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-