Formation of novel P-functionalised ligands by insertion of CyNC into the ZrP bonds of [Cp°2ZrCl(PHCy)] (Cp°=η5-C5EtMe4, Cy=cyclohexyl) and [Cp′2ZrCl(PHTipp)] (Cp′=η5-C5H4Me, Tipp=2,4,6-Pri3C6H2). Molecular structures of [Cp°2ZrCl{η2-NCyC(PHCy)}] and [Cp

[Cp′2ZrCl(PHTipp)] (1) (Cp′=η5-C5H4Me, Tipp=2,4,6-Pri3C6H2) and [Cp°2ZrCl(PHCy)] (2) (Cp°=η5-C5EtMe4, Cy=cyclohexyl) readily insert CyNC to give [Cp′2ZrCl{η2-NCyC(PHTipp)}] (3) and [Cp°2ZrCl{η2-NCyC(PHCy)}] (4). 3 and 4 were characterised spectroscopically (IR, NMR, MS) and by crystal structure determination, which showed an η2 bonding mode (C,N) of the NCyC(PHR) ligands. Of the two possible coordination modes of the ligand, 3 is obtained exclusively as the exo isomer, in which the NCy group is adjacent to the ZrCl bond, while for 4, both isomers (exo and endo) are formed [1:1.5 (4a:4b)], whereby the endo isomer is favoured. The exo isomer 4a was structurally characterised.