Transformation of the First Zirconocene Alkyne Complex without an Additional Phosphane Ligand into a Dinuclear σ‐Alkenyl Complex by Hydrogen Transfer from η⁵‐C₅H₅ to the Alkyne Ligand

[Cp2V(μ-η2:η4-butadiyne)MCp2′] (M=Ti, Zr; Cp′=C5H5, C5H4SiMe3): Heterodimetallic Complexes from a Bis(alkynyl)metallocene and Vanadocene—Unexpected Structure of [Cp2V(μ-η2:η4-butadiyne)Zr(C5H4SiMe3)2] Containing Two Planar-Tetracoordinate Carbon Atoms

“…[20] First, the C1 ± C2 and C3 ± C4 distances (1.336 and 1.331 , respectively) are in the range of a C C bond linkage and similar to the C C bond length observed in the zirconacyclopropene complex [Cp 2 Zr(Me 3 SiCCPh)(PMe 3 )]. [21] Second, the Zr ± C1 and Zr ± C4 distances of 2.224 and 2.235 , respectively, are in the range expected for a Zr ± C s bond (2.27 in [Cp 2 ZrMe 2 ] [22] ). Third, the Zr ± C2 and Zr ± C3 distances are 2.458 and 2.459 , respectively, which indicates that the Zr atom is coordinated in an olefinic s-plane fashion to both internal carbon atoms of the butadiene skeleton.…”

Synthesis, Structure, and Reactivity of Niobium and Tantalum Alkyne Complexes

“…Rosenthal and Burlakov,3,15 informed by initial studies by Vol'pin and Shur, 16,17 have developed an extensive body of work surrounding the chemistry of titanocene 18 (6) and zirconocene 19 (7) alkyne complexes (Scheme 3). In many cases, the reactivity of these complexes suggests that they can be regarded as synthons for "Cp 2 M" (i.e., formally M II , d 2 ) metallocenes.…”

Sulfur-containing stable five-membered “cycloallene” complexes: 1-thia-2-zircona- and 1-thia-2-titanacyclopenta-3,4-dienes

“…13 The Zr-C1 (2.308 Å) and Zr-C2 (2.344 Å) bond distances in 5b were significantly longer than those reported for Zr-η 2alkyne complexes, where the Zr-C bond distances are 2.18-2.26 Å. 14 The reported Zr-S covalent bond lengths in zir-conium thiolates are 2.5-2.6 Å, while Zr←S dative bonds are typically 2.7-2.8 Å. 15 Thus, the Zr-S bond in 5b (2.588 Å) can be regarded as a covalent bond.…”