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Transitions metals: synthesis of an inorganic compound (trans-dinitrobis(ethylenediamine)cobalt(iii) nitrate)

 

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.

Grading

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, [ Fe ( CN ) 6 ] 3 size 12{ \[ ital "Fe" \( ital "CN" \) rSub { size 8{6} } \] rSup { size 8{ - 3} } } {} . The Fe + 3 size 12{ ital "Fe" rSup { size 8{+3} } } {} and CN size 12{ ital "CN" rSup { size 8{ - {}} } } {} 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 Cu ( CN ) 2 size 12{ ital "Cu" \( ital "CN" \) rSub { size 8{2} } rSup { size 8{ - {}} } } {} , Ag ( NH 3 ) 2 + size 12{ ital "Ag" \( ital "NH" rSub { size 8{3} } \) rSub { size 8{2} } rSup { size 8{+{}} } } {} , 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 size 12{F rSup { size 8{ - {}} } } {} , Cl size 12{ ital "Cl" rSup { size 8{ - {}} } } {} , OH size 12{ ital "OH" rSup { size 8{ - {}} } } {} , H 2 O size 12{H rSub { size 8{2} } O} {} , NH 3 size 12{ ital "NH" rSub { size 8{3} } } {} and CN size 12{ ital "CN" rSup { size 8{ - {}} } } {} . 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 ( CH 2 NH 2 CH 2 NH 2 ) size 12{ \( ital "CH" rSub { size 8{2} } ital "NH" rSub { size 8{2} } ital "CH" rSub { size 8{2} } ital "NH" rSub { size 8{2} } \) } {} , 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 Cr ( H 2 O ) 6 Cl 3 size 12{ ital "Cr" \( H rSub { size 8{2} } O \) rSub { size 8{6} } ital "Cl" rSub { size 8{3} } } {} . One of these, violet in color, reacts immediately with AgNO 3 size 12{ ital "AgNO" rSub { size 8{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 [ CrCl 2 ( H 2 O ) 4 ] ( H 2 O ) 2 size 12{ \[ ital "CrCl" rSub { size 8{2} } \( H rSub { size 8{2} } O \) rSub { size 8{4} } \] cdot \( H rSub { size 8{2} } O \) rSub { size 8{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,

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Honors chemistry lab fall. OpenStax CNX. Nov 15, 2007 Download for free at http://cnx.org/content/col10456/1.16
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