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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 phosphaalkenes 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)5MBr (M = Mn, Re) in toluene at 50−80 °C led to complexes [X = 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 extensive π-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 η2(P,S)-μ(P) bridging ligand, a coordination mode without precedence in phosphaalkene chemistry.

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Reaction of (η5-C5Me5)(CO)2FeP(SiMe3)2 (4a) with carbon disulfide afforded the unstable metallophosphaalkene (η5-C5Me5)(CO)2Fe−PC[SSiMe3]2 (5a), which decomposed to the doubly metalated 1,3,4-thiadiphosphole 8a by extrusion of bis(trimethylsilyl)sulfide. The transient metallophosphaalkene 5a was intercepted as the isolable [(CO)5Cr]-adduct 6a by treatment with [(Z)-cyclooctene]Cr(CO)5. Similarly, the metallodisilylarsanes (η5-C5Me5)(CO)2M−As(SiMe3)2 (M = Fe, Ru) (11a,b) were converted to stable metalloarsaalkenes 12a,b by exposure to CS2. Pentacarbonylchromium complexes 13a,b were accessible by reaction with [(Z)-cyclooctene]Cr(CO)5. The X-ray structure analysis of 13a revealed the molecule as the first η1-arsaalkene complex.

The reaction of the phosphavinylidene complexes [Cp(CO)2M=P=C(SiMe3)2] [Cp = C5H5, M = Mo (2), W (3)] with the ferrioaarsaalkene [Cp*(CO)2Fe–As=C(NMe2)2] (1a) (Cp* = C5Me5) afforded the novel η3‐2‐phospha‐1‐arsaallyl complexes [η3‐{[Fe]–As–P–C(SiMe3)2}M(CO)2Cp] {M = Mo, [Fe] = [Cp*(CO)2Fe] (4a);W (5a)}. Similarly, treatment of equimolar amounts of 3 with arsaalkene tBu–C(O)–As=C(NMe2)2 (1b) gave rise to the formation of [η3‐{tBuC(O)–As–P–C(SiMe3)2}W(CO)2Cp] (5b) by an arsinidene transfer process. In contrast to this, the more reactive arsaalkene 4‐Et–C6H4C(O)–As=C(NMe2)2 (1c) and complex 3 underwent reaction to give the cyclic phosphenium complex [Cp(CO)2W=P–O–Ca(4‐Et–C6H4)=As–Cb(SiMe3)2(P–Cb)] (6). The novel compounds 4a, 5a, 5b, and 6 were characterized by elemental analyses and by means of spectroscopy (IR, 1H, 13C, 31P NMR). Moreover, the molecular structures of 4a, 5b, and 6 were elucidated by X‐ray diffraction analyses.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)