No abstract

The structure of 4a has been determined by X-ray diffraction.

Reaction of the phosphenium complexes Cp(OC)2W=P(tBu)(R) [R = tBu (2a), Ph (2b)] with ethyl isothiocyanate (3) leads to the formation of the phosphametallacycles Cp(OC)2W–P(tBu)(R)–C(=NEt)–S(W–S) (4a, b) by [2 + 2] cycloaddition. In contrast, the “in situ” reaction of 2a, b, generated from Cp(OC)2[H(tBu)(R)P]W–Cl (1a, b) with DBU in the presence of 3 leads to the spirocyclic phosphorus metal compounds {Cp(OC)2W–P(tBu)(R)–N(Et)–Ca[N(Et)–(CH)–N(Et)CbH2]–S(W–S)(Ca–Cb)}Cl (6a, b). The structure of 6a has been proved by X‐ray analysis.

The three-membered phosphametallacycles [R = o-Tol (3a), R = Ph(3b)] react with the tertiary phosphanes Me3P (4a), Me2PhP (4b) or MePh2P (4c) with ring opening and deselenation to the metallo-phosphanes fran.s-Cp(OC)2(R3P)WP(o-Tol)(R) (5a-d). Analogous reactions of the P-thioformamido- and formamido-substituted metallacycles [R = Mes, X = S (6a); R = t-Bu, X = O (6b)] with Me3P (4a) yield in the case of 6a the tungsten-phosphane Cp(OC)2(Me3P)W-P(Mes)[C(S)N(H)Et] (7), while 6b affords the tungsten-selenophosphorane Cp(OC)2(Me3P)W-P(Se)(f-Bu)[C(0)N(H)Et] (8 ). Treatment of 7 with hydrogen chloride affords {Cp(OC)2(Me3P)W-P(H)(Mes)[C(S)N(H)Et] }C1 (9). With methyliodide, 8 is transformed into {Cp(OC)2(Me3P)W-P(SeMe)(t-Bu)[C(O)N(H)Et]}I (10)