# 0.9 Transition metals

 Page 1 / 3

## Objectives

• To synthesize a transition metal complex of cobalt three, Co(III), and ethylenediamine.
• To characterize the resulting metal complex spectroscopically.
• To understand concept of limiting reactant.

Your will be determined according to the following:

• prelab (10%)
• lab report form (80%)
• TA points (10%)

## Introduction

The transition metals are the largest“group”(classification) of elements from the periodic table. These can be found in nature as ores or in its elemental form, such as gold. All transition metals have more than one oxidation state. Most transition metals (TMs) can complex with other species (called ligands in“TM Complex”jargon) by giving their electrons to them, forming a complex. These ligands, which are the nearest neighbor atoms to the metal center, constitute the inner (or first) coordination sphere. Complexes may be either neutral or charged and have distinctive properties that may be quite unlike those associated with their constituent molecules and ions, each of which is capable of independent existence. An example of a charged complex is ferricyanide, $\left[\text{Fe}\left(\text{CN}{\right)}_{6}{\right]}^{-3}$ . The ${\text{Fe}}^{+3}$ and ${\text{CN}}^{-}$ ions found in the ferricyanide complex ion exist as independent species and in other compounds. The transition metals are well known for forming a large number of complex ions. In this experiment we will synthesize a transition metal complex containing cobalt, Co(III), and ethylenediamine.

## Stereochemistry

The most common coordination numbers (the number of individual ligands bound) are two, four, and six, with geometries illustrated in Fig 1:

Fig 1. Common geometries for complex ions. (A) linear, (B) square planar, (C) tetrahedral, and (D) octahedral

Complexes of Cu(I), Ag(I), Au(I) and some of Hg(II) form linear structures (A) such as $\text{Cu}\left(\text{CN}{\right)}_{2}^{-}$ , $\text{Ag}\left({\text{NH}}_{3}{\right)}_{2}^{+}$ , etc. Four-fold coordination (C) is not too common with transition metals, and the square planar geometry (B) occurs in complexes of Pd(II), Pt(II), Ni(II), Cu(II), and Au(III). Six-fold coordination (D) is the most common and in fact the one we will study in this laboratory exercise.

A ligand that is capable of occupying only one position in the inner coordination sphere by forming only one bond to the central atom is called a monodentate (“one tooth”) ligand. Examples are ${F}^{-}$ , ${\text{Cl}}^{-}$ , ${\text{OH}}^{-}$ , ${H}_{2}O$ , ${\text{NH}}_{3}$ and ${\text{CN}}^{-}$ . If the ligand has two groups that are capable of bonding to the central atom, it is called a bidentate ("two teeth") ligand, and so forth. An example of a bidentate ligand is ethylenediamine $\left({\text{CH}}_{2}{\text{NH}}_{2}{\text{CH}}_{2}{\text{NH}}_{2}\right)$ , which is commonly abbreviated "en". Both nitrogen atoms in "en" can bond to the central atom in a complex at the same time.

Complex ion salts with the same chemical formulas often behave differently because the same number of atoms can be arranged into different forms called isomers. Hydrate isomerism is illustrated by the following example: There are three distinct compounds with the formula $\text{Cr}\left({H}_{2}O{\right)}_{6}{\text{Cl}}_{3}$ . One of these, violet in color, reacts immediately with ${\text{AgNO}}_{3}$ to precipitate all of the chlorines as AgCl. The second is light green but only⅔of the chlorine is precipitated as AgCl. The third compound is dark green and only⅓of the chlorine is precipitated as AgCl. The last compound has only one reactive Cl, so apparently two chlorines in this compound are bonded tightly to the Cr and are not available for reaction. We might thus write this compound as $\left[{\text{CrCl}}_{2}\left({H}_{2}O{\right)}_{4}\right]\cdot \left({H}_{2}O{\right)}_{2}$ , where the species within the brackets are regarded as ligands bonded fairly strongly to the central chromium, and this species would behave as a single ion in solution. i.e., in aqueous solution,

Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!