybdenum complexes in the mesophase.

Corma, A., Fuerte, A., Iglesias, M., Sanchez, F. (1996) Preparation of new chiral dioxomolybdenum complexes heterogenized on modified USY-zeolites. Efficient catalysts for selective epoxidation of allilic alcohols, J. 

However, the dimerization constant is low and even in non-polar acetone-dg, values were 12 M i (with 1), 30 M i (with 2, R = Me), and 100 M (3a), respectively. Crystallization from methanol and diffraction studies revealed the structure of Li[Li3 (3a)4(Mo02)2 ] (Figure 2.11, left). Two biscatecholate cis-dioxomolybdenum complexes are bridged by three lithium cations. One is found in a bis-salicylate environment, as observed earlier. The two other lithium cations bind only to one of the salicylates bridging to an oxo ligand of the second complex unit. Those two lithiums are coordinated also by one molecule of methanol each. ... 

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