“Bidentate” and “tridentate” sulfonamide ligands for titanium complexes: crystal structures and solution dynamics elucidating an η2 or η3-coordination mode

Abstract

Highly air-and moisture-sensitive complexes having sulfonamide ligands, (TsNR) 2 Ti(NMe 2 ) 2 (Ts = p-MeC 6 H 4 SO 2 ), were prepared by treatment of two equivalents of TsNHR with Ti(NMe 2 ) 4 at room temperature. One of the compounds, where R = i-Pr (1), was studied in detail; the crystal structure of 1 revealed that both of the TsNi-Pr ligands were bound to the metal in an η 2 -coordination mode. Solution dynamics of 1 showed that an η 1 /η 2 interconversion occurred above 60 ЊC with an activation energy of 15.8 kcal mol Ϫ1 . Treatment of Ti(NMe 2 ) 4 with the sulfonamide TsHN(CH 2 ) 2 O(CH 2 ) 2 NHTs (3), led to the formation of [TsN(CH 2 ) 2 O(CH 2 ) 2 NTs]Ti(NMe 2 ) 2 (2) in high yield, in which the sulfonamide moiety was coordinated to the titanium center in an η 3 (NON) mode. No sign of η 1 /η 2 interconversion of the sulfonamide ligands was seen in solution. Treatment of 2 with Me 3 SiCl resulted in the formation of [{TsN(CH 2 ) 2 O(CH 2 ) 2 NTs}Ti(NMe 2 )Cl] 2 (4) and [{TsN(CH 2 ) 2 O(CH 2 ) 2 NTs}TiCl 2 ] 2 (5). An X-ray structure determination of 4 revealed that sulfonyl oxygen bridging resulted in the formation of an eight membered ring.

Ligand Variations in New Sulfonamide-Supported Group 4 Ring-Opening Polymerization Catalysts

“…Indeed, 24 could also be described as a square-based pyramid (SBP) with O(1) occupying the axial site since the four angles O(1)−Ti(1)−N( x ) ( x = 1, 2, 3, 4) lie in the narrow range 102.8(1)−114.6(1) o . We note that Nagashima recently described Ti{O(CH 2 CH 2 NTs) 2 }(NMe 2 ) 2 ( 27 ), containing a tridentate bis(sulfonamide)ether ligand analogous to N 2 Ts N Ph (but with O in place of NCH 2 Ph) . In this compound the NMe 2 groups occupy the equatorial sites of a distorted TBP (N Ts −Ti−N Ts = 143.5(1) o ), in contrast to 19 , in which one NMe 2 is equatorial and one is axial.…”

Titanium(IV) Complexes Based on Tri­dentate N,N,O Ligands – Synthesis, Structure, and Thermal Decomposition

“…A similar situation was observed for 8 . From the previously reported data,35 it may be proposed that no (S)O→Ti coordination occurs in 8 and 9 for five‐coordinate Ti complexes.…”

“…The coordination of the sulfonyl group (intra‐ [34a,37,38b,39,40] or intermolecular)35 has been observed for related N,N‐type ligands (Scheme ). Some examples of uncoordinated sulfonamide groups are also shown.…”

“…At the same time, it is difficult to determine the presence of Ti←OS(O) coordination in solution. However, from the literature data for related compounds35 (Scheme , complex A ),41 it may be proposed that the dissociation of the Ti←OS(O) coordination bond occurs at room temperature, and some broadening of the NMR signals indicates a dynamic behavior of the five‐coordinate Ti species formed (Berry pseudorotation) 3b,42. Furthermore, the IR spectrum of 11 contains only one set of SO 2 N vibrations (like that of 10 ) and, therefore, only one type of S=O group is present, that is, the S=O group is not coordinated to the Ti atom.…”

Synthesis, characterization, biological evaluation, and molecular docking approach of nickel (II) complexes containing O, N‐donor chelation pattern of sulfonamide‐based Schiff bases

“…[ 27,28 ] Accordingly, there is an interaction between the metal ion with the sulfonamidic‐N and sulfonyl‐O atoms of L 1 through four‐membered ring formation in case of complex ( 1 ). [ 29,30 ] As well, the blue shift and the weakness of the ν(C=N) at 1532 cm −1 of the thiazole moiety of L 2 in the spectra of its complex ( 2 ) favoring the chelation of the thiazole‐N atom to give more stable six‐membered ring. [ 28,31 ] Unlikely, there is no remarkable change of the sulfonamide group vibrational modes in case of L 3 and L 4 complexes ( 3 ) and ( 4 ) (Table S1) ruling out its participation in coordination with Ni (II) in these cases.…”