Assignment 2
Chem 495: T-Metals
October 2nd, 2000
Due date is October 13th, 2000.


1) Answer all questions.
2. Use diagrams where appropriate.
3. Remember oxidation state and electron count are important (hint - if you don't give them I can't give you any marks!).
4. Notice the number of points per question. This should provide a hint as to how much information is required in your answer.
5. No joint work.
6. Use black, blue pens ONLY. No pencil. Use of pencil results in an automatic failure.


Q.1. Which of the following compounds will be stable (hint - to get full marks, I suggest you show working and rationalization. Also they may not be monomers) - 20 points.


(a) Cr(C6H6)2
(b) Re(O)(Cp)Me2
(c) Mo(CO)4(pyridine)2
(d) [Cr(CO)5]-
(e) Cp2Mo(C2H4)


Q.2. Provide the products (draw the structure) for the reaction of Ir(CO)Cl(PPh3)2 with the following (8 points):


(a) O2
(b) H2
(c) MeI
(d) CO


Q.3. Wilkinson's catalyst, RhCl(PPh3)3, catalyzes the reaction of Me3SiH with ethylene to give Me3SiCH2CH3. Suggest a mechanism for this reaction. (20 points)

 

ANSWERS

Q.1.

 

Oxidation state

dn

total e-

stable

Comments

(a) Cr(C6H6)2

0
d6

18

stable

 

(b) Re(O)(Cp)Me2

+5

d2

16

stable

 

(c) Mo(CO)4(pyridine)2

0

d6

18

stable

 

(d) [Cr(CO)5]-

-1

d7

18

stable

dimer

(e) Cp2Mo(C2H4)

+2

d4

18

stable

 

Q.2.


Q.3.