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Transition metal compounds have interesting magnetic properties. Diamagnetic Paramagnetic Ferromagnetic !"#$%&'()*+,*%+&'%-) ./01023456!"#$%&'()'*"+,"%"-%.$'/("0'1*)) ) *07010234568"2$3#'$('*"+,"%"-%.$'/("0'1*" ) 9477:10234568)4'5-%$'$)"-%.$'/("0'1*" " 85%$92/:$";')%19" 67" The magnetic properties of a complex depends on the number of unpaired electrons Na+ Mn2+ Ti2+ Co3+ Experiment shows: [Co(CN)6]3– has no unpaired electrons [CoF6]3– has four unpaired electrons WHY do they have different numbers of unpaired electrons? 85%$92/:$";')%19" 6<" CRYSTAL FIELD THEORY can be used to explain this result. "=" M in spherical Oh Field "=" "=" "=" "=" "=" E d orbitals in uniform, “spherical” field of negative charge; all orbitals raised in energy equally d orbitals in free metal ion (all degenerate)" Presence of ligand electrons raises energy of metal d orbitals due to electrostatic repulsion 85%$92/:$";')%19" 66" >?")@'"12.%$*9"%445:%(@")@'"-')%1"%1:$."%A'9":?"%" B%5)'92%$"(::5*2$%)'"9,9)'-"C:()%@'*5%1"(:-41'AD")@'" E0'1*F"29"$:)"#$2?:5-G"" ;</6<)14=0>)?):7@/=0>A)074)1:A=)0B46=4?)@C)=<4)14=0>D>/203?)@:3?/32)4>46=7:3AE) .4F43?A):3)24:14=7C):G)=<4)6:1F>4H8)IJ<474)074)=<4)4>46=7:3AEK)" I:5"%$":()%@'*5%1" (:-41'A!" 85%$92/:$";')%19" 6H" The octahedral ligand field (or crystal field) causes the d orbitals to split into two energy levels." *N<O"*A<P,<" '$'5.," ;')%1"2:$9"Q"12.%$*" C$'.%/R'"4:2$)"(@%5.'D" K" *A,"O"*AN"O"*,N" S412M$."(%#9'*"+,"" :()%@'*5%1"(5,9)%1"0'1*" I5''"-')%1"2:$" K"L"(5,9)%1"01'*"9412M$."'$'5.," 85%$92/:$";')%19" 6J" T:U"-%$,"#$4%25'*"'1'()5:$9"*:'9"%")5%$92/:$"-')%1"2:$"" @%R'"U@'$"2)"29"2$"%$":()%@'*5%1"0'1*"C"@%9"V"12.%$*9DW"" S(Q6 ""82Q6 ""XQ6 ""B5Q6 """;$Q6" e! config # unpaired e! P = spin pairing energy = energy needed to pair electrons in the same orbital. 85%$92/:$";')%19" 6V" For an ion with a d4 electron configuration the number of unpaired electrons will depend on ". Which one will be high spin (more unpaired e!)? Low spin (fewer unpaired e!)? " " " " " " " " " " " " " " K"1%5.'" " " " " " " " " " " " " " " K"9-%11" 85%$92/:$";')%19" 6Y" The magnitude of " (=Crystal field splitting energy) influences the properties of metal complexes. How big is " ? How does " affect properties of complexes? The magnitude of " depends on: 1. 2. 3. 4. 85%$92/:$";')%19" 6Z" [A41%2$")@'";\]^[8>B"_`a_[`8>[S":?"" OCTAHEDRAL COMPLEXES" #92$."(5,9)%1"0'1*")@':5,G"" Which of the diagrams below corresponds to [CoF6]3– and which corresponds to [Co(CN)6]3–? '$'5.," WHY?" K" K" What properties of these complexes would be different?"" 85%$92/:$";')%19" 6b" 8@'"S4'()5:(@'-2(%1"S'52'9"29"%"129)":?"12.%$*9"2$" :5*'5":?")@'25"%+212),"):"2$(5'%9'"KG" ) "@/>/=C):G)L)=:)/36740A4)=<4)43472C)20F" Cl! < F! < H2O < NH3 < en < NO2! < CN! '$'5.," Increasing"! " dB5IVe6=" .5''$" dB5CT<aDVe6Q" R2:1')" dB5C^T6DVe6Q" ,'11:U" 85%$92/:$";')%19" dB5CB^DVe6=" ,'11:U" Hc" a4/(%1"_5:4'5/'9":?"85%$92/:$";')%1"B:-41'A'9!"" -%$,")5%$92/:$"-')%1"(:-41'A'9"%5'"(:1:5'*G" The color of a complex depends on: 1. The element 2. Its oxidation state 3. Identity of ligands Example: V(H2O)63+ green V(H2O)62+ violet 85%$92/:$";')%19" H7" `'R2'U"9:-'"(:$('4)9"%+:#)"Bafa`" '$'5.," When light of a certain wavelength is absorbed by a complex, the complex will appear the complementary color of the wavelength absorbed (you see the light that is REFLECTED!) @g" 85%$92/:$";')%19" H<" How do we explain the colors of metal complexes? Visible absorption spectrum of [Ti(H2O)6]3+ : what color is it? 85%$92/:$";')%19" H6" (:>:7)0>A:)?4F43?A):3)/?435=C):G)=<4)>/203?A) Ni2+ (aq) [Ni(H2O)6]2+ + 6 NH3 h [Ni(NH3)6]3+ + 6 H2O 85%$92/:$";')%19" HH" '$'5.," The observed color is related to the amount of energy required to promote an electron. Compare " to energy absorbed. dB5IVe6=" .5''$" dB5CT<aDVe6Q" R2:1')" dB5C^T6DVe6Q" ,'11:U" 85%$92/:$";')%19" dB5CB^DVe6=" ,'11:U" HJ" Ba;_f[i[S!"Bafa`" Which of these complexes absorbs light at the shorter wavelength? Which complex has the larger !o?" 85%$92/:$";')%19" HV"