Improved Yields of Dichlorobis(triphenylphosphine)nickel(II) and Related Compounds by Employing Triethyl Orthoformate as an In Situ Dehydrating Agent: Rational Improvement of a Classic Undergraduate Inorganic Synthesis

The addition of a small excess of triethyl orthoformate to an alcoholic mixture of NiCl₂·6H₂O and triphenylphosphine (PPh₃) results in an increase in the typical isolated yield of [NiCl₂(PPh₃)₂] from below 50% to over 85%. The impact of water when present in the reaction medium in this system is discussed, and results from the application of the same synthetic approach to the syntheses of [NiBr₂(PPh₃)₂], [NiCl₂(dppe)], and [NiBr₂(dppe)] are presented. A simple synthesis of NiCl₂·2H₂O by the dehydration of NiCl₂·6H₂O at 80 °C can be performed as an optional step to decrease the quantity of triethyl orthoformate required for the preparation of [NiCl₂(PPh₃)₂] and/or [NiCl₂(dppe)]. The experiments are flexible and accommodate a variety of laboratory schedules and student skill levels. Each synthesis can be readily completed within a 3 h laboratory period.