Transformation of hydroxylamide into hydrazide units in the coordination spheres of group 4 metals

Abstract

Hydroxylamine units, bonded via their oxygen atom to a cyclo-pentadienyldimethylsilyl group are transformed into siloxy ligands and hydrazide units by the reaction with tetrakis(dimethylamido)-titanium and -zirconium by the same reaction principle but resulting in different aggregates of the products.

N–H activation of hydrazines by a heterobimetallic Zr–Co complex: promotion of one-electron chemistry at Zr

“…The hydrazide ligands in 2 and 4 exhibit N-N distances of 1.412(2) and 1.4335(3) Å, respectively, indicating N-N single bond character, consistent with typical Zr side-on hydrazide complexes. [21][22][23][24][25][26][27] The bond lengths between Zr and the anionic hydrazido nitrogen of 2 and 4 (2.040(1) and 2.137(2) Å) are shorter than the bonds between Zr and the datively bound hydrazido nitrogen atoms (2.332(1) and 2.265(2) Å), and all distances are in the range of previously reported zirconium Z 2hydrazido complexes (2.04-2.12 Å and 2.30-2.47 Å, respectively). [21][22][23][24][25][26][27] The geometry about the anionic nitrogen atom in both compounds 2 and 4 is planar which suggests p donation of the lone pair to the zirconium atom (vide infra).…”

“…[21][22][23][24][25][26][27] The bond lengths between Zr and the anionic hydrazido nitrogen of 2 and 4 (2.040(1) and 2.137(2) Å) are shorter than the bonds between Zr and the datively bound hydrazido nitrogen atoms (2.332(1) and 2.265(2) Å), and all distances are in the range of previously reported zirconium Z 2hydrazido complexes (2.04-2.12 Å and 2.30-2.47 Å, respectively). [21][22][23][24][25][26][27] The geometry about the anionic nitrogen atom in both compounds 2 and 4 is planar which suggests p donation of the lone pair to the zirconium atom (vide infra). Notably, there are few structurally characterized examples of transition metal complexes of unsubstituted terminal Z 2 -hydrazido(1À) N 2 H 3 À ligands, [28][29][30][31] and complex 2 represents the first example with Zr.…”

Molecular Alumo- and Gallosilicate Hydrides Functionalized with Terminal M(NR2)3 and Bridging M(NR2)2 (M = Ti, Zr, Hf; R = Me, Et) Moieties

“…Similarly, no molecular species with terminal Si–O–M­(NR 2 ) 3 groups have been reported so far, although such species were proposed to exist on silica surface . In fact, the only reports on structurally characterized O 3 Si–O–M­(NR 2 ) n containing compounds are from our group and feature only cyclic compounds based on A and B that contain the group 4 metal bound to two NR 2 ligands or the acyclic titanosilicate [( t BuO) 3 SiO] 3 TiNEt 2 with one dialkylamido group. ,− Other examples inform complete substitution of the amide ligands, or the silicon atom does not belong to a silicate moiety, as is the case of CpMe 4 (SiMe 2 O)­Ti­(NMe 2 )­(N 2 Me 3 ) and [CpMe 4 (SiMe 2 O)­Zr­(NMe 2 )­(N 2 Me 3 )] 2 reported by Mitzel and co-workers …”

“…29,44a−c Other examples inform complete substitution of the amide ligands, or the silicon atom does not belong to a silicate moiety, as is the case of CpMe 4 (SiMe 2 O)Ti(NMe 2 )(N 2 Me 3 ) and [CpMe 4 (SiMe 2 O)-Zr(NMe 2 )(N 2 Me 3 )] 2 reported by Mitzel and co-workers. 45 When the tetrakis(dimethylamido)titanium was used, the exclusive formation of monosilicate compounds LM III (H)(μ-O)Si(OtBu) 2 (μ-O)Ti(NR 2 ) 3 (M III = Al (3); M III = Ga (4)) was observed in Scheme 2. The formation of 3 and 4 is favored despite the different acidities of the M III metals in 1 and 2.…”