New access to homodinuclear half-sandwich vinylidenemanganese complexes

The d(6) low-spin Mn-1 half-sandwich dinuclear complexes of the type [{Mn(MeC5H4)(R2PCH2CH2PR2)=C=C(SnMe3)}(2){X}] (X = {mu-1,4-C6H4}, R = Me, 2a; X = {mu-1,4-C6H4}, R = Et, 2b; X = {mu-1,3-C6H4}, R = Me, 3a; X = {mu-1,3-C6H4}, R = Et, 3b; X = {mu-4,4-C6H4-C6H4}, R = Me, 4a; X = {mu-4,4-C6H4-C6H4}, R = Et, 4b; X = {mu-1,4-C4H2S}, R = Me, 5a; X = {mu-1,4-C4H2S}, R = Et, 5b) were obtained by the treatment of [Mn(C5H4Me) (eta(6)-cycloheptatriene)] with 0.5 equiv. of the corresponding acetylene Me3Sn-C C-X-C C-SnMe3 (X = {mu-1,4-C6H4}, {mu-1,3-C6H4}, {mu-4,4-C6H4-C6H4} {mu-1,4-C4H2S}) and R2PCH2CH2PR2 (R = Me, Et) at 50 degrees C for 12 h to yield the corresponding dinuclear complexes in very good yields. These dinuclear tin-substituted vinylidene complexes were further treated with an excess of MeOH to give the corresponding dinuclear parent vinylidene complexes of the type [{Mn(MeC5H4)(R2PCH2CH2PR2)=C=C(H)}(2){X}] (X {mu-1,4-C6H4}, R = Me, 6a; X = {mu-1,4-C6H4}, R = Et, 6b; X = {mu-1,3-C6H4}, R = Me, 7a; X = {mu-1,3-C6H4}, R = Et, 7b; X = {mu-4,4-C6H4-C6H4}, R = Me, 8a; X = {mu-4,4-C6H4-C6H4}, R = Et, 8b). All dinuclear compounds were characterised by NMR and IR spectroscopy and elemental analysis. X-ray diffraction studies were performed on complexes 2b, 3a, 4a and 6a. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).