Therefore, from the Boltzmann population analysis, it is noticed that for Yb-complexes 8CN geometry is most preferred for three and four PF6 -complexes, and for five and six PF6 -complexes, it is the second most abundant complex. The five and six PF6 -complexes are predominantly 10CN and 9CN, respectively -a similar trend of smaller coordination number to that seen in the Nd-complexes upon addition of PF6 -.