By: Mark A. Bruder
Purpose:
The purpose of this exercise is to use the GAMESS and MacMolPlt programs to calculate the energies, determine molecular properties and determine the minima geometries of molecules. Unlike Chem3D which can not provide all of these different calculations. The ground state of two molecules (carbene and formaldehyde) and the transition state between the two molecules will be calculated by the GAMESS program. Once these values are calculated the energy values between the molecules and the transition state can be determined.
Procedure:
1) Draw the structure in Chem3D
2) Save the file as a GAMESS input file and save the file in WinGAMESS folder (typically found in the c: drive)
3) Open MacMolPLT
4) Open the file and chose the subwindow
5) In the subwindow, select input builder
6) For the two ground states, run type = optimization energy, and Basis Set = 3-21G. For the Transition State, run type = saddle point
7) This will now calculate the Hessian stat. point. Save the new file in the WinGAMESS folder
8) Open the WinGAMESS folder and select batmaker
9) In batmaker chose the saved file from MacMolPLT and chose write file (this should produce a new .out file)
10) Re-Open MacMoltPLT and select the output file which should give you the molecule in the ground state with the energy
Analysis:
Carbene
Bond Lengths:
Minimum Energy of Carbene:
Energy = -113.1463
Energy Graph of Carbene:
Formaldehyde
Bond
Lengths of Formaldehyde:
Minimum Energy of Formaldehyde:
Energy = -113.2218
Energy Graph of Formaldehyde:
Minimum Energy of Formaldehyde:
Energy = -113.2218
Energy Graph of Formaldehyde:
Transition
State
Bond
Lengths of the Transition State:
Minimum Energy of the Transition State:
Energy = -113.0501
Energy Graph of the Transition State:
Calculated Energies: 1 Hartee = 627.51 kcal/mol)
Carbene = -113.1463 Hartrees
Formaldehyde = -113.2218 Hartrees
Transition State = -113.0501 Hartrees
Activation Energies (Ea)
Carbene to Intermediate:
Ea = -113.0501H - -113.1463H = .0962H or 60.366kcal/mol
Formaldehyde to Intermediate:
Ea = -113.0501H - -113.2218H = .1717H or 107.743kcal/mol
Formaldehyde to Carbene:
Ea= -113.1463H - -113.2218H = .0755H or 47.377kcal/mol
Conclusion:
After reviewing the data collected and the determined calculations the activiation energies from carbene to the intermediate was determined to be .0962H, from formaldehyde to the intermediate which is the reverse reaction was determined to be .1717H and from the formaldehyde to the carbene was .0755H. All of the determined activiation energies correspond to what is needed for carbene to the formation of formaldehyde. The results also show that formaldehyde is more stable which means it will also be the more favored in this overall reaction.
The formadehyde is more stable because all of the molecules have completed octets and there are no formal charges. The carbene molecule has higher energy because it has resonance structures which could either be in the cis or trans formation. These structures would contain double bonds which means the carbene has higher energy and is less stable.
The intermediate energy which should have the highest energy because of the violation of hydrogen's octet rule. In this structure hydrogen is forced to break the bond with oxygen and form a bond with carbon. When this process occurs it forms a highly strained ring and partial charges are formed on the oxygen. This now means at the saddle point of the intermediate it is the most unstable and has the highest amount of energy.
The overall results show that formaldehyde has the lowest energy and most stable versus the intermediate which has the highest energy and is the most unstable. The GAMESS program allowed for the analysis of this overall reaction and to determine the different energies for each step in the reaction. These results allowed for the analysis and determination on the different stabilities of the molecules involved in the overall reaction.
Minimum Energy of the Transition State:
Energy = -113.0501
Energy Graph of the Transition State:
Calculated Energies: 1 Hartee = 627.51 kcal/mol)
Carbene = -113.1463 Hartrees
Formaldehyde = -113.2218 Hartrees
Transition State = -113.0501 Hartrees
Activation Energies (Ea)
Carbene to Intermediate:
Ea = -113.0501H - -113.1463H = .0962H or 60.366kcal/mol
Formaldehyde to Intermediate:
Ea = -113.0501H - -113.2218H = .1717H or 107.743kcal/mol
Formaldehyde to Carbene:
Ea= -113.1463H - -113.2218H = .0755H or 47.377kcal/mol
Conclusion:
After reviewing the data collected and the determined calculations the activiation energies from carbene to the intermediate was determined to be .0962H, from formaldehyde to the intermediate which is the reverse reaction was determined to be .1717H and from the formaldehyde to the carbene was .0755H. All of the determined activiation energies correspond to what is needed for carbene to the formation of formaldehyde. The results also show that formaldehyde is more stable which means it will also be the more favored in this overall reaction.
The formadehyde is more stable because all of the molecules have completed octets and there are no formal charges. The carbene molecule has higher energy because it has resonance structures which could either be in the cis or trans formation. These structures would contain double bonds which means the carbene has higher energy and is less stable.
The intermediate energy which should have the highest energy because of the violation of hydrogen's octet rule. In this structure hydrogen is forced to break the bond with oxygen and form a bond with carbon. When this process occurs it forms a highly strained ring and partial charges are formed on the oxygen. This now means at the saddle point of the intermediate it is the most unstable and has the highest amount of energy.
The overall results show that formaldehyde has the lowest energy and most stable versus the intermediate which has the highest energy and is the most unstable. The GAMESS program allowed for the analysis of this overall reaction and to determine the different energies for each step in the reaction. These results allowed for the analysis and determination on the different stabilities of the molecules involved in the overall reaction.