Geometric isomers are two or more coordination compounds which contain the same number and types of atoms, and bonds (i.e., the connectivity between atoms is the same), but which have different spatial arrangements of the atoms.

Not all coordination compounds have geometric isomers.

For example, in the square planar molecule, Pt(NH₃)₂Cl₂, the two ammonia ligands (or the two chloride ligands) can be adjacent to one another or opposite one another.

Note that these two structures contain the same number and kinds of atoms and bonds but are non-superimposable. The isomer in which like ligands are adjacent to one another is called the cis isomer. The isomer in which like ligands are opposite one another is called the trans isomer.

Jmol._Canvas2D (JSmol) "jmolApplet0"[x] call loadScript core\corescript.z.js starting QueueThread0_2 script 1 started call loadScript core\corestate.z.js   FileManager.getAtomSetCollectionFromFile(cis.xyz) //XYZ::cis.xyz starting HoverWatcher_3 FileManager opening https://www.chem.purdue.edu/jmol/cchem/cis.xyz The Resolver assumes Xyz Time for openFile(XYZ::cis.xyz): 172 ms reading 11 atoms ModelSet: haveSymmetry:false haveUnitcells:false haveFractionalCoord:false 1 model in this collection. Use getProperty "modelInfo" or getProperty "auxiliaryInfo" to inspect them. Default Van der Waals type for model set to Babel 11 atoms created ModelSet: autobonding; use autobond=false to not generate bonds automatically Jmol JavaScript applet jmolApplet1_object__3880007130045113__ initializing getValue debug = null getValue logLevel = null AppletRegistry.checkIn(jmolApplet1_object__3880007130045113__) viewerOptions: { "name":"jmolApplet1_object","applet":true,"documentBase":"https://www.chem.purdue.edu/jmol/cchem/geomi.html","platform":"J.awtjs2d.Platform","fullName":"jmolApplet1_object__3880007130045113__","display":"jmolApplet1_canvas2d","signedApplet":"true","appletReadyCallback":"Jmol._readyCallback","statusListener":"[J.appletjs.Jmol.MyStatusListener object]","codeBase":"https://www.chem.purdue.edu/jmol/cchem/j2s/","syncId":"3880007130045113","bgcolor":"white" } (C) 2012 Jmol Development Jmol Version: 13.1.14_dev $Date: 2013-02-27 13:04:34 -0600 (Wed, 27 Feb 2013) $ java.vendor: j2s java.version: 0.0 os.name: j2s Access: ALL memory: 0.0/0.0 processors available: 1 useCommandThread: false appletId:jmolApplet1_object (signed) starting HoverWatcher_5 getValue emulate = null defaults = "Jmol" getValue boxbgcolor = null getValue bgcolor = white backgroundColor = "white" getValue ANIMFRAMECallback = null getValue APPLETREADYCallback = Jmol._readyCallback APPLETREADYCallback = "Jmol._readyCallback" getValue ATOMMOVEDCallback = null getValue CLICKCallback = null getValue ECHOCallback = null getValue ERRORCallback = null getValue EVALCallback = null getValue HOVERCallback = null getValue LOADSTRUCTCallback = null getValue MEASURECallback = null getValue MESSAGECallback = null getValue MINIMIZATIONCallback = null getValue PICKCallback = null getValue RESIZECallback = null getValue SCRIPTCallback = null getValue SYNCCallback = null language=en_US getValue script = null Jmol applet jmolApplet1_object__3880007130045113__ ready	Jmol._Canvas2D (JSmol) "jmolApplet1"[x] starting QueueThread0_6 script 1 started   FileManager.getAtomSetCollectionFromFile(trans.xyz) //XYZ::trans.xyz starting HoverWatcher_7 FileManager opening https://www.chem.purdue.edu/jmol/cchem/trans.xyz The Resolver assumes Xyz Time for openFile(XYZ::trans.xyz): 36 ms reading 11 atoms ModelSet: haveSymmetry:false haveUnitcells:false haveFractionalCoord:false 1 model in this collection. Use getProperty "modelInfo" or getProperty "auxiliaryInfo" to inspect them. Default Van der Waals type for model set to Babel 11 atoms created ModelSet: autobonding; use autobond=false to not generate bonds automatically 1 atoms selected spinY = 180 specularExponent = -6 specularPercent = 50 specularPower = 70 Script completed Jmol script terminated 1 atoms selected spinY = 180 specularExponent = -6 specularPercent = 50 specularPower = 70 Script completed Jmol script terminated	= Pt = N = H = Cl
cis-Pt(NH3)2Cl2 Note that the two NH3 ligands and the two Cl ligands are adjacent to one another. This compound is used medicinally to treat certain types of cancer. (tradename: "cisplatin").	trans-Pt(NH3)2Cl2 Note that the two NH3 ligands and the two Cl ligands are opposite one another. This compound does not exhibit any anti-tumor activity.

For the common structures which contain two or more different ligands, geometric isomers are possible only with square planar and octahedral structures (i.e., geometric isomers cannot exist for linear and tetrahedral structures).

Jmol._Canvas2D (JSmol) "jmolApplet2"[x]	Jmol._Canvas2D (JSmol) "jmolApplet3"[x] call loadScript core\package.js call loadScript core\core.z.js -- required by ClazzNode Jmol JavaScript applet jmolApplet0_object__225125073990907__ initializing getValue debug = null getValue logLevel = null AppletRegistry.checkIn(jmolApplet0_object__225125073990907__) viewerOptions: { "name":"jmolApplet0_object","applet":true,"documentBase":"https://www.chem.purdue.edu/jmol/cchem/geomi.html","platform":"J.awtjs2d.Platform","fullName":"jmolApplet0_object__225125073990907__","display":"jmolApplet0_canvas2d","signedApplet":"true","appletReadyCallback":"Jmol._readyCallback","statusListener":"[J.appletjs.Jmol.MyStatusListener object]","codeBase":"https://www.chem.purdue.edu/jmol/cchem/j2s/","syncId":"225125073990907","bgcolor":"white" } (C) 2012 Jmol Development Jmol Version: 13.1.14_dev $Date: 2013-02-27 13:04:34 -0600 (Wed, 27 Feb 2013) $ java.vendor: j2s java.version: 0.0 os.name: j2s Access: ALL memory: 0.0/0.0 processors available: 1 useCommandThread: false appletId:jmolApplet0_object (signed) starting HoverWatcher_1 getValue emulate = null defaults = "Jmol" getValue boxbgcolor = null getValue bgcolor = white backgroundColor = "white" getValue ANIMFRAMECallback = null getValue APPLETREADYCallback = Jmol._readyCallback APPLETREADYCallback = "Jmol._readyCallback" getValue ATOMMOVEDCallback = null getValue CLICKCallback = null getValue ECHOCallback = null getValue ERRORCallback = null getValue EVALCallback = null getValue HOVERCallback = null getValue LOADSTRUCTCallback = null getValue MEASURECallback = null getValue MESSAGECallback = null getValue MINIMIZATIONCallback = null getValue PICKCallback = null getValue RESIZECallback = null getValue SCRIPTCallback = null getValue SYNCCallback = null language=en_US getValue script = null Jmol applet jmolApplet0_object__225125073990907__ ready	= Co = N = H = Cl
cis-[Co(NH3)4Cl2]+ Note that the two chloride ligands are adjacent to one another in this octahedral complex ion. In aqueous solution, this complex ion has a violet color.	trans-[Co(NH3)4Cl2]+ Note that the two chloride ligands are opposite one another in this complex ion. In aqueous solution, this complex ion has a green color.