030.442 - Organometallic Chemistry - Karlin
Name_________________
Problem Set 1 - Spring 2010
1.
Comment/rationalize the following:
Infrared spectra of [V(CO)6]– and [Cr(CO)6] show absorptions at 1589 and 1981 cm–1,
respectively, assigned to ν(CO), and 460 and 441 cm–1, assigned to ν(MC). (MC = metalcarbon)
Backbonding stabilized MC and destabilizes CO. [V(CO)6)]- has greater backbonding
due to anionic charachter
2.
For which member of the following pairs of complexes would Δoct be the larger and why:
(a) [Cr(OH2)6]2+ and [Cr(OH2)6]3+ Higher charge density constricts orbitals
(b) [CrF6]3– and [Cr(NH3)6]3+
(c) [Co(en)3]3+ and [Rh(en)3]3+
Spectrochemical series
Ionic radius
3.
For each of the following diamagnetic compounds indicate the coordination number,
oxidation state, d-electron configuration and coordination geometry about the central transitionmetal.
Coordination #
Oxidation State
dn
Geometry
a) FeBr(CO)5
6
Fe(I)
b) Rh(π-C5H5)(C2H4)2
5
Rh(I)
d6
8
Octahedral
TBP
c) [Pt(SnCl3)5]3-
5
Pt(II)
8
TBP
d) (COT)Fe(CO3)
5
Fe(0)
8
TBP
e) Mo(π-C5H5)(CO)3H
7
Mo(II)
4
f) Pd(bipy)(C3H7)2
4
Pd(II)
8
Sq. Planar
g) (R3P)AuMe3
4
Au(III)
8
Sq. Planar
h) [Co(π-C5H5)2]+BF4-
6
Co(III)
6
Octahedral
COT = cyclooctatetraene
Capped Octahedral
i) Mn(CO)(NO)3
4
Mn(III)
10
Tetrahedral
j) Pt(PEt3)2(Me)2I2
6
Pt(IV)
6
Octahedral
030.442 - Organometallic Chemistry - Karlin
Problem Set 1 - Spring 2010 (page 2, continued)
Name_______________
4.
Assign the charge z (which may also be zero) to each of the following diamagnetic
complexes.
a)
[Mn(CNR)6]z
1
(b)
[Ni(dpe)(CF3)(I)]z
(c) [OsL3(CO)(H)(Cl)]z
31
0
0 (exhibits two P nmr signals)
d) [Co(CN)4((π-C5H5)(C3H5)]z
e) [Rh(Me2PCH2CH2PMe2)2(O2)]z
1
5.
Which of the two complexes has the lower energy CO stretching frequency in the infrared
spectrum? Rationalize your choice
6.
a)
[W(CO)5Cl]– or Re(CO)5Cl
Because it is anionic
b)
Mo(CO)4(PMe3)2 or Mo(CO)4(PPh3)2
PMe3 is a better electron donor than PPh3
Your textbook problems:
(a) Problem 3-1
(b) Problem 3-5
(c) Problem 3-10
(d) Problem 4-1
(e) Problem 4-3
(f) Problem 4-5
7.
Identify the central element in each of the following diamagnetic complexes
a)
M(NO)3CO (1st row element)
b)
M(PF3)4
c)
[M(dpe)2(H)(Cl)] (2nd row element) Ru
d)
[(π-Cp)2M]+ (3rd row element)
(3rd row element)
Mn
Pt
Ir
030.442 - Organometallic Chemistry - Karlin
Problem Set 1 - Spring 2010 (page 3, continued)
8.
Name_______________
Propose a logical structure for the following polynuclear (i.e. more that 1 metal) structures.
a)
Pt2(Me)4(COT)
b)
WMo(π-Cp)2(CO)6
c)
Mn2CO10
d)
[Me3Pt(I)]4
(Note: halides can doubly or even triply bridge metal ions)
e)
[(π-Cp)(CO)2Mo]2
(consider mulitple Mo-Mo bonding)
9.
10.
Predict the product of reaction:
a)
(CH3)Mn(CO)5 + PPh3
→→
b)
(Cl)Rh(PPh3)3
→→
c)
Ni metal +
d)
Re2O7 +
+
H2
(show likely geometry)
xs CO → →
xs CO → →
(a) Write out all the possible isomers of
Pt(NH3)2Cl2.
(b) What are the ligand hapticities (i.e., denticities) in [Cr(CpCH2CH2Cp)(CO)2] ?
Draw a three-dimensional formula.