Ti−Sn, Zr−Sn, and Hf−Sn Heterodimetallic Complexes:  Stabilizing Unsupported Group 4−Group 14 Metal−Metal Bonds

Abstract

Reaction of the tripodal amido complexes [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 ZrCl] and [MeSi-{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 HfCl] with LiSnPh 3 in toluene yielded the Zr-Sn and Hf-Sn complexes [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 ZrSnPh 3 ] (1) and [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 -HfSnPh 3 ] (2), while attempts to synthesize the corresponding Ti-Sn complex resulted in the oxidative coupling of the stannate to give Ph 3 Sn-SnPh 3 and unidentified titanium species. More stable group 4-group 14 complexes were obtained by reaction of the triamido stannate complex [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 SnLi(OEt 2 )] with the metallocene dichlorides [Cp 2 MCl 2 ] of all three titanium group metals, giving [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 SnM(η 5 -C 5 H 5 ) 2 (Cl)] (M ) Ti, 3; Zr, 4; Hf, 5). X-ray diffraction studies of 4 and 5 established Zr-Sn and Hf-Sn bond lengths of 3.02313(17) and 2.9956(3) Å, respectively.

Tripodal Triamidometallates of the Heavy Group 14 Elements: Inorganic Cages with Remarkable “Ligand Properties”

“…Single-crystal X-ray structure analyses of both 18 and 19 confirmed the molecular structures and established the presence of the group 4/group 14 metalϪmetal bonds (Figure 9). [31] The ZrϪSn bond length in compound 18 is, at 3.0231(2) Å , significantly longer than the sum of the covalent radii of the two metals as given by Pauling [32] (2) Å ] reported by Ellis and co-workers. [33] This observation is remarkable, since the latter compounds are low oxidation state zirconium complexes with high coordination numbers, and so should be expected to possess ZrϪSn bonds longer than those in 18.…”

“…[16] With the aim of obtaining heterodinuclear complexes of greater stability than previously observed, the triamidostannate complex [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 -SnLi(OEt 2 )] was treated with the metallocene dichlorides [Cp 2 MCl 2 ] of all three titanium group metals. [31] Nucleophilic substitution of one of the chloro ligands in the metallocene dichlorides occurred cleanly in all three cases, yielding the corresponding dinuclear complexes as thermally stable solids (Scheme 6). Single-crystal X-ray structure analyses of both 18 and 19 confirmed the molecular structures and established the presence of the group 4/group 14 metalϪmetal bonds (Figure 9).…”

A Triamidostannate(II) as a “Spectator Ligand” in an Organozirconium Complex: Insertion of CO into a Zr−CH3 Fragment in the Presence of a Zr−Sn Bond

“…The electronegative N-substituents at the divalent metal atoms render these less oxidizable as would be expected for alkyl- or aryl-substituted derivatives. The latter not only allowed the synthesis of stable Ag(I)−Sn or Au(I−III)−Sn compounds but provided the access to stannate(II) complexes of the early transition metals, in particular the tetravalent group 4 elements, without degradative single-electron transfer. , …”

“…This redox chemical degradation pathway was completely suppressed in the reaction of the triamido stannate complex [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 SnLi(OEt 2 )] 3c with the metallocene dichlorides [Cp 2 MCl 2 ] of all three titanium group metals to give the corresponding Sn−M complexes [MeSi{SiMe 2 N(4-CH 3 C 6 H 4 )} 3 Sn−M(η 5 -C 5 H 5 ) 2 (Cl)] . These new complexes were found to be thermally highly stable and the M−Sn bonds particularly inert toward displacement of the stannate from the group 4 metal.…”

A Tripodal Triaminostannate as a Metal Nucleophile: Synthesis of Transition Metal−Tin Heterodimetallic Complexes

“…[7Ϫ9] These triamidostannates were found to bind to potentially highly oxidizing metal centres such as the tetravalent group 4 metals [10] as well as Ag I , Au II and Au III to give thermally stable heterometallic compounds. [11Ϫ13] The electronegative nitrogen substituents at divalent group 14 metal centres thus appear to stabilize the metals with respect to oxidation by a heterometal centre to which they are bonded.…”