Addition Reactions of Organometallic Compounds with Conjugated Systems¹

Diphenylberyllium Reinvestigated: Structure, Properties, and Reactivity of BePh2, [(12‐crown‐4)BePh]+, and [BePh3]−

“…[29] We observed exchange between the terminal and the m 2bridging phenylu nits of 1 via exchange NMR Spectroscopy (EXSY), meaning that the phenyl groups constantly change their positions from terminal to bridging in solution.T he protons within the phenylg roups do not exchange with each other.T herefore, the BeÀCb ond is not broken and we assume that the interchange between terminal and bridging phenyl groups occurs via dissociation and recoordination of BePh 2 units. This exchange of the phenyl groups in conjunction with the quadrupolar nature of the 9 Be nucleusl eads to broadening of the signals in the 9 Be NMR spectrum as well as the 13 CNMR spectrum,e specially for the signals of the carbon atoms directly bound to the Be atoms, which makes them barely noticeable. Additional line broadening is also caused by the lows olubility of 1 in C 6 D 6 ,C D 2 Cl 2 and CDCl 3 .W hereas 1 is not stable in the latter for more than af ew days.…”

“…[10] With slight variation, the transmetallation remained the method of choice to obtain pure BePh 2 ,even though varioussources mention reproducibility problems and suggest numerousa dditives to improve the synthesis. [6,[9][10][11][12] Therefore, alternative syntheses for BePh 2 have been described, such as the phenylation of BeCl 2 either by LiPh [13] or through aG rignard reagent [14] that yield the corresponding ether adduct of BePh 2 .T hough, these sources mention that in contrastt ot he beryllium alkyls like BeMe 2 , [1,9,15] BeEt 2 [9] or BenBu 2 , [4] it is not possible to remove the ether from BePh 2 , [13,14] since it can neither be distilled nor sublimed. [14,16,17] These obstacles might be the reason why BePh 2 has hardly been investigated and compounds obtained from it are scarce.…”

High-valent Organomanganese Compounds

“…For example, treatment of MnCl 2 with 2 equiv. of the sterically-hindered pentadienyl derivative 3-Me-l,5-C 5 H 4 (TMS) 2 gives the manganate salt K[Mn{3-Me-l,4-C 5 H 4 (TMS) 2 } 3 ] (19), which is a three-coordinate high-spin manganese(II) complex with three unidentate pentadienyl ligands. 89 Attempts to prepare an open manganocene with the less sterically-hindered 3-methyl-2,4-pentadienyl anion led instead to the isolation of the trinuclear complex Mn 3 (3-MeC 5 H 6 ) 4 (20) .^ An x-ray crystallographic study shows that this cluster has a nearly linear Mn-Mn-Mn backbone (Mn-Mn = 0.2316 nm), and magnetic susceptibility measurements show that there are five unpaired electrons per cluster.…”

Reactions of Triethylaluminum with α,β-Unsaturated Carbonyl Compounds

“…(2). They have also further disclosed that, in the case of a homolog of methylene- (2) benzalanthrone for example, the 1,6-addition is inhibited and the 1,2-addition is realized.…”