Reactions of Dienes with a Mo(0) Complex with Tetraphosphine Coligand [Mo(P4)(Ph2PCH2CH2PPh2)] (P4 = Meso‐o‐C6H4(PPhCH2CH2PPh2)2)

Reaction of tetraphosphine complex Mo(κ⁴‐P4)(Ph₂PCH₂CH₂PPh₂)] (1; P4 = meso‐o‐C₆H₄‐(PPhCH₂CH₂PPh₂)₂) with E‐1,3‐pentadiene in toluene at 60 °C gave the η⁴‐diene complex Mo(η⁴‐E‐1,3‐pentadiene)(κ⁴‐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 η⁴‐diene complex Mo(η⁴‐cyclohexadiene)(κ⁴‐P4)] (6), that with cyclopentadiene led to the C‐H bond scission product η⁵‐C₅H₅)MoH(κ³‐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.