Syntheses and Structures of C-Monoamino-P-ferriophosphaalkenes[(η5-C5Me5)(CO)2FeP=CR1(NR)] (R1 = Ph, tBu, 3,4,5-(MeO)3C6H2;NR = NMe2, Piperidino)

Abstract

Reaction of equimolar amounts of the carbenium iodides [Me2N(R)CSMe]I [1a: R = Ph; Ib: tBu; Ic: 3,4,5-(MeO)(3)C6H2], [pip(Ph)CSMe]I (Id) (pip = piperidino), and LiP(SiMe3)(2). DME afforded phosphaalkenes Me2N(R)C=PSiMe3 (2a-c) and pip(Ph)C=PSiMe3 (2d). Combination of 2a-d with [(eta(5)-C5Me5)(CO)(2)FeCl] led to the formation of [(eta(5)-C5Me5)(CO)(2)FeP=C(R)NMe2] [3a: R=Ph; 3b: tBu; 3c: 3,4,5-(MeO)(3)C6H2] and [(eta(5)-C5Me5)(CO)(2)FeP=C(Ph)pip] (3d). Compounds 2a-d and 3a-d were characterized by means of spectroscopy (IR, H-1, C-13{H-1}, P-31{H-1} NMR). The molecular structures of 3a and 3b were determined by X-ray diffraction analysis. The results of an X-ray study on [(eta(5)-C5Me5) (CO)(2)Fe-P= C(Ph)SiMe3] (3g) for comparison are also included. AU experimental observations are rationalized by the assumption that complexes 3a, 3c, and 3d are phosphaalkenes with an inverse pi-electron distribution (Pdelta-Cdelta+) and are comparable to [(eta(5)-C5Me5) (CO)(2)FeP=C(NMe2)(2)] (3e), whereas 3b is better regarded as phosphaalkene with a normal polarization (Pdelta+ Cdelta-) of the P=C bond, similar to that given in 3g.