CHEM2090-PS9-KEY - ‘Iperties of the Transition Elements...

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Unformatted text preview: ‘Iperties of the Transition Elements »- (E) We first give the orbital dia am foreach f ' th ofunpairedelemna gr 0 eSpeCIes, and then count the number i f 7 éFe [Ar] MMi 45M 4unpaired electrons "st CW ’1' 0 [Ar] 3 n; Ounpairedelectrons Ti2+ A WT“ [1] MH— _ 4t; Zunpaired electrons 4+ = Mn [At] MMILL 43‘. 3unpairedelectrons ._, ‘ a : Cr [Ar] 31 1 1 1 4511 6unpairedelectrons kw cue tn; ttt __ m 4e; “1 unpaired electron Finally, mange in order of decreasing number of unpaired e": Cr > Fe > Mn“ > Ti} > Cuz‘ > Sc)" 2. (E) (a) -[Co(NHa)6]2+' Thecoorslination umber°fc°is¢ “3 monodentate NH 3 ligands attached (30. Since the NH3 ligand is; oxidation state of cobalt is +2, thesa‘me asathe charge for the co e hexaamminecobaltal) ion. ' . (b) (C) (d) (e) (i) [AIFGTV The coordination number of Al is 6; F’ is monodentate. Each F’ has a 1 — charge; thus the oxidation state of Al is +3; hexat'luoroaluminateUII) ion. [CuiCNLTT The coordination number of Cu is 4; CN’ is monodentatc. (‘N has a 1- charge; thus the oxidation state of Cu is +2 ; tetracyanocupratefll) ion [CrBr2 (NHQJ monodentate. NilI has no charge; Br' has a 1— charge. The oxidation state 01‘ The coordination number of Cr is 6; NH3 and Bi" are chromiumis +3; tetraamminedibromochromiuimIll) ion [Co(ox)l]4i The coordination number ofCo is 6; oxalate is bidentate. €205 (ox) has a 2—~ charge; thus the oxidation state of cobalt is +2 ; trioxalatocobaltateflI) ion. 37 7 i , 1 [Ag( $2032] The coordination number of Ag is 2; 8201’ IS monodcntate. SID; has a 2 — charge; thus the oxidation state of silver is +1 ; dithiosult‘atoargentatefl) ion. ( Although +1 is by far the most common oxidation state for silver in its compounds, stable silver(lll) complexes are known. Thus, strictly speaking, silver is not a non-variable metal, and hence when naming silver compounds, the oxidation state(s) for the silver atomts) should be specified). (d). 4-}{chJ {bond trans to the c Cl ' I ‘Cl ‘ ' Cl:(ii'——N\ Cl C N\C/ (e) [ Cir(en)3 T has only one geometric isomer; it has two optical isomers. C 3+ ' / \C N / l _N /N—/Ci'—~N\ C\ ,N bl] /C C \C (M) (a) There are three different square planar isomers With D, C and B, respectively trans to the A ligand. They are drawn below _ ABA BVAIC AB'BA \ / \ / _\ / \ / \ / /Pt\ /Pt\ /Pt\ ’Zm ’Zn\ CDDCDB c‘Dic‘D (b) Tetrahedral ZnABCD]2+ does display optical isomerism. The two optical isomers are drawn above. 1 IP‘LH'H- ISDH'ICJ' 16. {M} Complex IDJTS {a} and {b} are ldflflflfi 4 (611)] has only one isomer since the ethylenediamine (en) ligand cannot entral metal atom. (M) (it) Both of the central atoms have the same oxidation state, +3. We give the electron configuration of the central atom to the left, then the completed crystal field diagram‘ in the center, and finally the number of unpaired electrons. The chloro ligand is a ' weak field ligand in the‘ spectrocheinical series. Mo‘“ [Kr] 4d3 weak field B B (3g [KrLl llllII E] [It tzg 3 unpaired electrons; paramagnetic The ethylenediamine ligand is a strong field ligand in the spectrocheinicallseries. Co3+ [Ar] 3‘16 strongfield Cg [At] an BEEN lzg no unpaired electrons; diamagnetic (b) In [C004]? the oxidation state of cobalt is 2+. Chloro is a weak field ligand. The electron configuration of Co2+ is [Ar] 3a” or [Ar] Ill" The tetrahedral ligand field diagram is weakfield E] Ill ‘2? shown on the right. eg 3 unpaier electrons :22. (M) (a) In [Cu(py)4 T+ theoxidation state of copper is +2. Pyridine is a strong field ligand. The electron configuration of Cu” is [Ar] 3d° or [Ar] [J] There is no possible way that an odd number of electrons can be paired up. without 2' . . at least one electron being unpaired. [Cu (py)4] is paramagnetic. El i. 5: or hand side. In [FeCl4 1— state of iron is +3. Chloro is a weak field ligand The electron c f . on 1 is 362's or The ligand field diagram follows, below stron Id 63 g fie weak field El tzg m mg an e, 2 unpaired electr ons 5 unpaired electrons 41‘ than in [renews] in int-12,18 hr. 1 There are more unpaired electrons in [FeCl _ (M) The electron configuration of Ni“ 04 a ‘, (M)The chloro ligand, being lower in the spectrochemical seriestthan the ethylenediamine ligand, rs less strongly bonded to the central atom than is the ethylenediamine ligand. Therefore, of the ‘ two types of ligands, we expect the chloro ligand to be replaced more readily. In the cis isomer, the two chloro ligands are 90° from each other. This is the angular spacing that can be readily spanned by the oxalato ligand, thus we expect reaction with the cis isomer to occur rapidly. On the other hand, in the trans isomer, the two chloro ligands are located 180° from each other. After I the-chloro ligands are removed, at least one. end of one ethylenediamifi relocatedto allow the oxalate ligand to=bond as a bidentate ligand. Cod; the two chloro ligands by the oxalato ligand should be much slower for; the cis isomer. ...
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This note was uploaded on 03/01/2011 for the course CHEM 2090 taught by Professor Zax,d during the Winter '07 term at Cornell University (Engineering School).

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CHEM2090-PS9-KEY - ‘Iperties of the Transition Elements...

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