Ilia A. Guzei

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Name: Guzei, Ilia

Organization: University of Wisconsin?Madison , USA

Department: Department of Chemistry

Title: Lab Director(PhD)

TOPICS

Inorganic Chemistry

Chemicals
References

Deciphering composition and connectivity of a natural product with the assistance of MS and 2D NMR

Co-reporter:Anastasiya I. Vinokur;Paul B. White;Maurice Tagatsing Fotsing;Charmaine Arderne;Derek Tantoh Ndinteh;Martha M. Vestling

Acta Crystallographica Section C 2017 Volume 73(Issue 11) pp:994-1002

Publication Date(Web):2017/11/01

DOI:10.1107/S2053229617014966

A complementary application of three analytical techniques, viz. multidimensional nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and single-crystal X-ray diffractometry was required to identify and refine two natural products isolated from Millettia versicolor and solvent of crystallization. The two compounds, namely 3-(2H-1,3-benzodioxol-5-yl)-6-methoxy-8,8-dimethyl-4H,8H-pyrano[2,3-h]chromen-4-one, or durmillone, (I), and (2E)-1-(4-{[(2E)-3,7-dimethylocta-2,6-dien-1-yl]oxy}-2-hydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, (II), could not be separated by routine column chromatography and cocrystallized in a 2:1 ratio with 0.13 molecules of ethanol solvent. Compound (II) and ethanol could not be initially identified by single-crystal X-ray analysis due to complex disorder in the aliphatic chain region of (II). Mass spectrometry ensured that (II) represented only one species disordered over several positions in the solid state, rather than several species cohabitating on the same crystallographic site. The atomic identification and connectivity in (II) were established by several 2D (two-dimensional) NMR techniques, which in turn relied on a knowledge of its exact mass. The derived connectivity was then used in the single-crystal analysis to model the disorder of the aliphatic chain in (II) over three positions and allowed identification of a partially occupied ethanol solvent molecule that was disordered over an inversion center. The disordered moieties were refined with restraints and constraints.

Intricacies of ligand coordination in tricarbonylchromium(0) complexes with ortho- and para-fluorobiphenyls

Co-reporter:Ilia A. Guzei;Lara C. Spencer;Sondra C. Buechel;Leah B. Kaufmann;Curtis J. Czerwinski

Acta Crystallographica Section C 2017 Volume 73(Issue 8) pp:638-644

Publication Date(Web):2017/08/01

DOI:10.1107/S2053229617010774

The steric and electronic factors that influence which of the two rings of a substituted biphenyl ligand coordinates to chromium are of interest and it has been suggested that haptotropic rearrangements within these molecules may be limited if the arene–arene dihedral angle is too large. Two tricarbonylchromium(0) complexes and their respective free ligands have been characterized by single-crystal X-ray diffraction. In the solid state, tricarbonyl[(1′,2′,3′,4′,5′,6′-η)-2-fluoro-1,1′-biphenyl]chromium(0), [Cr(C12H9F)(CO)3], (I), exists as the more stable isomer with the nonhalogenated arene ring ligated to the metal center. Similarly, tricarbonyl[(1′,2′,3′,4′,5′,6′-η)-4-fluoro-1,1′-biphenyl]chromium(0) crystallizes as the more stable isomer with the phenyl ring bonded to the Cr0 center. The arene–arene dihedral angles in these complexes are 55.77 (4) and 52.4 (5)°, respectively. Structural features of these complexes are compared to those of the DFT-optimized geometries of ten tricarbonyl[(η6-C6H5)(4-F-C6H4)]chromium model complexes. The solid-state structures of the free ligands 2-fluoro-1,1′-biphenyl and 4-fluoro-1,1′-biphenyl, both C12H9F, exhibit arene–arene dihedral angles of 54.83 (7) and 0.71 (8)°, respectively. The molecules of the free ligands occupy crystallographic twofold axes and exhibit positional disorder. Weak intermolecular C—H…F interactions are observed in all four structures.

Ab initio X-ray structural characterization of an inclusion compound with a compositionally disordered chiral guest: no prior knowledge of the crystal composition

Co-reporter:Ilia A. Guzei;Kelsey C. Miles

Acta Crystallographica Section C 2016 Volume 72( Issue 3) pp:179-183

Publication Date(Web):

DOI:10.1107/S2053229616001972

The crystal structure and absolute configuration of a molecular host/guest/impurity inclusion complex were established unequivocally in spite of our having no prior knowledge of its chemical composition. The host (4R,5R)-4,5-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane, (I), displays expected conformational features. The crystal-disordered chiral guest 4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, (II), is present in the crystal 85.1 (4)% of the time. It shares a common site with 4a-hydroperoxymethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, (III), present 14.9 (4)% of the time, which is the product of autoxidation of (II). This minor peroxide impurity was isolated, and the results of nuclear magnetic resonance, mass spectrometry, and X-ray fluorescence studies are consistent with the proposed structure of (III). The complete structure was therefore determined to be (4R,5R)-4,5-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane–4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one–4a-hydroperoxymethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one (1/0.85/0.15), C₃₁H₃₀O₄·0.85C₁₀H₁₄O·0.15C₁₀H₁₄O₃, (IV). There are host–host, host–guest, and host–impurity hydrogen-bonding interactions of types S and D in the solid state. We believe that the crystals of (IV) were originally prepared to establish the chirality of the guest (II) by means of X-ray diffraction analysis of host/guest crystals obtained in the course of chiral resolution during cocrystallization of (II) with (I). In spite of the absence of `heavy' elements, the absolute configurations of all anomeric centres in the structure are assigned as R based on resonant scattering effects.

Investigation of ligand steric effect on the hydrogen gas produced via a nickel-catalyzed dehydrogenation of ammonia-borane utilizing unsymmetrical triazolylidene ligands

Co-reporter:Meghan O. Talbot, Theresa N. Pham, Marites A. Guino-o, Ilia A. Guzei, Anastasiya I. Vinokur, Victor G. Young Jr.

Polyhedron 2016 114() pp: 415-421

Publication Date(Web):16 August 2016

DOI:10.1016/j.poly.2016.02.034

Seven new unsymmetrical triazolylidene ligands 4-(4-R-phenyl)-1-R′-1,2,4-triazoly-1-lidene (where R = H, CH3, CF3, F; and R′ = CH3, iPr, Bzl, methylcyclohexane) were employed in a nickel-catalyzed dehydrogenation of ammonia borane to investigate the steric effects associated with the different N(1) substitutions in the triazole ring. The bulkier substituents benzyl and methylcyclohexane afforded the highest weight percent H2 gas produced. To quantify the steric effect, both percent buried volume (%Vbur) and solid angle G parameter (%) were employed. The G-parameter is a more useful tool when only the crystal structures of the precursor ligands are available.Seven new unsymmetrical triazolylidene ligands 4-(4-R-phenyl)-1-R′-1,2,4-triazoly-1-lidene (where R = H, CH3, CF3, F; and R′ = CH3, iPr, Bzl, methylcyclohexane) were employed in a nickel-catalyzed dehydrogenation of ammonia borane. The ligand’s reactivity is correlated to the steric bulk associated with the different R′ substitutions of the triazole using the solid angle G-parameter.

Polymorphism of dinitro[tris(2-aminoethyl)amine]cobalt(III) chloride

Co-reporter:Ilia A. Guzei ;Charmaine Arderne

Acta Crystallographica Section C 2015 Volume 71( Issue 8) pp:695-700

Publication Date(Web):

DOI:10.1107/S205322961501270X

Three polymorphs of bis(nitrito-κN)[tris(2-aminoethyl)amine-κ⁴N,N′,N′′,N′′′]cobalt(III) chloride, [Co(NO₂)₂(C₆H₁₈N₄)]Cl, have been structurally characterized in the 100–300 K temperature range. Two orthorhombic polymorphs are related by a solid-state enantiotropic order–disorder k2 phase transition at ca 152 K. The third, monoclinic, polymorph crystallizes as a nonmerohedral twin. In the structure of the high-temperature (300 K) orthorhombic polymorph, the Co^III complex cation resides on a crystallographic mirror plane, whereas the Cl⁻ anion occupies a crystallographic twofold axis. In the unit cell of the monoclinic polymorph, the cationic Co^III complex is in a general position, whose charge is balanced by two halves of two Cl⁻ anions, each residing on a crystallographic twofold axis.

Celebrating the International Year of Crystallography with a Wisconsin High School Crystal Growing Competition

Co-reporter:Ilia A. Guzei

Journal of Chemical Education 2014 Volume 91(Issue 12) pp:2013-2017

Publication Date(Web):November 17, 2014

DOI:10.1021/ed500792y

In honor of the 2014 International Year of Crystallography, the first Wisconsin Crystal Growing Competition was successfully organized and conducted. High school students from 26 schools across the state competed for prizes by growing large crystals of CuSO4·5(H2O). This paper describes how the event was planned and carried out as well as looking at the scientific impact it had on the participants. (Abstract graphic created by Kandis Elliot and Ilia Guzei and used with permission.)Keywords: Collaborative/Cooperative Learning; Crystals/Crystallography; Hands-On Learning/Manipulatives; High School/Introductory Chemistry; Laboratory Instruction; X-ray Crystallography;

Polymorphism of 5-(pyridin-2-ylmethylene)-3-phenyl-2-methylthio-3,5-dihydro-4H-imidazole-4-one

Co-reporter:Ilia A. Guzei, Erica M. Gunn, Lara C. Spencer, Jennifer M. Schomaker and Jared W. Rigoli

CrystEngComm 2011 vol. 13(Issue 10) pp:3444-3450

Publication Date(Web):10 Mar 2011

DOI:10.1039/C1CE05098B

The title compound, C16H13N3OS (1), exists in three polymorphic forms. Crystalline 1 undergoes an enantiotropic, first-order, k2 phase transition at 262.9(5) K with ΔH = 0.3(1) kJ mol−1. Upon cooling below the transition temperature, the high temperature orthorhombic polymorph (Form I, space groupPbcm) transforms into a low temperature orthorhombic polymorph (Form II, space groupPbca) with a unit cell twice the size of that of the Form I. A molten 1 can be cooled in a controlled fashion to generate a monoclinic Form III of 1 with the unit cell size similar to that of Form I. Metastable Form III, once isolated, is indefinitely stable between 100 K and its melting point of 466 K. If crystals of Form III are in contact with seed crystals of Form I, a monotropic t2 first-order Form III → Form I phase transition occurs upon heating with the onset between 420 and 448 K and ΔH = −1.7(4) kJ mol−1. The most substantial differences among the molecular geometries of 1 in Forms I–III are observed in the position and tilt of the phenyl ring relative to the rest of the molecule. The packing in Form III is very different from those in the other polymorphs. DFT molecular geometry optimizations produce the following order of stable molecule configurations: Form II (most stable), Form I (0.50 kJ mol−1), Form III (2.81 kJ mol−1).

Bruker SMART X2S Benchtop System: A Means To Making X-ray Crystallography More Mainstream in the Undergraduate Laboratory

Co-reporter:Ilia A. Guzei, Nicholas J. Hill, and Uzma I. Zakai

Journal of Chemical Education 2010 Volume 87(Issue 11) pp:1257-1259

Publication Date(Web):August 30, 2010

DOI:10.1021/ed100014a

Bruker SMART X2S is a portable benchtop diffractometer that requires only a 110 V outlet to operate. The instrument operation is intuitive and facile with an automation layer governing the workflow from behind the scenes. The user participation is minimal. At the end of an experiment, the instrument attempts to solve the structure automatically; however, the user can process the data manually if desired. On the basis of our examination of 19 samples, the Bruker SMART X2S yields publishable quality data and is ideally suited for undergraduate laboratories because of the ease of use and low maintenance.Keywords (Audience): Graduate Education/Research; Upper-Division Undergraduate; Keywords (Domain): Interdisciplinary/Multidisciplinary; Laboratory Instruction; Keywords (Pedagogy): Hands-On Learning/Manipulatives; Keywords (Topic): Instrumental Methods; Laboratory Equipment/Apparatus; Molecular Properties/Structure; X-ray Crystallography;

Concomitant Twinning and Polymorphism of Ti(C5H4tBu)2Cl2

Co-reporter:Ilia A. Guzei, Amitabha Mitra and Lara C. Spencer

Crystal Growth & Design 2009 Volume 9(Issue 5) pp:2287

Publication Date(Web):March 13, 2009

DOI:10.1021/cg8010772

The title compound (Ti(C5H4tBu)2Cl2, 1) exists in three polymorphs and undergoes two enantiotropic phase transitions between them. The low-temperature, non-merohedrally twinned monoclinic phase III (space group P21) undergoes a first-order phase transition into an orthorhombic phase II (space group P212121) at 147(1) K. Subsequent heating of the crystal results in a gradual second-order k2 transformation of this phase into the high-temperature orthorhombic phase I (P21212). This phase transition is completed at ∼330 K. The phase transitions were monitored by single-crystal X-ray diffraction, differential scanning calorimetry, and powder diffraction; however, the II → I transition did not register on the differential scanning calorimetry curve or powder patterns. The molecular conformations and mutual arrangement of molecules in the crystal in the three phases are very similar. The location of the ancillary ligands relative to the Cl−Ti−Cl wedge in the solid-state structures of 1 and 32 related Ti(C5H4R)2Cl2 complexes seems to be principally determined by weak C−H···Cl intramolecular interactions between the R substituents and Cl ligands rather than by steric factors. An example of an advanced structural refinement technique using SHELXL to compute standard uncertainties on mathematically derived parameters is also given.

Interesting Reactivity in the Thermolysis and Photolysis of 2,3-Diphenyl-1-naphthol

Co-reporter:Ilia A. Guzei;Howard E. Zimmerman;Sergey Shorunov

Journal of Chemical Crystallography 2009 Volume 39( Issue 6) pp:399-406

Publication Date(Web):2009 June

DOI:10.1007/s10870-008-9491-y

2,3-Diphenyl-1-naphthol (1) undergoes two unexpected reactions under different conditions. Compound (1) was heated in DMSO-d6 and underwent a Pummerer type thermal reaction to give two isomeric products, 1-(methylthio)methoxy-2,3-diphenyl naphthol-d5 which crystallized in the space group \( P{\bar{\text{1}}} \) with a = 7.1610(9) Å, b = 11.2795(15) Å, c = 12.8905(17) Å, α = 114.049(2)°, β = 96.589(2)°, and γ = 102.945(2)°, and 2-(methylthio)methyl-2,3-diphenyl 1(2H)-naphthalenone-d5 which crystallized in the space group \( P{\bar{\text{1}}} \) with a = 8.5981(5) Å, b = 10.4374(6) Å, c = 11.1078(6) Å, α = 78.748(2)°, β = 67.709(2)°, and γ = 83.184(2)°. Photolysis (254 nm) of (1) resulted in 2,2′,3,3′-tetraphenyl-1,1′-bi-2-naphthol which crystallized in the space group P21/c with a = 26.3616(11) Å, b = 10.1707(4) Å, c = 23.3376(9) Å, and β = 99.034(2)°.

Polymorphism and History of 2-Dimethylsufuranylidene-1,3-indanedione (YLID)†

Co-reporter:Ilia A. Guzei, Galina A. Bikzhanova, Lara C. Spencer, Tatiana V. Timofeeva, Tiffany L. Kinnibrugh and Charles F. Campana

Crystal Growth & Design 2008 Volume 8(Issue 7) pp:2411-2418

Publication Date(Web):June 12, 2008

DOI:10.1021/cg701260p

A second, centrosymmetric and monoclinic, form of 2-dimethylsufuranylidene-l,3-indanedione (YLID) has been synthesized and structurally characterized. Theoretical computations suggest that the monoclinic polymorph is ∼2.77 kcal/mol less stable than the noncentrosymmetric orthorhombic form. The molecular parameters of the monoclinic form, orthorhombic polymorph, and theoretically (DFT) optimized geometry of YLID in gas phase are in excellent agreement with each other. The two polymorphs are indefinitely stable in the 100−298 K temperature range, but their molecular packings have little in common. We do not believe an irreversible phase transition takes place upon cooling of the orthorhombic polymorph from 298 to 100 K. Spherically ground crystals of the orthorhombic form of YLID have been used as test crystals for diffractometer alignment and instrument testing by a major commercial diffractometry manufacturer since 1969. A statistical analysis of 223 complete room temperature data sets on orthorhombic YLID yields average cell constants of a = 5.961(4) Å, b = 9.038(4) Å, c = 18.390(9) Å, V = 990.8(13) Å3. The average a:b:c axial ratio is 1:1.5161(7):3.0850(15), while the realistic precision of the unit cell lengths determined from complete CCD area-detector data sets is ∼5 parts in 104. Temperature dependence of the unit cell parameters of both polymorphs of YLID is presented. The b axis of the monoclinic polymorph has a negative thermal expansion coefficient.

An improved method for the computation of ligand steric effects based on solid angles

Co-reporter:Ilia A. Guzei and Mark Wendt

Dalton Transactions 2006 (Issue 33) pp:3991-3999

Publication Date(Web):06 Jul 2006

DOI:10.1039/B605102B

An improved algorithm has been designed to characterize ligand interactions in organometallic and coordination complexes in terms of the percentage of the metal coordination sphere shielded by a given ligand. The computations for ligand solid angles are performed numerically and employ introduced atomic radii that are larger than covalent but smaller than van der Waals radii. This approach enables facile evaluation of steric congestion in the metal coordination sphere, quantification of unfavorable interligand contacts, and in some cases prediction of the complex composition or ligand coordination on purely geometrical grounds.

Crystallographic and theoretical studies of (η5-C5Me5)Ru(2,4-dimethyl-η5-pentadienyl) and [(η5-C5Me5)Rh(2,4-dimethyl-η5-pentadienyl)][BF4]

Co-reporter:Ilia A. Guzei, M. Esther Sánchez-Castro, Armando Ramirez-Monroy, Marisol Cervantes-Vásquez, Isaac Román Alemán Figueroa, M. Angeles Paz-Sandoval

Inorganica Chimica Acta 2006 Volume 359(Issue 2) pp:701-706

Publication Date(Web):20 January 2006

DOI:10.1016/j.ica.2005.09.007

The determination of the solid state structure of Cp*Ru(2,4-dimethyl-η5-pentadienyl) (1), where Cp* = pentamethylcyclopentadienyl, fills the gap in the series of previously established structures of closely related compounds. Compound 1 does not exhibit the ideal CS symmetry and its conformation is intermediate between the CS-synperiplanar eclipsed and CS-antiperiplanar arrangements of the ligands. Density functional theory studies indicate that the CS-synperiplanar eclipsed, CS-antiperiplanar, and intermediate conformations of 1 and Cp*Rh(2,4-dimethyl-η5-pentadienyl)+ (2) do not differ by more than a few tenths of 1 kcal/mol. The geometrical features of cation 2 are similar to those of 1, and in both complexes the pentadienyl ligands are not planar. The metal–carbon distances to the Cp* ligands in 1 and 2 are comparable, while the metal–carbon distances to the pentadienyl moiety are somewhat shorter in the Ru complex. A study of the conformational flexibility of the Cp* ligand in 5610 organometallic complexes showed that it usually shields the central metal by 36.2(10)%, provided the metal–centroid(Cp*) distances are normalized to 2.28 Å. The corresponding values in 1 and 2 are 37.2% and 37.4%, respectively.Synthesis, characterization, and crystal structures of Cp*Ru(2,4-dimethyl-η5-pentadienyl) and Cp*Rh(2,4-dimethyl-η5-pentadienyl)+, where Cp* = pentamethyl-cyclopentadienyl, are reported and the geometry of the complexes analyzed based on the density functional theory studies of their simplified analog Cp*Ru(η5-pentadienyl).