The synthesis of stable heavier analogues of nitriles as monomeric tetrylene−phosphinidenes Mes TerEP(IDipp) (E = Ge, Sn; Mes Ter = 2,6-Mes 2 C 6 H 3 , IDipp = C([N-(2,6-iPr 2 C 6 H 4 )CH] 2 ) was achieved by taking advantage of NHC (N-heterocyclic carbene, here IDipp) coordination to the low-valent phosphorus center. Multiple bonding character of the E−P bonds was examined experimentally and computationally. Both germanium and tin compounds undergo [2+2] cycloaddition with diphenylketene, whereas reaction of the tin derivative with tris(pentafluorophenyl)borane provided unique "push−pull" phosphastannene ( Mes Ter)(Ar)Sn = P(IDipp) (Ar = C 6 F 4 [B(F)(C 6 F 5 ) 2 ]). Going further, we demonstrated the potential of tetrylene−phosphinidene complexes in catalytic hydroboration of carbonyl compounds.

Two new bidentate ferrocene-bridged bis(N-heterocyclic carbene-phospinidenes) (bisNHCPs) were successfully isolated by treating 1,1’-bis-(dichlorophosphine)ferrocene with N-heterocyclic carbenes, followed by dechlorination using sodium naphthalenide. The bisNHCPs were used in complexation of various...

Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S-H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes 2 -C 6 H 3 , Mes = 2,4,6-Me 3 -C 6 H 2 ) to yield an NHC-stabilized thiosilaaldehyde B. The results of NBO and QTAIM analyses suggest a zwitterionic formulation of the product B as the most appropriate. Detailed mechanistic investigations are performed at the M06-L/6-311+G(d,p)(SMD: acetonitrile/benzene)//M06-L/6-311+G(d,p) level of density functional theory. Several pathways for the formation of thiosilaaldehyde B are examined. The energetically preferred route commences with a stepwise addition of H 2 S to the nucleophilic silicon center. Subsequent NHC dissociation and proton abstraction yields the thiosilaaldehyde in a strongly exergonic reaction. Intermediacy of a chlorosilylene or a thiosilylene is kinetically precluded. With an overall activation barrier of 15 kcal/mol, the resulting mechanistic picture is fully in line with the experimental observation of an instantaneous reaction at sub-zero temperatures.

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Herein, we report the synthesis and isolation of Si(IV) dications stabilized by a bidentate N-heterocyclic carbene-phosphinidene (NHCP). Treatment of the bis(NHCP) with Si(IV) bis(triflate) R 2 Si(OTf) 2 (with R = H, Ph) resulted in the instant formation of Si(IV) dicationic complexes [2 a] and [2 b] featuring a tetracoor-dinated silicon centre. The dications show expected high Lewis acidity. The bis(NHCP)-stabilized parent silyl dication 2a (SiH 2 2 +) presents the first isolable example of a parent SiH 2 dication. In addition, dication [2 a] is able to react with diphenylketene by insertion into the SiÀ P bond.