Nancy S. B. Williams

Associate Professor of Chemistry

Email: nwilliams@kecksci.claremont.edu
Office: Keck Science Center 228
Phone: 909-607-1603

Educational Background

Postdoctoral Fellow, UNC, Chapel Hill (Maurice Brookhart)
NSF-NATO Postdoctoral Fellowship, Universiteit Utrecht (Gerard van Koten)
M.S., Ph.D., University of Washington (Karen Goldberg)
B.S., Harvey Mudd College(Mitsuru Kubota)

Courses Taught

General Chemistry, Organic Chemistry, Inorganic Chemistry

Research Interests

Physical Organometallic Chemistry, Ligand Design and Effects on Fundamental Organic Transformations

Selected Publications

1. Jamieson, E. R.; Eppley, H. E.; Geselbracht, M. J.; Johnson, A. R. Reisner, B. A.; Smith, S. A.; Stewart, J. L. Watson, L. A.; Williams, B. S. (2011). Inorganic Chemistry and IONiC: An Online Community Bringing Cutting-Edge Research into the Classroom. Inorg. Chem.   50: 5849-5854.
   Abstract: This Viewpoint highlights creative ways that members of the Interactive Online Network of Inorganic Chemists (IONiC) are using journal articles from Inorganic Chemistry to engage undergraduate students in the classroom. We provide information about specific educational materials and networking features available free of charge to the inorganic community on IONiC’s web home, the Virtual Inorganic Pedagogical Electronic Resource (VIPEr, www.ionicviper.org) and describe the benefits of joining this community.
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2. Eppley, H. J; Geselbracht, M. J.; Jamieson, E. R; Johnson, A. R.; Reisner, B. A.; Smith, S. Stewart, J. L.; Watson, L. A., Williams, B. S. (2010). Building an Online Teaching Community: An Evolving Tale of Communication, Collaboration and Chemistry. Enhancing Learning with Online Resources, Social Networking, and Digital Libraries Belford, R.; Moore, J.; Pence, H. (Eds.) ACS Symposium Series: Chapter 16, 309-330.
   Abstract: The Interactive Online Network of Inorganic Chemists (IONiC) has grown from a small group of faculty to a national and international network focused on improving inorganic chemistry learning. IONiC’s vision is to create a community of teachers and learners who make teaching visible using social networking tools to share, discuss, test, and assess their teaching methods. The features that have allowed the IONiC community to develop and grow and IONiC’s vision for the future are described. It is likely that the lessons learned apply to other groups seeking to develop professional communities through social networking.
3. Williams, B. S. (2010). Sceptical Chymists Online: How the Practice, Teaching, and Learning of Science Will be Affected by Web 2.0. Enhancing Learning with Online Resources, Social Networking, and Digital Libraries Belford, R.; Moore, J.; Pence, H. (Eds.) ACS Symposium Series: Chapter 6, 95-114.
   Abstract: The current era of science and science education began in the 17th century, made possible by the earlier spread of the printing press. Science remains embedded in its 17th century context, and it is precisely these Gutenberg-era foundations that the Internet is replacing with new ones. The directions in which this is likely to lead science, given the ways in which the Internet is altering our social organizations are discussed.
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4. Reisner, B. A., Williams, B. S. (2010). Visible Teaching: Moving from a Solitary Practice to a Community Endeavor. J. Chem. Educ.  87: 252-253.
   Abstract: “Web 2.0” technologies are emerging as tools to enhance community and collaboration in scientific research. We believe that these tools will play a similar role in the practice of teaching by helping us to move from individual teaching spaces to community teaching spaces. By sharing and discussing our day-to-day successes, failures, experiments, innovations, and standard practices with the community using “Web 2.0” technologies, we believe that we can move to a model where teaching is visible. By engaging in Visible Teaching, we can build on the creative potential of our colleagues to improve the overall practice of teaching.
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5. Benatan, E.; Dene, J.; Eppley, H.; Geselbracht, M.; Jamieson, E.; Johnson, A.; Reisner, B.; Stewart, J.; Watson, L.; Williams, B. S. (2009). Come for the Content, Stay for the Community. Academic Commons: September.
   [Article – URL not found]
6. Benatan, E.; Eppley, H. J.; Geselbracht, M. J.; Johnson, A. R.; Reisner, B. A.; Stewart, J. L.; Watson, L.; Williams, B. S. (2009). IONiC: A Cyber-Enabled Community of Practice for Improving Inorganic Chemical Education. J. Chem. Educ. 86: 123 (summary).
   Abstract: Note that the portion of the paper in the print form of J. Chem Ed. is a 400 word abstract. The full publication is here: https://jchemed.chem.wisc.edu/JCEDLib/ConfChem/#a1, and is downloadable about 2/3 of the way down the page.
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7. Smythe, N. A.; Grice, K. A.; Williams, B. S.; Goldberg, K. I. (2009). Reductive Elimination and Dissociative Beta-Hydride Abstraction from Pt(IV) Hydroxide and Methoxide Complexes. Organometallics  28: 277-288.
   Abstract: The platinum(IV) hydroxide and methoxide complexes fac-(dppbz)PtMe3(OR) (dppbz = o-bis(diphenylphosphino)benzene; R = H (1), CH3 (2)) have been prepared and characterized. Thermolysis of hydroxide 1 produces (dppbz)PtMe2 (3) and methanol in a rare example of directly observed sp3 carbon−oxygen reductive elimination from a metal center to form an alcohol. Competitive carbon−carbon reductive elimination to form (dppbz)PtMe(OH) (5) and ethane also occurs. In contrast, the major reaction observed upon thermolysis of the methoxide analog 2 is neither carbon−oxygen nor carbon−carbon reductive elimination. Instead, products expected from formal β-hydride elimination followed by carbon−hydrogen reductive elimination are detected. Mechanistic studies suggest the operation of an alternative mechanism to that most commonly accepted for this fundamental reaction; a dissociative β-hydride abstraction pathway is proposed.
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8. Scheuermann, M. L.; Rheingold, A. L.; Williams, B. S. (2009). Reversible Carbonylation of an [NCN]PtMe Pincer Complex and Direct Evidence of Alkyl Migration. Organometallics 28: 1613-1615.
   Abstract: [NCN]PtMe (1) reacts with CO initially to form an adduct (2) and then again to form a carbonyl acyl complex (3). Reaction of 3 with Me₃NO generates 2 by alkyl migration rather than carbonyl deinsertion.
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9. Madison, B. L.; Thyme, S. B.; Keene, S.; Williams, B. S. (2007). Mechanistic Study of Competitive sp3-sp3 and sp2-sp3 Carbon-Carbon Reductive Elimination from a Platinum (IV) Center and the Isolation of a C-C Agostic Complex. J. Am. Chem. Soc. 129: 9538 -9539.
   Abstract: The addition of methyl triflate to an [NCN]PtCH3 pincer complex 1 ([NCN] = 2,6-bis(diethylaminomethyl)phenyl) results in kinetically controlled competitive reductive eliminations to generate both sp3-sp3 coupling products (ethane and [NCN]Pt(OTf), 3) and an sp2-sp3 coupling product, [[NC(CH3)N]PtCH3][OTf] (4). The last is a cationic complex that could either be formulated as an arenium species or, more likely, as a C-C agostic complex. The addition of CD3OTf to 1 affords 3, CH3CD3, and 4-d3, with the deuterated label in 4-d3 distributed between the arene methyl group and the platinum-bound methyl group, implicating the intermediacy of the five coordinate intermediate [[NCN]Pt(CH3)(CD3)]+ (I-d3).
   [Article – URL not found]
10. Medici, S.; Gagliardo, M., Williams, S. B.; Chase, P. A.; Gladiali, S.; Lutz, M; Spek, A. L.; van Klink, G. P. M.; van Koten, G. (2005). Novel P-Stereogenic PCP Pincer-Aryl Ruthenium(II) Complexes and Their Use in the Asymmetric Hydrogen Transfer Reaction of Acetophenone. Helv. Chim. Acta   88: 694 – 705.
    Abstract: Achiral P-donor pincer-aryl ruthenium complexes ([RuCl(PCP)(PPh3)]) 4c,d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3-phenylenebis(methylene)]bis[diisopropylphosphine] (2c) or [1,3-phenylenebis(methylene)]bis[diphenylphosphine] (2d) and the N-donor pincer-aryl complex [RuCl{2,6-(Me2NCH2)2C6H3}(PPh3)], (3; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P-donor pincer-aryl ruthenium complexes [RuCl(P*CP*)(PPh3)] 4a,b by reacting P-stereogenic pincer-arenes (S,S)-[1,3-phenylenebis(methylene)]bis[(alkyl)(phenyl)phosphines] 2a,b (alkyl=iPr or tBu, P*CHP*) and the complex [RuCl{2,6-(Me2NCH2)2C6H3}(PPh3)], (3; Scheme 3). The crystal structures of achiral [RuCl(iPr,iPrPCP)(PPh3)] 4c and of chiral (S,S)-[RuCl(tBu,PhPCP)(PPh3)] 4a were determined by X-ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh3)] complexes and chiral [RuCl(P*CP*)(PPh3)] complexes were tested as catalyst in the H-transfer reduction of acetophenone with propan-2-ol. With the chiral complexes, a modest enantioselectivity was obtained.
    [Article – URL not found]
11. Procelewska, J.; Zahl, A.; Liehr, G.; Van Eldik, R.; Smythe, N. A.; Williams, B. S.; Goldberg, K. I. (2005). Mechanistic Information on the Reductive Elimination from Cationic Trimethylplatinum(IV) Complexes to Form Carbon-Carbon Bonds. Inorg. Chem. 44: 7732-7742.
    Abstract: Cationic complexes of the type fac-[(L2)PtIVMe3(pyr-X)][OTf] (pyr-X = 4-substituted pyridines; L2 = diphosphine, viz., dppe = bis(diphenylphosphino)ethane and dppbz = o-bis(diphenylphosphino)benzene; OTf = trifluoromethanesulfonate) undergo C-C reductive elimination reactions to form [L2PtIIMe(pyr-X)][OTf] and ethane. Detailed studies indicate that these reactions proceed by a two-step pathway, viz., initial reversible dissociation of the pyridine ligand from the cationic complex to generate a five-coordinate PtIV intermediate, followed by irreversible concerted C-C bond formation. The reaction is inhibited by pyridine. The highly positive values for Sobs = +180 � 30 J K-1 mol-1, Hobs = 160 � 10 kJ mol-1, and Vobs = +16 � 1 cm3 mol-1 can be accounted for in terms of significant bond cleavage and/or partial reduction from PtIV to PtII in going from the ground to the transition state. These cationic complexes have provided the first opportunity to carry out detailed studies of C-C reductive elimination from cationic PtIV complexes in a variety of solvents. The absence of a significant solvent effect for this reaction provides strong evidence that the C-C reductive coupling occurs from an unsaturated five-coordinate PtIV intermediate rather than from a six-coordinate PtIV solvento species.
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12. Williams, B. S.; Leatherman, M. D.; White, P. S.; Brookhart, M. (2005). Reactions of Vinyl Acetate and Vinyl Trifluoroacetate with Cationic Diimine Pd(II) and Ni(II) Alkyl Complexes: Identification of Problems Connected with Copolymerizations of These Monomers with Ethylene. J. Am. Chem. Soc. 127: 5132-5146.
    Abstract: Vinyl acetate (VA) and vinyl trifluoroacetate (VAf) react with [(NN)Pd(Me)(L)][X] (M = Pd, Ni, (NN) = N,N’-1,2-acenaphthylenediylidene bis(2,6-dimethyl aniline), Arf = 3,5-trifluoromethyl phenyl, L = ArfCN, Et2O; X = B(Arf)4-, SbF6-) to form -adducts 3 and 5 at -40 C. Binding affinities relative to ethylene have been determined. Migratory insertion occurs in a 2,1 fashion (G = 19.4 kcal/mol, 0 C for VA, and 17.4 kcal/mol, -40 C for VAf) to yield five-membered chelate complexes [(NN)Pd(2-CH(Et)(OC(O)CH3))]+, 4, and [(NN)Pd(2-CH(Et)(OC(O)CF3))]+, 6. When VA is added to [(NN)Ni(CH3)]+, an equilibrium mixture of an 2 olefin complex, 8c, and a -oxygen complex, 8o, results. Insertion occurs from the 2 olefin complex, 8c (G = 15.5 kcal/mol, -51 C), in both a 2,1 and a 1,2 fashion to generate a mixture of five- and six-membered chelates, 92,1 and 91,2. VAf inserts into the Ni-CH3 bond (-80 C) to form a five-membered chelate with no detectable intermediate. Thermolysis of the Pd chelates results in -acetate elimination from 4 (G = 25.5 kcal/mol, 60 C) and -trifluoroacetate elimination from 6 (G = 20.5 kcal/mol, 10 C). The five-membered Ni chelate, 92,1, is quite stable at room temperature, but the six-membered chelate, 91,2, undergoes -elimination at -34 C. Treatment of the OAcf containing Pd chelate 6 with ethylene results in complete opening to the -complex [(NN)Pd(2-CH(Et)(OAcf))(CH2CH2)]+ (OAcf = OC(O)CF3), 18, while reaction of the OAc containing Pd chelate 4 with ethylene establishes an equilibrium between 4 and the open form 16, strongly favoring the closed chelate 4 (H = -4.1 kcal/mol, S = -23 eu, K = 0.009 M-1 at 25 C). The open chelates undergo migratory insertion at much slower rates relative to those of the simple (NN)Pd(CH3)(CH2CH2)+ analogue. These quantitative studies provide an explanation for the behavior of VA and VAf in attempted copolymerizations with ethylene.
    [Article – URL not found]
13. Farrington, E. J.; Martinez V. E.; Williams, B. S.; van Koten, G.; Brown, J. M. (2002). Synthesis and reactivity of a ferrocene-derived PCP-pincer ligand. Chem. Commun.: 308-309.
    Abstract: The 1,3-bis(diphosphinomethyl)ferrocene 3 readily reacts with [(C2H4)2RhCl]2 to form an equilibrating pair of diastereomers 8a and 8b by C–H insertion into the ferrocene.
    [Article – URL not found]
14. Meijer, M. D.; Kleij, A. W.; Williams, B. S.; Ellis, D.; Lutz, M.; Spek, A. L.; van Klink, G. P. M.; van Koten, G. (2002). Construction of Supported Organometallics Using Cycloplatinated Arylamine Ligands. Organometallics 21: 264-271.
    Abstract: The preparation of ortho-chelating aminoaryl ligands ([C6H3(CH2NMe2)-2-R-4]-, abbreviated as C,N) containing a pendant hydroxymethyl group is described. These ligands have been cycloplatinated with cis-PtCl2(DMSO)2, yielding the corresponding C,N-platinum(II) complexes. The pendant hydroxymethyl substituent is a versatile group for attachment of the organometallic moiety to macromolecules, which has been demonstrated by attaching the C,N-platinum complexes to a dendritic wedge and to C60.
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15. Williams, B. S.; Dani, P.; Lutz, M.; Spek, A. L.; Van Koten, G. (2001). Development of the first P-stereogenic PCP pincer ligands, their metallation by palladium and platinum, and preliminary catalysis. Helv. Chim. Acta 84: 3519-3530.
    Abstract – The potentially tridentate P-stereogenic [P*CP*] ligands 1,3-{bis[(tert-butyl)(phenyl)phosphino]methyl}benzene and 1,3-{bis[(tert-butyl)(phenyl)phosphino]methyl}-2-bromobenzene were synthesized as the protected phosphine-borane adducts. Deprotection with a secondary amine affords the free phosphine ligand which can be metalated by Pd and Pt with std. metal synthons. Two of the resultant [P*CP*] metal complexes were characterized by x-ray crystallog. The complexes exhibit a C2 sym. environment about the remaining binding site of the square-planar center, with t-Bu groups filling two quadrants of the open site. The Pd complexes can be converted using a Ag salt to the analogous aquo complex, which is catalytically active in the aldol condensation of Me 2-isocyanoacetate and benzaldehyde. Preliminary results and comparisons with previously reported catalysts with more distal C-stereogenicity are presented.
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16. Williams, B. S.; Goldberg, K. I. (2001). Studies of Reductive Elimination Reactions To Form Carbon-Oxygen Bonds from Pt(IV) Complexes. J. Am. Chem. Soc. 123: 2576-2587.
    Abstract: The platinum(IV) complexes fac-L2PtMe3(OR) (L2 = bis(diphenylphosphino)ethane, o-bis(diphenylphosphino)benzene, R = carboxyl, aryl; L = PMe3, R = aryl) undergo reductive elimination reactions to form carbon-oxygen bonds and/or carbon-carbon bonds. The carbon-oxygen reductive elimination reaction produces either methyl esters or methyl aryl ethers (anisoles) and L2PtMe2, while the carbon-carbon reductive elimination reaction affords ethane and L2PtMe(OR). Choice of reaction conditions allows the selection of either type of coupling over the other. A detailed mechanistic study of the reductive elimination reactions supports dissociation of the OR- ligand as the initial step for the C-O bond formation reaction. This is followed by a nucleophilic attack of OR- upon a methyl group bound to the Pt(IV) cation to produce the products MeOR and L2PtMe2. C-C reductive elimination proceeds from L2PtMe3(OR) by initial L (L = PMe3) or OR- (L2 = dppe, dppbz) dissociation, followed by C-C coupling from the resulting five-coordinate intermediate. Our studies demonstrate that both C-C and C-O reductive elimination reactions from Pt(IV) are more facile in polar solvents, in the presence of Lewis acids, and for OR- groups that contain electron withdrawing substituents.
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17. Williams, B. S.; Holland, A. W; Goldberg, K. I. (1999). Direct Observation of C-O Reductive Elimination from Pt(IV). J. Am. Chem. Soc. 121: 252-253.
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