16035-50-0Relevant articles and documents
Peralkynylated Tetraazaacene Derivatives
Bunz, Uwe H. F.,Freudenberg, Jan,Reiss, Hilmar,Rominger, Frank
, (2019)
The synthesis of a decaethynylated tetraazapentacene is described. It was obtained by a combination of condensation reactions giving the two pyrazine rings and subsequent consecutive Stille-type couplings. This is the first example of any higher (hetero)acene that is peralkynylated. The presence of the four nitrogen atoms removes the peri interaction of the substituted alkyne groups, giving this rock-stable and highly twisted heteroacene.
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.
Reactivity of bicyclic N-pyrrolylboranes
Wrackmeyer, Bernd,Schwarze, Bernd,Milius, Wolfgang
, p. 297 - 308 (2007/10/03)
Bicyclic B-alkyl-N-pyrrolylboranes (1-3) react with alkyl lithium or alkyl Grignard reagents to give the corresponding borates 5 which, in most cases can be protonated to the intramolecular 2 H-pyrrole-borane adducts 4. The molecular structure of 4d was d
Alkynyl-siibstituted tricarbonyl(cyclobutadlene)iron complexes: coupling of complexes sfannylalkynes
Bunz, Uwe H. F.,Jutta
, p. 785 - 797 (2007/10/03)
The synthesis of mono-, di-, tri- and tetraalkynylated tricartaonyl(cyclobutadiene)iron complexes is accomplished by a repetitive metalation/iodination/coupling sequence. Application of this sequence leads to the synthesis of oligomeric cyclobutadiene complexes with various topologies, inter alia to the synthesis of a perethynylated aimer 24. Alternatively a one-step coupling procedure (Stille-Farina) has been used to synthesize tetraalkynylated tricarbonyl(cyclobutadiene)irons 26, VCH Verlagsgesellschaft mbH, : 1996.
The β-effect with vinyl cations: Kinetic study of the protiodemetalation of silyl-, germyl-, and stannylalkynes
Dallaire, Carol,Brook, Michael A.
, p. 2332 - 2338 (2008/10/08)
The relative magnitude of the hyperconjugative stabilization of vinyl cations by adjacent C-M bonds (M = Si, Ge, Sn; the β-effect) has been examined by measuring the rate constants for the protonation and subsequent protiodemetalation of group 14 metalated (trimethylsilyl)-acetylenes (R3MC≡CSiMe3). The relative β-effect arising from the second-order rate constants Sn ? Ge > Si (maximum kM/kSi = 108, 5 × 102, 1, respectively) follows the same order as that reported for simple carbenium ions. The product ratio from the protonation of Ph3GeC≡CSiMe3 was found to be particularly sensitive to acid concentration and strength, leading to loss of Ph3Ge preferentially with weaker acids. With tin groups, the rate of destannylation decreased with increasing steric bulk, unlike the corresponding situation with silyl groups. The origins of both these observations may be attributed to nucleophilic interaction at the metal center during protonation.
Organometallic acetylene chemistry II. Disubstituted acetylenes of the type R3MCCM′R3
Findeiss, Wolfgang,Davidsohn,Henry
, p. 435 - 441 (2008/10/08)
A series of organometallic acetylenes has been prepared which contain two different organometallic moieties from the Group IV elements. These compounds were synthesized via a convenient new route starting with the corresponding organometalamino compound, organometallic halide, and sodium acetylide.
