How to Derive Force Field Parameters by Genetic Algorithms: Modellingtripod-Mo(CO)3 Compounds as an Example

How to Model the Conformational Behaviour of Saturated Diphosphane Chelate Cycles: The Conformational Rearrangement Processes of [{κ-PAr2CH2CH(OH)CH2-κ-PAr′2}Rh-(η4-COD)]+

“…Since, with the molecules analysed, the interactions between their organic parts dominate it is expected that the force constants derived for the ‘inorganic’ part of the molecules by GA‐optimisation will adapt to the major forces exerted by their organic part such that the scale of relative energies as calculated by the force field as a whole will be on scale with the observations. These expectations have been born out by similar analyses in related cases 14−16. If the energies are on scale with the observations it must be possible to calculate conformationally relevant energies and to compare these with experimental values wherever available.…”

“…It appears that the approach taken in deriving a force field model is a very promising one. The optimisation of the force field parameters on the basis of as many solid state structures as available for a class of compound had already been shown to lead to models of high predictive power 14−16. The case studied here is the most complicated one of the ones analysed by this method so far and at the same time the one for which pathways and energies have been experimentally determined to the maximum possible extent 8.…”

“…If a large number of a family of crystal structures is known the question of whether these structures are by and large uninfluenced by crystal forces can be addressed by statistical analysis. In the first report on the use of Genetic Algorithms in the refinement of force field parameters which dealt with modelling the behaviour of tripod ‐Mo(CO 3 ) compounds14 statistical analysis by a variety of methods including Neural Network analysis had shown that these premises are met in this case 11. Refinement of the force field parameters on the basis of solid state structures has been highly successful in this case 14.…”

How to Model the Conformational Behaviour of Saturated Diphosphane Chelate Cycles: The Conformational Rearrangement Processes of [{κ-PAr2CH2CH(OH)CH2-κ-PAr′2}Rh-(η4-COD)]+

“…Since, with the molecules analysed, the interactions between their organic parts dominate it is expected that the force constants derived for the ‘inorganic’ part of the molecules by GA‐optimisation will adapt to the major forces exerted by their organic part such that the scale of relative energies as calculated by the force field as a whole will be on scale with the observations. These expectations have been born out by similar analyses in related cases 14−16. If the energies are on scale with the observations it must be possible to calculate conformationally relevant energies and to compare these with experimental values wherever available.…”

“…It appears that the approach taken in deriving a force field model is a very promising one. The optimisation of the force field parameters on the basis of as many solid state structures as available for a class of compound had already been shown to lead to models of high predictive power 14−16. The case studied here is the most complicated one of the ones analysed by this method so far and at the same time the one for which pathways and energies have been experimentally determined to the maximum possible extent 8.…”

“…If a large number of a family of crystal structures is known the question of whether these structures are by and large uninfluenced by crystal forces can be addressed by statistical analysis. In the first report on the use of Genetic Algorithms in the refinement of force field parameters which dealt with modelling the behaviour of tripod ‐Mo(CO 3 ) compounds14 statistical analysis by a variety of methods including Neural Network analysis had shown that these premises are met in this case 11. Refinement of the force field parameters on the basis of solid state structures has been highly successful in this case 14.…”

Conformational behaviour of bridging diphenylphosphido ligands

“…There is a clear relationship between this symmetrical system and others for two phenyl rotors attached to a phosphorus atom [such as in M(dppe), M("-dppm), MPPh 3 and M(tripod) complexes] (see, for example, Morton & Orpen, 1992;Garner & Orpen, 1993;Hunger et al, 1998) previously studied. In all these cases the CSD studies show that the high-energy region around (0, 0) in the notation of this paper is devoid of structures and the populated regions lie within those regions populated in the [M 2 {"-PPh 2 }] system.…”

MM3 parametrization of four‐ and five‐coordinated rhenium complexes by a genetic algorithm—Which factors influence the optimization performance?

“…The most unfavorable result using this combination was still better than the best result of a simple GA with a roulette selector, which was the worst overall combination. This combination had been used in the previous calculations,13–16 and we recommend to switch to the best GA combination of this study for further investigations. The influence of the crossover and mutation rates is less important than the GA type and selection operator.…”

How to Model the Conformational Behaviour of Saturated Diphosphane Chelate Cycles: The Conformational Rearrangement Processes of [{κ-PAr2CH2CH(OH)CH2-κ-PAr′2}Rh-(η4-COD)]+

“…Since, with the molecules analysed, the interactions between their organic parts dominate it is expected that the force constants derived for the ‘inorganic’ part of the molecules by GA‐optimisation will adapt to the major forces exerted by their organic part such that the scale of relative energies as calculated by the force field as a whole will be on scale with the observations. These expectations have been born out by similar analyses in related cases 14−16. If the energies are on scale with the observations it must be possible to calculate conformationally relevant energies and to compare these with experimental values wherever available.…”

“…It appears that the approach taken in deriving a force field model is a very promising one. The optimisation of the force field parameters on the basis of as many solid state structures as available for a class of compound had already been shown to lead to models of high predictive power 14−16. The case studied here is the most complicated one of the ones analysed by this method so far and at the same time the one for which pathways and energies have been experimentally determined to the maximum possible extent 8.…”

“…If a large number of a family of crystal structures is known the question of whether these structures are by and large uninfluenced by crystal forces can be addressed by statistical analysis. In the first report on the use of Genetic Algorithms in the refinement of force field parameters which dealt with modelling the behaviour of tripod ‐Mo(CO 3 ) compounds14 statistical analysis by a variety of methods including Neural Network analysis had shown that these premises are met in this case 11. Refinement of the force field parameters on the basis of solid state structures has been highly successful in this case 14.…”

Conformational behaviour of bridging diphenylphosphido ligands

“…There is a clear relationship between this symmetrical system and others for two phenyl rotors attached to a phosphorus atom [such as in M(dppe), M("-dppm), MPPh 3 and M(tripod) complexes] (see, for example, Morton & Orpen, 1992;Garner & Orpen, 1993;Hunger et al, 1998) previously studied. In all these cases the CSD studies show that the high-energy region around (0, 0) in the notation of this paper is devoid of structures and the populated regions lie within those regions populated in the [M 2 {"-PPh 2 }] system.…”

MM3 parametrization of four‐ and five‐coordinated rhenium complexes by a genetic algorithm—Which factors influence the optimization performance?

“…The most unfavorable result using this combination was still better than the best result of a simple GA with a roulette selector, which was the worst overall combination. This combination had been used in the previous calculations,13–16 and we recommend to switch to the best GA combination of this study for further investigations. The influence of the crossover and mutation rates is less important than the GA type and selection operator.…”

How to Model the Conformational Behaviour of Saturated Diphosphane Chelate Cycles: The Conformational Rearrangement Processes of [{κ-PAr2CH2CH(OH)CH2-κ-PAr′2}Rh-(η4-COD)]+

“…Since, with the molecules analysed, the interactions between their organic parts dominate it is expected that the force constants derived for the ‘inorganic’ part of the molecules by GA‐optimisation will adapt to the major forces exerted by their organic part such that the scale of relative energies as calculated by the force field as a whole will be on scale with the observations. These expectations have been born out by similar analyses in related cases 14−16. If the energies are on scale with the observations it must be possible to calculate conformationally relevant energies and to compare these with experimental values wherever available.…”

“…It appears that the approach taken in deriving a force field model is a very promising one. The optimisation of the force field parameters on the basis of as many solid state structures as available for a class of compound had already been shown to lead to models of high predictive power 14−16. The case studied here is the most complicated one of the ones analysed by this method so far and at the same time the one for which pathways and energies have been experimentally determined to the maximum possible extent 8.…”

“…If a large number of a family of crystal structures is known the question of whether these structures are by and large uninfluenced by crystal forces can be addressed by statistical analysis. In the first report on the use of Genetic Algorithms in the refinement of force field parameters which dealt with modelling the behaviour of tripod ‐Mo(CO 3 ) compounds14 statistical analysis by a variety of methods including Neural Network analysis had shown that these premises are met in this case 11. Refinement of the force field parameters on the basis of solid state structures has been highly successful in this case 14.…”

Conformational behaviour of bridging diphenylphosphido ligands

“…There is a clear relationship between this symmetrical system and others for two phenyl rotors attached to a phosphorus atom [such as in M(dppe), M("-dppm), MPPh 3 and M(tripod) complexes] (see, for example, Morton & Orpen, 1992;Garner & Orpen, 1993;Hunger et al, 1998) previously studied. In all these cases the CSD studies show that the high-energy region around (0, 0) in the notation of this paper is devoid of structures and the populated regions lie within those regions populated in the [M 2 {"-PPh 2 }] system.…”

MM3 parametrization of four‐ and five‐coordinated rhenium complexes by a genetic algorithm—Which factors influence the optimization performance?

“…The most unfavorable result using this combination was still better than the best result of a simple GA with a roulette selector, which was the worst overall combination. This combination had been used in the previous calculations,13–16 and we recommend to switch to the best GA combination of this study for further investigations. The influence of the crossover and mutation rates is less important than the GA type and selection operator.…”