Alkylidyne Complexes Ligated by Poly(pyrazolyl)borates

Publisher Summary This chapter focuses on the alkylidyne complexes that are ligated by poly(pyrazolyl)borates. The terms carbyne and alkylidyne are used interchangeably in the chapter. The first alkylidyne–metal complexes were prepared more than 30 years ago. Since this pioneering event, the chemistry of the transition metal– carbon triple bond present in such complexes has developed into a major field of research and though the poly(pyrazolyl)borate ligands were discovered 7 years prior to the synthesis of the first alkylidyne complexes, their importance and significance in this field has only more recently been truly appreciated. Analogous reactions for the Cp-ligated complexes are also described in this chapter. A typical synthesis of poly(pyrazolyl)borate alkylidyne complexes involves the displacement of labile ligands from pre-existing alkylidynes prepared according to the classic oxide–abstraction Fischer preparation that is developed by Mayr and co-workers into an efficient approach to Group 6 alkylidynes. The most commonly employed synthetic strategy for inclusion of the bulky poly(pyrazolyl)borate ligand into the coordination sphere of alkylidyne complexes involves late incorporation of the Tp x anion into a more highly functionalized organometallic substrate in much the same way that Cp x derivatives are utilized to generate cyclopentadienyl-containing alkylidyne complexes.