Nowotny phase explained

In inorganic chemistry, a Nowotny chimney ladder phase (NCL phase) is a particular intermetallic crystal structure found with certain binary compounds. NLC phases are generally tetragonal and are composed of two separate sublattices. The first is a tetragonal array of transition metal atoms, generally from group 4 through group 9 of the periodic table. Contained within this array of transition metal atoms is a second network of main group atoms, typically from group 13 (boron group) or group 14 (carbon group). The transition metal atoms form a chimney with helical zigzag chain. The main-group elements form a ladder spiraling inside the transition metal helix.

The phase is named after one of the early investigators H. Nowotny.^{[1] [2] [3]} Examples are RuGa₂, Mn₄Si₇, Ru₂Ge₃, Ir₃Ga₅, Ir₄Ge₅ V₁₇Ge₃₁, Cr₁₁Ge₁₉, Mn₁₁Si₁₉, Mn₁₅Si₂₆, Mo₉Ge₁₆, Mo₁₃Ge₂₃, Rh₁₀Ga₁₇, and Rh₁₇Ge₂₂.^[4]

In RuGa₂ the ruthenium atoms in the chimney are separated by 329 pm. The gallium atoms spiral around the Ru chimney with a Ga–Ga intrahelix distance of 257 pm. The view perpendicular to the chimney axis is that of a hexagonal lattice with gallium atoms occupying the vertices and ruthenium atoms occupying the center. Each gallium atom bonds to 5 other gallium atoms forming a distorted trigonal bipyramid. The gallium atoms carry a positive charge and the ruthenium atoms have a formal charge of -2 (filled 4d shell).^[5]

In Ru₂Sn₃ the ruthenium atoms spiral around the tin inner helix. In two dimension the Ru atoms form a tetragonal lattice with the tin atoms appearing as triangular units in the Ru channels.^[6]

The occurrence of a LCP phase can be predicted by the so-called 14 electron rule. In it the total number of valence electrons per transition metal atom is 14.^{[7] [8] [9]}

Notes and References

1. Die Kristallstruktur von Mn₁₁Si₁₉ und deren Zusammenhang mit Disilicid-Typen. Monatshefte für Chemie und Verwandte Teile Anderer Wissenschaften. 95. 6. 1527–1537. 10.1007/BF00901708. 1964. Schwomma. O.. Preisinger. A.. Nowotny. H.. Wittmann. A..
2. Untersuchungen im System: Ru−Sn. Monatshefte für Chemie und Verwandte Teile Anderer Wissenschaften. 95. 6. 1538–1543. 10.1007/BF00901709. 1964. Schwomma. O.. Nowotny. H.. Wittmann. A..
3. 10.1007/BF00901710. Untersuchungen an Germaniden der Übergangsmetalle V, Cr, Mo und Mn. Monatshefte für Chemie und Verwandte Teile Anderer Wissenschaften. 95. 6. 1544–1549. 1964. Völlenkle. H.. Wittmann. A.. Nowotny. H..
4. RuGa_vSn_w Nowotny Chimney Ladder Phases and the 14-Electron Rule. Journal of Solid State Chemistry. 164. 2. 210–219. 10.1006/jssc.2001.9462. 2002. Lu. Guoxin. Lee. Stephen. Lin. Jianhua. You. Liping. Sun. Junliang. Schmidt. Joshua Teal. 2002JSSCh.164..210L.
5. The Relationship between the Nowotny Chimney Ladder. Revista de Chimie . 58. 5. 439–441. 2007. King, R. Bruce .
6. 10.1021/ic049427n. 15446859. The Nowotny Chimney Ladder Phases: Following thecpseudo Clue toward an Explanation of the 14 Electron Rule. Inorganic Chemistry. 43. 20. 6151–6158. 2004. Fredrickson. Daniel C.. Lee. Stephen. Hoffmann. Roald. Lin. Jianhua.
7. The crystal structure of Rh₁₇Ga₂₂, an example of a new kind of electron compound. Acta Crystallographica. 22. 3. 417–430. 10.1107/S0365110X67000799. 1967. Jeitschko. W.. Parthé. E.. 1967AcCry..22..417J .
8. 10.1107/S0567740870003564. Phases with Nowotny chimney-ladder structures considered as 'electron' phases. Acta Crystallographica Section B. 26. 7. 1044–1046. 1970. Pearson. W. B.. 1970AcCrB..26.1044P .
9. 10.1021/ic049897h. 15446860. The Nowotny Chimney Ladder Phases: Whence the 14 Electron Rule?. Inorganic Chemistry. 43. 20. 6159–6167. 2004. Fredrickson. Daniel C.. Lee. Stephen. Hoffmann. Roald.