The invention relates to a process for preparing a boronic anhydride compound of formula (1), wherein, R1-R4 are substituents as defined in the disclosure and ‘B’ stands for the element boron. The invention also describes a process of using the boronic anhydride of formula (1), to prepare a biphenyl metallocene complex of formula (4), wherein, R1 to R10, are substituents as defined in the disclosure; and wherein ‘M’ is a transition metal element, ‘Q’ is an halide anion, and ‘P’ is the valency of the transition metal element ‘M’ and indicates the number of halide anion present. In addition, the invention further describes a process of purifying the metallocene complex of formula (4) so as to render the overall metallocene complex synthesis process environmentally sustainable as well as cost effective by minimizing waste effluents.