The organometallic chemistry of cycloheptatrienyl zirconium complexes

Abstract

This tutorial review summarizes the organometallic chemistry derived from the half-sandwich complex [(η(7)-C(7)H(7))ZrCl(tmeda)], which was used as an efficient and versatile starting material for the incorporation of monoanionic ligands into the cycloheptatrienyl zirconium coordination sphere by conventional salt metathesis reactions. A broad variety of ligands was employed, affording novel and previously inaccessible cycloheptatrienyl (sandwich) complexes of the type [(η(7)-C(7)H(7))Zr(Y)]; Y comprises pentadienyl, cyclopentadienyl, allyl, phospholyl, boratabenzene, imidazolin-2-iminato and amido systems. The cycloheptatrienyl ring in these systems usually acts as an "innocent spectator ligand", but reactivity can arise from the second ligand Y or the Lewis acidity of the, formally, Zr(+iv) center, which was probed in selected examples and put in perspective to related studies. The corresponding results emphasize why the use of [(η(7)-C(7)H(7))ZrCl(tmeda)] is clearly an advancement in the chemistry of the still fairly unexplored area of cycloheptatrienyl transition metal complexes.

Colorimetric Detection of Small Molecules by a Frustrated Lewis Pair Containing a Phosphorus‐Functionalized CycloheptatrienylCyclopentadienyl Titanium Sandwich Complex

“…Therefore, we anticipated that the use of the most bulky troticenyl phosphane, [(η 7 ‐C 7 H 7 )Ti(η 5 ‐C 5 H 4 P t Bu 2 )] ( 7 ), together with B(C 6 F 5 ) 3 might also afford a suitable FLP system with a potential colorimetric response upon activation of small molecules. Herein, our initial results on the reactivity of 7 /B(C 6 F 5 ) 3 towards H 2 , CO 2 and N 2 O are reported, which is not only motivated by our interest in transition‐metal cycloheptatrienyl chemistry,6,12 but also part of our ongoing research on frustrated N‐heterocyclic carbeneborane Lewis pairs 13,14…”

Organozirconium Complex with Keggin-Type Mono-Aluminum-Substituted Silicotungstate: Synthesis, Molecular Structure, and Catalytic Performance for Meerwein–Ponndorf–Verley Reduction

“…Chemical shifts are reported as positive for resonances downfield of TMS ( 0). The 31 P, 29 Si, and 27 Al NMR spectra were measured in acetonitrile-d3 with reference to an external standard (a substitution method) of 85% H3PO4 in a sealed capillary, TMS, and a saturated AlCl3-D2O solution, respectively. Chemical shifts for 31 P and 29 Si NMR spectra were reported as negative on the  scale for resonances upfield of H3PO4 ( 0) and TMS ( 0).…”

“…Chemical shifts for 31 P and 29 Si NMR spectra were reported as negative on the  scale for resonances upfield of H3PO4 ( 0) and TMS ( 0). The chemical shifts in the 27 Al NMR spectra were reported as positive on the  scale for resonances downfield of AlCl3 ( 0). When a quartz tube was used for 27 Al NMR spectroscopy, a background signal was also observed in the spectrum.…”

“…The chemical shifts in the 27 Al NMR spectra were reported as positive on the  scale for resonances downfield of AlCl3 ( 0). When a quartz tube was used for 27 Al NMR spectroscopy, a background signal was also observed in the spectrum. Solid-state 27 Al, 13 C, and 29 Si NMR spectra were recorded at 400 MHz on a JEOL JNM-ECA 400 FT-NMR spectrometer with a JEOL ECP-400 NMR data-processing system.…”

“…To explore POMs that could be used as supports for grafting reactions, we focused on the aluminum-substituted POMs and successfully synthesized an organozirconium(IV)-supported polyoxometalate, [-PW11Al(OH)O39ZrCp2]2 6− (Cp =  5 -C5H5 − ) (P-Al-Zr), by a grafting reaction of -Keggin mono-aluminum-substituted phosphotungstate with a bis( 5cyclopentadienyl)zirconium(IV) fragment [25]. Although the chemistry of organometallic moieties possessing  5 -cyclopentadienyl ligands has rapidly expanded [26][27][28] In this study, we focused on the use of the tetra-n-butylammonium/potassium salt of - Cp2Zr(OTf)2THF (OTf = CF3SO3 − ) were synthesized by previously published methods [25,37]. All the reagents and solvents were obtained and used as received from commercial sources.…”