Formulae coordination compounds

Measurements on copper) I) chloride show the vapour to be the dimer of formula CU2CI2, but molecular weight determinations in certain solvents such as pyridine show it to be present in solution as single molecules, probably because coordination compounds such as py -> CuCl (py = pyridine) are formed. 

Besides structure and substructure searches, Gmclin provides a special search strategy for coordiuation compouuds which is found in no other database the ligand search system, This superior search method gives access to coordination compounds from a completely different point of view it is possible to retrieve all coordination compounds with the same ligand environment, independently of the central atom or the empirical formula of the compound. 

Free Radicals. In the formula of a polyatomic radical an unpaired electron(s) is(are) indicated by a dot placed as a right superscript to the parentheses (or square bracket for coordination compounds). In radical ions the dot precedes the charge. In structural formulas, the dot may be placed to indicate the location of the unpaired electron(s). 

Hofmann- and Werner-Type Inclusion Compounds. There is a wide range of clathrates having as the host component inorganic coordination compounds represented by the general formulae M(NH2)2 (CN) and X2Y4. The first formula is typical of Hofmaim-type clathrates... 

The oxidation-number system is easily extended to include other coordination compounds. Even the interesting substances represented by the formulas Na4Ni(CN)4 and K4Pd(CN)4 create no nomenclature problem they become sodium tetracyanonickelate(0) and potassium tetracyanopaHadate(0), respectively. 

You know die charge of die complex and those of the ligands. To find the formulas of the coordination compounds, apply the principle of electrical neutrality. 

The physical and chemical properties of complex ions and of the coordination compounds they form depend on the spatial orientation of ligands around the central metal atom. Here we consider the geometries associated with the coordination numbers 2,4, and 6. With that background, we then examine the phenomenon of geometric isomerism, in which two or more complex ions have the same chemical formula but different properties because of their different geometries. 

A certain coordination compound has the simplest formula Pt HjC. It has a molar mass of about 600 g/mol and contains both a complex cation and a complex anion. What is its structure ... 

This Formula Index consists of over 28 000 compounds that occur in the 6562 text pages of Volumes 1-6. Indexed compounds may appear in the text, equations, Schemes, Figures or Tables. Only specific compounds and not general classes of compound have been indexed the counter ion has been excluded. Limitations of space do not permit every coordination compound to be indexed each time it is mentioned, therefore compounds are only indexed when considered to be important in the context of the topic under discussion. 

The names of coordination compounds can become awesomely long because the identity and number of each type of ligand must be included. In most cases, chemists avoid the problem by using the chemical formula rather than the name itself. For instance, it is much easier to refer to [FeCl(H20)5]+ than to pen-taaquachloroiron(II) ion, its formal name. However, names are sometimes needed, and they can be constructed and interpreted, in simple cases at least, by using the rules set out in Toolbox 16.1. Table 16.4 gives the names of common ligands and their abbreviations, which are used in the formulas of complexes. 

Use the information in Table 16.4 to write the formula for each of the following coordination compounds ... 

Originally, compounds containing coordination complexes were given common names such as Prussian blue (KFe[Fe (CN)g ]), which is deep blue, or Reinecke s salt (NH4[Cr (NH3)2 (NCS)4]), named for its first maker. Eventually, coordination compounds became too numerous for chemists to keep track of all the common names. To solve the nomenclature problem, the International Union of Pure and Applied Chemistry (lUPAC) created a systematic procedure for naming coordination compounds. The following guidelines are used to determine the name of a coordination compound from its formula, or vice versa ... 

The most intriguing results were obtained for cobalt(III) chloride. By 1890, several ammonia compounds of C0CI3 had been isolated. These coordination compounds differed in several of their properties, the most striking of which were their beautiful colors. At the time, the formulas of these cobalt complexes were written as follows ... 

It is salutary to read the comment, At the time when I became interested in the reactions of coordination compounds the formula of not a single aquo complex was known with certainty, made by Taube in a recent review (364). In marked contrast, this review is predominantly concerned with the intimate detail of the mechanisms of sol-... 

The chief aim of this Formula Index, like that of other formula indexes, is to help in locating specific compounds, or even groups of compounds, that might not be easily found in the Subject Index, or in the case of compounds in tables or of many complex coordination compounds, not to be found at all in the Subject Index. All specific compounds, or in some cases ions, with definite formulas (or even a few less definite) are entered in this index, whether entered specifically in the Subject Index or not. As in the latter index, boldface type is used for formulas of compounds or ions whose preparations are described in detail, in at least one of the references cited. 

The two most common series of chromium halides have the formulas CrX2 and CrX3 (where X = F, Cl, Br, or I). However, CrF6 is also known. Compounds having the formula CrX3 are Lewis acids, and they also form many coordination compounds. For example, CrX3 reacts with liquid ammonia to yield... 

Trinuclear SCO coordination compounds of formula [Fe3(4-k-l,2,4-tria-zole)12 y(H20)y](anion)6-nH20 have been reported. Their SCO characteristics are listed in Table 1. 

Chemists are involved in both synthesis, that is creating compounds, and analysis, determing the nature of compounds. In this lab, a coordination compound containing Ni2+, NH3 and CL will be synthesized. Once it has been synthesized, the next step will be to analyze the coordination compound to determine its exact formula. 

This overview covers some of the rules for naming simple inorganic compounds. There are additional rules, and some exceptions to these rules. The first part of this overview discusses the rules for deriving a name from a chemical formula. In many cases, the formula may be determined from the name by reversing this process. The second part examines situations in which additional information is needed to generate a formula from the name of a compound. The transition metals present some additional problems therefore, there is a section covering transition metal nomenclature and coordination compounds. 

We have already mentioned the formulae for groups, such as S04 , without discussing the principles by which such formulae are assembled. These may (or may not) involve some reference to structure. The general approach is to select one or more atom(s) as the central or characteristic atom(s). This is so whether the ion or group is a coordination entity or not. Thus, I in ICl4 , V in V02 and Si and W in [SiW,204o] are all central atoms and are cited first. The subsidiary atoms then follow, in alphabetical order of symbols (this rule is slightly modified for coordination compounds). 

The formulae discussed so far rely on a minimum of structural information. Increasingly, chemists need to convey more than a list of constituents when providing a formula. They need to say something about structure to do this, simple line formulae (i.e. formulae written on a single line, as is text) need to be modified. How they are modified is determined by what information needs to be conveyed. Sometimes this can take a simple modification of a line formula to show extra bonds not immediately apparent, as in ring compounds, either organic or coordination compounds. 

It is usual for a coordination compound to write the formula of a ligand with the donor atom first. The nickel complex represented above has both S and P bonded to the metal (as well as all the carbon atoms of the C5H5). The ring structure for chlorocyclohexane should be obvious. 

The formulas for compounds described in volume 34 are entered in alphabetical order. They represent the total composition of the compounds, e.g., BF24KC38H21 for potassium tetra-3,5-bis(trifluoro-methyl)phenylborate. The elements in the formulas are arranged in alphabetical order, with carbon and hydrogen listed last. All formulas are permuted on the symbols other than carbon and hydrogen representing organic groups in coordination compounds. Thus potassium tetra-3,5-bis(trifluoro-methyl)phenylborate can be found under B, F, and K in this index. 

If materials are available, it is most instructive to prepare this unique compound. While usually given the name and formula of a basic salt, none of its properties agrees with this classification. It melts sharply at 285° and boils undecomposed at 330°. It is undoubtedly a highly coordinated compound, with the extra oxygen atom as the center of coordination. 

Coordination compounds. [In the formula of a coordination entity.] the symbol of the central atom(s) is placed first, followed by the ionic and then the neutru] ligands. Square brackets are used to enclose the whole coordination entity whether charged or not. This practice need not be used for simple species such us the common oxoanions (NO, NOT, SO -, OH-, etc.). Enclosing marks are nested within the square brackets as follows [()]. U<) , [()]>]. [( [()] ]]. etc. 

Formula for Mononuclear Coordination Compounds with Monodentate Ligands... 

Another candidate for the first coordination compound is Prussian Blue, potassium iron(III) hexacyanoferrate(II), a complex of empirical formula KCN-Fe(CN)2- Fe(CN)3. It was first obtained accidentally in 1704 by Diesbach, a manufacturer of artist s colors from Berlin. Initially it was described9 as a nontoxic pigment suitable for oil colors, but its method of preparation was kept secret, probably because Diesbach wished to benefit monetarily from his discovery. 

As the number of known coordination compounds increased, theories to explain their constitution were devised.35 Thomas Graham (1805-1869) is credited with originating the first theory of metal ammines, the so-called ammonium theory, in which metal ammines are considered as substituted ammonium compounds. Graham attempted to explain the constitution of compounds such as diamminecopper(II) chloride by the formula (1). 

Samuel Henry Clifford Briggs (1880-1935) devised formulas for coordination compounds that he claimed fulfilled the conditions required by experimental data and that indicated the manner in which the affinities of the atoms are disposed in the molecule.90 He did not claim to be proposing a new- theory of valency like Werner, he believed that a totally comprehensive and satisfactory... 

---