Transition metal complexes central metal ion surrounded by ligands ligand molecule or negative ion which bonds to metal ion by donation of at least one electron pair into unfilled metal orbitals common ligands water, H20 ammonia, NH3 cyanide ion, CN- halides, F-,Cl-,Br- & I- nitrite ion, NO2- hydroxide ion, OH- MM 2005 AH

Transition metal complexes 2 ligands monodentate e.g. CN-, H2O, NH3 bidentate e.g. ethanedioate (oxalate), 1,2-diaminoethane (ethylenediamine) C-C O O .. - H H H2N C C NH2 H H .. hexadentate e.g. ethylenediaminetetraacetic acid (EDTA) (p60) MM 2005 AH

Transition metal complexes 3 Number of ligands in a complex ion varies depending on the ligand e.g. [Cu(H2O)6]2+ & [CuCl4]2- both have ligands around the copper(II) ion Co-ordination number: number of bonds from the ligand to the central metal ion e.g. copper(II) above has co-ordination numbers of 6 and 4 , respectively . MM 2005 AH

Shapes of metal complexes X - M - X Co-ordination number Shape of complex 2 4 6 linear X X M X M X X X square planar tetrahedral X X M X octahedral X MM 2005 AH

Formulae of metal complexes Named according to IUPAC rules Formula should be enclosed within square brackets metal symbol written first, then negative ligands followed by neutral ligands e.g. [CoCl2(NH3)4] MM 2005 AH

Naming metal complexes If the complex is a salt, the name of the positive ion is written before the name of the negative ion e.g. K3[Fe(CN)6] The name of the complex part (ion or neutral) consists of 2 parts written as 1 word. Ligands are named first, in alphabetical order, and the central metal ion second. If the ligand is a negative ion: ‘ide’ is dropped and replaced with ‘o’ e.g. chloride becomes chloro , cyanide becomes cyano; ‘ate’ and ‘ite’ change to ‘ato’ or ‘ito’ e.g. oxalate becomes oxalato, nitrite becomes nitrito. MM 2005 AH

Naming metal complexes 2 K3[Fe(CN)6] 5. Water becomes aqua; ammonia - ammine; carbon monoxide - carbonyl 6. The ligand name is preceded by a Greek prefix indicating the number of each ligand type (di, tri, etc). 7. The metal name is followed by the oxidation number,in Roman numerals, in brackets. The overall charge on the complex part will be equal to the sum of the oxidation number and the total charge on the ligands 8. If the complex ion is negative, the metal name is followed by ‘ate’ and then the oxidation number in brackets e.g. cobaltate, chromate. Latin name is sometimes used e.g. cuprate, ferrate, plumbate, stannate. MM 2005 AH

Naming metal complexes 3 K3[Fe(CN)6] [Cu(NH3)4]Cl2 [PtCl2(NH3)2] [Co(H2O)6]Cl2 Na2[PtCl4] [CrCl(H2O)5]Cl2 [CoCl2(NH3)4]Cl [Cu(CN)2(H2O)2] potassium hexacyanoferrate(III) tetraamminecopper(II) chloride diamminedichloroplatinum(II) hexaaquacobalt(II) chloride sodium tetrachloroplatinate(II) pentaaquachlorochromium(III) chloride tetraamminedichlorocobalt(III) chloride diaquadicyanocopper(II) MM 2005 AH