Organoaluminates with Three Terminal Phenylethynyl Groups and Their Interactions with Alkali Metal Cations

Abstract

The synthesis of [K + ‚THF(2,6-iPr 2 C 6 H 3 N-(SiMe 3 )Al(CtCPh) 3 ) -] 2 (1), [Na + ‚THF (2, 4) with the corresponding phenylethynyl alkali metal salt is reported. In compound 1 the potassium (2, sodium) interacts with the CtC bonds of four phenylethynyl groups. A further coordination site of the potassium (sodium) is occupied by a THF molecule. Thus, the cation therein acts as a bridging moiety to form the dimer. In compound 3 each of the lithium cations is 2-fold coordinated by phenylethynyl ligands and two dioxane molecules. One of the dioxane molecules in 3 functions as a bridge forming the dimer. The herein described compounds are the first structurally characterized species having three terminal phenylethynyl groups bound to the aluminum atom.

Structural insights into mono-amido tris-alkyl potassium aluminates

“…Reported by Roesky et al, the transmetallation reaction of [2,6-i Pr 2 C 6 H 3 N(SiMe 3 )AlCl 2 ] 2 with six molar equivalents of potassium phenylacetylide (KCRCPh) produces the dimeric complex [THFÁK{2,6-i Pr 2 C 6 H 3 N(SiMe 3 )Al(CRCPh) 3 }] 2 . 10 Furthermore, the first reported reaction of a potassium TMP-aluminate has produced a novel result which justified a structural study of such heavier alkali metal derivatives. To elaborate, remarkably the TMP anion undergoes a deprotonation of one of its methyl arms via a bimetallic base mixture of KTMP, i Bu 2 Al(TMP), and TMEDA in a 1 : 1 : 1 ratio, to generate a TMP* dianion [QNC(Me) 2 (CH 2 ) 3 C(Me)(CH 2 )], which is trapped in the dialkyl potassium aluminate [(TMEDA)ÁK(TMP*)(m-i Bu)Al( i Bu)] (Scheme 1).…”

Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

“…Catalytically competent Cu I -complexes that contain nitrogen-based ligands have previously been synthesized and fully characterized structurally [ 47 – 51 ]. Triorganoaluminum complexes are also known to form triorganoaluminate species in the presence of anions in solution [ 52 – 57 ]. In addition, organoaluminum reagents have been demonstrated to undergo transmetalation with Cu salts based on their participation in allylic and conjugate addition reactions [ 11 , 15 , 43 ].…”

K+···Cπ and K+···F Non-Covalent Interactions in π-Functionalized Potassium Fluoroalkoxides

“…In addition, each metal ion is stabilized by multiple K + ···F contacts: K1, K2, K3, and K4 are respectively involved in four, seven, one, and three such interactions. They range from very strong (d K-F = 2.806(1) Å for K3) to mild (d K-F = 3.324(2) Å for K4) [31]. Another prominent feature of this complex is the presence of K + ···C π (arene) intramolecular interactions with three capping aromatic rings from the tethered side-arms of the ligands.…”

“…However, the K + ···Cπ(alkyne) interatomic distances in [2]4 (in the range 3.131(3)-3.495(3) Å, see Table 2) are, for most of them, much shorter than in this latter compound (3.406 and 3.470 Å). On the other hand, they are much longer than in K + ···Cπ(acetylide) compounds, where it often approximates 2.95-3.10 Å [21,22,31]. Relevant metric parameters for [2]4 are collated in Table 2.…”