Coordination Chemistry: IUPAC Nomenclature Dr. C. Haldar & Dr. RP John) Department of Applied Chemistry

Recommended Books D. J. Shriver, P. W. Atkins and C. H. Langford, Inorganic Chemistry, ELBS, 2nd Ed, 1994. J. E. Huheey, E. A. Keiter and R. L. Keiter, Inorganic Chemistry: Principle, structure and reactivity, Harper Collins, 4th Ed, 1993.

What is a Transition Metal?

Ligands Ligand Formula Name Fluoride F- Fluorido Nitrate NO3- Nitrato A ligand has only one donor atom is a “monodentate”; with two donor atoms will be “bidentate”; “tridentate” for three; “tetradentate” for four…..etc. Ligand Formula Name Fluoride F- Fluorido Nitrate NO3- Nitrato Nitrite NO2- Nitrito Carbonate CO32- Carbonato Cyanide CN- Cyanido Thiocyante SCN- Thiocyanto NCS- Isothiocyanato Hydride H- Hydrido Hydroxide OH- Hydroxido Water H2O Aqua Ammonia NH3 Ammine Carbon monoxide CO Carbonyl Nitric oxide NO Nitrosyl

Ligands A ligand that has more than one donor atom is of “multi-dentate/poly-dentate”. Some common bi-dentate ligands

Ligands Common tri-dentate ligands Common tetra-dentate ligands

Bridging ligands:

Polydentate Ligands The association mode of a multi-dentate is called “chelation”. Ethylenediaminetetraacetate, mercifully abbreviated EDTA, has six donor atoms Multi-dentate “chelating” ligand

Nomenclature of Coordination Complexes Rule 1: The names of neutral coordination complexes are given without spaces. For coordination compounds that are ionic the cation is named first and separated by a space from the anion, as is the case for all ionic compounds. Na [PtCl3(NH3)]: Sodium amminetrichloridoplatinate (II) K2 [CuBr4]: Potassium tetrabromidocuprate(II) Rule 2: The name of the coordination compound (neutral, cationic or anionic) begins with the names of the ligands. The metal is listed next, following in parentheses by the oxidation state of the metal. Rule 3: When more than one of a given ligand is bound to the same metal atom or ion, the number of such ligands is designated by the following prefixes: 2 di 6 hexa 10 deca 3 tri 7 hepta 11 undeca 4 tetra 8 octa 12 dodeca 5 penta 9 nona

Nomenclature of Coordination Complexes Rule 4: Neutral ligands are given the same name as the uncoordinated molecule, but with spaces omitted. Some examples are: (CH3)2SO dimethylsulfoxide (DMSO) (NH2)3CO urea C5H5N pyridine terpy terpyridine bpy 2,2’-bipyridine en ethylenediamine PCl3 trichlorophosphine PPh3 triphenylphopshine EXCEPTIONS: Some neutral molecules, when serving as ligands are given special names. These are: NH3 ammine H2O aqua NO nitrosyl CO carbonyl CS thiocarbonyl

Nomenclature of Coordination Complexes Rule 5: Anionic ligands are given names that end in the letter “o”. When the name of the free, uncoordinated anion ends in “ate”, the ligand name is changed to end in “ato”. Some examples are : CH3CO2- (acetate) acetato SO42- (sulfate) sulfato CO32- (carbonate) carbonato acac acetylacetonato When the name of the free, uncoordinated anion ends in “ide”, the ligand name is changed to end in “ido”. Some examples are:

Nomenclature of Coordination Complexes Certain anionic ligands are given special names, all ending in “o”: CN- cyanido F- fluorido Cl- chlorido O2- oxido O2- superoxido OH- hydroxido H- hydrido CH3O- methoxido Rule 6: The ligands are named alphabetically, ignoring the prefixes bis, tris, etc… Rule 7: When the coordination entity is an anion, the name of the metal is altered to end in “ate”. This is done for some metals by simply changing the ending “ium” to “ate”: Scandium scandate Titanium titanate Chromium chromate Zirconium zirconate

Nomenclature of Coordination Complexes For other metals, the name is given the ending “ate”: Manganese manganate Cobalt cobaltate Nickel nickelate Tantalum tantalate Tungsten tungstate Finally, the names of some metals are based on the Latin name of the element: Iron ferrate Copper cuprate Silver argentate Gold aurate Rule 8: Geometrical isomers are designated by cis- or trans- and mer- or fac-, the latter two standing for meridional or facial, respectively.

Nomenclature of Coordination Complexes Rule 9: In case of ligands that are capable of binding via different donor atoms, the atom involved in the attachment is denoted with an italized element symbol preceded by a ‘’ separated by ‘–’ at the end of the ligand name. -SCN- thiocyanato (thiocyanato-S) -NCS- isothiocyanto (thiocyanto-N) -NO2- nitrito-N -ONO- nitrito-O Examples: [Co(NH3)5CO3]Cl Pentaamminecarbonatocobalt(III) chloride [Cr(H2O)4Cl2]Cl Tetraaquadichloridochromium(III) chloride K2[OsCl5N] Potassium pentachloridonitridoosmate(VI) K3[Fe(CN)5NO] Potassium pentacyanidonitrosylferrate(II) [Mn(H2O)5I3]Cl hexaaquatriiodidomanganese(II) chloride [fac-Co(NH3)3(I)3] fac-triamminetris(iodido)cobalt(III) [cis-Co(NH3)4(N3)2]Br cis-tetraamminediazidocobalt(III) bromide

Nomenclature: additional rules To avoid confusion about the identity of poly halide ions the are prefixed by di, tri etc, while their monodentate counter parts are prefixed by bis, tris etc. Example: I3- is triiodido (I-)3 is termed tris(iodido) In case of ligands that are compounds having multiple substituents they are prefixed with bis, tris, tetrakis etc. to avoid repetition of di, tri, tetra etc. Example: bis(ethylenediammine) In case multiple atoms of the same ligand is bound to the same central metal ion, the atom that is bound is identified by ‘’ followed by element symbol perfixed by ‘-’ separated by ‘:’ or ‘,’ at the end of the ligand name Example: Slide no. 18, example 1, i.e. glycinato-N:O If multiple identical atoms of the same ligand is linked to the same central metal ion the number is indicated by the Arabic numeral exponent to . Example: see slide no.19, example 2

Nomenclature: additional rules If two atoms of the same ligand that are bound to the central metal ion is bound to each other, then ‘’ symbol is prefixed followed by’-’ before the name of the ligand. The number of such atoms that is bound to the central metal is denoted by the arabic numeral exponent on ‘’. Example: see slide no.19, example 2 If a ligand is linked to multiple metal ions then, then the ligand name is prefixed by ‘µ’ followed by ’-’, and the number of such metal ions linked is indicated by the arabic numeral subscript to ‘µ’ Example: See slide no 19 If a ligand is linked to multiple metal ions via same donor atoms elements and if the donor atoms identity is different, then the atoms are identified by arabic numeral superscript to the atom symbol, and the metal ions to which they are attached are identified by using arabic numeral labels prefixes to the symbol ‘’. Example: See slide no. 18, example 3

Simple Problem Write the names of the following coordination compounds: [Co(NH3)4Cl2]Cl K3[Fe(CN)6] [Pt(NH3)4)][Pt(Cl)4] [CoCl(ONO)(NH3)4]Cl Tetraamminedichloridocobalt(III) chloride Potassium hexacyanidoferrate(III) Tetraammineplatinum(II) tetrachloridoplatinate(II) Tetraamminechloridonitrito-Ocobalt(III) chloride Write formulas for the following compounds: Pentaamminechloridocobalt(III) chloride Dichloridobis(ethylenediamine)platinum(IV) nitrate Amminetetraaquasulfatochromium(II) Solution [Co(NH3)5Cl]Cl2 [Pt(en)2Cl2](NO3)2 [Cr(H2O)4(NH3)(SO4)]

Nomenclature contd…… Cis-bis(glycinato-N:O)platinum(II) (PdCl2)n catena-poly-di-µ-chloridopalladium(II) [Cu2(CH3COO)4(H2O)2] tetrakis(µ-acetato-1O1:2O2)-diaquadicopper(II) [Mn2(CO)10] bis(pentacarbonylmanganese)(Mn—Mn) Os3(CO)12 Cyclo-tris(tetracarbonylosmimum)(3Os-Os) W2Me6 bis(trimethyltungsten)(W-W) trans-[Co(en)2I(H2O)](NO3)2 trans-aquabis(ethylenediamine)iodidocobalt(III) nitrate mer-[Ru(PPh3)3Cl3] mer-trichloridotris(triphenylphosphine)ruthenium(III)

Name the compounds Pentaammineaquacobalt(III) chloride Bis(ethane-1,2-diamine-2N)2-peroxidocobalt(III) Dichloridobis(triphenylphosphane- P)platinum(II) Dicarbonyl(5-cyclopentadienyl)(cyclopenta-2,4-dien-1-yl- C1)iron

Problem:

Exercise: Identify name or formula µ-amido-µ-peroxidobis[pentaamminecobalt(III)] chloride

Exercise: Answers