Insertion of Acetonitrile into the Zr−P Bond of [Cp°2ZrCl(PHCy)] (Cy = Cyclohexyl, Cp° = η5-C5EtMe4) Followed by PHCy Elimination To Give [Cp°2(Cl)Zr(μ-NCMe−CMeN)Zr(Cl)Cp°2]

[Cp° 2 ZrCl(PHCy)] (Cy = cyclohexyl, Cp° = η 5 -C 5 EtMe 4 ) undergoes insertion of MeCN into the Zr−P bond, yielding [Cp° 2 ZrCl{N C(Me)(PHCy)}] ( 1 ). Isomers with a Z ( 1a ) or E ( 1b ) configuration at the C−N double bond are obtained in a ratio of 13:1. At room temperature, 1 slowly decomposes in solution with elimination of a PHCy fragment and formation of [Cp° 2 (Cl)Zr(μ-N CMe−CMe N)Zr(Cl)Cp° 2 ] ( 2 ). Two isomers are obtained with a trans ( 2a ) or cis ( 2b ) arrangement around the C−N double bonds of the bridging butane-2,3-diimino(2-)- N, N ‘ ligand. 1a, 2a, and 2b were isolated and characterized by IR, MS, and NMR spectroscopy ( 1 H, 31 P, 13 C), and crystal structure determinations were carried out on 1a and 2a . In the solid state, the short Zr−N bonds and the almost linear Zr−N−C angles of 1a and 2a indicate the presence of Zr−N double bonds.