Skip to main content

Sterically encumbered 2,6-dibenzhydryl-4-methylphenyl derived ligand systems: synthesis and structures


 Bulky 2,6-dibenzhydryl-4-methylaniline, I undergoes diazotization upon treatment with \(\hbox {H}_{2}\hbox {SO}_{4}/\hbox {NaNO}_{2}\), which upon further reaction with KI affords 1-iodo-2,6-dibenzhydryl-4-methylbenzene, 1. Reaction of I with one equivalent of acetylacetone in ethanol under reflux condition affords mono-Schiff base, 4-(2,6-dibenzhydryl-4-methylphenylamino)pent-3-ene-2-one, 2. Similarly, I reacts with half equivalent of 2-hydroxy-5-methylisophthalaldehyde or one-third equivalent of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde in ethanol under reflux condition to afford bis-Schiff base, 2,6-bis(((2,6-dibenzhydryl-4-methylphenyl)imino)methyl)-4-methylphenol, 3 and tris-Schiff base, 2,4,6-tris(((2,6-dibenzhydryl-4-methylphenyl)amino)methylene)cyclohexane-1,3,5-trione, 4, respectively. Further, I upon reaction with triflic acid affords (2,6-dibenzhydryl-4-methylphenyl)ammonium triflate, 5 whereas upon reaction with HBr and HCl affords co-crystals I \(\cdot \)HBr, 6 and I \(\cdot \)HCl, 7. All the new products were isolated in moderate to good yield and characterized by spectroscopic (IR, ESI-mass, NMR, UV-Vis) and microanalytical (CHN) techniques, in addition to a single crystal X-ray diffraction study for 1, 2 and 4-7.

Graphical Abstract

JCSC-D-17-00649 Synopsis A bulky amine was employed to synthesise various compounds containing 2,6-dibenzhydrylphenyl group. These compounds include a bulky iodo-derivative, one mono-, one bis- and one tris-Schiff base, one triflate salt of the bulky amine and two co-crystals of the bulky amine with HBr or HCl.

This is a preview of subscription content, access via your institution.

Scheme 1
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13


  1. 1.

    Puri M and Que Jr L 2015 Toward the synthesis of more Reactive S \(=\) 2 non-hemeoxoiron (IV) complexes Acc. Chem. Res. 46 1822

    Google Scholar 

  2. 2.

    Gao J, Zhang O, Ren J, Wu C and Zhao Y 2016 Aromaticity/Bulkiness of surface ligands to promote the interaction of anionic amphiphilic gold nanoparticles with lipid bilayers Langmuir 48 2443

    Google Scholar 

  3. 3.

    Jiang B. Gu Y, Qin J, Ning X, Gong S, Xiea G and Yang C 2016 Deep-red iridium (III) complexes cyclometalated by phenanthridine derivatives for highly efficient solution-processed organic light-emitting diodes J. Mater. Chem. C 4 3492

    CAS  Article  Google Scholar 

  4. 4.

    Al-Qahtani A, Alkahtani S, Kolli B, Tripathi P, Dutta S, Al-Kahtane A A, Jiang X-J, Ng D K P and Chang K P 2016 Aminophthalocyanine-mediated photodynamic inactivation of leishmaniatropica 2016 Antimicrob. Agents and Chemother. 60 2003

    CAS  Article  Google Scholar 

  5. 5.

    Liu B, Li S, Wang M and Cui D 2017 Coordination polymerization of renewable 3-methylenecyclopentene with rare-earth-metal precursors Angew. Chem. Int. Ed. 56 4560

    CAS  Article  Google Scholar 

  6. 6.

    Yang X, Yan X, Guo H, Liu B, Zhao J, Zhou G, Wu Y, Wu Z and Wong W-Y 2017 Charged dinuclear Cu(I) complexes for solution-processed single-emitter warm white organic light-emitting devices Dyes Pigm. 143 151-164

    CAS  Article  Google Scholar 

  7. 7.

    Xu K, Zheng X, Wang Z and Zhang X 2014 Easily accessible and highly tunable bisphosphine ligands for asymmetric hydroformylation of terminal and internal alkenes Chem. Eur. J. 20 4357

    CAS  Article  Google Scholar 

  8. 8.

    DeAngelis A J, Gildner P G, Chow R and Colacot T J 2015 Generating active “L-Pd(0)” via neutral or cationic \(\uppi \)-allylpalladium complexes featuring biaryl/bipyrazolylphosphines: synthetic, mechanistic, and structure-activity studies in challenging cross-coupling Reactions J. Org. Chem. 80 6794

    CAS  Article  Google Scholar 

  9. 9.

    Wolters L P, Koekkoek R and Bickelhaupt F M 2015 Role of steric attraction and bite-angle flexibility in metal-mediated C-H bond activation ACS Catal. 5 5766

    CAS  Article  Google Scholar 

  10. 10.

    Yang X, Yang Y, Rees R J, Yang Q, Tian Z and Xue Y 2016 How dirhodium catalyst controls the enantioselectivity of [3 + 2]-cycloaddition between nitrone and vinyldiazoacetate: a density functional theory study J. Org. Chem. 81 8082

    CAS  Article  Google Scholar 

  11. 11.

    Longato B, Coppo R, Pilloni G, Corvaja C, Toffoletti A and Bandoli G 2001 Synthesis and characterisation of rhodium(0) and rhodium(-1) complexes stabilised by 1,1-bis(diphenylphosphino)ferrocene (dppf). Crystal structures of [\(\text{ Rh(dppf) }_{2}\)] and [\(\text{ Na(THF) }_{5}\)][\(\text{ Rh(dppf) }_{2}\)]\(\cdot \) THF J. Organomet. Chem. 637–639 710

    Article  Google Scholar 

  12. 12.

    Staveren D R van, Bill E, Bothe E, Bühl M, Weyhermüller T and Metzler-Nolte N 2002 Fluxional processes in diamagnetic and paramagnetic allyl dicarbonyl and 2-methylallyl dicarbonyl molybdenum histidinato complexes as revealed by spectroscopic data and density functional calculations Chem. Eur. J. 8 1649

    Article  Google Scholar 

  13. 13.

    Yang D, Guo J, Wu H, Ding Y and Zheng W 2012 Synthesis and structural characterization of two-coordinate low-valent 14-group metal complexes bearing bulky bis(amido)silane ligands Dalton Trans. 41 2187

    CAS  Article  Google Scholar 

  14. 14.

    Fohlmeister L and Jones C 2014 Low-valent iron complexes stabilised by a bulky guanidinate ligand: synthesis and reactivity studies Aus. J. Chem. 67 1011

    CAS  Article  Google Scholar 

  15. 15.

    Hickey A K, Lee W-T, Chen C-H, Pink M and Smith J M 2016 A bidentate carbene ligand stabilizes a low-coordinate iron(0) carbonyl complex Organometallics 35 3069

    CAS  Article  Google Scholar 

  16. 16.

    Gallagher M, Wieder N L, Dioumaev V K, Carroll P J and Berry D H 2010 Low-valent organometallics-synthesis, reactivity, and potential applications Chem. Eur. J. 16 6416

    Article  Google Scholar 

  17. 17.

    Schulz S 2010 Low-valent ruthenium complexes of the non-innocent 2,6-bis(imino)pyridine ligand Organometallics 29 591

    Article  Google Scholar 

  18. 18.

    Causero A, Ballmann G, Pahl J, Färber C, Intemann J and Harder S 2017 \(\upbeta \)-Diketiminate calcium hydride complexes: the importance of solvent effects Dalton Trans. 46 1822

    CAS  Article  Google Scholar 

  19. 19.

    Tang Z, Chen X, Yang Y, Pang X, Sun J, Zhang X and Jing X 2004 Stereoselective polymerization of rac-lactide with a bulky aluminum/schiff Base complex J. Polym. Sci. A Polym. Chem. 42 5974

    CAS  Article  Google Scholar 

  20. 20.

    Zhang J, Liang J-L, Sun X-R, Zhou H-B, Zhu N-Y, Zhou Z-Y, Chan P W H and Che C-M 2005 Chiral osmium complexes with sterically bulky schiff-base ligands. Crystal structures of Os(IV) derivatives and the reactivity and catalytic cyclopropanation of alkenes with EDA Inorg. Chem. 44 3942

    CAS  Article  Google Scholar 

  21. 21.

    Han F, Teng Q, Zhang Y, Wang Y and Shen Q 2011 Influence of Schiff Base and Lanthanide Metals on the Synthesis, Stability, and Reactivity of Monoamido Lanthanide Complexes Bearing Two Schiff Bases Inorg. Chem. 50 2634

    CAS  Article  Google Scholar 

  22. 22.

    Chen L, Zhao N, Wang Q, Hou G, Song H and Zi G 2013 Synthesis, structure, and catalytic activity of titanium complexes with chiral biaryl Schiff-base ligands Inorg. Chim. Acta 402 140

    CAS  Article  Google Scholar 

  23. 23.

    Leppin J, Förster C and Heinze K 2014 Molybdenum complex with bulky chelates as a functional model for molybdenum oxidases Inorg. Chem. 53 12416

    CAS  Article  Google Scholar 

  24. 24.

    Clarke R M and Storr T 2014 The chemistry and applications of multimetallic salen complexes Dalton Trans. 43 9380

    CAS  Article  Google Scholar 

  25. 25.

    Liu H, Zhao W, Hao X, Redshaw C, Huang W and Sun W-H 2011 2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-methylbenzenamine nickel dibromides: synthesis, characterization, and ethylene polymerization Organometallics 30 2418

    CAS  Article  Google Scholar 

  26. 26.

    Rhinehart J L, Mitchell N E and Long B K 2014 Enhancing \(\upalpha \)-diimine catalysts for high-temperature ethylene polymerization ACS Catal. 4 2501

    CAS  Article  Google Scholar 

  27. 27.

    Dai S, Sui X and Chen C 2015 Highly robust palladium(II) \(\upalpha \)-diimine catalysts for slow-chain-walking polymerization of ethylene and copolymerization with methyl acrylate Angew. Chem. Int. Ed. 54 9948

    CAS  Article  Google Scholar 

  28. 28.

    Hicks J, Hoyer C E, Moubaraki B, Manni G L, Carter E, Murphy D M, Murray K S, Gagliardi L and Jones C 2014 A two-coordinate manganese(0) complex with an unsupported Mn-Mg bond: Allowing access to low coordinate homo- and heterobimetallic compounds J. Am. Chem. Soc. 136 5283

    CAS  Article  Google Scholar 

  29. 29.

    Hering-Junghans C, Thomas M, Villinger A and Schulz A 2015 Synthesis of elusive chloropnictenium ions Chem. Eur. J. 21 6713

    CAS  Article  Google Scholar 

  30. 30.

    Dange D, Davey A, Abdalla J A B, Aldridge S and Jones C 2015 Utilisation of a lithium boryl as a reducing agent in low oxidation state group 15 chemistry: synthesis and characterisation of an amido-distibene and a boryl-dibismuthene Chem. Commun. 51 7128

    CAS  Article  Google Scholar 

  31. 31.

    Hicks J, Underhill E J, Kefalidis C E, Maron L and Jones C 2015 A mixed-valence tri-zinc complex, [LZnZnZnL] (L= bulky amide), bearing a linear chain of two-coordinate zinc atoms Angew. Chem. Int. Ed. 54 10000

    CAS  Article  Google Scholar 

  32. 32.

    Marder S R, Perry J W and Yakymyshyd C P 1994 Organic salts with large second-order optical nonlinearities Chem. Mater. 6 1137

    CAS  Article  Google Scholar 

  33. 33.

    Kelley S P, Narita A, Holbrey J D, Green K D, Reichert W M and Rogers R D 2013 Understanding the effects of ionicity in salts, solvates, co-crystals, ionic co-crystals, and ionic liquids, rather than nomenclature, is critical to understanding their behaviour Cryst. Growth Des. 13 965

    CAS  Article  Google Scholar 

  34. 34.

    D’Anna F and Noto R 2014 Di- and tricationic organic salts: an overview of their properties and applications Eur. J. Org. Chem. 4201

  35. 35.

    Berry D J and Steed J W 2017 Pharmaceutical cocrystals, salts and multicomponent systems; intermolecular interactions and property based design Adv. Drug Deliv. Rev. doi:10.1016/j.addr.2017.03.003

  36. 36.

    Saxena P and Murugavel R 2017 Bulky 2,6-Dibenzhydryl-4-methylaniline derived Schiff base complexes of Pd(II), Cu(II) and Co(II) as efficient catalysts for Suzuki coupling and alcohol oxidation reactions ChemistrySelect 2 3812

    CAS  Article  Google Scholar 

  37. 37.

    Kalita A C, Roch-Marchal C and Murugavel R 2013 Cationic D4R zinc phosphate–anionic polyoxometalate hybrids: synthesis, spectra, structure and catalytic studies Dalton Trans. 42 9755

    CAS  Article  Google Scholar 

  38. 38.

    Berthon-Gelloz G, Siegler M A, Spek A L, Tinant B, Reek J N H and Markó I E 2010 Dalton Trans. 39 1444

    CAS  Article  Google Scholar 

  39. 39.

    Hryniewicka A, Morzycki J W and Witkowski S 2010 New efficient ruthenium metathesis catalyst containing chromenyl ligand J. Organomet. Chem. 695 1265

    CAS  Article  Google Scholar 

  40. 40.

    Chong J H, Sauer M, Patrick B O and MacLachlan M J 2003 Highly stable keto-enamine salicylideneanilines Org. Lett. 5 3823

    Article  Google Scholar 

  41. 41.

    Perrin D D and Armarego W L F 1988 In Purification of Laboratory Chemicals \(3^{{\rm rd}}\) ed. (Oxford: Pergamon Press)

    Google Scholar 

  42. 42.

    CrysAlisPro, version, 2006 Oxford Diffraction Ltd, Oxford, U.K.

  43. 43.

    Farrugia L J 1999 WinGXsuite for smallmolecule single-crystal crystallography J. Appl. Cystallogr. 32 837

    CAS  Article  Google Scholar 

  44. 44.

    Altomare A, Cascarano G, Giacovazzo C and Guagliardi A 1993 Completion and refinement of crystal structures with SIR92 J. Appl. Cystallogr. 26 343

    Article  Google Scholar 

  45. 45.

    Sheldrick G M 2008 A short history of SHELX Acta Crystallogr. A64 112

    Article  Google Scholar 

  46. 46.

    Sluis P V D and Spek A L 1990 BYPASS: An effective method for refinement of crystal structures containing disordered solvent regions Acta Crystallogr. A46 194

    Article  Google Scholar 

  47. 47.

    Nakamoto K 1997 In Infrared and raman spectra of inorganic and coordination compounds, theory and applications in inorganic chemistry \(5^{{\rm th}}\) ed. (New York: John Wiley and Sons, Inc.)

    Google Scholar 

  48. 48.

    Riddle J A, Bollinger J C and Lee D 2005 Escape from a nonporous solid: mechanically coupled biconcave molecules Angew. Chem. Int. Ed. 44 6689

    CAS  Article  Google Scholar 

  49. 49.

    Jiang X, Vieweger M C, Bollinger J C, Dragnea B and Lee D 2007 Reactivity-based fluoride detection: evolving design principles for spring-loaded turn-on fluorescent probes Org. Lett. 9 3579

    CAS  Article  Google Scholar 

  50. 50.

    Jiang X, Bollinger J C and Lee D 2006 Two-dimensional electronic conjugation: cooperative folding and fluorescence switching J. Am. Chem. Soc. 128 11732

    CAS  Article  Google Scholar 

  51. 51.

    Stanciu C, Fox A R, Richards A F, Fettinger J C and Power P P 2006 ipso- and para-Functionalization of meta-terphenyl ligands with substituted methyl groups: Unusual head-to-tail coupling of terphenyl moieties J. Organomet. Chem. 691 2546

    CAS  Article  Google Scholar 

  52. 52.

    Vicente J, Lyakhovych M, Bautista D and Jones P G 2001 Polymetalated aromatic compounds. 1. synthesis of mono-, di-, and tripalladatedmesitylene derivatives Organometallics 20 4695

    CAS  Article  Google Scholar 

  53. 53.

    Sasaki S, Murakami F and Yoshifuji M 2006 Synthesis and redox properties of (3-Phenothiazinomesityl)- and (4-Phenothiazinoduryl)dimesitylphosphines and the corresponding arsines Organometallics 25 140

    CAS  Article  Google Scholar 

  54. 54.

    Lu W, Wei Z, Yuan D, Tian J, Fordham S and Zhou H-C 2014 Rational design and synthesis of porous polymer networks: toward high surface area Chem. Mater. 26 4589

    CAS  Article  Google Scholar 

  55. 55.

    Ichikawa J, Hoshino N, Takeda T and Akutagawa T 2015 Collective in-plane molecular rotator based on dibromoiodomesitylene \(\uppi \)-stacks J. Am. Chem. Soc. 137 13155

    CAS  Article  Google Scholar 

  56. 56.

    Schulz A 2014 On The Steric Hindrance of Bulky Substituents – Determination of Their Cone Angles Z. Anorg. Allg. Chem. 640 2183

    CAS  Article  Google Scholar 

  57. 57.

    Allen F H, Kennard O, Watson D G, Brammer L, Orpen A G and Taylor R 1987 Tables of Bond Lengths determined by X-Ray and Neutron Diffraction. Part I. Bond Lengths in Organic Compounds J. Chem. Soc., Perkin Trans. 2 S1

    Article  Google Scholar 

  58. 58.

    Kabak M, Elmali A and Elerman Y 1998 Tautomeric properties, conformations and structure of N-(2-hydroxyphenyl)-4-amino-3-penten-2-on J. Mol. Struct. 470 295

    CAS  Article  Google Scholar 

  59. 59.

    Hamaki H, Takeda N, Yamasaki T, Sasamori T and Tokitoh N 2007 Synthesis and properties of alkaline metal complexes with new overcrowded \(\beta \)-diketiminato ligands J. Organomet. Chem. 692 44

    CAS  Article  Google Scholar 

  60. 60.

    Sachse A, Mösch-Zanetti N C, Lyashenko G, Wielandt J W, Most K, Magull J, Dall’Antonia F, Pal A and Herbst-Irmer R 2007 Rhenium(V) oxo complexes with acetylacetone derived schiff Bases: structure and catalytic epoxidation Inorg. Chem. 46 7129

    CAS  Article  Google Scholar 

  61. 61.

    Sedaghat T, Naseh M, Bruno G, Rudbari H A and Motamedi H 2012 Synthesis, spectral and structural investigations, theoretical studies, and antibacterial activity of 4-(2-hydroxynaphthalen-3-ylamino)pent-3-en-2-one and its diphenyltin (IV) complex J. Coord. Chem. 65 1712

    CAS  Article  Google Scholar 

  62. 62.

    Lin T-H, Das K, Datta A, Leu W-J, Hsiao H-C, Lin C-H, Guh J-H and Huang J-H 2016 Synthesis and characterization of ruthenium compounds incorporating keto-amine ligands. The applications of catalytic transfer hydrogenation and cancer cell inhibition J. Organomet. Chem. 807 22

    CAS  Article  Google Scholar 

  63. 63.

    Lim Y K, Jiang X, Bollinger J C and Lee D 2007 Molecular engineering of two-dimensional \(p\)-conjugation: expected and unexpected photophysical consequences of a simple particle-in-a-box approach J. Mater. Chem. 17 1969

    CAS  Article  Google Scholar 

  64. 64.

    Kandambeth S, Mallick A, LukoseB, Mane M V, Heine T and Banerjee R 2012 Construction of crystalline 2D covalent organic frameworks with remarkable chemical (acid/base) stability via a combined reversible and irreversible route J. Am. Chem. Soc. 134 19524

    CAS  Article  Google Scholar 

  65. 65.

    DeBlase C R, Silberstein K E, Truong T-T, Abruña H D and Dichtel W R 2013 \(\beta \)-Ketoenamine-linked covalent organic frameworks capable of pseudocapacitive energy storage J. Am. Chem. Soc. 135 16821

    CAS  Article  Google Scholar 

Download references


R. M. is grateful to SERB, New Delhi for a J. C. Bose Fellowship (SB/S2/JCB-85/2014) through which this research work was carried out. P. S. thanks IIT Bombay for a Post-doctoral Fellowship. IIT Bombay is greatly acknowledged for providing analytical and instrumental facilities.

Author information



Corresponding author

Correspondence to Ramaswamy Murugavel.

Electronic supplementary material

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Saxena, P., Murugavel, R. Sterically encumbered 2,6-dibenzhydryl-4-methylphenyl derived ligand systems: synthesis and structures. J Chem Sci 129, 1499–1512 (2017).

Download citation


  • Sterically encumbered ligands
  • bulky aryl groups
  • Schiff bases
  • acid-base adducts
  • co-crystals