NMR (13C, 17O), IR and Raman Studies of Poly-nuclear Carbonyls Transition Metal Carbonyls : A DFT Application

Abstract

DFT implemented in ADF 2012.01 was used to know about the relative spatial displacements of three/four metals and the surrounding12 terminal and bridging CO groups in 5 poly-nuclear carbo nyls: [M 3 (CO) O), 2 diamagnetic and 4 paramagnetic contributing terms in the s values of constituents.The k and j values of constituents were obtained from the same program by using a new Input File.There after, the software was run with Frequencies and Raman full to obtain frequencies of the normal modes of all the (3n-6) Fundamental vibration bands of the carbonyls. All the metals in the above named first three carbonyls were spatially equivalent while in the latter two carbonyls,all the metals were not equivalent.But no where, the two metals or any two COs were found to be magnetically equivalent.Excepting Ir 4 (CO) 12 where all the12 CO groups were spatially equivalent,in other four carbonyls, CO groups were found to be two or more types spatially.The first metal and the responding spatially equivalent other metal/s possessed same k and j values. For CO groups attached to one metal and spatially equivalent CO groups attached to other spatially equivalent metal/s, k and j values of 13 C nuclei possessed the same values. A perturbing metal and spatially equivalent responding metal/s along with spatially equivalent CO groups had same k and j values respectively. The study was important in four ways. Firstly,using these parameters, we could calculate quite a more number of parameters such as Effective Spin O and metals along with spatial displacements/stereochemical equivalences of constituents. Secondly, we could correlate these NMR parameters with their reported IR/Raman results which lent credence to their П-acid character.Thirdly,we classified their fundamental vibration bands types into four types.Fourthly, we could arrive at some optimization and thermal parameters of carbonyls.

Benchmarking DFT Calculations of 1H and 13C Chemical Shifts in Monosubstituted Ferrocenes

“…From this perspective, the reported benchmarks rarely cover typical organometallic ligands or classes of compounds. [ 56 ] To our knowledge, the only exception is the family of metal carbonyls, [ 57–60 ] which was studied quite systematically.…”