Transition metal complexes containing the S(NtBu)4(2-) tetraimidosulfate dianion.

Three novel metal complexes [(acac)2Cu2(NtBu)4S] (), [Li(thf)4]2[I4Cd2(NtBu)4S] () and [(thf)2Li{(SiMe3)2N}Zn(NtBu)4S] () are prepared from the intended transmetalation of the dilithium complex of N,N',N'',N'''-tetrakis(tert-butyl)tetraimidosulfate [(thf)4Li2(NtBu)4S] (). The two lithium cations are replaced by either the cationic (acac)Cu(ii) moiety, the neutral I2Cd(ii) residue or only a single lithium cation is substituted by the cationic (Me3Si)2NZn(ii) fragment. The complexes show two main results: first the S(NtBu)4(2-) tetrahedron can serve as a ligand to transition metals from the soft Cu(ii) to the harder Zn(ii) at opposite sides and second the S-N bond distances vary only marginally in response to the various metals and the four distances constantly sum up to 6.

Oxidative addition versus substitution reactions of group 14 dialkylamino metalylenes with pentafluoropyridine.

Dialkylamino compounds of group 14 elements (Si, Ge, Sn) in the +2 oxidation state supported by benzamidinate ligands were synthesized and treated with pentafluoropyridine. Two different modes of reactivity were observed, depending on the metal atom and the basicity of the substituent at the metal. Pentafluoropyridine undergoes oxidative addition reaction at the Si(II) and Ge(II) atoms whereas at the Sn(II) atom substitution of the NMe(2) group by the para fluorine of pentafluoropyridine occurs.

Synthesis of tetrasubstituted alkenes through a palladium-catalyzed domino carbopalladation/C-H-activation reaction.

Helical tetrasubstituted alkenes (7) were obtained in a highly efficient way through a palladium-catalyzed domino-carbopalladation/CH-activation reaction of propargylic alcohols 6 in good to excellent yields. Electron-withdrawing- and electron-donating substituents can be introduced onto the upper and lower aromatic rings. The substrates (6) for the domino process were synthesized by addition of the lithiated alkyne (20) to various aldehydes (19); moreover, the substrates were accessible enantioselectively (in 95% ee) by reduction of the corresponding ketone using the Noyori procedure.

Elegant approach to spacer arranged silagermylene and bis(germylene) compounds.

Herein we report on the reactions of the stable LSiCl (1) and LGeCl (2) [L = PhC(NtBu)(2)] with L(1)Ge, [L(1) = CH{(C[double bond, length as m-dash]CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}] (3) to yield 1-sila-5-germylene (4) and a 1,5-bis(germylene) (5). The reactions proceed through the 1,4 nucleophilic addition of the M-Cl (M = Si or Ge) to 3 without any modification of the oxidation state although the change of the oxidation state is thermodynamically more favorable. Compounds 4 and 5 were investigated by single crystal X-ray structural analyses, multi-nuclear NMR spectroscopy, and micro-analysis.

Pentafluoropyridine as a fluorinating reagent for preparing a hydrocarbon soluble β-diketiminatolead(II) monofluoride.

A well-designed method for the preparation of a β-diketiminatolead(II) monofluoride has been developed using LPbNMe(2) (L = [CH{C(Me)(2,6-iPr(2)C(6)H(3)N)}(2)]) and pentafluoropyridine (C(5)F(5)N). The resulting LPbF was used for the synthesis of amidinatosilicon(II) monofluoride. Moreover the activation of a ketone was observed when the LPbF was treated with PhCOCF(3).

A stable silicon(II) monohydride.

A stable silicon(II) monohydride is accomplished through a covalent shared interaction of the silylene lone-pair and a sp(3)-hybridized boron atom of the Lewis acidic BH(3). Experimental charge density investigations reveal a central positively charged silicon atom bound to a negatively charged hydrogen atom. The positively charged H-Si-BH(3) moiety is coordinated by the lone-pairs of electrons of the benzamidinate ligand.

Reaction of β-diketiminate tin(II) dimethylamide LSnNMe₂ [L = HC(CMeNAr)₂; Ar = 2,6-iPr₂C₆H₃] with ketones and alkynes.

The reactions of stable β-diketiminate tin(II) dimethylamide LSnNMe₂ [L = HC(CMeNAr)₂; Ar = 2,6-iPr₂C₆H₃] (1) with ketones and activated terminal alkynes are described. 1 reacts with 2-benzoylpyridine and 2,2,2-trifluoroacetophenone to give the tin(II)-alkoxides LSnOCPh(2-Py)NMe₂ (2) and LSnOCPh(CF₃)NMe₂ (3), respectively, by nucleophilic addition of the dimethylamido group to the carbonyl moiety. Furthermore, the reaction of 1 with terminal alkynes (HCCCO₂R, R = Me, Et) forms tin(II)-alkynyl LSnCCCO₂R (R= Me, (4); R = Et, (5)) compounds under elimination of Me₂NH rather than undergoing a nucleophilic addition reaction at the carbon–carbon triple bond.

Dehydrogenation of LGeH by a Lewis N-heterocyclic carbene borane pair under the formation of L'Ge and its reactions with B(C(6)F(5))(3) and trimethylsilyl diazomethane: an unprecedented rearrangement of a diazocompound to an isonitrile.

Herein we report the dehydrogenation of LGeH (1) [L = CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)] by a frustrated Lewis NHC borane pair under the formation of an imidazolium borate salt (2) and the heterocyclic germylene L'Ge (3) [L' = CH{(C horizontal lineCH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}]. The reaction of 3 with B(C(6)F(5))(3) in toluene results in the formation of a zwitterion containing a germylene moiety, [B(C(6)F(5))(3)L''Ge] (4) [L'' = CH{(CCH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}]. Subsequent treatment of 4 with 1 equiv of 1,3-di-tert-butylimidazol-2-ylidene (NHC) gives B(C(6)F(5))(3)L'''Ge (5) [L''' = CH{(C horizontal lineCH(2))(CCH(2)B(C(6)F(5))(3))(2,6-iPr(2)C(6)H(3)N)(2)}] under formation of the imidazolium cation.

A germanium(II) hydride as an effective reagent for hydrogermylation reactions.

Herein we report on the reactivity of the stable germanium(II) hydride LGeH (L = CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)) (2), which contains a low-valent germanium atom. 2 is prepared from the corresponding germanium(II) chloride LGeCl (1) using H(3)Al x NMe(3) or K[HB(iBu)(3)] in toluene. The reaction of 2 with carbon dioxide in toluene at room temperature affords a germanium(II) ester of formic acid, LGe-O-C(O)H (3), which is formed by insertion of the carbon dioxide into the germylene hydrogen bond.

Cleavage of a N-H bond of ammonia at room temperature by a germylene.

The reaction of LGeCl [1; L = CH{(CMe)(2,6-(i)Pr(2)C(6)H(3)N)}(2)] with 1,3-di-tert-butylimidazol-2-ylidene results in the formation of the germylene L'Ge [2; L' = CH{(C=CH(2))(CMe)(2,6-(i)Pr(2)C(6)H(3)N)(2)}]. 2 reacts with ammonia under N-H cleavage to give LGeNH(2) (3). This type of reaction can also be used to activate primary amines.