Mutual conjugation negative

The first iteration in a CG method is the same as in SD, with a step along the current negative gradient vector. Successive directions are constructed differently so that they form a set of mutually conjugate vectors with respect to the (positive-definite) Hessian A of a general convex quadratic function. 

It is not necessary for two substituents to constructively reinforce each other. If the first and second substituents are of — / or —E type, then the combined effect of R + S will be less than the sum of the effects of R and of S. Here there is negative mutual conjugation. A simple example is provided by resorcinol and hydroquinone. Reaction of these with bases gives the corresponding phenate ions. Since —O" is a more powerfully —E group than... 

Substituent effects due to mutual conjugation between -f E and — E groups are described as the mesomeric effect and those due to mutual conjugation between a -f 7 substituent and — E reaction center as the n-inductive effect or inductoelectromeric effect The stabilizing effects of + and -f 7 substituents on an odd AH anion are both proportional to the formal negative charge at the position to which these are attached. If a substituent exerts both -f and + 7 effects, the stabilizations due to them will then be in fixed proportion to one another for all odd AH anions. It follows that mutual... 

Polycyclic systems bearing more than one negative charge present two problems, (a) The early method of studying ion-pairing of monoanions failed as the UV-Vis measurements have limitations which arise from difficulties in distinguishing between discrete ion-pair states in systems with extended ir-conjugation K2). In such cases a situation may occur where one cation is solvated while the other one appears as a c.i.p. Due to the limited time scale of the optical methods, no distinction could be made between the two species, (b) The mutual location of the cations presents an additional problem. The description of the system itself is complicated due to Coulomb repulsions between the cations. The ion-solvation equilibria of dibenzo[b,f]pentalene dianion (32 ) (dibenzopentalenide) 82>, its 5,10-dimethyl derivative (72-), and acenaphthylene dianion (82 )S3) have been studied in detail. 

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