SYNTHESIS, STRUCTURE, AND COORDINATION CHEMISTRY OF P-ACYL-SUBSTITUTED, P-THIOCARBAMOYL-SUBSTITUTED, AND P-DITHIOCARBOXYL-SUBSTITUTED PHOSPHAALKENES R(X)C-P=C(NME2)(2) (R = PH, TBU, SSIME3, N(PH)SIME3 X = O, S)

Reaction of Me3SiP = C(NMe2)(2) (1) with pivaloyl chloride and benzoyl chloride afforded the acylated phosphaalkenes RC(O)P = C(NMe2)(2) 2a (R = tBu) and 2b (R = Ph). Carbon disulfide and phenyl isothiocyanate were inserted into the P-Si bond of 1 to give the functionalized phosp haalkenes R(X)C-P = C(NMe2)(2) 2c [R(X)C = Me3Si-S(S)C] and 2d [R(X)C = Ph(Me3Si)N(S)C]. Heating 2c and 2d with (CO)(5)MBr (M = Mn, Re) in t oluene at 50-80 degrees C led to complexes [X = CSM(CO)(3)-mu-PC(NMe2) (2)](2) 3c (M = Mn, X = S), 3d (M = Mn, X = NPh), 4c (M = Re, X = S), and 4d (M = Re, X = NPh). The X-ray structure analysis of 2c showed ex tensive pi-delocalization of electron density from phosphorus into the C = S group. The structure determination of 4d revealed the molecule as a tricyclic system with an anti orientation of the peripheric four- membered rings. The organophosphorus fragment serves as eta(2)(P,S)-mu (P) bridging ligand, a coordination mode without precedence in phospha alkene chemistry.