REACTION BEHAVIOR OF METAL COORDINATE 1-M OLYBDA-2-PHOSPHA-1,3-DIENESWITH ALKYNES AND DIYNES

Treatment of eta(2)-((R-1)[(Ph)(H)C=CH]P=[MO]}Fe(CO)(4) (1) or eta(4)- {(R-1)[(Ph)(H)C=CH]P=[Mo]}Fe(CO)(3) (2) {[Mo] = Mo(eta(5)-C5H5)(CO)(2) ; R-1=2,4,6-(Bu3C6H2O)-Bu-t) with HC=R-2 [3a: R-2=(CH2)(2)CH3; 3b: R-2 =Ph] or HC=C-C6H4-C=CH (5) produces complexes eta(3)-((R-1)[(Ph)(H)C=C H] P-Fe-III(CO)(3) -C-III(R-2)-C-III(H))[Mo] [4a: R-2 = (CH2)(2)CH3; 4 b: R-2 = Ph] or (eta 3-((R-1)- [((Ph)(H)C=CH] P-Fe-III(CO)(3) -C-III-C -III(H)}[Mo]}(2)C6H4 (6) respectively. Each of these molecules contain s a 1-ferraallyl moiety, which is eta(3)-coordinated to an [Mo] buildi ng block. A possible reaction sequence for the formation of compounds 4 and 6 is described. The presented mechanism is corroborated by syste matic studies of the reaction behaviour of 2 with different Lewis base s L [L = CO, PPh3, PPh2(C=CPh)]. As an initial step, the formation of eta(2)-((R-1)[(Ph)(H)C=CH]P=[Mo]}Fe(CO)(3)(L) [1: L= CO; 8a: L=PPh3; 8 b: L = PPh2(C=CPh)] is discussed. The result of the X-ray structure an alysis of compound eta(3)-((R-1)[(Ph)(H)C=CH]- P-Fe-III(CO)(3)-C-III(P h)-C-III(H)}[MO] (4b) is reported. 4b crystallizes in the triclinic sp ace group P (1) over bar with the cell parameters a = 1064.7(2), b = 1 411.0(3), c = 1617.3(4)pm, alpha = 81.74(2), beta = 80.89(2), gamma = 73.05(2)degrees, V = 2282.5(9) X 10(6) pm(3) and Z = 2.