The reactions of silylenes with organic azides are quite diverse, depending on the substituents of the silylene center and on the nature of the azide employed. Elusive silaimine with three-coordinate silicon atom L(1)SiN(2,6-Triip(2)-C(6)H(3)) (5) {L(1) = CH[(C═CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)] and Triip = 2,4,6-triisopropylphenyl} was synthesized by treatment of the silylene L(1)Si (1) with a sterically demanding 2,6-bis(2,4,6-triisopropylphenyl)phenyl azide (2,6-Triip(2)C(6)H(3)N(3)). The reaction of Lewis base-stabilized dichlorosilylene L(2)SiCl(2) (2) {L(2) = 1,3-bis(2,6-iPr(2)C(6)H(3))imidazol-2-ylidene} with Ph(3)SiN(3) afforded four-coordinate silaimine L(2)(Cl(2))SiNSiPh(3) (6). Treatment of 2,6-Triip(2)C(6)H(3)N(3) with L(3)SiCl (3) (L(3) = PhC(NtBu)(2)) yielded silaimine L(3)(Cl)SiN(2,6-Triip(2)-C(6)H(3)) (7) possessing a four-coordinate silicon atom. The reactions of L(3)SiN(SiMe(3))(2) (4) with adamantyl and trimethylsilyl azide furnished silaimine compounds with a four-coordinate silicon atom L(3)(N(Ad)SiMe(3))SiN(SiMe(3)) (8) (Ad = adamantyl) and L(3)(N(SiMe(3))(2))SiN(SiMe(3)) (9). Compound 8 was formed by migration of one of the SiMe(3) groups. Compounds 5-9 are stable under inert atmosphere and were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray studies.
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. The C-F bond activation by the lone pair of germanium is the first report of this kind. The Sn(II) fluoride obtained has an elongated Sn-F bond length and can be used as a good fluorinating agent. The compounds were characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray structural analysis. Single crystal X-ray structural analysis of the tin fluoride shows an asymmetric dimer with weak [Formula: see text] interactions.
The organobismuth(III) and dibismuthine complexes bearing
N,N′-disubstituted
1,8-diaminonaphthalene ligand were prepared. The reaction of LBiNMe2 (1) [L = 1,8-(NSiMe3)2C10H6] with ClSiMe3 results in the
elimination of Me3SiNMe2, while PhCCH, Cp*H,
and PhOH proceed via HNMe2 elimination and provide the
complexes of LBiCl (2), LBiCCPh (3), LBiCp*(4), and LBiOPh (5), respectively. Reaction of 1 with AlMe3 in n-hexane yields
LBiMe (6). Compound 1 reacts with diisopropylcarbodiimide
and phenyl isocyanate under insertion at the Bi–NMe2 bond to give the addition products LBi(N-iPr)2CNMe2 (7) and LBiN(Ph)C(O)NMe2 (8). The reactions of 1 with sulfur
and PhSiH3 result in
the formation of LBi–S–BiL (9) and LBi–BiL
(10), respectively. Compounds 2–10 were characterized by elemental analysis, 1H, 13C, and 29Si NMR spectroscopy, and X-ray crystallographic
studies.
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 6.38(2) Å. Hence the electropositive sulfur atom responds by internal shift to the metal-polarized negative charge at the outside of the S(NR)4(2-) tetrahedron.
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