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7 Cards in this Set
- Front
- Back
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What is the 18 electron rule ? |
A stable complex (with the electron configuration of thenext highest noble gas) is obtained when the sum ofthe metal d-electrons, electrons donated by the ligandsand the overall charge of the complex equals 18. • The 18-electron rule enables us to decide whether a d-block metalcomplex is likely to be stable. Inorganic chemists count additionally the five d-orbitals in which to place their electrons. |
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What are the 5 d orbitals and what are there orientations ? |
3dyz, 3dxy, 3dxz, 3dz2, 3dx2-y2 The d-orbitals are definedby 3 quantum numbersn, l and mlthatdetermine energy,shape and orientationin space, respectively. Note that the d-orbitalsmay have the samevalue for n and l, but theycannot have the samevalue for ml. Hence,each orbital must have adifferent orientation inspace and as a resultthey all point indifferent directions |
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How does an octahedral complex satisfy the 18e rule ? |
An octahedral complex uses sp3d2 orbitals to form 6 M-L sigma bondingand 6 M-L sigma* antibonding orbitals = 12e. This uses dx2-y2, dz2 (dpi/eg set, point along x, y, z axis) dxy, dxz, dyz(dpi/t2g set, point along in-between the x, y, z axis) are used as NonBonding= 6e. 18 electrons give rise to a filled dpi/t2g set |
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Explain how square planer geometry satisfys the 16e rule ? |
• Square Planar complexes form 4 M-L sigma-bonds using sp2d hybrids (pzand dz2 orbitals are not used in bonding).• The remaining 4 d-orbitals are non-bonding.• The Square Planar geometry is common for metals in the d8configuration. |
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How does the z axis effect square planar geometry ? |
The axis from which the ligands are removed is defined as the Zdirection.• Removal of the ligands along the Z-axis stabilises those orbitals, whichare orientated either directly or partially along the Z direction. he consequence is that the dz2, dxz and dyz orbitals are stabilised,hence, they drop in energy. |
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What are the 2 classes of ligands and give examples ? |
Covalent Bonds - 1e donor ligands, share electrons. e.g. CH3, Cl, H (given symbol X). Dative Bonds - 2e donor ligands, donate a pair of electrons. e.g. CO, PR3(phosphines), NH3(given symbol L) |
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The formal oxidation state of a given metal ion in a mononuclear coordinationcomplex is commonly defined as ? |
“The charge left on the metal after all ligands have beenremoved in their normal, closed-shell configurationthatis with their electron pair”. |
