With the manganocenes (RC5H4)2Mn (R = H, Me) as starting materials, paramagnetic d5 half-sandwich complexes (RC5H4)Mn(dmpe)(C⋮CR‘) (dmpe = 1,2-bis(dimethylphosphino)ethane; R = Me, R‘ = Ph, 1a; R = Me, R‘ = SiMe3, 2a; R = H, R‘ = Ph, 1b; R = H, R‘ = SiMe3, 2b) have been prepared by the reaction with terminal or SnMe3-substituted acetylenes and dmpe. The derivatives 1a and 2a could be isolated, while 1b and 2b have been identified in mixtures with the bis(dmpe)bis(acetylide)manganese species 3 (R‘ = Ph) and 4 (R‘ = SiMe3). The latter compounds are obtained as the sole products, when the manganocenes are reacted with dmpe and the corresponding acetylenes in a 1:2:2 ratio. 1a and 2a can be reversibly oxidized to the corresponding cationic Mn(III) complexes [(MeC5H4)Mn(dmpe)(C⋮CR‘)][BF4] (R‘ = Ph, [1a]+; R‘ = SiMe3, [2b]+). Compounds 1a and 2a act as scavengers of H• radicals in the 1:1:1 reaction mixtures or in the presence of n-Bu3SnH or (C5Me5)Mo(CO)3H, forming the vinylidene species (MeC5H4)Mn(dmpe)(CC(H)R‘) (R‘ = Ph, 5; R‘ = SiMe3, 6). In the absence of a special H• donor, 1a slowly dimerizes to give the binuclear complex 7. A similar process occurs with [1a]+ to form the bis(carbyne) complex 8. 8 can be reduced to 7 by a reaction with 2 equiv of (MeC5H4)2Co, and in turn 7 can be oxidized to 8 with 2 equiv of a ferrocenium salt. Equal amounts of 7 and 8 comproportionate to afford the mixed-valence complex [7]+. If applicable, the new compounds have been characterized by spectroscopic (NMR, EPR, near-IR) and electrochemical measurements, as well as X-ray diffraction studies (2a, 5, 7, and 8) and DFT calculations.

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Ferrocenium salts [(C5H5)2Fe]X (X = BF4, PF6) (I+·) react with tertiary phosphines PR3 (PMe3, PEt3, PnBu3, PMe2Ph, and PMePh2) in dichloromethane at room temperature to form a mixture of the corresponding ferrocenylphosphonium salts [(C5H5)FeC5H4PR3]X (III), ferrocene (I), and phosphonium salts [HPR3]X. The same reaction was carried out in an electrochemical cell as the electrolysis of a solution of ferrocene and phosphine in dichloromethane at the oxidation potential of ferrocene. Possible reaction pathways for phosphination of ferrocenium ion were studied by DFT at the M06‐L/6‐311++G(d,p) theory level. The experimental and theoretical studies of this reaction suggest it to proceed according to the Scheme of oxidative nucleophilic substitution of hydrogen in I+· including the following steps: a) nucleophilic exo addition of a phosphine to the cyclopentadienyl ring of I+· to form the radical cation adduct [(η5‐C5H5)Fe·(η4‐C5H5–+PR3)]X (II+·); b) redox reaction of the initial adduct II+· with the starting ferrocenium salt I+· to result in ferrocene (C5H5)2Fe (I) and iron phosphoniocyclopentadiene dication [(η5‐C5H5)Fe+(η4‐C5H5–+PR3)](X)2 (II2+) where the Csp3–H bond is involved in the agostic interaction with the metal atom; and c) deprotonation of the Csp3–H bond in II2+ by the starting phosphine to form III. The relation between the data obtained and current concepts of C–H functionalization in transition metal arene and cyclopentadienyl complexes is discussed.

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The reactions of the MenC6H6_,~M(CO)_~ (M = Cr, Mo, W; n = 3, 5, 6) and CsRsM(CO) 3 (M = Mn, Re; R = H, Me) complexes wilh propargyl alcohol in acidic media under UV irradiation were studied. Novel MenC6H6_nM(CO)2(H3-C3H3)BF4 (M = Mo, W; n = 3,5,6) and CsRsRe(CO)2(rl3-C3H3)CF3SOa complexes with the 3e-propargyl ligand were synthesized, and their properties compared with those of similar rl3-allyl derivatives. The structure and dynamic properties of the compounds obtained are discussed.Key words: 2-hydroxyallyl complexes, ri3-propargyl complexes, synthesis, temperature dependence, IR spectra, IH and )3C NMR spectra.Generation of the carbenium center at the ~x-position to the double bond coordinated with the transition metal atom results in the formation of stable cationic complexes with the rl3-allyl ligand. These transformations have previously been studied IJ in detail for complexes of Group VI--Vlli metals with olefinic ligands based on allyl alcohol or conjugated dienes in acidic media. The works on studying stabilization of carbenium ions at the (z-position to the coordinated triple bond resulted in synthesis of sufficiently stable cationic complexes of Mo, 3,4 W, 3 Re, 5-7 Zr, 8 Pd, 9,10 and Pt 9,11-14 with the three-electron rl3-propargyl ligand. This work is devoted to studying the regularities of formation of mononuclear cationic complexes of Group VI and VII metals with the 3~-rl3-propargyl ligand and their structure.We have previously found I that UV irradiation of arenechromiumtricarbonyl derivatives in the presence of propargyl alcohol and aqueous tetrafluoroboric acid or its ether'ate (Scheme 1) results in the formation of cationic complexes with the 2-hydroxyallyl ligand (la--e). Cr(CO) 3Scheme 1 + HC --CCH20H + HBF a Et20 Unlike arenechromiumtricarbonyls, a similar onestage reaction of CpM(CO) 3 (M = Mn, Re) resulted in the formation of cationic complexes in low yields and was accompanied by a considerable decomposition of the reagents. For example, according to the data of ]H NMR spectroscopy, UV irradiation of an ethereal solution of CpMn(CO) 3 and propargyl alcohol followed by treatment of the n-complex with propargyl alcohol (2) formed in situ with 48% aqueous HBF 4 (Scheme 2) affords a mixture of two rt-allyl complexes 3 and 4 approximately in a ratio of 2.5 : 1.0, which, however, does not necessarily reflect the initial ratio of reaction products, because their multiple precipitation with ether from nitromethane was required to obtained a satisfactory" ~H NMR spectrum. In the case of CpRe(CO)3, this reaction in ether is impeded by the formation of a sufficiently stable

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