| In this work,the binuclear tungsten carbonyl nitrosyls W2(NO)2(CO)n(n=9,8,7,6,5)havebeen studied by two density functional theory (DFT) methods, i.e., BP86 and MPW1PW91.The pseudopotential basis set SDD(Stuttgart double-ζ)is used for tungsten atom.For carbon,nitrogenandoxygen, theall-electronDZP(double-ζpluspolarization)basissetsareused.Series of W2(NO)2(CO)n(n=9,8,7,6,5) are setted for the starting points of optimizationand the equilibrium geometries after optimization are analyzed by 18-electronics calculation.The vibrational frequency caculations are carried out to predict the frequncies of the ligandswhich can further substantiate the presumed structures. In order to compare these lowestenergystructures, the stepwise dissociation energies of W-CO are predicted.We compare thelowest energystructures of isoelectronic W2(NO)2(CO)nand Re2(CO)n+2 derivatives based onthe informationfromearlierstudy.For highly saturated W2(NO)2(CO)9, the lowest energy structure doesn't form a regularmetal bondandthestructures withoneNObridge are energeticallypreferredoverothers.Theglobal minimum for saturated W2(NO)2(CO)8 is a staggered D4d unbridged structure,analogous to the experimental structure for the isoelectronic Re2(CO)10. However, forunsaturated W2(NO)2(CO)n derivatives, the lowest energy structures are different fromthoseof the isoelectronic Re2(CO)n+2 derivatives.The two low-lying structures for W2(NO)2(CO)7with C1and Cssymmetry respectively are close to each other in energy, which are derivedfrom the two low-lying structures for W2(NO)2(CO)8 by removal of one the terminal COgroup.The global minimum forW2(NO)2(CO)6has two bridging CO groups.The structures ofW2(NO)2(CO)5 have the unsymmetrical bridging CO and NO groups because of their highunsaturation and the structures with CO bridge are more stable.All the data of thesegeometriesareusefulfor the studyandpreparationofthoseanaloguesinthefuture. |
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