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Dinitrogen Cleavage by Three-Coordinate Molybdenum(III) Complexes:  Mechanistic and Structural Data

Laplaza, Catalina E. and Johnson, Marc J. A. and Peters, Jonas C. and Odom, Aaron L. and Kim, Esther and Cummins, Christopher C. and George, Graham N. and Pickering, Ingrid J. (1996) Dinitrogen Cleavage by Three-Coordinate Molybdenum(III) Complexes:  Mechanistic and Structural Data. Journal of the American Chemical Society, 118 (36). pp. 8623-8638. ISSN 0002-7863. http://resolver.caltech.edu/CaltechAUTHORS:20141204-152547970

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Abstract

The synthesis and characterization of the complexes Mo[N(R)Ar]_3 (R = C(CD_3)_2CH_3, Ar = 3,5-C_6H_3Me_2), (μ-N_2){Mo[N(R)Ar]_3}_2, (μ-^(15)N_2){Mo[N(R)Ar]_3}_2, NMo[N(R)Ar]_3, ^(15)NMo[N(R)Ar]_3, Mo[N(t-Bu)Ph]_3, (μ-N_2){Mo[N(t-Bu)Ph]_3}_2, and NMo[N(t-Bu)Ph]_3 are described. Temperature-dependent magnetic susceptibility data indicate a quartet ground state for Mo[N(R)Ar]_3. Single-crystal X-ray diffraction studies for Mo[N(R)Ar]_3 and NMo[N(t-Bu)Ph]_3 are described. Extended X-ray absorption fine structure (EXAFS) structural studies for Mo[N(R)Ar]_3, (μ-N_2){Mo[N(R)Ar]_3}_2, and NMo[N(R)Ar]_3 are reported. Temperature-dependent kinetic data are given for the unimolecular fragmentation of (μ-N_2){Mo[N(R)Ar]_3}_2 to 2 equiv of NMo[N(R)Ar]_3 and for the fragmentation of (μ-^(15)N_2){Mo[N(R)Ar]_3}_2 to 2 equiv of ^(15)NMo[N(R)Ar]_3. The temperature dependence of the ^(15)N_2 isotope effect for the latter N_2 cleavage process was fitted to a simple harmonic model, leading to a prediction for the difference in NN stretching frequencies for the two isotopomers. The latter prediction was consistent with the Raman spectroscopic data for (μ-N_2){Mo[N(R)Ar]_3}_2 and (μ-^(15)N_2){Mo[N(R)Ar]_3}_2. The Raman spectroscopic data and EXAFS results are both consistent with an NN bond order of approximately 2 in (μ-N_2){Mo[N(R)Ar]_3}_2. Temperature-dependent magnetic susceptibility data consistent with a triplet ground state are given for (μ-N_2){Mo[N(t-Bu)Ph]_3}_2.


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http://dx.doi.org/10.1021/ja960574xDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja960574xPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ja960574xPublisherSupporting Information
Additional Information:© 1996 American Chemical Society. Received February 22, 1996. Publication Date (Web): September 11, 1996. This work made use of MRSEC Shared Facilities supported by the National Science Foundation under Award No. DMR-9400334. The Stanford Synchrotron Radiation Laboratory is funded by the Department of Energy, Office of Basic Energy Sciences. The Biotechnology Program is supported by the National Institutes of Health, Biomedical Research Technology Program, Division of Research Resources. Further support is provided by the Department of Energy, Office of Health and Environmental Research. We are indebted to Roger C. Prince of Exxon Research and Engineering Company for his assistance in data collection and Martin J. George of SSRL for use of his data collection software. We are also grateful to John Rehr of the University of Washington for providing us with a special extended k-range version of his program feff. Raman spectra were collected in the Harrison Spectroscopy Laboratory at MIT, supported in part by the National Institutes of Health. C.C.C. thanks Professors Richard R. Schrock and Barry K. Carpenter for helpful discussions. For funding, C.C.C. thanks the National Science Foundation (CAREER Award CHE-9501992), DuPont (Young Professor Award), the Packard Foundation (Packard Foundation Fellowship), Union Carbide (Innovation Recognition Award), and 3M (Innovation Fund Award). C.E.L. thanks MIT’s UROP (Undergraduate Research Opportunities Program) for funding. M.J.A.J. is grateful for an NSERC graduate research fellowship.
Funders:
Funding AgencyGrant Number
NSFDMR-9400334
Department of Energy (DOE)UNSPECIFIED
NIHUNSPECIFIED
NSFCHE-9501992
DuPont Young Professor AwardUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Union Carbide Innovation Recognition AwardUNSPECIFIED
3MUNSPECIFIED
MIT Undergraduate Research Opportunity Program (UROP)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Record Number:CaltechAUTHORS:20141204-152547970
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141204-152547970
Official Citation:Dinitrogen Cleavage by Three-Coordinate Molybdenum(III) Complexes:  Mechanistic and Structural Data Catalina E. Laplaza, Marc J. A. Johnson, Jonas C. Peters, Aaron L. Odom, Esther Kim, Christopher C. Cummins, Graham N. George, and Ingrid J. Pickering Journal of the American Chemical Society 1996 118 (36), 8623-8638
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52411
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Dec 2014 23:46
Last Modified:04 Dec 2014 23:46

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