Zirconium compounds of hexamethyldisiloxane. Synthesis and structure of (.eta.5-C5H5)2Zr(CH2SiMe2OSiMe3)2 and (.eta.5-C5Me5)ZrCl2(.eta.2-CH2SiMe2OSiMe3) and their reactivity with methyl isocyanide

Abstract

A preliminary investigation into the feasibility of using organozirconium reagents to functionalize the methyl groups of polydimethylsiloxanes is made. Hexamethyldisiloxane is deprotonated and then bound to Zr to give CpaZrtCHaSiMeaOSiMesla (1) and Cp*ZrCl2(CH2-SiMe2OSiMe3) (3). These represent the first well-characterized compounds possessing methylsiloxane coordinated to zirconium. X-ray crystallography of 1 and 3 reveals a monodentate and a bidentate coordination mode, respectively, with 3 possessing an unexpected and very weak bond to the siloxane oxygen [Zr-0 = 2.427 (3) Á]. This is among the longest Zr-0 bonds known. Data for 1: cell constants a = 8.330

Synthesis, Structure, and Reactivity of Metal Complexes with Alkoxysilylmethyl Ligands

“…However, a zirconium compound has been described where the oxygen atom of a siloxane intramolecularily binds to the metal centre (compound analogue to formula B in scheme 2) [4]. However, a zirconium compound has been described where the oxygen atom of a siloxane intramolecularily binds to the metal centre (compound analogue to formula B in scheme 2) [4].…”

Synthesis and structure of zirconium(IV) alkyl complexes with bi-, tri-, tetra- and penta-dentate amido ligands

“…1.9 Å if π bonding leads to double-bond character. 17, 21 The siloxymethyl complex [Zr(η-C 5 Me 5 )Cl 2 (CH 2 SiMe 2 OSiMe 3 )], 22 by comparison, possesses a Zr᎐O bond length of 2.427(3) Å, only slightly shorter than that in 5. In that case, however, the Si᎐O᎐Si angle is significantly more acute at 131.10(16)Њ.…”

A novel molecular species incorporating a cyclic organolithate anion and a disiloxane-solvated lithium cation

“…(b) As far as we can ascertain compound 3 is the first example of a structurally characterized disiloxane-metal complex in which the ligand is attached to the metal only through its oxygen atom. In all other examples of coordination of disiloxane oxygen to a metal this bonding is supported by bonding through another atom of the ligand; examples include systems of the types Me 3 SiO-Pd-Si, 6 Me 3 SiO-Zr-CH 2 SiMe 2 , 7 and Me 3 SiO-Li-N-Si. 8 (A polysiloxane analogue of a crown ether complex, [K(OSiMe 2 ) 7 ] + , 9 and siloxane-solvation of Na and K centres within complex polysiloxane frameworks 10 were recently reported.)…”

“…8 (A polysiloxane analogue of a crown ether complex, [K(OSiMe 2 ) 7 ] + , 9 and siloxane-solvation of Na and K centres within complex polysiloxane frameworks 10 were recently reported.) Remarkably, since siloxanes are normally thought to be much weaker donors than organic ethers, 6,7,11 the Li-O bond to the siloxane oxygen in 3, 1.917(12) Å, is not significantly longer than those to the thf molecules, mean 1.912(12) Å. [See also (d) below.…”

“…In contrast, the O-M bonds in the Pd and Zr compounds mentioned above are rather long, and this was attributed to the poor donor ability of siloxanes. 6,7 ] The interaction of the oxygen lone pair with Li leads to a large increase in the Si-O(1) bond length to a mean of 1.704(5) Å from the 1.63-1.64 Å usually found in disiloxanes. 5 (c) The mean Li-C bond length in 3, 2.12(2) Å, is not significantly different from that in 1, 2.…”