Praseodymium compounds are compounds formed by the
lanthanide metal
praseodymium (Pr). In these compounds, praseodymium generally exhibits the +3
oxidation state, such as PrCl3, Pr(NO3)3 and Pr(CH3COO)3. However, compounds with praseodymium in the +2 and +4 oxidation states, and unlike other
lanthanides, the +5 oxidation state, are also known.
Halides
Praseodymium(III) chloride in its heptahydrate form
Praseodymium metal reacts with all the stable
halogens to form green trihalides:[1]
Praseodymium(III) bromide is the only stable bromide of praseodymium. It adopts the
UCl3 crystal structure.[7] The praseodymium ions are 9-coordinate and adopt a
tricapped trigonal prismatic geometry.[8] The praseodymium–bromine bond lengths are 3.05 Å and 3.13 Å.[9]Praseodymium(III) iodide can be prepared by heating praseodymium and
iodine in an inert atmosphere produces praseodymium(III) iodide,[10] or by heating praseodymium with mercury(II) iodide.[11] It forms
orthorhombic crystals which are
hygroscopic.[10] It crystallizes in the
PuBr3 type[11][12] with space group Cmcm (No. 63) with a = 4.3281(6) Å, b = 14.003(6) Å and c = 9.988(3) Å.[13]
Praseodymium can form many different
oxides, although the only oxides that are stable at room temperature are
Pr2O3,
Pr6O11 and
PrO2. Praseodymium(III) oxide is a green powder that forms hexagonal crystals,[14] and crystallizes in the
manganese(III) oxide or
bixbyite structure.[15] Praseodymium(IV) oxide can be produced by boiling
Pr6O11 in water or
acetic acid:[16]
Organopraseodymium compounds are compounds with a
praseodymium-to-
carbon bond. These compounds are very similar to
those of the other lanthanides, as they all share an inability to undergo
π backbonding. They are thus mostly restricted to the mostly ionic
cyclopentadienides (isostructural with those of lanthanum) and the σ-bonded simple alkyls and aryls, some of which may be polymeric.[22] The coordination chemistry of praseodymium is largely that of the large, electropositive Pr3+ ion, and is thus largely similar to those of the other early lanthanides La3+, Ce3+, and Nd3+. For instance, like lanthanum, cerium, and neodymium,
praseodymium nitrate forms both the 4:3 and 1:1 complexes with
18-crown-6, whereas the middle lanthanides from
promethium to
gadolinium can only form the 4:3 complex and the later lanthanides from
terbium to
lutetium cannot successfully coordinate to all the ligands. Such praseodymium complexes have high but uncertain coordination numbers and poorly defined stereochemistry, with exceptions resulting from exceptionally bulky ligands such as the tricoordinate [Pr{N(SiMe3)2}3]. There are also a few mixed oxides and fluorides involving praseodymium(IV), but it does not have an appreciable coordination chemistry in this oxidation state like its neighbour cerium.[23] However, the first example of a molecular complex of praseodymium(IV) has recently been reported.[24] Like the other organolanthanide compounds, properties of organopraseodymium compounds include:
Organopraseodymium compounds are very air- and water-sensitive and
pyrophoric.
Chemistry in the 0
oxidation state is far more limited. In fact, their electropositive nature makes their organometallic compounds more likely to be ionic.
Organopraseodymium compounds form no stable
carbonyls at room temperature; organopraseodymium carbonyl compounds have been observed only in
argon matrices, and decompose when heated to 40
K.
σ-Bonded complexes
Metal-carbon σ bonds are found in alkyls of praeodymium such as [PrMe63− and Pr[CH(SiMe3)23.
π-Bonded complexes
Cyclopentadienyl complexes, are known for praseodymium. It can be produced by the following reaction scheme:
3 Na[Cp] + PrCl3 → Pr[Cp]3 + 3 NaCl
These compounds are of limited use and academic interest.[25]
Applications
Praseodymium(III) nitride is used in high-end electric and semiconductor products, and as a raw material to produce phosphor. Also it is used as a magnetic material and sputtering target material.[26] Many praseodymium compounds, such as
praseodymium(III) oxalate, are used to colour some glasses and enamels. If mixed with certain other materials, praseodymium(III) oxalate paints glass intense yellow.[27]
Praseodymium(III,IV) oxide has a number of potential applications in chemical
catalysis, and is often used in conjunction with a promoter such as
sodium or
gold to improve its catalytic performance. It has a high-K dielectric constant of around 30 and very low leakage currents[28] which have also made it a promising material for many potential applications in
nanodevices and
microelectronics.[20]
^J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).
^L. F. Druding, J. D. Corbett, "Lower Oxidation States of the Lanthanides. Neodymium(II) Chloride and Iodide", J. Am. Chem. Soc.83, 2462 (1961); J. D. Corbett, Rev. Chim. Minerale10, 239 (1973),
^
abF. T. Edelmann, P. Poremba, in: Synthetic Methods of Organometallic and Inorganic Chemistry, (W. A. Herrmann, ed.), Vol. 6, Georg Thieme Verlag, Stuttgart, 1997.
^J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).
^Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 421.
ISBN978-0-19-965763-6.
^Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 421.
ISBN978-0-19-965763-6.
^E. Warkentin, H. Bärnighausen (1979), "Die Kristallstruktur von Praseodymdiiodid (Modifikation V)", Zeitschrift für anorganische und allgemeine Chemie (in German), vol. 459, no. 1, pp. 187–200,
doi:
10.1002/zaac.19794590120
^Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, Florida: CRC Press, pp. 478, 523,
ISBN0-8493-0594-2
^
abMatović, Branko; Pantić, Jelena; Prekajski, Marija; Stanković, Nadežda; Bučevac, Dušan; Minović, Tamara; Čebela, Maria (2013). "Synthesis and characterization of Pr6O11 nanopowders". Ceramics International. 39 (3): 3151–3155.
doi:
10.1016/j.ceramint.2012.09.098.
^
abShamshi Hassan, M., Shaheer Akhtar, M., Shim, KB. et al. Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods. Nanoscale Res Lett 5, 735 (2010).
https://doi.org/10.1007/s11671-010-9547-8
Praseodymium compounds are compounds formed by the
lanthanide metal
praseodymium (Pr). In these compounds, praseodymium generally exhibits the +3
oxidation state, such as PrCl3, Pr(NO3)3 and Pr(CH3COO)3. However, compounds with praseodymium in the +2 and +4 oxidation states, and unlike other
lanthanides, the +5 oxidation state, are also known.
Halides
Praseodymium(III) chloride in its heptahydrate form
Praseodymium metal reacts with all the stable
halogens to form green trihalides:[1]
Praseodymium(III) bromide is the only stable bromide of praseodymium. It adopts the
UCl3 crystal structure.[7] The praseodymium ions are 9-coordinate and adopt a
tricapped trigonal prismatic geometry.[8] The praseodymium–bromine bond lengths are 3.05 Å and 3.13 Å.[9]Praseodymium(III) iodide can be prepared by heating praseodymium and
iodine in an inert atmosphere produces praseodymium(III) iodide,[10] or by heating praseodymium with mercury(II) iodide.[11] It forms
orthorhombic crystals which are
hygroscopic.[10] It crystallizes in the
PuBr3 type[11][12] with space group Cmcm (No. 63) with a = 4.3281(6) Å, b = 14.003(6) Å and c = 9.988(3) Å.[13]
Praseodymium can form many different
oxides, although the only oxides that are stable at room temperature are
Pr2O3,
Pr6O11 and
PrO2. Praseodymium(III) oxide is a green powder that forms hexagonal crystals,[14] and crystallizes in the
manganese(III) oxide or
bixbyite structure.[15] Praseodymium(IV) oxide can be produced by boiling
Pr6O11 in water or
acetic acid:[16]
Organopraseodymium compounds are compounds with a
praseodymium-to-
carbon bond. These compounds are very similar to
those of the other lanthanides, as they all share an inability to undergo
π backbonding. They are thus mostly restricted to the mostly ionic
cyclopentadienides (isostructural with those of lanthanum) and the σ-bonded simple alkyls and aryls, some of which may be polymeric.[22] The coordination chemistry of praseodymium is largely that of the large, electropositive Pr3+ ion, and is thus largely similar to those of the other early lanthanides La3+, Ce3+, and Nd3+. For instance, like lanthanum, cerium, and neodymium,
praseodymium nitrate forms both the 4:3 and 1:1 complexes with
18-crown-6, whereas the middle lanthanides from
promethium to
gadolinium can only form the 4:3 complex and the later lanthanides from
terbium to
lutetium cannot successfully coordinate to all the ligands. Such praseodymium complexes have high but uncertain coordination numbers and poorly defined stereochemistry, with exceptions resulting from exceptionally bulky ligands such as the tricoordinate [Pr{N(SiMe3)2}3]. There are also a few mixed oxides and fluorides involving praseodymium(IV), but it does not have an appreciable coordination chemistry in this oxidation state like its neighbour cerium.[23] However, the first example of a molecular complex of praseodymium(IV) has recently been reported.[24] Like the other organolanthanide compounds, properties of organopraseodymium compounds include:
Organopraseodymium compounds are very air- and water-sensitive and
pyrophoric.
Chemistry in the 0
oxidation state is far more limited. In fact, their electropositive nature makes their organometallic compounds more likely to be ionic.
Organopraseodymium compounds form no stable
carbonyls at room temperature; organopraseodymium carbonyl compounds have been observed only in
argon matrices, and decompose when heated to 40
K.
σ-Bonded complexes
Metal-carbon σ bonds are found in alkyls of praeodymium such as [PrMe63− and Pr[CH(SiMe3)23.
π-Bonded complexes
Cyclopentadienyl complexes, are known for praseodymium. It can be produced by the following reaction scheme:
3 Na[Cp] + PrCl3 → Pr[Cp]3 + 3 NaCl
These compounds are of limited use and academic interest.[25]
Applications
Praseodymium(III) nitride is used in high-end electric and semiconductor products, and as a raw material to produce phosphor. Also it is used as a magnetic material and sputtering target material.[26] Many praseodymium compounds, such as
praseodymium(III) oxalate, are used to colour some glasses and enamels. If mixed with certain other materials, praseodymium(III) oxalate paints glass intense yellow.[27]
Praseodymium(III,IV) oxide has a number of potential applications in chemical
catalysis, and is often used in conjunction with a promoter such as
sodium or
gold to improve its catalytic performance. It has a high-K dielectric constant of around 30 and very low leakage currents[28] which have also made it a promising material for many potential applications in
nanodevices and
microelectronics.[20]
^J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).
^L. F. Druding, J. D. Corbett, "Lower Oxidation States of the Lanthanides. Neodymium(II) Chloride and Iodide", J. Am. Chem. Soc.83, 2462 (1961); J. D. Corbett, Rev. Chim. Minerale10, 239 (1973),
^
abF. T. Edelmann, P. Poremba, in: Synthetic Methods of Organometallic and Inorganic Chemistry, (W. A. Herrmann, ed.), Vol. 6, Georg Thieme Verlag, Stuttgart, 1997.
^J. Cybinska, J. Sokolnicki, J. Legendziewicz, G. Meyer, Journal of Alloys and Compounds, 341, 115–123 (2002).
^Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 421.
ISBN978-0-19-965763-6.
^Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 421.
ISBN978-0-19-965763-6.
^E. Warkentin, H. Bärnighausen (1979), "Die Kristallstruktur von Praseodymdiiodid (Modifikation V)", Zeitschrift für anorganische und allgemeine Chemie (in German), vol. 459, no. 1, pp. 187–200,
doi:
10.1002/zaac.19794590120
^Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, Florida: CRC Press, pp. 478, 523,
ISBN0-8493-0594-2
^
abMatović, Branko; Pantić, Jelena; Prekajski, Marija; Stanković, Nadežda; Bučevac, Dušan; Minović, Tamara; Čebela, Maria (2013). "Synthesis and characterization of Pr6O11 nanopowders". Ceramics International. 39 (3): 3151–3155.
doi:
10.1016/j.ceramint.2012.09.098.
^
abShamshi Hassan, M., Shaheer Akhtar, M., Shim, KB. et al. Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods. Nanoscale Res Lett 5, 735 (2010).
https://doi.org/10.1007/s11671-010-9547-8