177283-11-3Relevant articles and documents
Versatile routes to mono- and bis(alkynyl) manganese(II) and manganese (III) complexes via manganocenes
Unseld, Dieter,Krivykh, Vassily V.,Heinze, Katja,Wild, Ferdinand,Artus, Georg,Schmalle, Helmut,Berke, Heinz
, p. 1525 - 1541 (2008/10/08)
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.
