Question

What is the IUPAC name of ferrocene?
A) bis (cyclopentadienyl) iron
B) dicyclopentadienyl iron
C) dicyclopentadienyl iron
D) bis (cyclopentyl) iron

Answer 1

We first discuss briefly about IUPAC name and its importance and significance. Then we discuss how an organic compound is named using IUPAC rules and regulations. Finally we find the IUPAC name of the given organic compound ferrocene.

Complete step by step answer:

In chemical nomenclature, the IUPAC nomenclature of natural science is a strategy for naming natural chemical compounds as suggested by the International Union of Pure and Applied Chemistry (IUPAC). It is distributed in the Nomenclature of Organic Chemistry (casually called the Blue Book). In a perfect world, each conceivable natural compound ought to have a name from which an unambiguous basic equation can be made. There is furthermore an IUPAC nomenclature of inorganic chemistry.
To avoid long and tedious names in ordinary communication, the legit IUPAC naming pointers are not usually followed in exercise, besides while it's important to offer an unambiguous and absolute definition to a compound. IUPAC names can from time to time be less complicated than older names, as with ethanol, in preference to ethyl alcohol. For exceedingly easy molecules they can be greater without difficulty understood than non-systematic names, which ought to be learnt or regarded over. However, the not unusual or trivial name is often considerably shorter and clearer, and so preferred. These non-systematic names are often derived from an unique source of the compound. In addition, very lengthy names can be much less clear than structural systems.

In chemistry, a number of prefixes, suffixes and infixes are used to describe the type and position of the functional groups in the compound.

The steps for naming an organic compound are:

Identification of the parent hydrocarbon chain: This chain must obey the following rules, in order of precedence:
It have to have the most number of substituents or branches noted as prefixes
It should have the maximum wide variety of substituents of the suffix functional group. By suffix, it is supposed that the figure functional group must have a suffix, not like halogen substituents. If a couple of functional institutions is present, the only with the highest priority should be used.
It ought to have the maximum length.
It needs to have the widest variety of multiple bonds.
It should have the maximum quantity of single bonds.
Identification of the parent functional group: if any, with the highest order of precedence.
Identification of the side-chains: Side branches are the carbon chains that are not within the figure chain, however are branched off from it.
Identification of the ultimate useful groups, if any, and naming them by their ionic prefixes (along with hydroxy for -OH, oxy for =O, oxyalkylene for O-R, and so on.).
Different side-chains and useful groups may be grouped together in alphabetical order. (The prefixes di-, tri-, and many others. Are not considered for grouping alphabetically. For instance, ethyl comes earlier than dihydroxy or dimethyl, because the "e" in "ethyl" precedes the "h" in "dihydroxy" and the "m" in "dimethyl" alphabetically. The "di" isn't taken into consideration in either case). When each side chain and secondary functional groups are present, they should be written together in one group rather than in two separate groups.
Identification of double/triple bonds:
Numbering of the chain This is carried out by means of first numbering the chain in both instructions (left to right and proper to left), and then selecting the numbering which follows these rules, so as of priority
Has the bottom-numbered locanto (or locants) for the suffix functional group. Locants are the numbers at the carbons to which the substituent is without delay attached.
Has the lowest-numbered locants for multiple bonds (The locant of a more than one bond is the wide variety of the adjoining carbon with a lower quantity).
Has the bottom-numbered locants for prefixes.
Identification of double/triple bonds:
Numbering of the many substituents and bonds with their locants: If there may be more than one of the equal kind of substituent/double bond, a prefix is showing what number of there are ( di – 2 tri – three tetra – 4 then as for the number of carbons below with 'a' added)
The numbers for that form of aspect chain could be grouped in ascending order and written before the name of the two sided-chain. If there are side-chains with the equal alpha carbon, the number could be written two times.
Now, let us see the structure of the ferrocene.
Ferrocene is an organometallic compound with the formula $Fe{{\left( {{C}_{5}}{{H}_{5}} \right)}_{2}}$ . It is a type of organometallic compound along with two cyclopentadienyl rings certain on opposite sides of a central metal atom. Such organometallic compounds are also known as Sandwich compounds. So while naming cyclopentadienyl rings can be ligand and named as 'dicyclopentadienyl' observed via the name of metal 'iron' and as its a neutral molecule oxidation state could be (zero). It also can be written as (cyclopentadienyl) iron (0).
Therefore, the IUPAC name of ferrocene is bis (cyclopentadienyl) iron.
Hence, option A is the correct answer.

Note:
IUPAC uses one-word names throughout. This is why all parts are connected. One must number the chain in a correct order, else the IUPAC name would get wrong. And one must be careful while counting the number of atoms in the organic compound.