Synthesis and Structural Characterization of Butadienylcalcium‐based Heavy Grignard Reagents and a Ca₄[O] Inverse Crown Ether Complex

Abstract

The structure elucidation of heavy Grignard reagents (RAeX, Ae=Ca, Sr, and Ba, X=halides) has been greatly strived after, mainly because of their inaccessibility and remarkable instability. The synthesis of a series of butadienylcalcium compounds is presented, including 1-calcio-4-lithio-1,3-butadiene, 1,4-dicalcio-1,3-butadiene, and a Ca [O] inverse crown ether complex, via the reaction between 1,4-dilithio-1,3-butadienes and calcium iodide in THF. Single-crystal X-ray analysis of these unprecedented heavy Grignard reagents revealed unique structural characteristics and bonding modes. Preliminary reaction chemistry was investigated. This study provides a novel class of alkenyl heavy Grignard reagents and a useful synthetic strategy for otherwise unavailable reactive organometallic compounds.

Selective Transformation of Well‐Defined Alkenyllithiums to Alkenylmagnesiums via Transmetalation

“…Only a few lithium organomagnesiate complexes with Mg−C(alkenyl) bonds were generated in situ for further reactions or predicted by theory . As far as we are aware, lithium organomagnesiate complexes, for example, 1‐Li‐4‐(MgR)‐butadienes, have not been reported, which promotes us to prepare 1‐Li‐4‐(MgR)‐butadienes.…”

Cyclic Bis‐alkylidene Complexes of Titanium and Zirconium: Synthesis, Characterization, and Reaction

“…The Li1ÀC1 and Li1ÀC4 distances are 2.139(5) and 2.145(6) ,r espectively,w hich are consistent with knownl ithium-coordinated metallacycles. [14] Scheme2.Synthesis of 4 and 5. 11, C2-C1-Ti1 83.23 (17), C1-C2-C3 120.1(2), C2-C3-C4 119.5(2), C3-C4-Ti1 83.65(15).…”

Synthesis and Structural Characterization of Butadienylcalcium‐based Heavy Grignard Reagents and a Ca4[O] Inverse Crown Ether Complex

“…ORTEP drawing of 2 with ellipsoidss et at 30 %probability. [18] Hydrogen atoms are omitted for clarity.Selected bond lengths []and angles [8 8]: C1-C2 1.349 (7), C2-C3 1.534 (7), C3-C4 1.355 (7), C1-Li1 2.260(10), C4-Li1 2.145(10), C1-Ca1 2.569 (5), C4-Ca1 2.568(5), Ca1-I1 3.2238 (11),L i1-I1 2.838 (9);C 1-Ca1-C4 69.99 (16), C1-Li1-C4 83.9(3). [18] Hydrogen atoms are omitted for clarity.S elected bond lengths []and angles [8 8]: C1-C2 1.359 (10), C2-C3 1.539 (9), C3-C4 1.368 (10), C1-Ca1 2.549(7), C4-Ca1 2.558 (6), C1-Ca2 2.584 (6), C4-Ca2 2.545 (6), Ca1-I1 3.1891 (13), Ca1-I2 3.1515 (14), Ca2-I2 3.1723 (14), Ca1-Ca2 3.3632 (18);C1-Ca1-C4 70.6(2), C1-Ca2-C4 70.…”

“…ORTEP drawing of 4 with ellipsoidss et at 30 %probability. [18] Hydrogen atoms are omitted for clarity.Selected bond lengths []: Ca1-I1 3.1955(19),C a1-I1 ' 3.1812(18), Ca1-I2 3.2084(18), Ca2-I2 3.2464 (2), C1-Ca1 2.522(8), C4-Ca1 2.574 (9), C1-Ca22.552 (9), C4-Ca2 2.544 (10). .…”

“…ORTEP drawing of the central anionic framework of 7 with ellipsoids set at 30 %p robability. [18] Hydrogen atoms, carbon atoms in coordinated THF molecules and peripheralc ounterions are omitted for clarity.S elected bond lengths []and angles [8 8]: C1-C2 1.329 (14), C2-C3 1.542 (15), C3-C4 1.304 (13), C1-Ca1 2.644(10), C4-Ca1 2.909(10), C1-Ca2 2.671(10), C4-Ca2 2.723(10), Ca1-I1 3.230(3), Ca1-I2' 3.237-(2), Ca2-I2 3.172(3), Ca2-I1' 3.247(2), Ca1-Ca2 3.093(3), Ca1-Ca2' 3.515(3), Ca1-O1 2.332(2), Ca2-O1 2.349(2), Ca1-O2 2.366(8), Ca2-O3 2.361(8);C1-Ca1-C4 67.5(3), C1-Ca2-C4 70.0(3), Ca2-Ca1-Ca2' 90.38 (7), Ca1-Ca2-Ca1' 89.62 (7), Ca1-O1-Ca2 82.70(8), Ca1-O1-Ca2' 97.30(8).…”