Group 14 carbene analogs

The addition of isocyanates (isoelectronic to CO) to group 14 carbene analogs was investigated in order to see if the resulting molecules w ould have an allene-like framework. In the first study, Wcidenbruch et attempted to synthesize... 

Insertion of highly reactive group 14 carbene analogs into metal-metal bonds is a step toward cluster building and germylenes readily insert into the Fe—Fe bond of [CpFe(CO)2]2 under mild conditions (equation 20)101. 

In the case of the FpGeMe2SnMe3, this compound rearranges prior to loss of the group 14 carbene analog to form FpSnMe2GeMe3. This illustrates the more or less equal stability of the stannylene and germylene intermediates, as may be expected. 

The synthesis and characterization of the monomeric amidinato-indium(I) and thallium(I) complexes [Bu C(NAr)2]M[But(NAr(NHAr)] (M = In, Tl Ar = 2,6-Pr2CgH3) have been reported. Both compounds were isolated as pale yellow crystals in 72-74% yield. These complexes, in which the metal center is chelated by the amidinate ligand in an N, j -arene-fashion (Scheme 33), can be considered as isomers of four-membered Group 13 metal(I) carbene analogs. Theoretical studies have compared the relative energies of both isomeric forms of a model compound, In[HC(NPh)2]. ... 

It is often difficult to deduce from the restricted experimental data the main trends in reactivity. Theoretical calculations could give the needed information to fill these gaps. In other words, they could be used to sometimes interpolate scarce experimental data, e.g. in studying substituent effects. To examine general trends in the series of Group 14 elements carbene analogs, data for silylenes and even for carbenes are presented in this section for some cases. 

N. J. Hardman, A. D. Phillips, and P. P. Power, Bonding and Reactivity of a /3-Diketiminate, Gallium(l), Carbene Analog, in Group 13 Chemistry. From Fundamentals to Applications , ACS Symposium Series 822, eds. P. J. Shapiro... 

Claims for the synthesis of small unsaturated ring systems containing a metalloid atom have an interesting history. In the early 1960s, a series of papers appeared describing the products of reaction of Group IV analogs of carbene with tolan 197, 208, 346, 350-353) ... 

If the groups are lost from a single center (a-elimi-nation, 1/1/elimination), the resulting product is a car-bene or a carbene analog. 

Heavier Group 14 Analogs of Carbene and Carbyne Complexes... 

Scheme 14.5 An example of the coordination of an N-heterocyclic carbene analog to a Group 14 center, generating single Ga-E bonds.

Lappert, M. F., Heavy Atom Main Group IVA Analogs of Carbenes, Radicals, and Alkenes. The Use of Bulky Trimethylsilyl-Substituted Ligands, Silicon, Germanium, Tin Lead Comp. 9 [1986] 129/54. 

Aziridines can be prepared directly from double-bond compounds by photolysis or thermolysis of a mixture of the substrate and an azide. The reaction has been carried out with R = aryl, cyano, EtOOC, and RSO2, as well as other groups. The reaction can take place by at least two pathways. In one, the azide is converted to a nitrene, which adds to the double bond in a manner analogous to that of carbene addition (15-62). Reaction of NsONHC02Et/ CuO [Ns = A(/7-toluenesulfonyl-inimo)] and a conjugated ketone, for example, leads to the A-carboethoxy aziridine derivative.Calcium oxide has also been used to generate the nitrene.Other specialized reagents have also been used." ... 

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