1H CIDNP Study of the Addition Reaction of Me2E (E = Si,Ge) to a CarbonCarbon Triple Bond

Fast Processes and Intermediates in Photochemistry of 7-Dimethyl-germanorbornadiene

“…γ T1 ) 0.34 indicates that the dissociation of the biradical (eq 19) determines almost one-third of the total yield of photoreaction. The detection of photo CIDNP effects in reactions of triplet dimethylgermylene [20][21][22] points to the existence of the reaction in eq 20, but the yield of the triplet state is not defined.…”

“…Therefore, an application of the 1 H CIDNP method suggests two different pathways of GNB phototransformation. [20][21][22] The first pathway involves a one-step mechanism of GNB dissociation, accompanied by the simultaneous cleavage of both Ge-C bonds. The second pathway is a two-step mechanism of GNB photocleavage through the consecutive cleavage of two Ge-C bonds.…”

Silylenes

“…The observation of 1 H CIDNP signals during the addition of Me 2 Si (and Me 2 Ge) to a strained alkyne (equation 60), has been interpreted as indicating stepwise addition of excited triplet states of the divalent species to the triple bond 135 . One wonders, however, if there are not other viable explanations for the CIDNP signals, such as silylene(germylene) transfer from a diradical formed by homolysis of one of the bridging Si C(Ge C) bonds in the precursor (Scheme 3, Section II.C.2).…”

Paramagnetic intermediates in the photoinduced reaction between dodecamethylcyclohexasilane and 9,10-phenanthraquinone: Time-resolved CIDNP study

“…However, high sensitivity and accuracy of structural identification of short-lived particles by spin chemistry methods -Chemically Induced Dynamic Nuclear Polarization (CIDNP), Chemically Induced Dynamic Electron Polarization (CIDEP), and Magnetic Field Effects (MFE) -make them extremely useful for the investigation of structure and reactivity of organometallic paramagnetic intermediates. Numerous examples demonstrate the successful application of these methods to the investigations of organometallic reactions involving Si-and Ge-derivatives [12][13][14][15][16][17].…”