Michael Denk

Publications

Total Citations 2478 (May 2016) 1157 (Aug 2005)

41. Denk, M. K.; Milutinović, N. S.; Marczenko, K. M., Sadowski, N. M.; Paschos, A. Nature’s Hydrides. RSC Chemical Science, published on-line Nov 17 2016.

40. Denk, M.K. The Variable Strenght of the Sulfur-Sulfur Bond, Denk, M.K., Eur. J. Inorg. Chem. 2009, 1358-1368.
Keywords: Sulfur / Radicals / Density functional calculations / Thermochemistry / Bond order / Spin density

Experimental values for the strength of the sulfur–sulfur bond scatter over a wide range and are frequently in dis- agreement with each other. For S8, reliable experimental data seem to lack entirely. To check experimental data and establish the strength of the sulfur–sulfur bond in S8, high- precision thermochemical calculations (G3, CBS-Q) and DFT methods were employed. The calculations confirm a stun- ning range for the strength of the sulfur–sulfur bond with energies between 77.7 kcal for FSSF and only 41.8 kcal for tetrasulfane, HSS–SSH. For the pivotal bond energy of elemental sulfur, S8, the bond energy is 40.5 kcal but can be narrowed to 38.0–39.2kcalmol–1 by including CBS-QB3 data. While older DFT methods are not well suited to accu- rately reproduce the S–S bond energies, excellent data can be obtained with the recently introduced Boese–Martin (BMK) hybrid DFT method. Atoms in molecules (AIM) calculations reveal significant multiple bonding and spin delocal- ization in the sulfur radicals XS·.
Citations: 13

39. Denk, M.K.: Ye, Xuan Isothioures - Thioureas - A CBS-Q Study

38. Denk, M.K.; Zheng, Feng-Lan, Hezarkhani, Azardokht Steric and Electronic Effects in the Dimerization of Wanzlick Carbenes: The Alkyl Effect Eur. J. Inorg. Chem. 2007, 3527-3534.

The steric and electronic influence of N-alkyl substituents on the dimerization energies DG° of Wanzlick carbenes (imidazolidin-2-ylidenes) was investigated experimentally and through DFT methods for a series of non-symmetrically substituted Wanzlick carbenes. A series of 3-alkyl-1-tert-butylimidazolidin-2-ylidenes with decreasing steric demand of the alkyl substituent (isopropyl, ethyl and methyl) were obtained in four steps from the commercially available N-alkylaminoethanol compounds. The carbenes are hydrolytically sensitive, colorless oils that can be distilled without decomposition and show no sign of dimerization to the respective enetetramines, even after prolonged heating. Calculations at the B98/6-31G(d) level confirm that the dimerization of all three carbenes is thermodynamically unfavorable. To separate the steric and electronic stabilization of Wanzlick carbenes by N-alkyl substituents, the formation energies of R,H3 mono-alkyl enetetramines were used to derive electronic increments for the N-alkyl substituents. The computational data show that all alkyl substituents electronically stabilize Wanzlick carbenes vs. their dimerization products with increments ranging from 2.97 kcal mol-1 (N-methyl) to as high as 6.28 kcal mol-1 (N-tert-butyl). For combinations of N-methyl, N-ethyl and N-isopropyl substituents, the increments are additive and the dimerization energies were found to be free of noticeably steric effects. Significant steric strain was found for all tBu-substituted carbenes with strain energies of the dimerization products ranging from 6.92 kcal mol-1 [formation of (E)-Me2tBu2-enetetramine] to 24.23 kcal mol-1 (formation of tBu4 enetetramine). The tert-butyl substituent thus assumes a unique position by strongly stabilizing the carbenes electronically as well as sterically.

Citations: 23

37. Denk, M.K.;Ye, Xuan Alkylation of Ethylenehiourea with Alcohols: A Convenient Synthesis of S-alkyl-isothioureas Without Toxic Alkylating Agents, Tetrahedron Letters 2005, 46, 7597-7599.

Citations: 5

36. Denk, M.K.; Hezarkhani, A. A. "The Thermodynamic Satbility of P8 - A CBS-Q Study Heteroatom Chemistry 2005, 16, 453-457.

Citations: 6

35. Denk, M.K.; Krause, M.; Niyogi, D.F.; Gill, N.K. "Reaction of 1,2-dibromoethane with primary amines - formation of N,N'disubstituted ethylendiamines and homologous polyamines H-[N(R)-CH2CH2]-NHR" Tetrahedron, 2003, 59, 7565-7570.

Citations: 11

34. Denk, M.K.; Gill, N.K.; Singh, G. "Potential explosion hazard of alpha-lithiated amines", C & E News, June 30, p2, 2003.

33. Hui Zhou, Y.; Denk, M. K.; "A New One-Step Three-Component Synthesis for Selenoureas"Tetrahedron Lett., 2003, 44, 1295-1299.

Citations: 13

32. Denk, M. K.; Hatano, K.; Lough, A. J. "Synthesis and Characterization of a Carbene-SO2 Adduct8" Eur. J., Inorg. Chem. 2003, 224-231.

Citations: 14

31. Denk, M. K.; Gupta, S.; Brownie, J.; Tajammul, S.; Lough, A. J. "CH Activation with Elemental Sulfur (I): Synthesis of Cyclic Thioureas from Formaldehyde Aminals and S8" Chem. Eur. J., 2001, 7 (20): 4477-4486.

Citations: 25

30. Hitchcock, A. P.; Ennis, L. E.; Lehmann, J. F.; Denk, M.K., "Transient ISEELS: a new probe of chemical reactions" J. El. Spec. 2001, 114, 1037-1041.

Citations: 4

29. Denk, M. K.; Rodezno, J., Gupta, S.; Lough, A. J. "Oxidation, Hydrogenation And Hydrolysis of Stable Diamino Carbenes" J. Organometal Chem. 2001, 617-618, 242 - 253.

Citations: 94

28. Leites, L. A.; Bukalov, S. S.; Denk, M. K.; West, R.; Haaf M., Raman Evidence of Aromaticity of the Thermally Stable Silylene (tBuNCH=CHNtBu)Si:" J. Molecular Structure - THEOCHEM, 2000, 550, 329-335.

Citations: 12

27. Published twice by editorial error:

Denk, M. K.; Rodezno, J., Fast deuterium labeling and the basicity of stable diamino carbenes (imidazole-2-ylidenes) J. Organometal. Chem. 2000, 608, 122-125.

Citations: 24

Denk, M. K.; Rodezno, J., Fast deuterium labeling and the basicity of stable diamino carbenes (imidazole-2-ylidenes) J. Organometal. Chem. 2001, 617-618, 737 - 740.

Citations: 28

26. Denk, M. K.; Gupta, S.; Ramachandran, R. "Aromatic Phosphenium Cations" Eur. J. Inorg. Chem. 1999, 41 - 49.

Citations: 59

25. Denk, M. K.; Hatano. K.; Ma, M.. J. "Nucleophilic Carbenes and the Wanzlick Equilibrium - A Reinvestigation" Tetrahedron Lett. 1999, 40, 2057 - 2060.

Citations: 25

24. Lehmann, J. F. ; Urquhart, S. G.; Ennis, L. E.; Hitchcock, A. P.; Hatano, K.; Gupta, S.; Denk, M. K. "Core Excitation Spectroscopy of Stable Cyclic Diaminocarbenes, -Silylenes, and -Germylenes Organometallics 1999, 18, 186- 1872.

Citations: 61

23. Haaf, M.; Schmiedl, A.; Schmedake, T. A.; Powell, R. A.; Millevolte, A. J.; Denk, M.; West, R. "Synthesis and Reactivity of a Stable Silylene" J. Am. Chem. Soc. 1998, 120, 12714 - 12719.

Citations: 137

22. Denk, M. K., Khan, M., Lough, A. J., Shuchi, K. "Redetermination of the Germanium Dichloride complex with 1,4-Dioxane at 173K". Acta Cryst. 1998, C54, 1830 - 1831.

Citations: 22

21. Denk, M. K.; Hatano, K.; Lough, A. J. "Reactions Between Stable Carbene Analogues - Oxidation of a Stable Silylene by Tin(II)chloride" Eur. J. Inorg. Chem. 1998, 1067-1070.

Citations: 31

20. Urquhart, S.; Hitchcock, A. P.; Lehmann, J.F.; Denk, M. K. "Probing Delocalization In Stable Silylenes: Core Excitation Spectra of Si(NRCH=CHNR), Si(NRCH2CH2NR), H2Si(NRCH=CHNR) and H2Si(NRCH2-CH2NR), (R= tBu)." Organometallics 1998, 17, 2352 - 2360.

Citations: 32

19. Denk, M. K.; Thadani, A.; Hatano, K.; Lough, A. J. "The Steric Stabilization of Nucleophilic Carbenes" Angew. Chem. Int. Ed. Engl. 1997, 36, 2607-2609; Angew. Chem. 1997, 109, 2719 - 2721.

Citations: 64

18. Denk, M.K.; Gupta, S.; Ramachandran, R. "Aromatic Phosphenium Cations" Tetrahedron Lett. 1996, 9025 9028.

Citations: 141

17. Metzler, N.; Denk, M. K. "Synthesis of a Silylene Borane Adduct and its slow Conversion into a Silylborane", Chem. Commun. 1996, 2657 - 2658.

Citations: 43

16. West, R.; Denk, M. "Stable Silylenes: Synthesis, Structure, Reactions" Pure & Appl. Chem. 1996, 68 , 785 - 788.

Citations: 160

15. Denk, M.; Aromatic Silylenes and Phosphenium Cations Abstr. Pap. Am. Chem. Soc. S 209: 163-INOR Part 1 Apr 2 1995.

14. Arduengo, A.J.; Bock, H.; Chen, H.; Denk, M.; Dixon, D. A.; Green, J. C.; Herrmann, W. A.; Jones, N. L.; Wagner, M.; West, R. "Photoelectron-spectroscopy of a Carbene/Silylene/Germylene series, J. Am. Chem. Soc. 1994, 116, 6641 - 6649.

Citations: 274

13. Denk , M.; Lennon, R.; Hayashi, R.; West, R.; Haaland, A.; Belyakov, A. V.; Verne, H. P.; Wagner, M.; Metzler, N. "Synthesis and Structure of a Stable Silylene" J. Am. Chem. Soc. 1994, 116, 2691 - 2692.

Citations: 448

12. Denk, M.; Hayashi, R. K.; West, R. "Reaction of a Stable Silylene with Covalent Azides - A New Synthesis for Silaimines" J. Am. Chem. Soc. 1994, 116, 10813 - 10814.

Citations: 74

11. Denk, M.; Green, J. C.; Metzler, N.; Wagner, M. "Electronic Structure of a Stable Silylene: Photoelectron Spectra and Calculations" J. Chem. Soc., Dalton Trans. 1994, 2405-2410.

Citations: 91

10. Denk, M.; Hayashi, R. K.; West, R. "Reaction of a Stable Silylene with Ni(CO)4 "Silylene Complexes from A Stable Silylene and Metal Carbonyls - Synthesis and Structure of [Ni(tBuN-CH=CH-NBut)Si)2(CO)2], a Donor-Free Bis-Silylene Complex" J. Chem. Soc., Chem. Commun. 1994, 33-34.

Citations: 117

9. Denk, M.; A stable Silylene, Synthesis Structure Reactivity. Abstr. Pap. Am. Chem. Soc. S 207: 49-INOR Part 1 Mar 13 1994.

8. Herrmann, W. A.; Denk, M.; Scherer, W.; Kleine, M. "Volatile Boranate Complexes of Titanium and Zirconium " J. Organomet. Chem. 1993, 444, C21 - C24.

Citations: 46

7. Herrmann, W. A.; Anwander, R; Denk, M. "Neodym and Yttrium Alkoxides with Bulky Chelate Ligands" Chem. Ber. 1992, 125, 2399 - 2405.

Citations: 37

6. Herrmann, W. A.; Bogdanovic, S.; Behm, J.; Denk, M. "Methyl Nitridomolybdenum(VI) Complexes " J. Organomet. Chem. 1992, 430, C33 - C38.

Citations: 35

5. Herrmann, W. A.; Denk, M.; Behm, J.; Scherer, W.; Klingan, F.-R.; Bock, H.; Solouki, M.; Wagner, M. "Stable, Cyclic Germylenes: Synthesis, Structure, Metal Complexes, Thermolytic Studies " Angew. Chem. 1992, 104, 1489 - 1492; Angew. Chem. Int. Ed. Engl. 1992, 31, 1485-1488.

Citations: 240

4. Herrmann, W. A.; Denk, M.; Härter, P.; Dyckhoff, F.; Huber, N.; "Novel Hard Coatings from the Decomposition of Metal-Organic Compounds" Dünnschichttechnologien ´92, VDI-Verlag GmbH, Düsseldorf, 1992.

3. Herrmann, W. A.; Denk, M.; Albach, R.; Behm, J.; Herdtweck, E. "Cyclic Metal Amides" Chem. Ber. 1991, 124, 683 - 689.

Citations: 54

2. Herrmann, W. A.; Huber, F.; Härter, P.; Denk, M.; Dyckhoff, N. "Volatile MN4-Complexes with Dimethylsilyl Substituents" Chem. Ber. 1992, 125, 117-118.

Citations: 8

1. Herrmann, W. A.; Denk, M;. Dyckhoff, F.; "Niobium and Tantalum Complexes with Imido Ligands" Chem. Ber. 1991, 124, 2401 - 2403.

Citations: 7

Patents

5 Denk, M. K.; Fournier, S. "Volatile Amidinates and their Use in CVD." This invention has been disclosed to the University, patent pending. The process allows the chemical vapor deposition of thin copper films under chloride and oxygen free conditions and may be of significant importance to the manufacturing of microelectronic devices.

4 US Patent 5,728,856. "Silylene, A Process for Its Production And Its Use" Inventor: Denk, M.K., (1996)

3 German Patent 42 14 281.4 - Co 9201. "Procedure for the Synthesis of Germaniumdichloride Ether Adducts". Inventors: Denk, M.; Herrmann, W. A, patents pending in the U. S., Japan, Korea and the EC (1994).

2 German Patent 42 34 998.2. "Chemical Vapor Deposition of Germanium from Cyclic Germanium Amides". Inventors: Denk, M.; Herrmann, W. A., patents pending in the U. S., Japan, Korea and the EC (1993, 1999).

1 German Patent 43 16 883 A1. "Synthesis of Stable Silylenes by Reduction Processes". Inventor: Denk, M., (1994)