The reaction of [Mn₂{μ-σ:η²-C(R)=CHR}(μ-PPh ₂)(CO)₇] (R = H or Ph) with nucleophiles: X-ray crystal structures of [N(PPh₃)₂][Mn ₂(μ-H){μ-C(O)C(Ph)=CHPh}(μ-PPh₂)(CO) ₆], [Mn₂{PPh₂C(Ph)=CHPh}(CO)₉], [Mn₂(μ-PPh₂CH=CH...

full title:The reaction of [Mn₂{μ-σ:η²-C(R)=CHR}(μ-PPh ₂)(CO)₇] (R = H or Ph) with nucleophiles: X-ray crystal structures of [N(PPh₃)₂][Mn ₂(μ-H){μ-C(O)C(Ph)=CHPh}(μ-PPh₂)(CO) ₆], [Mn₂{PPh₂C(Ph)=CHPh}(CO)₉], [Mn₂(μ-PPh₂CH=CH₂)(CO)₈], [Mn₂{μ-C(O)C(Ph)=CHPh}(μ-PPh₂)(CO) ₆(CNBu^t)₂], [Mn₂{μ-σ:η²-C(Ph)=CHPh}(μ-PPh ₂)(CO)₆(CNBu^t)], and [mn(μ-PPh₂CH=CH₂)(CO)₇(PEt₃)] The reaction of [Mn₂{μ-σ:η²-C(R)=CHR}(μ-PPh ₂)(CO)₇] (R = H or Ph) with the nucleophiles H^-, CO, Bu^tNC, and PEt₃ have been studied and the structures of six of the products of these reactions have been determined by X-ray diffraction. In all of the products the nucleophile is bound to the metal but the course of a given reaction is highly sensitive both to the nature of the nucleophile and to the substituents on the μ-vinyl group. With H^- as the nucleophile and R = Ph the principal product is the μ-acyl complex [N(PPh₃)₂][Mn ₂(μ-H){μ-C(O)C(Ph)=CHPh}(μ-PPh₂)(CO)₆] in which the Mn-Mn distance of 2.813(1) Å indicates the presence of a metal-metal bond. With CO as the nucleophile a P-C coupling reaction between the μ-PPh₂ and the μ-vinyl ligand is induced (R = H or Ph) leading via [Mn₂{μ-PPh₂C(R)=CHR}(CO)₈] to the final product [Mn₂{PPh₂C(R)=CHR}(CO)₉] which results from the addition of a second molecule of the nucleophile. The structures of both of these P-C linked complexes have been determined by X-ray diffraction, the former for R = H and the latter for R = Ph. The Mn-Mn separations for these two complexes are 2.957(1) and 2.941(1) Å, respectively. With Bu^tNC as the nucleophile and R = Ph a μ-acyl complex, [Mn₂{μ-C(O)C(Ph)=CHPh}(μ-PPh₂)(CO) ₆(CNBu^t)₂], is also obtained as the principal product but the X-ray diffraction study reveals an Mn-Mn separation of 3.820(2) Å indicating the absence of a metal-metal interaction. A second product obtained in this reaction has been shown by an X-ray diffraction study to be the Bu^tNC-substituted vinyl derivative [Mn₂{μ-σ:η²-C(Ph)=CHPh}(μ-PPh ₂)(CO)₆(CNBu^t)] in which the Mn-Mn distance is 2.758(1) Å. With phosphines as the nucleophiles, complex mixtures of products are, in general, obtained and these products have not all been characterised. With PEt₃ and R = H, however, the principal product is the P-C linked complex [Mn₂(μ-PPh₂CH=CH₂)(CO)₇(PEt ₃)] and this has been isolated and structurally characterised by an X-ray diffraction study which shows that the Mn-Mn distance is 2.989(3) Å. Finally, with Bu^tNC as the nucleophile and R = H a compound is formed which is tentatively assigned a structure analogous to that obtained with PEt₃ as the nucleophile. Some reaction pathways which account for the formation of the major products in the above reactions are proposed and discussed.