Synthesis of Titanium CCC-NHC Pincer Complexes and Catalytic Hydroamination of Unactivated Alkenes

Abstract

The previously reported amine elimination methodology using group 4 tetrakis(dimethylamido) starting materials for the synthesis of CCC-NHC pincer Zr and Hf complexes has been extended to include Ti. Use of excess Ti(NMe 2 ) 4 with 1,3bis(3-butylimidazol-1-yl)benzene diiodide (1) yielded (1,3-bis(3-butylimidazol-1-yl-2-idene)-2-phenylene)bis(dimethylamido)iodotitanium(IV) (2), which subsequently reacted with CH 2 Cl 2 to afford (1,3-bis(3-butylimidazol-1-yl-2-idene)-2-phenylene)trichlorotitanium(IV) (3). Combining complex 2 with TMSCl yielded complex 3 along with the geometric isomers of (1,3-bis(3butylimidazol-1-yl-2-idene)-2-phenylene)dichloroiodotitanium(IV) (4a,e). The salt, 1,3-bis(3-butylimidazol-1-yl)benzene dichloride (5), was reacted with Ti(NMe 2 ) 4 in a stoichiometric amount to yield (1,3-bis(3-butylimidazol-1-yl-2-idene)-2phenylene)dichloro(dimethylamido)titanium(IV) (6), while use of excess Ti(NMe 2 ) 4 yielded (1,3-bis(3-butylimidazol-1-yl-2idene)-2-phenylene)chlorobis(dimethylamido)titanium(IV) ( 7). An efficient direct synthesis of trichloro complex 3 was accomplished by reacting the chlorobis(dimethylamido)titanium complex 7 with TMSCl. The catalytic activity of the bis(dimethylamido)iodotitanium complex 2 and chlorobis(dimethylamido)titanium complex 7 toward the hydroamination/ cyclization of unactivated alkene-amines was also evaluated.

Crystalline bis(η5-cyclopentadienyl)bis(benzoato/carboxylato)titanium(IV) precursor-directed route to functional titanium dioxide nanomaterials

“…Titanium(IV) complexes form a major class of organometallic and coordination compounds which display effective and tuneable reactivities [1][2][3]. These compounds are also marked as effective catalysts [4][5][6][7][8], have featured in metallo-supramolecular chemistry [9,10] and have applications in medicinal and bioinorganic chemistry [11,12]. Among the latter, Cp2TiCl2 was investigated as an anti-cancer drug, based on the presence of the dichloride entity under the assumption its mode of biological action would be closely aligned with that of cisplatin, [cis-PtCl2(NH3)2].…”

Cationic Rh and Ir complexes containing bidentate imidazolylidene–1,2,3-triazole donor ligands: synthesis and preliminary catalytic studies

“…7 The hydroamination of alkynes and alkenes is an atom economical method for the synthesis of C-N bonds and can be catalysed by lanthanides, actinides as well as early and late transition metal complexes. [8][9][10][11][12][13][14][15][16][17][18][19] Finding catalysts that are stable as well as effective for promoting a range of different hydroamination reactions remains an important challenge. Late transition metal complexes have lower oxophilicity and higher functional group tolerance in comparison to lanthanides, actinides and early transition metal complexes, and hence have great potential for a wider application as hydroamination catalysts.…”

Aminopyridine stabilized group-IV metal complexes and their applications

“…However, these catalysts are associated with certain limitations; for example, Zr-catalyst Ind 2 TiMe 2 predominantly gives branched product by the reaction of 1-alkenes and secondary amines (N-methylaniline) [107][108][109][110]. Hydroaminoalkylation reactions of group IV metals-based complexes are rare and are active for styrene polymerization, but they produce branched products instead of desired linear hydroaminoalkylated products of alkenes which are industrially more important.…”