Ortho-Linked Polyaryloxide Ligands and Their Titanium Complexes

Abstract

Ortho-linked polyphenols, quaterphenol L(OH)4, and moderately hindered terphenol PhL(OH)3 are developed as new multidentate polyaryloxide ligands for transition-metal chemistry. The polyphenols are synthesized using ortho-metalation and metal-catalyzed cross-coupling methodologies; the synthetic routes allow for facile electronic and steric modification of the basic ligand design. The Ti(IV) coordination chemistry of these ligands reveals a diverse collection of bridged structures: dimeric [Ti(mu-PhLO3)(OiPr)]2 (P2(1)/n, a = 12.2699(5) A, b = 11.7957(5) A, c = 21.238(1) A, beta = 94.551(1) degrees, Z = 2, T = 170(2) K), dimeric [Ti2(mu-PhLO3)2(mu-Cl)(Cl)(THF)] (P1, a = 11.212(1) A, b = 14.165(1) A, c = 22.447(2) A, alpha = 90.440(4) degrees, beta = 93.345(4) degrees, gamma = 111.164(4) degrees, Z = 2, T = 170(2) K), and trimeric [Ti3(mu,mu'-LO4)(mu-OiPr)2(OiPr)6] P2(1)/n, a = 11.1022(5) A, b = 18.7015(9) A, c = 24.409(1) A, beta = 95.369(2) degrees, Z = 4, T = 170(2) K). The reaction of TiCl3(THF)3 with [PhLO3]3- results in oxidation of Ti(III) to Ti(IV) and formation of the oxo dimer [Ti(PhLO3)(THF)]2(mu-O) (P1, a = 10.8649(6) A, b = 12.1882(7) A, c = 14.3349(9) A, alpha = 65.602(3) degrees, beta = 84.390(3) degrees, gamma = 86.582(3) degrees, Z = 1, T = 200(2) K); the oxo group presumably originates from the THF solvent. The titanium centers in these environments are either 5- or 6-coordinate, with distorted square pyramidal/trigonal bipyramidal and distorted octahedral geometries, respectively; the polyphenoxide chelate ligands are capable of bridging multiple oxophilic titanium sites.

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

“…The synthesis of 33Cz (Scheme 4) began from the di(boronic acid) 6 which was easily synthesized in multi‐gram quantities according to the procedure of Kayal, Ducruet and Lee [36] . Compound 6 was reacted with 1‐bromo‐2‐nitrobenzene under Suzuki coupling conditions to produce quaterphenyl 7 in 56 % yield.…”

Synthetic Approaches to Zigzag‐Shaped Oligophenylene Strands Laterally Decorated with Hydroxy Functions

“…The synthesis of 7 was first attempted through a condensation under Suzuki–Miyaura conditions between 1,4‐dibromobenzene and 6 , which could be easily obtained on a large scale from the commercially available 2,2′‐dimethoxy‐1,1′‐biphenyl by a recently described procedure 7f. In order to disfavor the formation of polymeric species, a large excess of 1,4‐dibromobenzene (10 equiv.)…”

Synthesis of coordination polymers based on a 2,2′-dimethoxy-1,1′-biphenyl scaffold and Hg(II), Co(II), or Zn(II)

“…Afterward, a degassed solution of 2,2'-dimethoxy-1,1'-biphenyl-3,3'-bisboronic acid [27] (2g, 6.64 mmol) in 30 mL of methanol was transferred via cannula to the mixture. The resulting solution was stirred and heated at 120°C for 24 hours.…”

“…The ligand L (Scheme 1.) was synthesis by Suzuki -Miyaura coupling reactions between 2,2'dimethoxy-1,1'-biphenyl-3,3'-bisboronic acid [27] and 4-bromopyridine in the presence of Pd(0), which was obtained as two 4-pyridyl units in good overall yield (67%). Colorless crystals (67%) were obtained by slow diffusion of n-pentane into a CH2Cl2 solution of L.…”