【摘要】 采用MPW1PW91和BP86 2种密度泛函方法对中性单核锇羰基化合物Os(BF)(CO)n(n=4,3)及双核锇羰基化合物Os2(BF)2(CO)n(n=7,6,5,4)进行理论计算研究,优化得到22个低能异构体.研究发现,单核配位饱和Os(BF)(CO)4的能量最低的异构体对称性为C2v,其BF基团在三角双锥赤道面上.该异构体失去1个赤道面上的CO可得到Os(BF)(CO)3的能量最低异构体.单核Os(BF)(CO)n(n=4,3)的能量最低异构体的BF基团都位于配体三角双锥及缺顶点结构的赤道面上.配位饱和双核Os2(BF)2(CO)7有4个能量接近的异构体,其中能量最低的异构体结构中含有2个呈蝶形的桥配位BF基团.配位不饱和的Os2(BF)2(CO)6的2个能量接近的异构体结构相似,2个桥配位BF基团与2个Os原子构成平行四边形结构单元.配位不饱和的Os2(BF)2(CO)5和Os2(BF)2(CO)4的能量最低异构体都含有由2个桥配位BF基团与2个Os原子构成的平行四边形结构单元.双核Os2(BF)2(CO)n(n=7,6,5,4)能量最低异构体的BF基团都以桥配位形式和Os原子相连.离解能研究表明,单核配位饱和的Os(BF)(CO)4具有一定的热力学稳定性.双核的Os2(BF)2(CO)n(n=7,6)失去1个CO或者分裂为单核的Os(BF)(CO)4或Os(BF)(CO)3所需能量较高,表明其具有一定的热力学稳定性.更多还原

【Abstract】 Mononuclear and binuclear osmium fluoroborylene carbonyls Os( BF)( CO)n( n = 4,3) and Os2( BF)2( CO)n( n = 7,6,5,4) were investigated using MPW1PW91 and BP86 density functional theories.Twenty two isomers were obtained. For Os( BF)( CO)4,the lowest-energy structure 14-1 is a singlet C2 vsymmetrical trigonal bipyramid. The lowest energy structures for Os( BF)( CO)3are derived from the trigonal bipyramidal Os( BF)( CO)4structures by removal of a CO group. Four low energy isomers are predicted to be close in energy for Os2( BF)2( CO)7,the lowest-energy isomer,27-1,has butterfly structure containing two bridging BF groups. For Os2( BF)2( CO)6. Two isomers,26-1 and 26-2,are predicted to be nearly degenerated in energy. Both 26-1 and 26-2 are predicted to have two bridging BF groups. The global minimum isomer of Os2( BF)2( CO)5and Os2( BF)2( CO)4are similar to 26-1 with two BF groups bridging to two Os atoms. It seems that Os2( BF)2( CO)n( n = 7,6,5,4) are favored to form structures containing bridging fluoroborylene groups. The study of dissociation energy shows that the CO dissociation energy and dissociation energy of Os2( BF)2( CO)n( n = 7,6) into the mononuclear fragments Os( BF)( CO)4or Os( BF)( CO)3are large,suggesting those isomers are quite thermodynamically favorable.更多还原