Alkyne Cycloaddition to a Titanocene Oxide as a Route to Cyclopentadienyl Modification

Abstract

Addition of terminal or internal alkynes to a base-free titanocene oxide results in synthesis of the corresponding oxometallocyclobutene. With appropriate cyclopentadienyl substitution, these compounds undergo reversible C-C reductive elimination offering a unique approach to cyclopentadienyl modification.

η6‐Arene‐Zirconium‐PNP‐Pincer Complexes: Mechanism of Their Hydrogenolytic Formation and Their Reactivity as Zirconium(II) Synthons

“…AU V/Vis spectrum of the deep purple-colored complex 7 iPr Cl (see the Suppporting Information) displays two strong absorptionb ands with maxima at 538 nm (e = 6954 m À1 cm À1 )a nd 344 nm (e = (2) 1.8298 (13), N(2)ÀSi 1.7209 (13), P(2)-Zr-P(1)1 75.122 (12), N(1)-Zr-I 131.92(3), I-Zr-N(2) 117.49 (4), N(2)-Zr-N(1) 110.47 (5), Si-N(2)-Zr 171.17 (9). Selectedb ond lengths [] and angles [8]f or 5 iPr Cl-NAd:Zr ÀCl 2.5173(9), ZrÀP(1) 2.7890(12), ZrÀP(2) 2.7842(10), ZrÀN(1)2.2762 (16), ZrÀN(2) 1.8185 (17), N(2)ÀC(36) 1.444(2), P(2)-Zr-P(1)1 44.98 (2), N(2)-Zr-Cl 107.83 (6), N(2)-Zr-N(1) 102.08 (6), C(36)-N(2)-Zr1 73.70 (13). Figure 9.…”

“…Low-valent Group4m etal complexesp lay an important role in the activation of small, inert molecules. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] In particular,Z r II and Hf II species have been found to display spectacular reactivity in the cleavage of dinitrogen,a nd in the further functionali-zationo ft he activated species. Landmark discoveries in this field have been reported by Fryzuk, [20][21][22][23][24][25][26][27][28] Chirik, [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] and coworkers.…”

“…Low‐valent Group 4 metal complexes play an important role in the activation of small, inert molecules . In particular, Zr II and Hf II species have been found to display spectacular reactivity in the cleavage of dinitrogen, and in the further functionalization of the activated species.…”

How does binding of imidazole-based inhibitors to heme oxygenase-1 influence their conformation? Insights combining crystal structures and molecular modelling

“…The CSD search yielded 14 individual crystal structures, 13 of which are organometallic compounds binding several metallic centres in a metallocene-like coordination mode. The five structures selected [i.e BIXSUY (Pappas & Chirik, 2014), DIVXUC (To et al, 2008), FOLNEA (Kowalski et al, 2005), PUFLAD (Ahmed et al, 1997) and VAZLAK (Wang et al, 2005)] are those for which coordination does not constrain significantly the overall conformation of the molecule. None of these five selected structures contain an imidazole ring.…”

Synthesis and carbonylation of oxotitanocyclobutanes derived from allene cycloaddition to a monomeric titanocene oxide

“…Facile 1,2-addition of H 2 and silanes has been observed and treatment of 1 with alkynes resulted in observation and in some cases, crystallographic characterization of the resulting oxametallacyclobutene, 1-HCCR. The latter class of compounds underwent reversible C-C reductive elimination with the cyclopentadienyl rings ultimately leading to ejection of [SiMe 3 ] radical and formation of a new titanocene substructure (Scheme 1) [24].…”