MINDO/3 molecular orbital calculations

Tsuda and Oikawa (1989) investigated the photolysis of the 1,2-isomer of 10.89 (1,2-benzoquinone diazide) by means of MINDO/3 molecular orbital calculations with configurational interaction. These authors came to the conclusion that no ketocarbene of the type of 10.90 is formed, but that the rearrangement into the cyclopentadienyl ketene 10.94 is a concerted reaction in which the elimination of nitrogen and the rearrangement take place simultaneously. In the opinion of the present author the theoretical result for 1,2-quinone diazide is not necessarily in contradiction to the experimental investigations of Sander, Yankelevich et al., and Nakamura et al., as the reagents used were not exactly the same. 

Donald B. Boyd (Eli Lilly and Company), David W. Smith, James J. P. Stewart (U.S. Air Force Academy), and Erich Wimmer (Cray Research) Importance of Criteria for Self-Consistent Field Convergence and Geometry Optimization in AMI, MNDO, and MINDO/3 Molecular Orbital Calculations. ... 

HyperChem currently supports one first-principle method ab initio theory), one independent-electron method (extended Hiickel theory), and eight semi-empirical SCFmethods (CNDO, INDO, MINDO/3, MNDO, AMI, PM3, ZINDO/1, and ZINDO/S). This section gives sufficient details on each method to serve as an introduction to approximate molecular orbital calculations. For further details, the original papers on each method should be consulted, as well as other research literature. References appear in the following sections. 

Boyd DB, Smith DW, Stewart JJP, Wimmer E. Numerical sensitivity of trajectories across conformational energy hypersurfaces from geometry optimized molecular orbital calculations AMI, MNDO, and MINDO/3. J Comput Chem 1988 9 387-398. 

Tel. 913-268-3271, fax 913-268-3445, e-mail aholder vaxl.umkc.edu Semiempirical molecular orbital calculations with M. J. S. Dewar s SAMI parameterization, including d orbitals for transition metals, and a graphical user interface. MINDO/3, MNDO, MNDOC, AMI, and PM3 methods. DEC, Cray, Silicon Graphics, Sun, and PCs (under X-Windows). 

Preferred geometry of the benzene oxide-oxepin system can be predicted by molecular orbital methods. Thus benzene oxide la is predicted to be markedly non-planar (with the epoxide ring at an angle of 73° to the benzene ring), while the oxepin lb has been predicted to prefer a shallow boat structure (MINDO/3) or a planar structure ab initio) As previously mentioned, the proportion of each tautomer present at equilibrium is both temperature and solvent-dependent. Molecular orbital calculations have been used to rationalize the solvent effects, both in terms of the more polar character of the arene oxide that is favored in polar solvents and the strengthening of the oxirane C-C bond upon coordination of the oxygen atom lone pair in polar solvents. Thus values in the range 1.5-2.0 D and 0.76-1.36 D for the dipole moments of arene oxide la and oxepin lb have been calculated. 

A long-standing difficulty of most semiempirical molecular orbital calculations (HMO, EHT, PPP, CNDO, INDO, MINDO, etc.) has been the... 

H. Halim, N. Heinrich, W. Koch, J. Schmidt, and G. Frenking, /. Comput. Chem., 7, 93 (1986). MlNDO/3 and MNDO Calculations of Closed- and Open-Shell Cations Containing C, H,N, andO. D. B. Boyd, D. W. Smith,/. J. P. Stewart, and E. Wimmer,/. Comput. Chem., 9,387 (1988). Numerical Sensitivity of Trajectories Across Conformational Energy Hypersurfaces from Geometry Optimized Molecular Orbital Calculations AMI, MNDO, and MINDO/3. 

Geometric Optimization. The structure of the molecule as built by CHEMLAB (or a input from other methods) can be optimized through either a full force field molecular mechanics calculation (MMII) or with the semi-empirical molecular orbital methods MINDO-3 and MNDO. 

The semiempirical molecular orbital (MO) methods of quantum chemistry [1-12] are widely used in computational studies of large molecules. A number of such methods are available for calculating thermochemical properties of ground state molecules in the gas phase, including MNDO [13], MNDOC [14], MNDO/d [15-18], AMI [19], PM3 [20], SAMI [21,22], OM1 [23], OM2 [24,25] MINDO/3 [26], SINDOl [27,28], and MSINDO [29-31]. MNDO, AMI, and PM3 are widely distributed in a number of software packages, and they are probably the most popular semiempirical methods for thermochemical calculations. We shall therefore concentrate on these methods, but shall also address other NDDO-based approaches with orthogonalization corrections [23-25],... 

Semiempirical molecular orbital methods23-25 incorporate parameters derived from experimental data into molecular orbital theory to reduce the time-consuming calculation of two-electron integrals and correlation effects. Examples of semiempirical molecular orbital methods include Dewar s AMI, MNDO, and MINDO/3. Of the three quantum chemical types, the semiempirical molecular orbital methods are the least sophisticated and thus require the least amount of computational resources. However, these methods can be reasonably accurate for molecules with standard bond types. 

The semi-empirical molecular orbital method MINDO/3 has been used to calculate transition state geometries for the following decompositions. 

There have been several molecular orbital treatments of the structure and reactivity of oxazole these are summarized by Turchi and Dewar (75CRV389). Table 1 lists the a, it and net charge distributions calculated by the all-valence ab initio method, the net charges obtained by the MINDO/3 method and the bond lengths calculated by the latter method. 

Semiempirical molecular orbital computations have been used in numerous studies to establish various properties of heteroaromatics, such as conformations and rotational barriers. The value of such calculations is more difficult to estimate sometimes good agreement with experiment is obtained, sometimes not, making their predictional power questionable. The benefits of semiempirical MO computations are, of course, that large systems may be studied at much lower expense in terms of computer time. Thus, MINDO/3 calculations, which also take solvent effects into account, have been used to rationalize the syn-anti preference in the 2-formyl derivatives of furan, pyrrole, and thiophene (81JHC1055). 

According to a modified intermediate neglect of differential overlap (MINDO)/3 calculation, the highest occupied molecular orbital (HOMO) of a dicyanoDHI 7 shows a wave function similar to the lowest unoccupied molecular orbital (LUMO). Thus a locally excited (LE) transition (n-Jt ) is most probably hidden under this band. The assignment of a second band of 7 is less clear. 

Tel. 800-424-9737, fax 415-491-8311 (U.S.A.), tel. 41-38-337633 (U.K.) Model building, display, charge density, electrostatic potential, and molecular orbital plots. Stick, sphere, and dot surface display. 2D to 3D conversion. Protein and DNA fragment libraries. MM+, BIO+ (implementations of MM2 and CHARMM, respectively), OPLS, and AMBER molecular mechanics and dynamics. Solvent box. Semiempirical calculations by Extended Hiickel, CNDO, INDO, MINDO/3, MNDO, AMI, and PM3. Originated at Hypercube, Inc. (Dr. N. Ostlund et al.), of Ontario, Canada. Runs under Windows on a 386 or 486 PC and under Motif on a Silicon Graphics workstation. 

TABLE 38 Results of Semiempirical (MINDO/3) Quantum Chemical Calculations of Energies of the Highest Occupied Molecular Orbitals (HOMO) and Lowest Unoccupied Molecular Orbitals (LUMO) for a Series of Aromatic Adsorbates and Model Carbon Clusters... 

The MOPAC (molecular orbital package), which has been explored by Dr. James J.P. Stewart, is the method by which the electron characteristics of a molecule is calculated. The MOPAC determines both an optimum geometry and the electron properties of molecule by solving the Schrodinger equation, using the MINDO/3 [6], MNDO [7], or AMI [8] semi-empirical Hamiltonians developed by M.J.S. Dewar, the MIND-d Hamiltonian developed by W. Thiel, or the PM3 [9] or PM5 semi-empirical Hamiltonians developed by J.J.P. Stewart. 

MINDO/3 calculations relative to cyclopropane and cyclopropene show that the two highest molecular orbitals for silacyclopropane and silacyclopropene are destabilized. As a result, silacyclopropane and silacyclopropene are predicted to be more reactive toward electrophiles than their carbon analogues <79JCS(P1)443>. 

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