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Title: Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds

Abstract

Hydrides of numerous transition metal complexes can be generated by the heterolytic cleavage of H{sub 2} gas such that they offer alternatives to using main group hydrides in the regeneration of ammonia borane, a compound that has been intensely studied for hydrogen storage applications. Previously, we reported that HRh(dmpe){sub 2}, dmpe = 1,2-bis(dimethylphosphinoethane) was capable of reducing a variety of BX{sub 3} compounds having hydride affinity (HA) greater than or equal to HA of BEt{sub 3}. This study examines the reactivity of less expensive cobalt and nickel hydride complexes, (HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +}), to form B-H bonds. The hydride donor abilities ({Delta}G{sub H{sup -}}{sup o}) of HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +} were positioned on a previously established scale in acetonitrile that is cross-referenced with calculated HAs of BX{sub 3} compounds. The collective data guided our selection of BX{sub 3} compounds to investigate and aided our analysis of factors that determine favorability of hydride transfer. HCo(dmpe){sub 2} was observed to transfer H{sup -} to BX{sub 3} compounds with X = H, OC{sub 6}F{sub 5} and SPh. The reaction with B(SPh){sub 3} is accompanied by formation of (BH{sub 3}){sub 2}-dmpe and (BH{sub 2}SPh){sub 2}-dmpe products that follow from reductionmore » of multiple BSPh bonds and loss of a dmpe ligand from Co. Reactions between HCo(dmpe){sub 2} and B(SPh){sub 3} in the presence of triethylamine result in formation of Et{sub 3}N-BH{sub 2}SPh and Et{sub 3}N-BH{sub 3} with no loss of dmpe ligand. Reactions of the cationic complex [HNi(dmpe){sub 2}]{sup +} with B(SPh){sub 3} under analogous conditions give Et{sub 3}N-BH{sub 2}SPh as the final product along with the nickel-thiolate complex [Ni(dmpe){sub 2}(SPh)]{sup +}. The synthesis and characterization of HCo(dedpe){sub 2} (dedpe = diethyldiphenyl(phosphino)ethane) from H{sub 2} and a base is also discussed; including the formation of an uncommon trans dihydride species, trans-[(H{sub 2})Co(dedpe){sub 2}][BF{sub 4}].« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1033061
Report Number(s):
PNNL-SA-79240
Journal ID: ISSN 0020-1669; INOCAJ; EB4202000; TRN: US201202%%563
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 50; Journal Issue: 23
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; ACETONITRILE; AFFINITY; AMMONIA; CLEAVAGE; COBALT; HYDRIDES; HYDROGEN STORAGE; NICKEL HYDRIDES; REGENERATION; SYNTHESIS; TRANSFER REACTIONS; TRANSITION ELEMENTS; hydride transfer; transition metal; cobalt; nickel; GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; AMMONIA-BORANE; DONOR ABILITIES; HYDROGEN; PROTON; NI; FEH(DMPE)2(BH4)

Citation Formats

Mock, Michael T., Potter, Robert G., O'Hagan, Molly J., Camaioni, Donald M., Dougherty, William G., Kassel, W. S., and DuBois, Daniel L. Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds. United States: N. p., 2011. Web. doi:10.1021/ic200857x.
Mock, Michael T., Potter, Robert G., O'Hagan, Molly J., Camaioni, Donald M., Dougherty, William G., Kassel, W. S., & DuBois, Daniel L. Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds. United States. doi:10.1021/ic200857x.
Mock, Michael T., Potter, Robert G., O'Hagan, Molly J., Camaioni, Donald M., Dougherty, William G., Kassel, W. S., and DuBois, Daniel L. 2011. "Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds". United States. doi:10.1021/ic200857x.
@article{osti_1033061,
title = {Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds},
author = {Mock, Michael T. and Potter, Robert G. and O'Hagan, Molly J. and Camaioni, Donald M. and Dougherty, William G. and Kassel, W. S. and DuBois, Daniel L.},
abstractNote = {Hydrides of numerous transition metal complexes can be generated by the heterolytic cleavage of H{sub 2} gas such that they offer alternatives to using main group hydrides in the regeneration of ammonia borane, a compound that has been intensely studied for hydrogen storage applications. Previously, we reported that HRh(dmpe){sub 2}, dmpe = 1,2-bis(dimethylphosphinoethane) was capable of reducing a variety of BX{sub 3} compounds having hydride affinity (HA) greater than or equal to HA of BEt{sub 3}. This study examines the reactivity of less expensive cobalt and nickel hydride complexes, (HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +}), to form B-H bonds. The hydride donor abilities ({Delta}G{sub H{sup -}}{sup o}) of HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +} were positioned on a previously established scale in acetonitrile that is cross-referenced with calculated HAs of BX{sub 3} compounds. The collective data guided our selection of BX{sub 3} compounds to investigate and aided our analysis of factors that determine favorability of hydride transfer. HCo(dmpe){sub 2} was observed to transfer H{sup -} to BX{sub 3} compounds with X = H, OC{sub 6}F{sub 5} and SPh. The reaction with B(SPh){sub 3} is accompanied by formation of (BH{sub 3}){sub 2}-dmpe and (BH{sub 2}SPh){sub 2}-dmpe products that follow from reduction of multiple BSPh bonds and loss of a dmpe ligand from Co. Reactions between HCo(dmpe){sub 2} and B(SPh){sub 3} in the presence of triethylamine result in formation of Et{sub 3}N-BH{sub 2}SPh and Et{sub 3}N-BH{sub 3} with no loss of dmpe ligand. Reactions of the cationic complex [HNi(dmpe){sub 2}]{sup +} with B(SPh){sub 3} under analogous conditions give Et{sub 3}N-BH{sub 2}SPh as the final product along with the nickel-thiolate complex [Ni(dmpe){sub 2}(SPh)]{sup +}. The synthesis and characterization of HCo(dedpe){sub 2} (dedpe = diethyldiphenyl(phosphino)ethane) from H{sub 2} and a base is also discussed; including the formation of an uncommon trans dihydride species, trans-[(H{sub 2})Co(dedpe){sub 2}][BF{sub 4}].},
doi = {10.1021/ic200857x},
journal = {Inorganic Chemistry},
number = 23,
volume = 50,
place = {United States},
year = 2011,
month =
}
  • Hydrides of numerous transition metal complexes can be generated by the heterolytic cleavage of H₂ gas such that they offer alternatives to using main group hydrides in the regeneration of ammonia borane, a compound that has been intensely studied for hydrogen storage applications. Previously, we reported that HRh(dmpe)₂ (dmpe = 1,2-bis(dimethylphosphinoethane)) was capable of reducing a variety of BX₃ compounds having a hydride affinity (HA) greater than or equal to the HA of BEt₃. This study examines the reactivity of less expensive cobalt and nickel hydride complexes, HCo(dmpe)₂ and [HNi(dmpe)₂] +, to form B–H bonds. The hydride donor abilities (ΔGmore » H °) of HCo(dmpe)₂ and [HNi(dmpe)₂] + were positioned on a previously established scale in acetonitrile that is cross-referenced with calculated HAs of BX₃ compounds. The collective data guided our selection of BX₃ compounds to investigate and aided our analysis of factors that determine favorability of hydride transfer. HCo(dmpe)₂ was observed to transfer H to BX₃ compounds with X = H, OC₆F₅, and SPh. The reaction with B(SPh)₃ is accompanied by the formation of dmpe-(BH₃)₂ and dmpe-(BH₂(SPh))₂ products that follow from a reduction of multiple B–SPh bonds and a loss of dmpe ligands from cobalt. Reactions between HCo(dmpe)₂ and B(SPh)₃ in the presence of triethylamine result in the formation of Et₃N–BH₂SPh and Et₃N–BH₃ with no loss of a dmpe ligand. Reactions of the cationic complex [HNi(dmpe)₂] + with B(SPh)₃ under analogous conditions give Et₃N–BH₂SPh as the final product along with the nickel–thiolate complex [Ni(dmpe)₂(SPh)] +. The synthesis and characterization of HCo(dedpe)₂ (dedpe = Et₂PCH₂CH₂PPh₂) from H₂ and a base is also discussed, including the formation of an uncommon trans dihydride species, trans-[(H)₂Co(dedpe)₂][BF₄].« less
  • Rate constants for the quenching of poly(pyridine)ruthenium(II) (RuL/sub 3//sup 2 +/) excited states by caged cobalt(III) amine complexes (Co(cage)/sup 3 +/) range from 2 x 10/sup 8/ to 1 x 10/sup 9/ M/sup -1/ s/sup -1/ at 25/sup 0/C. The quenching process involves parallel energy transfer (k/sub en/ approx. 1 x 10/sup 8/ M/sup -1/ s/sup -1/) and electron transfer (k/sub el/ = (0.1-1) x 10/sup 9/ M/sup -1/ s/sup -1/) from RuL/sub 3//sup 2 +/ to Co(cage)/sup 3 +/. The rate constants for electron-transfer quenching are consistent with expectations based on an adiabatic semiclassical model. The yields of electron-transfermore » products range from 0.3 to 1.0, increasing as the rate constants for the back-reaction of RuL/sub 3//sup 3 +/ with Co(cage)/sup 2 +/ diminish. The relatively low magnitudes of the back-reaction rate constants, (0.08-8) x 10/sup 8/ M/sup -1/ s/sup -1/, are consistent with the high yields of electron-transfer products and derive from poor coupling of the RuL/sub 3//sup 3 +/ and Co(cage)/sup 2 +/ orbitals. 30 references, 3 figures, 4 tables.« less
  • Methyl vinyl ketone reacts with RuH(BH{sub 4})(triphos) (triphos = ttp, Cyttp) to give Ru({eta}{sup 4}-CH{sub 2}{double bond}CHCOMe)(triphos). The compound Ru({eta}{sup 4}-CH{sub 2}{double bond}CHCOMe)(Cyttp) is also formed from the reaction of RuH{sub 4}(Cyttp) with methyl vinyl ketone. RuH{sub 4}(Cyttp) reacts with 2-vinylpyridine to produce two isomers of RuH(CH{double bond}CHC{sub 5}H{sub 4}N)(Cyttp), with vinyl acetate to give RuH(O{sub 2}CMe)(Cyttp), and with methyl acrylate to yield RuH{sub 2}(CO)(Cyttp). The reaction products were characterized by multinuclear NMR and IR spectroscopy. The structure of Ru({eta}{sup 4}-CH{sub 2}{double bond}CHCOMe)(ttp) has been confirmed by single-crystal X-ray diffraction. Ru({eta}{sup 4}-CH{sub 2}{double bond}CHCOMe)(ttp) crystallizes in the space group P2{submore » 1}/c with cell parameters a = 10.236 (1) {angstrom}, b = 20.845 (3) {angstrom}, c = 16.922 (2) {angstrom}, {beta} = 106.58 (1){degree}, Z = 4, V = 3,460 {angstrom}{sup 3}, R = 0.031, and R{sub w} = 0.038 for the 5,829 intensities with F{sub o}{sup 2} > 3{sigma}(F{sub o}{sup 2}) and the 418 variables.« less