Reactions of Mo(II)-tetraphosphine complex [MoCl2{meso-o-C6H4(PPhCH2CH2PPh2)2}] with a series of small molecules

Reactions of Mo(II)-tetraphosphine complex [MoCl2(κ4-P4)] (2; P4 = meso-o-C6H4(PPhCH2CH2PPh2)2) with a series of small molecules have been investigated. Thus, treatment of 2 with alkynes RCtriple bond; length of mdashCR′ (R = Ph, R′ = H; R = p-tolyl, R′ = H; R = Me, R′ = Ph) in benzene or toluene gave neutral mono(alkyne) complexes [MoCl2(RCtriple bond; length of mdashCR′)(κ3-P4)] containing tridentate P4 ligand, which were converted to cationic complexes [MoCl(RCtriple bond; length of mdashCR′)(κ4-P4)]Cl having tetradentate P4 ligand upon dissolution into CDCl3 or CD2Cl2. The latter complexes were available directly from the reactions of 2 with the alkynes in CH2Cl2. On the other hand, treatment of 2 with 1 equiv. of XyNC (Xy = 2,6-Me2C6H3) afforded a seven-coordinate mono(isocyanide) complex [MoCl2(XyNC)(κ4-P4)] (7), which reacted further with XyNC to give a cationic bis(isocyanide) complex [MoCl(XyNC)2(κ4-P4)]Cl (8). From the reaction of 2 with CO, a mono(carbonyl) complex [MoCl2(CO)(κ4-P4)] (9) was obtained as a sole isolable product. Reaction of 9 with XyNC afforded [MoCl(CO)(XyNC)(κ4-P4)]Cl (10a) having a pentagonal–bipyramidal geometry with axial CO and XyNC ligands, whereas that of 7 with CO resulted in the formation of a mixture of 10a and its isomer 10b containing axial CO and Cl ligands. Structures of 7 and 9 as well as [MoCl(XyNC)2(κ4-P4)][PF6](8′) and [MoCl(CO)(XyNC)(κ4-P4)][PF6] (10a′) derived by the anion metathesis from 8 and 10a, respectively, were determined in detail by the X-ray crystallography.