Characterization of the E Isomer of Tetrasubstituted [5]Cumulene and Trapping of the Z Isomer as a Zirconocene Complex

Abstract

The E isomer of a [5]cumulene derivative, 2,2, 9,9-tetramethyl-3,8-diphenyldeca-3,4,5,6,7-pentaene (1), which was previously believed to be unisolable owing to very fast E/Z isomerization, was isolated and structurally characterized. The Z isomer was trapped as the transition-metal complex 5, and the molecular structure was determined. DFT calculations and an electrochemical study on 1 are also described.' ASSOCIATED CONTENT b S Supporting Information. Text, figures, tables, and CIF and MOL files giving details of the preparation, spectroscopic data, and CIF files for 1 and 5, spectroscopic data for 6, an NMR study of 1, electrochemical studies of 1, 3, and 4, details of the DFT calculations, and structures of (E)-and (Z)-1. This material is available free of charge via the Internet at http://pubs.acs.org.

Haptotropic Shift of [5]Cumulenes in Zirconocene Complexes and Effects of Steric Factors

“…We previously reported that 1,1,6,6-tetrakis(4-ethylphenyl)hexa-1,2,3,4,5-pentaene (13a) 14 reacted with low-valent zirconocene species Cp 2 Zr(PMe 3 ) 2 to form the 1-zirconacyclopent-3-yne compound of 2,5-bisalkylidene moieties 14a. 6c, 15 In the present study, we found that the reaction of 3,8-di-tert-butyl-2,2,9,9-tetramethyldeca-3,4,5,6,7-pentaene (13b), 16 under similar conditions, afforded the phosphine-coordinated η 2 -π-complex 15b (92%) selectively, instead of the 1-zirconacyclopent-3-yne 14b (Scheme 8). In the 1 H NMR spectroscopy of 15b, the cyclopentadienyl (= Cp) signal appeared at 5.45 ppm as a doublet ( 3 J PH = 1.8 Hz) because of the coupling with 31 P. The number of 13 C signals assignable to the [5]cumulene ligand in the 13 C NMR spectra indicated its unsymmetrical structure because of PMe 3 coordination.…”

Helical orbitals and circular currents in linear carbon wires

“…† Such systems have been reported in the literature and may hold promise for further functionalization at the chemically stable phenyl rings. [52][53][54][55][56] The possibility of systematically splitting the helical frontier orbitals of cumulenes by chemical design opens the Fig. 3 Optimized molecular structure and Newman projections along each C-N axis (approximate).…”

Palladium-Catalyzed Carbonyl Allylation Reactions Using Tin Chloride: A Mini-Review

“…Thereafter, he taught and did research at Sophia University in Japan. He is involved in several works other than Pd-catalyzed and Sn(II)-mediated carbonyl allylation, namely: molybdenummediated/catalyzed reactions (Kurusu, Masuyama, Saito M & Saito S, 1986;Masuyama, Takahashi & Kurusu, 1984;Masuyama, Tsuhako & Kurusu 1981;Masuyama, Kurusu & Segawa, 1987a;Masuyama, Yamada & Kurusu, 1987b;Trost & Masuyama, 1984), tetrabromooxomolybdate complex-catalyzed oxidations , synthesis of some dinuclear metal complexes (Guidote et al, 2001a(Guidote et al, , 2001b, hydrodesulfurization of dibenzothiophene derivatives over metal catalysts (Saih et al, 2005), various syntheses other than allylations using tin as catalyst, such as aziridination and amination (Masuyama, Ohtsuka, Harima & Kurusu, 2006a), carbonyl propargylation (Masuyama, Yamazuki, Ohtsuka & Kurusu, 2006c), aldol condensations (Masuyama, Ohtsuka & Kondo, 2006b), cyclotrimerization of terminal alkynes (Masuyama, Miyazaki & Suzuki, 2013a), and aldehyde-alkyne couplings (Masuyama, Takamura & Suzuki, 2013b), synthesis and characterization of zirconium complexes (Podiyanachari et al, 2012;Suzuki et al, 2014Suzuki et al, , 2013Suzuki et al, , 2012Suzuki et al, , 2011bSuzuki et al, , 2011a and even the synthesis of an amino acid used for diagnostic studies (Usuki et al, 2012).…”