Reactions of Dienes with a Mo(0) Complex with Tetraphosphine Coligand [Mo(P4)(Ph 2 PCH 2 CH 2 PPh 2 )] (P4 = Meso‐o ‐C 6 H 4 (PPhCH 2 CH 2 PPh 2 ) 2 )

Reaction of tetraphosphine complex [Mo(κ 4 ‐P4)(Ph 2 PCH 2 CH 2 PPh 2 )] (1; P4 = meso‐o ‐C 6 H 4 ‐(PPhCH 2 CH 2 PPh 2 ) 2 ) with E ‐1,3‐pentadiene in toluene at 60 °C gave the η 4 ‐diene complex [Mo(η 4 ‐ E ‐1,3‐pentadiene)(κ 4 ‐P4)] (2), which is present as a mixture of two isomers due to the orientation of the Me group in the diene ligand. Treatment of 1 with Z‐1,3‐pentadien also resulted in the formation of 2 as the sole product after heating the reaction mixture at 90 °C. Whereas the reaction of 1 with 1,3‐cyclohexadiene at 60 °C afforded the η 4 ‐diene complex [Mo(η 4 ‐cyclohexadiene)(κ 4 ‐P4)] (6), that with cyclopentadiene led to the C‐H bond scission product [η 5 ‐C 5 H 5 )MoH(κ 3 ‐P4)] (7). Detailed structures were determined by X‐ray crystallography for 2, 6,and 7, and fluxional feature of 6 in solution was clarified based on the VT‐NMR studies.