Isolobal Relationships and Bonding

Course details

Course lecturer: Dr Chris Russell.
Date: November 2009.
See also: Wikipedia notes on islobal relationships.

Table of contents

  1. Textbooks
    1. Texts recommended by the lecturer
    2. Other coverage
  2. Molecular polyhedra
    1. Boron cages
      1. History of boron cages
    2. Wade's Rules
  3. Isolobal relationships
  4. Multiple bonds between metal atoms
    1. Quadruple bonds
    2. Quintuple bonds

Textbooks

Texts recommended by the lecturer

Other coverage

  • Loads in Greenwood & Earnshaw on boron clusters, including carboranes and metalloboranes

  • Probably a fair bit in Crabtree on carbyne complexes and the like

  • Probably plenty of structural images and orbitals in Housecroft. Third edition page numbers:
    • isolobal principle: 365(B), 821
      • applications: 401, 822
    • cluster compounds: 362
      • boron hydrides: 362-369
      • carbaboranes: 369-371
      • d-block organometallic compounds: 818, 821, 922, 931-932
      • Wade's rules: 364

Molecular polyhedra

Boron cages

History of boron cages

1912–1936

Stock and co. synthesise B2H6, B4H10, B5H9, B5H11, B6H10, B10H14
Vacuum line techniques are developed
1947 Structure of B2H6 determined by IR spectroscopy
W. C. Price, J. Chem. Phys. (1947) 15, 614
1948 Structure of B10H14 determined by X-ray crystallography
J. S. Kasper, C. M. Lucht, D. Harker, American Mineralogist (1948) 33, 768
1951 Structure of B5H9 determined by X-ray crystallography
W. J. Dulmage, W. N. Lipscomb, Acta Cryst. (1952) 5, 260–264
1951 Hoard, Geller and Hughes determine the structure of boron T-50
1955 Longuet-Higgins and Roberts predict the stability of [B12H12]2− (3D aromaticity)
Proc. Royal Soc. Lond. A (1955) 230, 110–119
1960 Synthesis (Pitochelli and Hawthorne) and structure (Lipscomb) of [B12H12]2−
1963 Synthesis of the first carborane, 1,2-C2B10H12
1965 First heteroborane containing a transition metal (Hawthorne)
1971 Williams' structure proposal based on deltahedral fragments is elaborated by Wade and Rudolph
1990s–present Application to boron neutron capture therapy (BNCT)
10B has a high neutron cross section: 10B + n → [11B]* → α + 7Li

Synthesis of boron hydrides

Wade's Rules

Named after Prof. Ken Wade, FRS, Wade's Rules are also known as polyhedral skeletal electron pair theory or the Wade/Mingos Rules.

Jmol models of parent deltahedra are available here.

Isolobal relationships

The isolobal principle was introduced by Roald Hoffmann in the 1970s (e.g. Inorg. Chem. (1975) 14, 1058–1076).

Multiple bonds between metal atoms

Quadruple bonds

Quintuple bonds