Annulated 1,4-Disilabenzene-1,4-diide and Dihydrogen Splitting.

The isolation of silicon analogues of phenyl anions such as (CH) and (CH) is challenging owing to their extremely high reactivity associated with their silylene character and weak C-Si π-interaction. Herein, we report the first annulated 1,4-disilabenzene-1,4-diide compound [(ADC)Si] () based on anionic dicarbene (ADC) scaffolds (ADC = PhC{N(Dipp)C}; Dipp = 2,6-PrCH) as a green-yellow crystalline solid. Compound is prepared by KC reduction of the Si(IV) chloride [(ADC)SiCl] () or the cyclic bis-chlorosilylene [(ADC)SiCl] (), which are also prepared for the first time.

Divergent Reactivity of a Cyclic Bis-Hydridostannylene: A Masked Sn(I) Diradicaloid.

Herein, reactivity studies of a cyclic bis-hydridostannylene [(ADC)SnH] (1-H) (ADC=PhC{(NDipp)C}; Dipp=2,6-iPrCH) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1-H afford mixed acetylide-vinyl-functionalized bis-stannylenes via dehydrogenation and hydrostannylation. Treatment of 1-H with PhC≡CCH gives a unique distannabarrelene via dehydrogenative C-H stannylation and hydrostannylation of the C≡CCH moiety.

Isolation of an Anionic Dicarbene Embedded Sn P Cluster and Reversible CO Uptake.

Decarbonylation of a cyclic bis-phosphaethynolatostannylene [(ADC)Sn(PCO)] based on an anionic dicarbene framework (ADC = PhC{N(Dipp)C} ; Dipp = 2,6-iPr C H ) under UV light results in the formation of a Sn P cluster compound [(ADC)SnP] as a green crystalline solid. The electronic structure of [(ADC)SnP] is analyzed by quantum-chemical calculations. At room temperature, [(ADC)SnP] reversibly binds with CO and forms [(ADC) {SnOC(O)P}SnP].

Mesoionic Dithiolates (MIDts) Derived from 1,3-Imidazole-Based Anionic Dicarbenes (ADCs).

Mesoionic dithiolates [(MIDt )Li(LiBr) (THF) ] (MIDt ={SC(NDipp)} CAr; Dipp=2,6-iPr C H ; Ar=Ph 3 a, 3-MeC H (3-Tol) 3 b, 4-Me NC H (DMP) 3 c) and [(MIDt )Li(THF) ] (4) are readily accessible (in≥90 % yields) as crystalline solids on treatments of anionic dicarbenes Li(ADC ) (2 a-c) (ADC ={C(NDipp) } CAr) with elemental sulfur. 3 a-c and 4 are monoanionic ditopic ligands with both the sulfur atoms formally negatively charged, while the 1,3-imidazole unit bears a formal positive charge. Treatment of 4 with (L)GeCl (L=1,4-dioxane) affords the germylene (MIDt )GeCl (5) featuring a three-coordinated Ge atom.

Isolation of a Ge(I) Diradicaloid and Dihydrogen Splitting.

The cyclic Ge(I) compound [(ADC)Ge] () (ADC = {CN(Dipp)}CPh, Dipp = 2,6-PrCH) containing a 6π-electron CGe framework has been isolated as a red crystalline solid. CASSCF calculations reveal a closed-shell singlet ground state for with a considerable diradical character ( = 34%). Thus, the diradicaloid readily splits dihydrogen at room temperature to yield the elusive bis-hydridogermylene [(ADC)GeH] ().

The Viability of C5-Protonated- and C4,C5-Ditopic Carbanionic Abnormal NHCs: A New Dimension in NHC Chemistry.

The first C5-protonated abnormal N-heterocyclic carbene (aNHC), PhC{N(2,6-iPr C H )} CHC: (4) is readily accessible by C4-deprotonation of [ArC{N(2,6-iPr C H )} CHCH]X (3 a-X) (Ar=Ph, X=Br or I) with a base. The aNHC 4 is stable at 298 K in [D ]THF solution and has been spectroscopically characterized. The facile availability of 4 enables the synthesis of a series of main-group compounds as well as transition-metal complexes featuring a new phosphorus-aNHC hybrid ligand.