thuyet truong tinh the - thuyet mo

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Lun im c bn:

Phc cht tn ti mt cch bn vng l do tng tc tnh in gia ion trung tm v cc phi t phn b i xng xung quanh

Ch xt n cu hnh electron chi tit ca ion trung tm v xt n bin i do in trng ca cc phi t gy nn. Ch coi phi t nh cc in tch im to nn trng tnh in bn ngoi. Phi t nm xung quanh ion trung tm trn cc nh ca hnh a din nn phc cht c s i xng nht nh.

Phc cht bt din

z

x y

d z2

d x2 y 2

d xy

d xz

d yz

S o phan bo mat o electron cua 5 orbitan d tng ng vi 6 ien tch am tap trung cac nh cua hnh bat dien

E3 o 52 o 5

o

Ion t do

Ion trong trng i xng cu

Trong trng bt din

Phc cht t din

E2 td 5 3 td 5

td

Ion t do

Ion trong trng i xng cu

Trong trng t din

u im: Cho php gii thch mu sc v t tnh ca cc cht. Nhc im: Khng gii thch bn cht ca lin kt S phn b mt e trong phc cht khng cho php xc nh 1 cch nh lng chnh xc cc c trng nng lng v cc c trng khc Khng gii thch c dy ha quang ph.

QUAN IM CA THUYT MOV PHC CHTPhc cht c xem nh mt h thng CHLT thng nht trong cc nguyn t ring bit v phn t mt nhng c tnh ring ca mnh Cc e ha tr ca h c phn b trn cc obital phn t (MO) nhiu tm. Chuyn ng ca mi e c xc nh bi v tr ca cc ht nhn v c im chuyn ng ca cc e cn li.

S dng cc phng php gn ng (phng php gn ng 1 e)

Phng php gn ng cho rng mi chuyn ng c lp trong trng hiu ng trung bnh c to bi tt c cc ht nhn v cc e trung bnh khc.

XY DNG CC MOXy dng MO trn c s cc AO ca cht to phc v ca cc phi t. My e xen ph cc i v c li v mt nng lng hnh thnh MO lin kt ( ) Xen ph m ca cc my e v s tng nng lng ca h hnh thnh MO phn lin kt ( *) Nu AO ca cht to phc khng xen ph hoc hu nh khng xen ph vi cc obital ca cc phi t nng lng chng khng bin i cc AO chuyn thnh MO vi mc nng lng (MO khng lin kt)

Phc bt din khng c lin kt Phc bt din

Phc bt din c lin kt b sung

z

y

x

PHC BT DIN KHNG C LIN KTGi thuyt: Cc phi t ch s dng cc obital phn b theo tr c hng n ion trung tm xen ph vi cc obital ca cht to phc to thnh 1 lin kt.iu kin i xng

Chng khng th to thnh lin kt , trong trng hp ny phc ch to lin kt

IU KIN TO THNH LIN KT to thnh lin kt, cht to phc (nguyn t d) s dng cc AO ha tr ns, np ca lp e ngoi cng v (n-1)d ca lp e k ngoi cng. S xen ph gia cc obital ca cht to phc v phi t cng ch xy ra khi c nng lng gn nh nhau v tng ng vi s nh hng khng gian ca chng

Trong s 9 obital ha tr ca cht to phc: 6 obital d z2 , dx2 y2 ,s, px, py, pz c kh nng tham gia cc lin kt 3 obital dxy, dxz, dyz thch hp trong vic hnh thnh lin kt vi cc phi t.

Obital ns c tnh i xng cu c kh nng xen ph vi c 6 phi t phn b dc theo cc trc x, y, zz y +

+

x

2 MO 7 tm

s v s*

Mi AO p ca cht to phc s xen ph vi 2 obital ca phi t phn b trn 2 trc tng ng 2 MO 3 tm

p v

* p

3 MO lin kt px , py , pzC 3 AO pz y

6 MO

3 MO phn lin kt * ,* ,* px py pz

px

+

x

z y

x

pYz

+

y

+

x

-

-

pZ

Vi cc AO d: Ch c obital d z2 , dx2 y2 c kh nng xen ph vi cc obital ca 6 phi t phn b dc theo cc trc x, y, z to thnh 4 MO d v * d 2 MO lin kt

d v dz2 z2

x2 y 2

d* v d * 2 MO phn lin kt

x2 y 2

Cc AO d (dxy, dxz, dyz) c mt e phn b gia cc phi t khng th xen ph c vi cc phi t v chuyn thnh cc MO khng lin 0 kt 1 tm d : 0 ,0 ,0 v nh v cht to d d d phc.xy xz yz

z y

+ -

d x 2 -y 2z

+

d z2

-

+

x

+

y

+

x

y

z

z

x

x

y

+

+

+

Tm li: 9 AO cht to phc 6 AO phi t t hp 15 MO ca phc cht

s < p

x

=

pdz

y

= L) c hnh thnh do s xen ph gia obitan d cha cp e ca cht to phc v obt *,p* trng ca phi t Mt phn mt e ca cht to phc s chuyn v phi t. Thng s tch delta s tng ln so vi phc khng c lin kt

VD :phc cht [CoF6]3Lin kt c hnh thnh do s xen ph ca obitan 3d ca CO3+ vi obitan 2p c cp e ca F(lin kt cho nhn) *d *d E

s to lin kt lm gim xung, do F- ng u dy ph

0

d

*

d

pd

lk

Gin nng lng cc MO d ca [CoF6]3-

VD :phc [Cr(CO)6]

c hnh thnh do xen ph gia obitan 0d Lin kt

Cha cp electron ca Cr vi MO * t do ca CO

a)b) + M M + + + C O + + + C O M C O + M C

O-

+

-

a)s hnh thnh lin kt

b) S hnh thnh lin kt

E

d

*

*d

*d

*

d

lkd

Gin nng lng cc MO d vi phi t CO S to lin kt cui dy ph

ca phc cht

lm

tng ln,do CO ng

Thuyt MO gii thch c t tnh,mu sc ca phc,c dy quang phPhi t c th l cht cho

,cho ,nhn

Phi t nhn ,Dy quang ph:

ln.b.

Phi t l cht cho ,

I-< Br- < Cl - < SCN- < F-