Zwitterionic CS2 Adducts of Bis(dialkylphosphino)amines: Syntheses, Spectroscopy, and Structures

Abstract

Both bis(diisopropylphosphino)amine and bis(di-t-butylphosphino)amine react with CS 2 to give bright red zwitterionic adducts of the form R 2 P(CS 2 )NP(R 2 )H (R ¼ i Pr or t Bu). The P-H tautomer is the exclusive species present in solution, and there is no evidence of CS 2 lability. The tautomeric hydrogen can undergo exchange with deuterium in protic solvents such as CD 3 OD. The products were characterized by single-crystal X-ray diffraction, IR and multinuclear ( 1 H, 2 H, 13 C, 31 P) NMR spectroscopies. * In memory of Professor Richard F. Langler, whose students, including DAD, will remember him for the high expectations he set for them in the classroom and in research, and the high standards to which he held them. His work with undergraduates has inspired us to train many young scientists, and we note that our coauthor RPUS was a high school student when he performed many of the experiments described in this work.

P- and N-Coordination of the Ambidentate Ligand HN[P(i-Pr)2]2 with Group 13 Trihalides

“…The 1 H NMR spectra of each of the complexes 2−5 (2 = In, 3 = Ga, 4 = Al, 5 = B) were quite similar to one another, as well as to the previously prepared adduct of 1 with B(C 6 F 5 ) 3 . 25 In each case, two sets of isopropyl peaks were observed, indicating that the symmetric Similar N/P tautomerization was first reported for HN(PR 2 ) 2 ligands by Bertrand 26 and has since been observed experimentally specifically for 1 in its reactions with tris-(pentafluorophenylborane) 25 as well as carbon disulfide, 27 elemental selenium, 28 and tellurium. 29 Computational studies have been preformed for the latter two examples.…”

“…The proton-coupled 31 P NMR spectra allowed the assignment of the more upfield of the two signals to a P−H group, but the downfield doublet showed no signs of broadening or coupling that would be consistent with a P−Al bond. Likewise, no P−Al coupling was resolved in the very broad resonance at δ 52 ppm in the 27 Al NMR spectrum, although a small, sharp doublet at δ 108 ppm ( 1 J Al−P = 316 Hz) was also present. Given that 1 is an ambidentate molecule with both "hard" N and "soft" P donor atoms, the spectroscopic data of 4 could be explained if AlCl 3 , the hardest of the four MCl 3 Lewis acids used, was bound to N instead of P with only trace amounts of the P-bound isomer being present in solution.…”

“…52 1 H and 13 C{ 1 H} spectra were referenced to residual solvent downfield of TMS. 31 P{ 1 H}, 27 Al, 11 B{ 1 H}, and 19 F{ 1 H} spectra were referenced to 85% H 3 PO 4 , Al(NO 3 ) 3 , BF 3 •Et 2 O, and CFCl 3 , respectively. IR spectra were recorded as mulls or thin films on KBr windows.…”

“…31 P{1 H} NMR (121 MHz, C 6 D 6 ) δ 86.6 (d,2 J PP = 54 Hz, P), 56.3 (d,2 J PP = 54 Hz, PH) ppm 27. Al NMR (78 MHz, C 6 D 6 ) δ 52 (br) ppm.…”

Richard (Rick) Francis Langler Memorial Issue

“…[11] Diane A. Dickie (University of New Mexico), another former student inspired by Rick's teaching and high standards, along with her colleagues describe their synthesis and characterisation of zwitterionic CS2 adducts of bis(dialkylphosphino) amines. [12] Catalytic asymmetric C-C formation implementing terminal alkyl-metal nucleophiles in tandem hydrometallationisomerisation is reported by Stephen Fletcher and his research students from the University of Oxford. [13] Stephen obtained his undergraduate honours degree working in Rick's research laboratory developing potent antifungal disulfides.…”