02271nas a2200181 4500008004100000022001400041245007900055210006900134260011000203300001600313490000700329520156600336100002601902700001401928700001801942700001901960856011001979 2015 eng d a1477-922600aCations and dications of heavier group 14 elements in low oxidation states0 aCations and dications of heavier group 14 elements in low oxidat aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUN a12903-129230 v443 a

Cations and dications of heavier group 14 elements in their low oxidation state have received widespread attention in recent years. The journey started with the isolation of a series of cations of the composition [(C5Me5)E:](+) [E = Si-Pb], followed by the more recent isolation of a Ge(II) dication encapsulated within a cryptand, a carbodiphosphorane stabilized [GeCl](+) monocation with a two coordinate Ge atom, Si(II) cations and dications stabilized by N-heterocyclic carbenes (NHCs), which highlights the ongoing growth and interest in the chemistry of tetrel(II) cations. This is presumably because the central atom (E) in these compounds contains two or three unoccupied valence orbitals as well as holds a lone pair of electrons. Such an electronic description represents ambiphilicity, which is of great interest for catalysis. The successful synthesis of divalent group 14 cations requires new synthetic strategies based on the sterically demanding neutral or monoanionic ligands, utilization of counter anions, and solvents with low nucleophilicity in order to minimize the degree of interactions with the cations. An alternative approach for the realization of divalent cations of group 14 elements is their coordination to the transition metals. This synthetic approach was successfully applied for the isolation of a range of transition metal coordinated divalent cations of group 14 elements. Apart from arousing academic interest some of these cations have found application as activators in the Ziegler-Natta polymerization of alkenes.

1 aSwamy, V., S. V. S. N1 aPal, Shiv1 aKhan, Shabana1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/cations-and-dications-heavier-group-14-elements-low-oxidation-states-001429nas a2200289 4500008004100000022001400041245008100055210006300136260000800199490000700207520052100214653002200735653001300757653003100770653001700801653001200818653002800830653002300858653002600881653002500907653002900932100002600961700002000987700001501007700001901022856009801041 2017 eng d a1359-734500aC(sp(3))-F, C(sp(2))-F and C(sp(3))-H bond activation at silicon(II) centers0 aCsp3F Csp2F and Csp3H bond activation at siliconII centers cSEP0 v533 a

Silylene [PhC(NtBu)(2)SiN(SiMe3)(2)] (1) cleaves the C(sp(3))-H and C-F bonds of acetophenone and 1,1,1-trifluoroacetophenone, respectively, under mild conditions. The reaction is initiated via a nucleophilic attack from the oxygen to the silicon atom followed by C-F/H bond cleavage. The scope of C-F bond activation has further been extended with C6F6 and C6F5CF3.

10aBoron triple bond10aC-F Bond10aFluorinated Building-Block10aH Activation10aKetones10aN-heterocyclic carbenes10aOxodative Addition10aPerfluorinated Arenes10aSelective Activation10aTransition-Metal Centers1 aSwamy, V., S. V. S. N1 aParvin, Nasrina1 aRaj, Vipin1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/csp3-f-csp2-f-and-csp3-h-bond-activation-siliconii-centers