Unusual phosphorus compounds

The Hey-Hawkins group was one of the first to use the reactive transition metal-phosphorus bond in metal phosphanido complexes[1a] for the synthesis of novel phosphorus-based ligands in the coordination sphere of a transition metal.[1b] More recently, the synthesis of functionalised ferrocenyl phosphines,[2a] especially chiral primary ferrocenyl phosphines[2b] has attracted much attention. These are highly versatile starting materials for chiral tertiary ferrocenyl phosphines via asymmetric organometallic synthesis[2c] and are also suitable precursors for a novel type of heterometallic hybrid materials.[2d] Recently, we reported the first switchable, catalytically active dendritic ferrocenyl phosphines,[2e] followed by the first C3 symmetrical switchable redox-active tris(ferrocenylphosphine)triazine or -arene ligands.[2f]

Furthermore, we have succeeded in providing a facile route to long-sought strained four-membered phosphorus heterocycles, i.e., diphosphetanes,[3a] and have shown their remarkable reactivity.[3b] With these studies we have paved the way for the exploration of this exciting new class of strained P-based heterocycles. Recent highlights include the oxidative P‒P bond addition to cobalt(‒I) with formation of an unusual low-spin cobalt(III) phosphanido complex[4] or the formation of a sixteen-membered Au8P8 macrocycle.[5]

The Hey-Hawkins group was also the first to report on an asymmetric phospha-Diels-Alder reaction of phospholes[6] resulting in a plethora of chiral mono- and bidentate P-based ligands. An extension to a phospha-aza-Diels-Alder reaction followed.[7] In addition to highly interesting basic research, these compounds have also great potential as ligands for transition metal complexes in homogeneous catalysis.

Another approach focuses on the use of selective phosphorus-based macrocycles, nano-frames or containers[8] as receptors for catalytically active transition metals, generating molecular nanosized reactors that should allow specific interactions of the cavity with substrates during a catalytic process. Variation of the coordinated metal atom or the size of the cavity should influence the selectivity in catalytic processes.
Furthermore, metal-organic frameworks (MOFs) with well-defined structures and porosity can be used for sensing, generating specific optical properties[9] or for selective drug delivery.[10]

Complexes containing two different metal centres are highly attractive in catalysis since cooperative and synergistic effects open new reaction pathways by simultaneously activating one or more substrates or two reacting functional groups. The Hey-Hawkins group has successfully designed heteroditopic ligands[11] with distinct coordination sites which distinguish between two metal ions and can be used in the synthesis of well-defined heterobimetallic complexes. Current work focuses on N,P-based ligand systems and their application in homogeneous catalysis for CO2 hydrogenation, co-polymerisation reactions and tandem catalysis.

Phosphorus-rich compounds

Compounds with high phosphorus content such as alkali metal oligophosphanides are highly attractive due to their reactivity and interesting structural properties.[12a,b] Furthermore, the corresponding transition metal complexes could be suitable precursors for binary metal phosphides, which have a wide range of applications such as corrosion resistors, catalysts for hydrodesulfurisation and hydrodenitrogenation, oxygen barriers, semiconductors, magnetic materials, and anode materials in lithium ion batteries. During the past two decades, the Hey-Hawkins group has pioneered this synthetically highly challenging area with striking contributions in the field of phosphorus-rich transition metal complexes and has shown their use as precursors for binary metal phosphides.[12c] More recently, facile synthetic routes to neutral oligophosphines, such as octaphosphines, have been developed, facilitating their use in versatile coordination chemistry as well as providing precursors for phosphorus-rich metal phosphides.[13]


The Hey-Hawkins group has been involved in carborane chemistry for more than 20 years. Thus, we were one of the first research groups to use carboranes as electron-poor backbone in bis-phosphine ligands for catalysis, and have reviewed this area for the book on Boron Science, New Technologies and Applications.[14] Furthermore, the use of carborane derivatives in organocatalysis has recently been demonstrated.[15]
The Hey-Hawkins group has also made important contributions concerning the use of carboranes as pharmacophores, specifically by replacement of phenyl rings in pharmaceuticals,[16] e.g., in COX inhibitors[17] and LOX inhibitors.[18] Prof. Hey-Hawkins has also co-edited a book on Boron-Based Compounds: Potential and Emerging Applications in Medicine[19] with Wiley VCH in 2018.

In the field of boron neutron capture therapy (BNCT) the Hey-Hawkins group is one of the leading research groups in Germany.[20] Here, carboranes and their derivatives, to be used as the boron sources in this therapy, were highly modified and incorporated in tumour-selective biomolecules. Research, in cooperation with the Beck-Sickinger group, lead to promising results in peptide-assisted BNCT.[21] More recent approaches focus on the application of less complex biomolecules like small molecule receptor agonists to open up a broader area of potential BNCT drugs.


[1] a) E. Hey-Hawkins, Chem. Rev. 94 (1994) 1661-1717; b) E. Hey, M. F. Lappert, J. L. Atwood, S. G. Bott, J. Chem. Soc., Chem. Commun. (1987) 597-599.
[2] a) S. Tschirschwitz, P. Lönnecke, E. Hey-Hawkins, Dalton Trans. (2007) 1377-1382, Cover; b) C. Limburg, P. Lönnecke, S. Gómez-Ruiz, E. Hey-Hawkins, Organometallics 29 (2010) 5427-5434; c) S. Tschirschwitz, P. Lönnecke, E. Hey-Hawkins, Organometallics 26 (2007) 4715-4724; d) S. Tschirschwitz, P. Lönnecke, J. Reinhold, E. Hey-Hawkins, Angew. Chem. 117 (2005) 3025-3029; Angew. Chem. Int. Ed. 44 (2005) 2965-2969; e) P. Neumann, H. Dib, A.-M. Caminade, E. Hey-Hawkins, Angew. Chem. Int. Ed. 54 (2015) 311-314, Inside back cover; f) A. Straube, P. Coburger, M. R. Ringenberg, E. Hey-Hawkins, Chem. Eur. J. 26 (2020) 5758-5764, Front Cover and Cover Profile.
[3] a) A. Kreienbrink, M. B. Sárosi, E. Rys, P. Lönnecke, E. Hey-Hawkins, Angew. Chem. 123 (2011) 4798-4800; Angew. Chem. Int. Ed. 50 (2011) 4701-4703, Back Cover; b) A. Kreienbrink, S. Heinicke, Thi Thuy Duong Pham, R. Frank, P. Lönnecke, E. Hey-Hawkins, Chem. Eur. J. 20 (2014) 1434-1439.
[4] P. Coburger, S. Demeshko, C. Rödl, E. Hey-Hawkins, R. Wolf, Angew. Chem. Int. Ed. 56 (2017) 15871-15875; Angew. Chem. 129 (2017) 16087-16091.
[5] A. K. Adhikari, M. B. Sárosi, T. Grell, P. Lönnecke, E. Hey-Hawkins, Angew. Chem. Int. Ed. 56 (2017) 4061-4064; Angew. Chem. 129 (2017) 4120-4123.
[6] a) T. Möller, M. B. Sárosi, E. Hey-Hawkins, Chem. Eur. J. 18 (2012) 16604-16607; b) T. Möller, P. Wonneberger, N. Kretzschmar, E. Hey-Hawkins, Chem. Commun. 50 (2014) 5826-5828.
[7] P. Wonneberger, N. König, F. B. Kraft, M. B. Sárosi, E. Hey-Hawkins, Angew. Chem. Int. Ed. 58 (2019) 3208-3211; Angew. Chem. 131 (2019) 3240-3244.
[8] a) E. Musina, T. Wittmann, S. Latypov, S. Kondrashova, P. Lönnecke, I. Litvinov, E. Hey-Hawkins, A. Karasik, Eur. J. Inorg. Chem. (2019) 3053-3060; b) R. Hoy, P. Lönnecke, E. Hey-Hawkins, Dalton Trans. 47 (2018) 14515-14520; c) P. Boar, M. Streitberger, P. Lönnecke, E. Hey-Hawkins, Inorg. Chem. 56 (2017) 7285-7291; d) E. I. Musina, T. I. Wittmann, A. B. Dobrynin, P. Lönnecke, E. Hey-Hawkins, A. A. Karasik, O. G. Sinyashin, Pure Appl. Chem. 89 (2017) 331-339.
[9] L. R. Mingabudinova, A. A. Vinogradov, V. A. Milichko, A. V. Vinogradov, E. Hey-Hawkins, invited contribution to special issue “Smart Inorganic Polymers”, Chem. Soc. Rev. 45 (2016) 5408-5431.
[10] a) V. V. Vinogradov, A. S. Drozdov, L. R. Mingabudinova, E. M. Shabanova, N. O. Kolchina, E. I. Anastasova, A. A. Markova, A. A. Shtil, V. A. Milichko, G. L. Starova, R. L. M. Precker, A. V. Vinogradov, E. Hey-Hawkins, E. A. Pidko, J. Mater. Chem. B 6 (2018) 2450-2459; b) A. Valente, R. L. M. Precker, E. Hey-Hawkins, in: Smart Inorganic Polymers: Synthesis, Properties, and Emerging Applications in Materials and Life Sciences, ed. E. Hey-Hawkins and M. Hissler, ISBN:9783527819140, Wiley-VCH Verlag GmbH & Co. KGaA, pp. 243-276, 2019.
[11] a) D. J. Hutchinson, R. Clauss, M.-B. Sárosi, E. Hey-Hawkins, Dalton Trans. 47 (2018) 1053-106; b) D. J.
Hutchinson, E. Hey-Hawkins, Eur. J. Inorg. Chem. (2018) 4790-4796.
[12] a) A. Schisler, P. Lönnecke, U. Huniar, R. Ahlrichs, E. Hey-Hawkins, Angew. Chem. Int. Ed. 40 (2001) 4217-4219; b) R. Wolf, E. Hey-Hawkins, Angew. Chem. Int. Ed. 44 (2005) 6241-6244; c) S. Gómez-Ruiz, E. Hey-Hawkins, Coord. Chem. Rev. 255 (2011) 1360-1386.
[13] a) T. Grell, E. Hey-Hawkins, Chem. Eur. J. 26 (2020) 1008-1012; b) T. Grell, E. Hey-Hawkins, Europ. J. Inorg. Chem. (2020) 732–736, Front Cover and Cover Profile; c) T. Grell, E. Hey-Hawkins, Inorg. Chem. 59 (2020) 7487-7503, Front Cover.
[14] S. Bauer, E. Hey-Hawkins, in: Boron Science, New Technologies and Applications, chapter 22, ed. N. S. Hosmane, ISBN 978-1-4398266-3-8, CRC Press: Boca Raton, FL, USA, 2012, 529-577.
[15] S. Selg, W. Neumann, P. Lönnecke, E. Hey-Hawkins, K. Zeitler, Chem. Eur. J. 23 (2017) 7932-7937.
[16] a) P. Stockmann, M. Gozzi, R. Kuhnert, M. B. Sárosi, E. Hey-Hawkins, Chem. Soc. Rev. 48 (2019) 3497-3512; b) M. Scholz, E. Hey-Hawkins, Chem. Rev. 111 (2011) 7035-7062
[17] A. Buzharevski, S. Paskas, M.-B. Sárosi, M. Laube, P. Lönnecke, W. Neumann, B. Murganić, S. Mijatović, D.
Maksimović-Ivanić, J. Pietzsch E. Hey-Hawkins, Sci. Rep. (2020) 10:4827.
[18] a) R. Kuhnert, M.-B. Sárosi, S. George, P. Lönnecke, B. Hofmann, D. Steinhilber, B. Murganic, S. Mijatovic, D. Maksimovic-Ivanic, E. Hey-Hawkins, ChemMedChem 12 (2017) 1081-1086; b) R. Kuhnert, M.-B. Sárosi, S. George, P. Lönnecke, B. Hofmann, D. Steinhilber, S. Steinmann, R. Schneider-Stock, B. Murganić, S. Mijatović, D. Maksimović-Ivanić, E. Hey-Hawkins, ChemMedChem 14 (2019) 255-261.
[19] Boron-Based Compounds: Potential and Emerging Applications in Medicine, ed. E. Hey-Hawkins and C. Viñas Teixidor, ISBN 9781119275558, Wiley, 2018.
[20] M. Kellert, E. Hey-Hawkins, Mitteilungen der Wilhelm-Ostwald-Gesellschaft e.V. 25/1 (2020) 26-50; ISSN 1433-3910.
[21] a) D. J. Worm, S. Els-Heindl, M. Kellert, R. Kuhnert, S. Saretz, J. Koebberling, B. Riedl, E. Hey-Hawkins, A. G. Beck-Sickinger, J. Pept. Sci. 24 (2018) e3119; b) M. Kellert, P. Hoppenz, P. Lönnecke, D. J. Worm, B. Riedl, J. Koebberling, A. G. Beck-Sickinger, E. Hey-Hawkins, Dalton Trans. 49 (2020) 57-69; c) D. J. Worm, P. Hoppenz, S. Els-Heindl, M. Kellert, R. Kuhnert, S. Saretz, J. Koebberling, B. Riedl, E. Hey-Hawkins, A. G. Beck-Sickinger, J. Med. Chem. 63 (2020) 2358-2371; d) P. Hoppenz, S. Els-Heindl, M. Kellert, R. Kuhnert, S. Saretz, H.-G. Lerchen, J. Koebberling, B. Riedl, E. Hey-Hawkins, A. G. Beck-Sickinger, J. Org. Chem. 85 (2020) 1446-1457.

last modified: 22.09.2020