Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymer...Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.展开更多
The colored associated compounds of phosphomolybdotungstate and arsenomolybdotungstate with crystal violet are introduced. Their main characters have been studied. These two associated compounds may be used to determi...The colored associated compounds of phosphomolybdotungstate and arsenomolybdotungstate with crystal violet are introduced. Their main characters have been studied. These two associated compounds may be used to determine low tungsten with fairly high sensitivity and selectivity. Their strong point is that the interference of molybdenum can be overcome. In the presence of polyvinyl alcohol, tungsten can be determined directly in the aqueous solution.展开更多
Reaction of benzyl chloride with η5-CH3COC5H4W(CO)2Na formed in situ from η6-CH3CO C6H4Na and W(CO)2 gives η6-CH3COC6H4W(CO)3CH2C5H5.The single crystal structure of the product was determined by X-ray diffraction m...Reaction of benzyl chloride with η5-CH3COC5H4W(CO)2Na formed in situ from η6-CH3CO C6H4Na and W(CO)2 gives η6-CH3COC6H4W(CO)3CH2C5H5.The single crystal structure of the product was determined by X-ray diffraction method. It crystallizes in the triclinlc space group P1 with unit cell parameters a= 10.199(5),b=12.116(7), c=14.207(6)A;a=69.47(5),β=72. 38(3),γ= 85.89(4);V= 1569. 9A3, Dc= 1.98 g/cm2; Z=4. Least-square refinement led to final R value of 0. 0539 and Rw value of 0. 0553, based on 3548 independent observed reflections.展开更多
Gas sensor materials of bismuth tungstate and bismuth iron tungstate were prepared. Sintered bismuth iron tungstate gas sensors have a high sensitivity and selectivity to ethanol and acetone, show long-term stability ...Gas sensor materials of bismuth tungstate and bismuth iron tungstate were prepared. Sintered bismuth iron tungstate gas sensors have a high sensitivity and selectivity to ethanol and acetone, show long-term stability of response under most operating conditions and insensitivity to atmospheric humidity and respond more quickly in relative case. The changes of the sensors in conductance are mediated by oxygen vacancy donors which caused by the direct reduction. Also, they are highly mobile and can quickly diffuse through the sample, thereby having a direct effect on the electronic carrier density. The phase composition and structure of these gas sensor materials were investigated by XRD technique.展开更多
文摘Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.
文摘The colored associated compounds of phosphomolybdotungstate and arsenomolybdotungstate with crystal violet are introduced. Their main characters have been studied. These two associated compounds may be used to determine low tungsten with fairly high sensitivity and selectivity. Their strong point is that the interference of molybdenum can be overcome. In the presence of polyvinyl alcohol, tungsten can be determined directly in the aqueous solution.
文摘Reaction of benzyl chloride with η5-CH3COC5H4W(CO)2Na formed in situ from η6-CH3CO C6H4Na and W(CO)2 gives η6-CH3COC6H4W(CO)3CH2C5H5.The single crystal structure of the product was determined by X-ray diffraction method. It crystallizes in the triclinlc space group P1 with unit cell parameters a= 10.199(5),b=12.116(7), c=14.207(6)A;a=69.47(5),β=72. 38(3),γ= 85.89(4);V= 1569. 9A3, Dc= 1.98 g/cm2; Z=4. Least-square refinement led to final R value of 0. 0539 and Rw value of 0. 0553, based on 3548 independent observed reflections.
文摘Gas sensor materials of bismuth tungstate and bismuth iron tungstate were prepared. Sintered bismuth iron tungstate gas sensors have a high sensitivity and selectivity to ethanol and acetone, show long-term stability of response under most operating conditions and insensitivity to atmospheric humidity and respond more quickly in relative case. The changes of the sensors in conductance are mediated by oxygen vacancy donors which caused by the direct reduction. Also, they are highly mobile and can quickly diffuse through the sample, thereby having a direct effect on the electronic carrier density. The phase composition and structure of these gas sensor materials were investigated by XRD technique.
