Silole

Intereshngly it is also possible to form a stable silicon-fluonne bond by treatment of a methoxysilole with boron-tnfluonde etherate or of a silole with tntyl tetrafluoroborate [106] The resultant fluorosilane is also a buildmg block for further transformations of the silole (equation 84)... 

The polymeric species containing silole nuclei also form the Fe(CO)3 complexes -coordinated via the heteroring on interaction with Fe(CO)5 [93JOM(456)35 990M1717],... 

Silole reacts with Co2(CO)g to form the monosubstituted ri -silacyclopentadiene complex 286 [85JOM(293)295]. The 2,5-diphenyl analog of the latter with excess silole yields the corresponding disubstituted derivative 287 [87JOM(320)C7]. The similar complex was previously made for the 1,1-dimethyl derivative [76JCS(D)2484], Treatment of 287 with iodine gives 288. 

Organometallic chemistry of silole and germole, recently dominated by the -q species, tends to enhancement of the range of the representatives. Cases of the TiVSi, Ge) coordination in the pure and mixed situations are known as well. 

The fourth chapter of this volume comprises the second part of an ongoing series by Professor A. P. Sadimenko (Fort Hare University, South Africa) dealing with organometallic compounds of pyrrole, indole, carbazole, phospholes, siloles, and boroles. This follows the review in Volume 78 of Advances covering organometallic compounds of thiophene and furan. The enormous recent advances in this area are summarized and classified according to the nature of the heterocycle and of the metals. 

Pyrroles, indoles, carbazoles, phospholes, siloles and boroles in... 

In contrast to other heterocyclopentadienes (e.g. siloles and pyrroles), phospholes possess a reactive heteroatom. This feature allows direct access to a range... 

To see if silacyclobutenes (28) would react in the same manner as the alkynyl-polysilanes (1) and respond similarly to steric differences, compounds 28a and b were heated in the presence of NiCl2(PEt3)2 and PTMSA (Scheme 9). " Compound 28a gave silole 20a in 94% yield,but the only isolable products from the thermolysis of 28b were 26 (51%) and 27b (36%). The products from the thermolysis of silacyclopropene 28b were very similar to that for alkynylsilane lb, but for some reason there were many fewer products for the thermolysis of 28a than for alkynylsilane la. These results suggest that the more sterically hindered lb... 

Cyclic Anions (Silole and Germole Anions and Dianions) 91... 

Reductive cleavage of the Si-Si bond of bis(siloles) with alkali metals resulted in the formation of silole monoanions (Scheme 2.49). Silole monoanions were found to be aromatic on the basis of NMR spectral data and calculations. 

In contrast to the case of the silole dianion and similar to the case of ger-mole dianion (Section 2.3.2.5), stannole dianion 68 [Li+(Et20)]2 has both Li ions above and below the plane being pentahaptocoordinated to the SnC4 five-membered ring. " The stannole ring is nearly planar and the endocyclic C-C bonds are... 

For R = H the silole 51 had a at 278 nm while the silylene 48 absorbed at 250 and 480 nm. The isomeric silenes 49 and 50 absorbed at 2% and 270 nm, respectively. The UV absorptions for these species have been calculated and assigned, and their IR spectra have also been obtained. When R = Me, there was little change in the A.max, the four species absorbing at 280, 255 and 480, 312, and 274 nm, respectively. 

Thermal cracking at 150°C of the dimer (mixed isomers) of the silole in presence of reactive dienophiles (maleic anhydride, tetracyanoethylene or dimethyl acetylenedicarboxylate) inevitably produced violent explosions arising from exothermic Diels-Alder reactions. 

Reaction of 1-boraadamantane with di-alkynylsilicon and -tin compounds <2001CEJ775> is accompanied by intramolecular 1,1 -vinylboration giving rise to siloles or stannoles 87 and permitting the enlargement of the 1-boraadamantane system by two carbon atoms (Scheme 39, pathway a). 

The reaction of the tetrayne pentasilane with triallylboranes furnishes a mixture of silole 121 and compound 122 in a 1 5 ratio (Scheme 51). An excess of AII3B did not induce further allylboration with the remaining C C bonds even upon prolonged heating <2002JOM(649)232>. 

The reaction of triallylborane with silicon triyne 123 is interesting. A113B attacks both internal and external triple bonds giving rise to silole 124 and two heterocycles with bridgehead boron 125 and 126 in a 1 3 3 ratio as a result of competitive sequential reactions (Scheme 52). When 1,1-allylboration of the internal C C bond followed by intramolecular 1,1-vinyIboration takes place, the silole 124 is formed, while in another case 1,1-allylboration followed by a series of intramolecular 1,2-allylboration reactions leads to boron derivatives 125 and 126 <2002JOM(657)146>. 

The silole and germole anions have been a topic of interest for quite some time, with initial theoretical studies of the silole anion dating back to 1983.198 The following narrative provides a brief glimpse into this area. 

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