Volume 2 Chapter 2 2D-Constrain Sub-menu TANI

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TOTAL-COORD-NO

Function

TOTAL-COORD-NO is used to specify that an atom has a total coordination number n,

where

n = nca + nh

nca = number of connected atoms, excuding terminal hydrogen atoms

nh = number of attached terminal hydrogen atoms

Examples

Ex. 1 Suppose we have built the fragment (i) - see below.

(i)

Suppose we require that atom 1 is sp2- hybridised.

The fragment is now as in (ii).

(ii)

A search conducted with this fragment would register hits for (iii) and (iv), but not (v) since atom 1 in (v) is sp3-hybridised.

(iii)

(iv)

(v)

If we wished to restrict the hits to structures of type (iii) then in addition to specifying T3 we would assign zero HYDROGENS to atom 1.

Ex. 2 This simply illustrates how to change or remove a total coordination number specification.

Suppose we have the fragment

(a) If we wish to change T3 to T4

The fragment is now

(b) If we now wish to remove the T4 specification

The fragment is now

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Volume 2 Chapter 3 3D-Constrain Sub-menu CONTENTS.