Cationic linear triphos, L [PhP(CH2CH2PPh2)2], alkyne complexes of molybdenum(II) and tungsten(II); crystal structures of [WI(CO)(L-P,P′,P ″)(η2-MeC2Me)]2[W6O19], [WI(CO)(L-P,P ′,P ″)(η2-MeC2Me)][BPh4] and [MoBr2(O){Ph2P(CH2)2PPh(CH2)2POPh2-P,P ′,O}

Abstract

Equimolar quantities of [MoX(Y)(CO)(NCMe)(η2-RC2R)2] and L [= PhP(CH2CH2PPh2)2] reacted in CH2Cl2 at room temperature to give the cationic tridentate linear triphos complexes [MoX(CO)(L-P,P′,P″)(η2-RC2R)]Y 1–5 (X = Y = Br, R = Me or Ph; X = Cl, Y = I, R = Me or Ph; X = Br, Y = I, R = Me) in high yield. Refluxing the tungsten complexes [WX2(CO)(L-P,P′)(η2-RC2R′)] in dry acetonitrile afforded the cationic complexes, [WX(CO)(L-P,P′,P″)(η2-RC2R′)]X 6–8 (X = Br or I, R = R′ = Me; X = I, R = Me, R′ = Ph), whereas refluxing [WI2(CO)(L-P,P′)(η2-MeC2Me)] in slightly wet acetonitrile yielded the unusual crystallographically characterised complex [WI(CO)(L-P,P′,P″)(η2-MeC2Me)]2[W6O19] 9. Silver tetrafluoroborate reacted with an equimolar amount of [MI2(CO)(L-P,P′)(η2-RC2R′)] in acetonitrile to give the cationic complexes [MI(CO)(L-P,P′,P″)(η2-RC2R′)][BF4] 10–13 (M = Mo, R = R′ = Me or Ph; M = W, R = R′ = Me, R = Me, R′ = Ph). The tetraphenylborate complexes [WI(CO)(L-P,P′,P″)(η2-RC2R′)][BPh4] (R = R′ = Me 14, R = Me, R′ = Ph 15) were prepared by an iodide exchange reaction of [WI(CO)(L-P,P′,P″)(η2-RC2R′)]I with Na[BPh4] in acetonitrile. The crystal structure for 14 has been determined. The dicationic complexes [W(CO)(NCMe)(L-P,P′,P″)(η2-RC2R′)][BF4]2 16–18 (R = R′ = Me or Ph; R = Me, R′ = Ph) were prepared by treating [WI2(CO)(L-P,P′)(η2-RC2R′)] with 2 equivalents of Ag[BF4] in acetonitrile. The cationic bromomolybdenum complexes [MoBr(CO)(L-P,P′,P″)(η2-RC2R)]Br (R = Me or Ph) rearrange in refluxing CHCl3 in air to give the unusual molybdenum(IV) product [MoBr2(O){Ph2P(CH2)2PPh(CH2)2POPh2-P,P′,O}] 19, which has been crystallographically characterised.