Shigeru Nagase

Huazhong University of Science and Technology, Wu-han-shih, Hubei, China

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Publications (589)2955.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Reaction of the stable digermyne BbtGeGeBbt (Bbt = 2,6-[CH(SiMe3)2]2-4-[C(SiMe3)3]-C6H2) with ethylene initially afforded the corresponding 1,2-digermacyclobutene. Depending on the reaction conditions applied, further reaction of this 1,2-digermacyclobutene with ethylene furnished two different reaction products: a 1,4-digerma-bicyclo[2.2.0]hexane or a bis(germiranyl)ethane. Combined experimental and theoretical results suggested that the 1,4-digerma-bicyclo[2.2.0]hexane and the bis(germiranyl)ethane are the thermodynamic and kinetic reaction products, respectively. A reaction mechanism in agreement with these results is proposed.
    Chemical Science 06/2015; DOI:10.1039/C5SC01266J · 8.60 Impact Factor
  • Jing-Dong Guo, Shigeru Nagase, Philip P. Power
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    ABSTRACT: The dissociation of the sterically encumbered diphosphanes and diarsanes [:E{CH(SiMe3)2}2]2 (E = P or As) and [:E{N(SiMe3)2}2]2 (E = P or As) into :Ė{CH(SiMe3)2}2 or :Ė{N(SiMe3)2}2 radical monomers was studied computationally using hybrid density functional theory (DFT) at the B3PW91 with the 6-311+G(d) basis set for P and As, and the 6-31G(d,p) basis set for other atoms. The structures were reoptimized with the dispersion corrected B3PW91-D3 method to estimate dispersion force effects. The calculations reproduced the experimental structural data for the tetraalkyls with good accuracy. Without the dispersion correction, negative dissociation energies of −10.3 and −6.5 kcal mol-1 were calculated for the phosphorus and arsenic tetraalkyls, indicating that the radical monomers are more stable. In contrast, the incorporation of dispersion force effects afforded high, positive dissociation energies of +37.6 and +37.1 kcal mol-1 that favored dimeric structures. The dissociation energies (without dispersion) calculated for the tetraamido-substituted dimer are also negative, but changed to positive values of +29.3 and +32.5 kcal mol-1 upon optimization with the D3 dispersion term. In contrast to earlier calculations, which indicated that the release of accumulated strain energy within the tetraalkyl dimers was the driving force for dissociation to monomers (i.e., the “Jack-in-the-Box” molecular model), the current calculations show that dispersion force attractive interactions exceed those of ligand relaxation and stabilize the dimeric structures. Single-point MP2 (second-order Møller-Plesset perturbation theory) calculations including dispersion effects afforded dissociation energies of 30.4 and 30.8 kcal mol-1 for the tetraalkyl species, suggesting that the addition of the D3 dispersion term to the B3PW91 functional may overestimate such forces by 7-8 kcal mol-1. It is concluded that the balance of dispersion forces and entropic effects are the major determinants of the dissociation equilibria.
    Organometallics 05/2015; 34(10):150513115037004. DOI:10.1021/acs.organomet.5b00254 · 4.25 Impact Factor
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    ABSTRACT: The reaction mechanism and origin of regioselectivity of (2 + 2) cycloadditions of benzyne to endohedral metallofullerenes M3N@C80 (M = Sc, Y) were investigated with density functional calculations. The reaction was demonstrated to follow a diradical mechanism rather than a carbene mechanism, in which the formation of the diradical intermediate is the rate-determining step. Through rotation of benzyne moiety on the fullerene surface, the diradical intermediate on 566 site could isomerize to two new diradical intermediates which result in two distinct (5,6) and (6,6) benzoadducts respectively. However, the diradical intermediate on 666 site only produces the (6,6) benzoadduct. The nature of the endohedral cluster not only influences the regioselectivity, but also determines the cycloadduct geometry. For Sc3N@C80, the (5,6) benzoadduct is preferred kinetically and thermodynamically, whereas in the case of Y3N@C80, both (5,6) and (6,6) benzoadducts are favorable. In contrast to closed-cage benzoadducts of Sc3N@C80, Y3N@C80 affords open-cage benzoadducts, making it the first example that the endohedral cluster could alter cycloadducts from the closed cage to open cage. With further analysis, it is revealed that the origin of regioselectivity results from the local strain energy of the fullerene cage.
    Journal of the American Chemical Society 05/2015; 137(21). DOI:10.1021/jacs.5b01444 · 11.44 Impact Factor
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    ABSTRACT: The water-dimer thermodynamics is recomputed, combining the dimerization potential-energy change evaluated from the G3 theory (–5.142 kcal/mol, almost equal to the recently observed term) and the an harmonic partition functions from the MP2 = FC/6-3111 + +G** approach. The combined treatment reproduces the observed terms basically within possible experimental errors. Thus, the calculated thermodynamic characteristics are recommended for wider use and applied to the issue of temperature increase of clustering degree in the saturated steam, confirming the temperature enhancement also in the an harmonic regime and hence pointing out higher-temperature region to spectroscopy interest and also for the water-dimer encapsulations into fullerene cages like (H2O)2 @C60 and (H2O)2 @C84. The results also have some significance for the atmospheric greenhouse effect.
    Journal of Computational and Theoretical Nanoscience 04/2015; 12(6). DOI:10.1166/jctn.2015.3835 · 1.34 Impact Factor
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  • Organometallics 01/2015; 34(1):56-62. DOI:10.1021/om500814g · 4.25 Impact Factor
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    ABSTRACT: A 1,2-digermabenzene bearing bulky substituents on its two germanium atoms was successfully synthesized and isolated as a stable, crystalline compound via the reaction of a digermyne precursor with 2 equiv of acetylene. Even though its molecular structure, which was revealed by X-ray crystallographic analysis, showed a trans-bent geometry for the Ge-Ge moiety, theoretical calculations suggested substantial levels of aromaticity.
    Organometallics 01/2015; 34(11):150106110816000. DOI:10.1021/om501204u · 4.25 Impact Factor
  • Xing Lu, Lipiao Bao, Takeshi Akasaka, Shigeru Nagase
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    ABSTRACT: Putting metal atoms or metallic clusters into fullerenes has generated a new class of hybrid molecules, defined as endohedral metallofullerenes (EMFs), possessing novel structures and fascinating properties which are different from those of empty fullerenes. In particular, it has been revealed that the chemical properties of the cage carbons of EMFs depend strongly on the nature of the internal metallic species, such as their electronic configuration, location and even motion. Since the first report describing the successful derivatization of La@C-82 in 1995, great efforts have been devoted to the chemical modification of EMFs during the last two decades. Although earlier studies mainly focused on readily available species such as M@C-82, M-2@C-80 and M3N@C-80 and the related results have been systematically summarized in our previous review paper (Chem. Commun., 2011, 47, 5942-5957), recent concerns about some relatively rare EMFs have developed rapidly. Moreover, taking advantage of single crystal X-ray crystallography, we can now clearly demonstrate the mutual influences between the internal metallic species and the chemical behaviours of the surrounding cage carbons, and the addends as well. In this article, we present recent achievements in the chemical functionalization of EMFs, which were mainly published during the last four years. For consistency, we will still pay special attention to the role that the metals play in controlling the properties of the whole EMF molecules. In this review, however, we will not only focus on concrete experimental results such as X-ray crystallographic and NMR spectroscopic data but will also include computational studies which have indeed enhanced our understanding of the chemical properties of EMFs. Applicable materials based on EMFs are also mentioned but are not discussed in detail.
    ChemInform 01/2015; 46(2). DOI:10.1002/chin.201502239
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    ABSTRACT: The thermal reaction of the endohedral metallofullerene La2@D2(10611)-C72, which contains two pentalene units at opposite ends of the cage, with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single-crystal X-ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the CC bond connecting two pentagon rings of C72. Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open-cage derivative having three seven-membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open-cage derivatives were similar to those of La2@D2-C72 whereas the oxidation potentials were shifted more negative than those of La2@D2-C72. These results point out that further oxidation could occur easily in the derivatives.
    Angewandte Chemie 12/2014; 127(7). DOI:10.1002/ange.201410012
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    ABSTRACT: The thermal reaction of the endohedral metallofullerene La2@D2(10611)-C72, which contains two pentalene units at opposite ends of the cage, with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single-crystal X-ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the CC bond connecting two pentagon rings of C72. Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open-cage derivative having three seven-membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open-cage derivatives were similar to those of La2@D2-C72 whereas the oxidation potentials were shifted more negative than those of La2@D2-C72. These results point out that further oxidation could occur easily in the derivatives.
    Angewandte Chemie International Edition 12/2014; 54(7). DOI:10.1002/anie.201410012 · 11.34 Impact Factor
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    ABSTRACT: Fullerenyl radicals can be generated by addition of a free radical to a fullerene surface, by nucleophilic addition followed by one-electron oxidation, or by thermal dissociation of singly-bonded fullerene dimers. However, fullerenyl radicals are usually very reactive and generally cannot be isolated. On the contrary, we have found that the reactions of the dimetallic endofullerenes, La2@Ih-C80 and La2@D5h-C80, with 3-chloro-5,6-diphenyltriazine resulted in mono-addition of the triazinyl radical to the fullerene cages to yield isolable fullerenyl radicals. The unusual stability of these fullerenyl radicals arises from the confinement of the unpaired electron to an internal, metal-metal bonding orbital. Accordingly, the fullerene cage protects the radical center from other reactive species. Furthermore, we demonstrate that the fullerenyl radical adduct of La2@Ih-C80 reacts with toluene to afford additional benzylation. Interestingly, the benzylated derivative is diamagnetic in solution, while it forms a paramagnetic dimer when crystallized.
    Journal of the American Chemical Society 12/2014; 137(1). DOI:10.1021/ja509956y · 11.44 Impact Factor
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    ABSTRACT: By means of density functional theory methods together with statistical thermodynamic analysis, the C82 monometallofullerenes including special heterogeneous triangular clusters were theoretically probed for the first time. Despite having analogous structures, the YCN@C82 and TbCN@C82 series exhibit dissimilar thermodynamic stabilities, which lead to different components of experimental products. Significant relationship between the thermodynamic stabilities and geometry structures of C82 metallofullerenes is disclosed. Studies of the electronic configurations of MCN@C82 species not only explain their redox potentials but also recover complicated interaction mechanisms within them. In addition, predictions of the optical spectra of observed MCN@C82 species coincide with experimental detections well, indicating that simulations for other structures will be helpful for future characterization of these cyanoclusterfullerenes.
    Inorganic Chemistry 12/2014; 53(24). DOI:10.1021/ic501911z · 4.79 Impact Factor
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    ABSTRACT: Synthesizing unprecedented diamagnetic adducts of an endohedral metallofullerene was achieved by using 1,3-dipolar cycloaddition reaction of paramagnetic La@Cs-C82 with a simultaneous hydrogen addition. The selective formation of two main products, La@Cs-C82HCMe2NMeCHPh (2a and 2b), was first detected by HPLC analysis and MALDI-TOF mass spectrometry. 2a and 2b-O, which was readily formed by the oxidation of 2b, were isolated by multistep HPLC separation and were fully characterized by spectroscopic methods, including 1D and 2D-NMR, UV-vis-NIR measurements and electrochemistry. The hydrogen atom was found to be connected to the fullerene cage directly in the case of 2a, and the redox behavior indicated that the C-H bond can still be readily oxidized. The reaction mechanism and the molecular structures of 2a and 2b were reasonably proposed by the interplay between experimental observations and DFT calculations. The feasible order of the reaction process would involve a 1,3-dipolar cycloaddition followed by the hydrogen addition through a radical pathway. It is concluded that the characteristic electronic properties and molecular structure of La@Cs-C82 resulted in a site-selective reaction, which afforded a unique chemical derivative of an endohedral metallofullerene in high yields. Derivative 2a constitutes the first endohedral metallofullerene where the direct linking of a hydrogen atom has been structurally proven.
    Journal of the American Chemical Society 12/2014; DOI:10.1021/ja509407j · 11.44 Impact Factor
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    ABSTRACT: [11]Cycloparaphenylene ([11]CPP) selectively encapsulates La@C82 to form the shortest possible metallofullerene–carbon nanotube (CNT) peapod, La@C82⊂[11]CPP, in solution and in the solid state. Complexation in solution was affected by the polarity of the solvent and was 16 times stronger in the polar solvent nitrobenzene than in the nonpolar solvent 1,2-dichlorobenzene. Electrochemical analysis revealed that the redox potentials of La@C82 were negatively shifted upon complexation from free La@C82. Furthermore, the shifts in the redox potentials increased with polarity of the solvent. These results are consistent with formation of a polar complex, (La@C82)δ−⊂[11]CPPδ+, by partial electron transfer from [11]CPP to La@C82. This is the first observation of such an electronic interaction between a fullerene pea and CPP pod. Theoretical calculations also supported partial charge transfer (0.07) from [11]CPP to La@C82. The structure of the complex was unambiguously determined by X-ray crystallographic analysis, which showed the La atom inside the C82 near the periphery of the [11]CPP. The dipole moment of La@C82 was projected toward the CPP pea, nearly perpendicular to the CPP axis. The position of the La atom and the direction of the dipole moment in La@C82⊂[11]CPP were significantly different from those observed in La@C82⊂CNT, thus indicating a difference in orientation of the fullerene peas between fullerene–CPP and fullerene–CNT peapods. These results highlight the importance of pea–pea interactions in determining the orientation of the metallofullerene in metallofullerene–CNT peapods.
    Chemistry - A European Journal 10/2014; 20(44). DOI:10.1002/chem.201403879 · 5.70 Impact Factor
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    Tao Yang, Xiang Zhao, Shigeru Nagase, Takeshi Akasaka
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    ABSTRACT: The reaction mechanism and regioselectivity of the Diels–Alder reactions of C68 and Sc3N@C68, which violate the isolated pentagon rule, were studied with density functional theory calculations. For C68, the [5,5] bond is the most favored thermodynamically, whereas the cycloaddition on the [5,6] bond has the lowest activation energy. Upon encapsulation of the metallic cluster, the exohedral reactivity of Sc3N@C68 is reduced remarkably owing to charge transfer from the cluster to the fullerene cage. The [5,5] bond becomes the most reactive site thermodynamically and kinetically. The bonds around the pentagon adjacency show the highest chemical reactivity, which demonstrates the importance of pentagon adjacency. Furthermore, the viability of Diels–Alder cycloadditions of several dienes and Sc3N@C68 was examined theoretically. o-Quinodimethane is predicted to react with Sc3N@C68 easily, which implies the possibility of using Diels–Alder cycloaddition to functionalize Sc3N@C68.
    Chemistry - An Asian Journal 09/2014; 9(9). DOI:10.1002/asia.201402435 · 3.94 Impact Factor
  • Fullerenes Nanotubes and Carbon Nanostructures 08/2014; 23(1):35-39. DOI:10.1080/1536383X.2012.749461 · 0.64 Impact Factor
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    ABSTRACT: The neutral triple-decker ruthenocenes and anionic ruthenocene bearing a stannole dianion were successfully synthesized by the reactions of dilithiostannoles with [Cp*RuCl]4. This is the first example of a transition-metal complex bearing a group 14 metallole dianion with μ-ŋ(5):ŋ(5) coordination mode, which cannot be achieved using the original Cp ligand. These complexes were fully characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. In the complexes, each of the ruthenium atoms is co-ordinated by the stannole ring in an ŋ(5)-fashion. The aromaticity of the stannole dianion moieties is retained judging from no C-C bond alternation in the stannole rings. CH/π interaction was found in the packing structure of the SiMe3 derivative, which leads to a well-ordered column-like structure. The oxidation wave of the triple-decker complex was observed at -0.43 V (vs. ferrocene), which reveals that the triple-decker type heavy ruthenocene is oxidized more easily than the ferrocene. Comparison of the oxidation potential between the triple-decker complex and decamethyl-ruthenocene (Cp*2Ru, Cp* = ŋ(5)-C5Me5-) reveals that a stannole ligand functions as an electron-donating ligand much stronger than the conventional electron-rich Cp* ligand.
    Journal of the American Chemical Society 08/2014; 136(37). DOI:10.1021/ja507330p · 11.44 Impact Factor
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    ABSTRACT: In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc2S@C76 which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc2S@Td(19151)-C76 which satisfies the isolated-pentagon rule (IPR) possesses the lowest energy, followed by three non-IPR structures (Sc2S@C2v(19138)-C76, Sc2S@Cs (17490)-C76, and Sc2S@C1(17459)-C76). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc2S@Td(19151)-C76, Sc2S@C2v(19138)-C76, and Sc2S@C1(17459)-C76 have noticeable molar fractions at the fullerene-formation temperature region (500–3000K), and the Sc2S@C1(17459)-C76 with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non-IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV-vis-NIR adsorptions, and 13C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc.
    Journal of Computational Chemistry 08/2014; 35(22). DOI:10.1002/jcc.23671 · 3.60 Impact Factor
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    ABSTRACT: Reactions of Sc3N@Ih-C80 with aziridine derivatives were conducted to afford the corresponding mono-adducts. A pair of diastereomers of the mono-adduct [5,6]-pyrrolidino-Sc3N@Ih-C80 was isolated and characterized by means of mass spectrometry, Vis-NIR absorption spectroscopy, and electrochemical measurements. Structural analysis of the mono-adducts was conducted by NMR and single-crystal X-ray structure determinations.
    Chemical Communications 08/2014; 50(83). DOI:10.1039/C4CC04946B · 6.72 Impact Factor
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    ABSTRACT: Regioselective cycloaddition of adamantylidene carbene to Pr@C2v(9)-C82 affords the first derivative of praseodymium-containing metallofullerenes. Single-crystal X-ray crystallographic data in combination with theoretical studies demonstrate that the addition is dictated by the single metal ion encapsulated inside the fullerene cage.
    Chemical Communications 07/2014; 50(69). DOI:10.1039/c4cc02949f · 6.72 Impact Factor

Publication Stats

11k Citations
2,955.03 Total Impact Points


  • 2013–2015
    • Huazhong University of Science and Technology
      • State Key Laboratory of Material Processing and Die & Mould Technology
      Wu-han-shih, Hubei, China
  • 2012–2015
    • Fukui Institute for Fundamental Chemistry
      Kioto, Kyōto, Japan
  • 2014
    • University of California, Davis
      • Department of Chemistry
      Davis, California, United States
  • 2002–2014
    • Kyoto University
      • • Fukui Institute for Fundamental Chemistry
      • • Institute for Chemical Research
      Kioto, Kyōto, Japan
    • Hiroshima University
      • Division of Chemistry
      Hiroshima-shi, Hiroshima-ken, Japan
  • 1988–2014
    • University of Tsukuba
      • Graduate School of Pure and Applied Sciences
      Tsukuba, Ibaraki, Japan
  • 2008–2013
    • National Institutes Of Natural Sciences
      Edo, Tōkyō, Japan
    • Kinki University
      • Department of Applied Chemistry
      Ōsaka, Ōsaka, Japan
  • 2004–2013
    • Tokyo Gakugei University
      Koganei, Tōkyō, Japan
    • Athens State University
      Athens, Alabama, United States
  • 2006–2012
    • Saitama University
      • Department of Chemistry
      Saitama, Saitama, Japan
    • The Graduate University for Advanced Studies
      • Department of Structural Molecular Science
      Миура, Kanagawa, Japan
    • Capital Normal University
      • Department of Physics
      Peping, Beijing, China
    • University of Arkansas
      • Department of Chemistry and Biochemistry
      Fayetteville, Arkansas, United States
  • 2011
    • Osaka Prefecture University
      Sakai, Ōsaka, Japan
  • 2010
    • National Chung Cheng University
      Chia-i-hsien, Taiwan, Taiwan
  • 2004–2010
    • Nagoya University
      • • Department of Chemistry
      • • Graduate School of Environmental Studies
      Nagoya, Aichi, Japan
  • 2000–2010
    • Niigata University
      • Graduate School of Science and Technology
      Niahi-niigata, Niigata, Japan
  • 2007
    • Nankai University
      • Institute of New Energy Material Chemistry
      T’ien-ching-shih, Tianjin Shi, China
    • Peking University
      • Department of Chemistry
      Peping, Beijing, China
  • 2006–2007
    • Charles University in Prague
      • Department of Physical and Macromolecular Chemistry
      Praha, Praha, Czech Republic
  • 2005–2006
    • Josai University
      Saitama, Saitama, Japan
  • 2004–2006
    • Rikkyo University
      • Department of Chemistry
      Edo, Tōkyō, Japan
  • 2002–2006
    • Waseda University
      • Department of Chemistry and Biochemistry
      Edo, Tōkyō, Japan
  • 2001–2006
    • Academia Sinica
      • Institute of Chemistry
      Taipei, Taipei, Taiwan
  • 1993–2006
    • The University of Tokyo
      • Department of Chemistry
      Tōkyō, Japan
    • Tokyo Metropolitan University
      • Department of Chemistry
      Edo, Tōkyō, Japan
  • 2002–2005
    • Institute for Molecular Science
      Okazaki, Aichi, Japan
  • 2003
    • University of Prince Edward Island
      • Department of Chemistry
      Charlottetown, Prince Edward Island, Canada
  • 2000–2001
    • University of Houston
      • Department of Chemistry
      Houston, Texas, United States
  • 1997
    • Osaka University
      • Division of Applied Chemistry
      Suika, Ōsaka, Japan
  • 1981–1995
    • Yokohama National University
      Yokohama, Kanagawa, Japan
  • 1989
    • Dalmia Institute of Scientific and Industrial Research
      Sundergarh, Orissa, India