Homework #1-Answers - Chemistry

Organometallic Chemistry - 4571
Homework # 1: Due: February 8, 2007
ANSWER KEY
Check the box to the right if you want your graded homework to be placed out in the public rack outside
Prof. Stanley’s office. Otherwise you will have to pick up your homework from Prof. Stanley in person:
1. (38 pts) Sketch out a structure showing the geometry about the metal center as accurately as possible and
clearly show the electron counting for the complexes below. Phosphine ligand abbreviations are defined in
your notes (phosphine ligand section). Most molecules (some simplified) are from Organometallics, 2003, # 1
& 2, from the Chem Library or on-line at the Library E-Journal site (only accessable from a campus computer).
a) Fe(η 4 -C 4 H 4 )(CO) 3 (cover molecule) b) cis-[CpZrCl 2 (NMe 2 ) 2 ] −
OC
C
O
Fe
C
O
Fe(0) d8
η 4 -C 4 H 4 4e-
3 CO 6e-
Total 18e-
C 4 H 4 is cyclobutadiene, a
neutral 4e- donor
Me 2 N
Me 2 N
Zr
Cl
Cl
Zr(+4) d0
Cp − 6e-
2 NMe − 2 8e-
2 Cl − 4e-
Total 18e-
c) Pd(NCN)Br (NCN ligand shown below) d) [Pd 2 (μ-CH 3 )(μ-CH 2 )(N-N) 2 ] + (one N-N
ligand shown below)
Me 2 N
Br Pd
Me 2 N
Pd(+2) d8
NCN − 6e-
Br − 2e-
Total 16e-
Me
N
N
Me
Pd
H 2
C
Pd
C
H 3
Me
N
N
Me
Pd(+2) d8
N-N 4eμ-CH
2− 2 2eμ-CH
− 3 1e-
Pd-Pd 1e-
Total 16e-
e) CpRuCl(Me 2 NCH 2 CH 2 NMe 2 ) f) Cp 2 Y 2 (μ-H) 2 (NR 2 ) 2 (THF) 2
Y(+3) d0
Ru(+2) d6
Cp − 6e-
Cp − 6e-
2 μ-H
O NMe − 2e-
2 NR 3 4e-
2
THF 2e-
Ru
Cl − 2e-
H
Y Y
NMe − 2 4e-
NMe 2 H
Cl
Total 18e-
O
Total 14e-
Me 2 N
NMe 2
g) Ru(=CHMe)Cl 2 (PMe 3 ) 2 h) CpReCl 2 (η 2 -SCH 2 CH 2 S)
Ru(+4) d4
PMe 3
Ru
Cl
Cl
=CHR 2− 4e-
2 PR 3 4e-
2 Cl − 4e-
Total 16e-
Also OK to count the =CHR
group as a neutral carbene
that is a 2e- donor – you will
still get the same total e-
count
Cl
Cl
Re
S
S
No Y-Y bonding due to d 0
electron count!
Re(+5) d2
Cp − 6e-
2 SR − 4e-
2 Cl − 4e-
Total 16e-

HW # 1 – 2007 2
i) [CpFe(C 6 H 6 )] + j) Cp 2 Nb(CH 3 )(CH 2 =CH 2 )
Fe
Fe(+2) d6
C 6 H 6 6e-
Cp − 6e-
Total 18e- Nb CH 3
Nb(+3) d2
2 Cp − 12e-
H 2 C=CH 2 2e-
CH − 3 2e-
Total 18e-
k) CpOs(H)(Cl)(SiMe 3 )(PR 3 ) l) NiPh(PPh 3 )(N~O) N~O ligand shown below
H
Os
PR 3
Os(+4) d4
Cp − 6e-
SiR − 3 2e-
H- 2e-
PR 3 2e-
Cl − 2e-
R
Ph 3 P Ni(+2) d8
N~O − 4e-
Ni
N
PPh 3 2e-
Ph
O
− 2e-
Total 16e-
Cl SiMe 3
Total 18e-
m) cis-Re(CO) 3 (bipy)(NR 2 ) bipy = bipyridine n) [Ru(C 6 H 6 )(C~N)(NCCH 3 ] + C~N below
OC
OC
N
Re
C
O
NR 2
N
Re(+1) d6
Ru(+2) d6
NR − 2 2e-
C~N − 4ebipy
4e-
C
Ru
6 H 6 6e-
3 CO 6e-
N C
NCCH 3 2e-
CH3
Total 18e- NMe 2 Total 18e-
o) Cp 2 Fe 2 (μ-C≡C)(CO) 4 p) [Cp 2 Fe] +
O
C
Fe
C
O
O
C
Fe
O
C
Fe(+2) d6
Cp − 6eμ-C≡C
2− 2e-
2 CO 4e-
Total 18e-
Fe
Fe(+3) d5
2 Cp − 12e-
Total 17e-
q) (C 6 H 6 )Cr(CO) 3 r) Co 2 (μ-CO) 2 (CO) 6
OC
C
O
Cr
C
O
Cr(0) d6
C 6 H 6 6e-
3 CO 6e-
Total 18e-
O
C O
C
C
O Co(0) d9
2 μ-CO 2e-
Co Co
C
C
O 3 CO 6e-
O
1 Co-Co 1e-
OC
C
O
C
O
Total 18e-

HW # 1 – 2007 3
2. (12 pts) Propose an 18e- structure for the following metal/ligand combinations. Use at least one of each
metal and ligand listed. Complexes must be neutral. Don’t use more than 2 metal centers. Clearly show your
electron counting. Ligands are shown without charges, please indicate the proper ligand charge in your electron
counting. Draw a reasonable structure showing the geometry about the metal center(s).
a) Tc, Cp, O, P(OMe) 3 b) Ni, dmpe (chelating), μ-CO, CO
O
Tc
P(OMe) 3 Total 18e-
Tc(+3) d4
Cp − 6e-
O 2− 4e-
2 PR 3 4e-
P(OMe) 3
O
C O
C
C
O Ni(0) d10
2 μ-CO 2e-
Ni Ni
CO 2e-
C
PR 2 O R 2 P
2 PR 3 (dmpe) 4e-
Total 18e-
R 2 P PR 2
c) Ta, Cp, C-R d) Cr, Cl, C≡NMe
Ta C R
Ta(+5) d0
2 Cp − 12e-
CR 3− 6e-
Total 18e-
RN
RN
Cl
C
C
Cr
C
N
R
Cl
C
C
NR
NR
Cr(+2) d4
2 Cl − 4e-
5 C≡NR 10e-
Total 18e-
7-coordinate Cr with
“skinny” ligands is A-OK