Observation and characterization by N-15 CPMAS NMR of a double proton transfer in cyclic dimers of N-15,N-15'-di-(4-bromophenyl)-formamidine in the solid state | Health & Environmental Research Online (HERO)

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HERO ID

7550762

Reference Type

Journal Article

Title

Observation and characterization by N-15 CPMAS NMR of a double proton transfer in cyclic dimers of N-15,N-15'-di-(4-bromophenyl)-formamidine in the solid state

Author(s)

Mannle, F; Wawer, I; Limbach, HH

Year

1996

Is Peer Reviewed?

Yes

Journal

Chemical Physics Letters
ISSN: 0009-2614

Volume

256

Issue

Page Numbers

657-662

DOI

10.1016/0009-2614(96)00511-8

Web of Science Id

WOS:A1996UX54200016

URL

http://://WOS:A1996UX54200016
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Abstract

Using dynamic N-15 CPMAS NMR spectroscopy a novel double proton transfer was detected in the cyclic hydrogen bonded dimers of polycrystalline N-15,N-15'-di-(4-bromophenyl)-formamidine. Rate constants of this process, which is degenerate within the margin of error, were obtained by lineshape (k(12) = 10(6.6) exp(-9.7 kT mol(-1)/RT) s(-1), 110 K less than or equal to T less than or equal to 142 K) and N-15 T-1 data analysis (minimum at 324 K and 9.12 MHz, H-1-N-15 distance r(HN) = 1.11 Angstrom, k(12) = 10(10.9) x exp(-21.5 kJ mol(-1)/RT) s(-1), 240 K less than or equal to T less than or equal to 370 K). The non-Arrhenius behavior observed indicates proton tunneling at low temperatures.