INTRODUCTION

Bond order is the chemical bonds between a pair of atom. Single, double, and triple is mainly known for bond order and is direct result of the number of s and p orbitals and the spatial orientation. Although it is not that known, d orbitals can also be a part of bond order; it was discovered to have a bond order of four, or quadruple. A d-orbital can only make a quadruple bond. There are metal-metal single bonds which are in transition metal clusters that have metal centers with low oxidation states. The bond orders of metal-metal bonds are dependent of the ligands attached and the number of d electrons available. If there is a small number of d electrons, then the M-M bond order will be as well. M-M bond antibonding orbitals will be filled, and the bond order will be small, even if there are many delectrons. There has to be exactly four d electrons on each metal center to make a quadruple bond order. Quadruple metal-metal bonds molecular orbital diagrams are similar to unsaturated organic compounds, but instead of two overlapping p orbitals, it has two overlapping d orbitals. The MO diagram has d and d* because of the overlap of two d_xy orbitals. The electron configuration of a quadruple bond compounds is s²p⁴d⁴.

In this experiment, a family of molybdenum compounds with a quadruple bond order will be synthesized. The first compound will be tetra(acetate)dimolybdenum(II), Mo₂(O₂CCH₃)₄, which is a diamagnetic molecule. Each Mo(II) atom has four valence d electrons, creating a total of eight d electrons. The structure of Mo₂(O₂CCH₃)₄ has four acetate groups that bridge the two metal centers. The next compound synthesized will be the octachlorodimolybdenum(II) anion, Mo₂Cl₈^4-, which is an unbridged quadruple bond. Once KMo₂Cl₈ is treated with tributylphosphine it forms Mo₂Cl₄ [P(C₄H₉) ₃] ₄.