Reactions between the 1,3-diphosphete complex [Cp'''Co(η -P C tBu )] (1) and Ag[Al{OC(CF ) } ] (Ag[pftb]) were carried out under different conditions. In CH Cl , the unprecedented 1,2-diphosphete isomerization product [Ag {Cp'''Co(μ,η :η :η -1,2-P C tBu )} {Cp'''Co(μ,η :η -1,2-P C tBu )} ]⋅2[pftb] (2) could be isolated. In diffusion experiments of 1 in n-hexane with Ag[pftb] in CH Cl , the triphosphacobaltocenium complex [Cp'''Co(η -P C tBu )][pftb] (4) and the phosphirenylium complex [Cp'''Co(η -PC tBu )][pftb] (5) were obtained, showing a ring expansion and a ring contraction, respectively, under mild conditions. Moreover, addition of pyridine to the Ag complex 2 led to the new 1,2-diphosphete complex [Cp'''Co(η -1,2-P C tBu )] (3). Compound 3 is also formed by thermolysis of 1, making it a promising method for this type of isomerization. 1,2-Diphosphete complexes like 3 are thermodynamically more stable but also synthetically more elusive than their 1,3-isomer counterparts.

By using [(CpЈЈЈCo) 2 tol] (CpЈЈЈ = η 5 -C 5 H 2 tBu 3 , tol = toluene), a new synthesis of the 1,3-diphosphete complexes [CpЈЈЈCo(η 4 -P 2 C 2 tBu 2 )] (1a) and [CpЈЈЈCo(η 4 -P 2 C 2 iPr 2 )] (1b) was found, and their reactions with the Lewis acids W(CO) 4 and Cu I halides were investigated. The reaction of 1b with W(CO) 4 (nbd) (nbd = norbornadiene) leads to the complex [(CpЈЈЈCo)(μ,η 4:1 -{PCiPr} 2 )] 2 W(CO) 4 (2) with the two diphosphete complexes 1b coordinated trans to a central W(CO) 4 moiety. The reactions of 1a with Cu I halides result in different products depending on the stoichiometry. In a 1:1 ratio, the dimeric compounds 3a-c [(CpЈЈЈCo)(μ,η 4:1 -{PCtBu} 2 )Cu(μ-X)] 2 (3a: X = Cl; 3b: X = Br, 3c: X = I) were isolated, whereas[a]

The missing member [Cp′′2Zr(η2‐P3CtBu)] (Cp′′=η5‐C5H3tBu2) of the phosphorus‐containing bicyclobutane zirconium complex family was synthesized by reaction between tetraphosphazirconocene derivative [Cp′′2Zr(η2‐P4)] and a phosphaalkyne with the release of a formal P2 unit. Synthetic evidence of another unknown isomer [Cp′′2Zr(η2‐P2(CtBu)2)] was found; according to DFT calculations, it is the stable form if a Cp′′2Zr moiety is used.

The reaction of LCr5CrL (L = N2C25H29, 1) with the phosphaalkynes R-CΞP (R = tBu, Me, Ad) yields the neutral dimerisation compounds [L2Cr2(µ,η1:η1:η2:η2-P2C2R2)] (R = tBu (2), Me (3)) and...