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WF ----> SF
I− < Br− < S2− < SCN− < Cl− < NO3− < N3− < F− < OH− < C2O42− < H2O < NCS− < CH3CN < py < NH3 < en < bipy < phen < NO2− < PPh3 < CN− < CO
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Trends in liability of metal complexes
- d e- WF(high spin) SF(Low Spin)
- 1 Liable Liable
- 2 Liable Liable
- 3 Inert Inert
- 4 Liable Inert
- 5 Liable Inert
- 6 Liable Inert
- 7 Liable Inert
- 8 intermediate (sq. planar) inert
- 9 Liable Liable
- 10 Liable Liable
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Liable Vs Inert
- Liable
- - low Ea
- - thermodynamically stable
- - Filling eg weakens M-L bonds, b/c they are antibonding,
- - t1/2 < 1 minute, Taube
- Inert
- - high Ea
- - t2g^3-6 and eg^ 0
- - eg electrons weaken M-L bonds & promote subst.
- - t2g doesn't affect bonding and makes L' approach unfavorable b/c of e/e repulsion
- - crystalized more easily than labile
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Pt2+, Pd2+, Ir+, Au3+ geometry w/ SF ligands
- Square planar
- - dx2-y2 is empty & points directly at ligands
- - z2 no ligands there (doesn't matter if electrons are there)
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Lability & period, oxidation state
- 3d > 4d > 5d
- - 3d smaller therefore more polarizable --> less electrostatic interxns, hard bond to break - also better orbital overlap
- high oxidation
- - less labile, electrons more tightly held so more Erequired to dissocate
- low oxidation
- - more likely to occupy eg orbitals, easier M-L bond discc.
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Experimental Kinetics
determine Ea and Sa --> study rxn at diff T
- activation volume
- - D generally result in +values for Vactivation, because one species splits into two
A result in - Vactivation values, because two species combine into one, with a presumed volume smaller than the total for the reactants
Caution because solvation effects, particularly for highly ox. cations, may be larger than the difference expected for the reaction otherwise
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