Bond_Order Property

CDXML Name:Order
CDX Constant Name:kCDXProp_Bond_Order
CDX Constant Value:0x0600
Data Size:INT16
Property of objects:kCDXObj_Bond
First written/read in:ChemDraw 4.0


The order of a bond object.

Dative and Ionic bonds are specified with the Bond_Begin as the positive end (e.g. the N in pyridine N-oxide). Hydrogen bonds are specified with Bond_Begin as the hydrogen. Three center bonds are specified with two Bond objects, each with Bond_Begin as the center atom.

Bond order values may be combined. For example, a value of 3 would represent a "single or double" bond, which is useful for substructure queries.

Ionic, hydrogen, and three-center bonds are not currently supported by ChemDraw, but are defined for future compatibility.

This is a bit-encoded property. The values shown in the following list may be combined:
Value CDXML Name Description
0xFFFF Unspecified order (omitted entirely in CDXML)
0x0001 1 Single bond
0x0002 2 Double bond
0x0004 3 Triple bond
0x0008 4 Quadruple bond (used for some inorganic complexes)
0x0010 5 Quintuple bond (used for some inorganic complexes)
0x0020 6 Hextuple bond (used for some inorganic complexes)
0x0040 0.5 Bond of order one-half
0x0080 1.5 Bond of order one and one-half (an aromatic bond)
0x0100 2.5 Bond of order two and one-half (in benzyne, for example)
0x0200 3.5 Bond of order three and one-half (used for some inorganic complexes)
0x0400 4.5 Bond of order four and one-half (used for some inorganic complexes)
0x0800 5.5 Bond of order five and one-half (used for some inorganic complexes)
0x1000 dative Dative bond, from the "begin" atom to the "end" atom
0x2000 ionic Ionic bond
0x4000 hydrogen Hydrogen bond
0x8000 threecenter Three-center-bond (in boranes, for example)

If this property is absent:

The bond is treated as a single bond.


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