Q: What is EAN for metal ion in [ Fe(CN) _6]^ 3- ?

The atomic number of iron (Fe) is 26. Let the oxidation state of Fe in [ Fe(CN) _6]^ 3- be x. x + 6(-1) = -3 x = +3 The formula for Effective Atomic Number (EAN) is: EAN = Z - Oxidation state + 2 ( Coordination number ) EAN = 26 - 3 + 2 6 EAN = 23 + 12 = 35 Answer: 35

Question 1

Which of the following coordinate complexes is heteroleptic?

Accepted Answer

A homoleptic complex has only one type of ligand attached to the central metal atom or ion. A heteroleptic complex has more than one type of ligand attached to the central metal atom or ion. Pentacarbonyliron(0) is [Fe(CO)_5], which has only CO ligands (homoleptic). Triamminetrinitrocobalt(III) is [Co(NH_3)_3(NO_2)_3], which has two different types of ligands, NH_3 and NO_2^ - (heteroleptic). Tetraamminecopper(II) ion is [Cu(NH_3)_4]^ 2+ , which has only NH_3 ligands (homoleptic). Tetracyanonick

Question 2

Which of the following complex is neutral?

Accepted Answer

A neutral complex is a coordination compound that does not have an overall electrical charge and does not dissociate into ions in solution. K _3[ Fe(CN) _5 NO ] is an ionic complex that dissociates into 3 K ^+ and [ Fe(CN) _5 NO ]^ 3- ions. [ Zn(NH _3)_4]^ 2+ is a cationic complex with a +2 charge. [ Co(NH _3)_5 Cl ]^ 2+ is a cationic complex with a +2 charge. [ Ni(CO) _4] has no overall charge and no counter ions, making it a neutral complex. Answer: [ Ni(CO) _4]

Question 3

What is the coordination number of central metal ion in [ Co(en) _3]^ 3+ complex ?

Accepted Answer

The given complex is [ Co(en) _3]^ 3+ . The ligand 'en' stands for ethylenediamine, which is a bidentate ligand. This means each 'en' molecule coordinates to the central metal ion through two donor nitrogen atoms. Since there are three 'en' ligands attached to the central cobalt ion, the total number of coordinate bonds formed is 3 2 = 6. Therefore, the coordination number of the central metal ion is 6. Answer: 6

Question 4

Identify the formula of Bis(ethylenediamine)dithiocyanatoplatinum(IV)ion from following.

Accepted Answer

The central metal ion is Platinum in the +4 oxidation state, denoted as Pt ^ 4+ . The ligands are: Bis(ethylenediamine) two ethylenediamine (en) molecules. Since 'en' is a neutral ligand, its charge contribution is 0. dithiocyanato two thiocyanato ( SCN ^ - ) ions. Each SCN ^ - has a charge of -1, so their total charge contribution is -2. The net charge on the complex ion is calculated as: Net charge = Charge of Pt + Charge of 2( en ) + Charge of 2( SCN ^ - ) Net charge = +4 + 0 + 2(-1) = +2 Wri

Question 5

Which from following complexes is an example of MA _4 BC type distereoisomers ?

Accepted Answer

The general formula MA _4 BC represents an octahedral complex with one central metal atom M , four identical ligands A , and two different ligands B and C . Analyzing the given options: [ Pt ( NH _3)( H _2 O )\, Cl _2] is of the type MA _2 BC (where A = Cl , B = NH _3, C = H _2 O ). [ Pt ( NH _3)_4\, ClBr ]^ 2+ is of the type MA _4 BC (where A = NH _3, B = Cl , C = Br ). Pt ( NH _3)_2\, Cl _2 is of the type MA _2 B _2 (where A = NH _3, B = Cl ). [ Co ( NH _3)_4\, Cl _2]^+ is of the type MA _4 B

Question 6

Which from following coordinate complexes contains neutral ligand ?

Accepted Answer

Pentacarbonyliron (0) has the formula [Fe(CO)_5]. The ligand present is carbonyl (CO), which is a neutral molecule. Hexacyanoferrate (II) ion has the formula [Fe(CN)_6]^ 4- . The ligand is cyanide (CN^-), which is an anionic ligand. Trioxalatocobaltate (III) ion has the formula [Co(C_2O_4)_3]^ 3- . The ligand is oxalate (C_2O_4^ 2- ), which is an anionic ligand. Sodium hexanitrocobaltate (III) has the formula Na_3[Co(NO_2)_6]. The ligand is nitro (NO_2^-), which is an anionic ligand. Therefore,

Question 7

What is the oxidation state of cobalt in [ Co ( NH _3)_6]^ 3+ ?

Accepted Answer

Let the oxidation state of cobalt be x. Ammonia ( NH _3) is a neutral ligand, so its charge is 0. The sum of the oxidation states of all atoms in the complex ion is equal to the net charge on the ion. x + 6(0) = +3 x = +3 The oxidation state of cobalt in [ Co ( NH _3)_6]^ 3+ is +3. Answer: +3

Question 8

What type of hybridization is found in [ Ni ( Cl )_4]^ 2- ?

Accepted Answer

The given complex is [ NiCl _4]^ 2- . Let the oxidation state of Ni be x. x + 4(-1) = -2 x = +2 The electronic configuration of neutral Ni is [ Ar ] 3d^8 4s^2. The electronic configuration of Ni^ 2+ is [ Ar ] 3d^8. Cl^ - is a weak field ligand, so it does not cause the pairing of electrons in the 3d orbitals of Ni^ 2+ . To accommodate the four electron pairs donated by the four Cl^ - ligands, the Ni^ 2+ ion undergoes hybridization using one 4s and three 4p empty orbitals. Therefore, the hybridiz

Question 9

Which of the following is a correct increasing order of ligand field strength ?

Accepted Answer

According to the spectrochemical series, the ligands are arranged in the increasing order of their crystal field splitting energy (CFSE) or ligand field strength as follows: I^ - From the given options, the correct increasing order of ligand field strength is: C_2O_4^ 2- Answer: C _2 O _4^ 2- < H _2 O < EDTA < en

Question 10

What is EAN for metal ion in [ Fe(CN) _6]^ 3- ?

Accepted Answer

The atomic number of iron (Fe) is 26. Let the oxidation state of Fe in [ Fe(CN) _6]^ 3- be x. x + 6(-1) = -3 x = +3 The formula for Effective Atomic Number (EAN) is: EAN = Z - Oxidation state + 2 ( Coordination number ) EAN = 26 - 3 + 2 6 EAN = 23 + 12 = 35 Answer: 35

Question 11

Find EAN of Fe in Fe(CO) _5

Accepted Answer

The Effective Atomic Number (EAN) is calculated using the formula: EAN = Z - Oxidation State + 2 Coordination Number For Fe(CO) _5: Atomic number of Fe (Z) = 26 Oxidation state of Fe = 0 (since CO is a neutral ligand) Coordination number = 5 EAN = 26 - 0 + 2 5 EAN = 26 + 10 = 36

Question 12

Identify a ligand with highest field strength among the following.

Accepted Answer

According to the spectrochemical series, the arrangement of ligands in the increasing order of their crystal field splitting energy (CFSE) values is: I^- From the given options, the order of field strength is S^ 2- Thus, NH _3 has the highest field strength. Answer: NH _3

Question 13

Identify a ligand with lowest field strength among the following.

Accepted Answer

The field strength of ligands is determined by the spectrochemical series, which arranges ligands in order of increasing field strength. The spectrochemical series is given as: I ^- Comparing the given ligands based on the series, the order of field strength is: Br ^- Therefore, Br ^- has the lowest field strength among the given options. Answer: Br ^-

Question 14

What is the EAN of metal ion in [ Cu(NH _3)_4]^ 2+ ?

Accepted Answer

The effective atomic number (EAN) is calculated using the formula: EAN = Z - O.S. + 2 C.N. For the complex [ Cu(NH _3)_4]^ 2+ : Atomic number of copper (Z) = 29 Oxidation state of copper ( O.S. ) = +2 Coordination number ( C.N. ) = 4 Substituting the values: EAN = 29 - 2 + 2 4 EAN = 27 + 8 = 35 Answer: 35

Question 15

Identify the total number of complexes from following list having monodentate ligands in them (a) Tetracyanonickelate (II) ion (b) Potassium hexafluoroaluminate (III) (c) Tetraamminecopper(II) ion (d)

Accepted Answer

(a) Tetracyanonickelate (II) ion: [Ni(CN)_4]^ 2- . The ligand is CN^-, which is a monodentate ligand. (b) Potassium hexafluoroaluminate (III): K_3[AlF_6]. The ligand is F^-, which is a monodentate ligand. (c) Tetraamminecopper(II) ion: [Cu(NH_3)_4]^ 2+ . The ligand is NH_3, which is a monodentate ligand. (d) Potassium trioxalatoaluminate (III): K_3[Al(C_2O_4)_3]. The ligand is C_2O_4^ 2- (oxalate), which is a bidentate ligand. Therefore, there are 3 complexes having monodentate ligands. Answer:

Question 16

What is EAN of Co in [ Co ( NH _3)_6]^ 3+ ?

Accepted Answer

The effective atomic number (EAN) is calculated using the formula: EAN = Z - O.S. + 2 C.N. For the complex [ Co ( NH _3)_6]^ 3+ , the central metal is cobalt. Atomic number of Co (Z) = 27 Oxidation state of Co ( O.S. ) = +3 Coordination number ( C.N. ) = 6 Substituting the values into the formula: EAN = 27 - 3 + 2 6 EAN = 24 + 12 = 36 Answer: 36

Question 17

The number of ligands which are directly bonded to the metal is known as

Accepted Answer

The number of ligand donor atoms to which the metal is directly bonded is defined as the co-ordination number of the metal in the complex. For example, in the complex ion [PtCl_6]^ 2- , the co-ordination number of platinum is 6 because it is directly bonded to six chloride ligands. Answer: co-ordination number

Question 18

Identify the ionization isomer of [ Cr ( H _2 O )_4\, Cl ( NO _2)]\, Cl from the following.

Accepted Answer

Ionization isomerism occurs when a ligand inside the coordination sphere is exchanged with an anion outside the coordination sphere (counter ion), resulting in a complex that yields different ions in solution. In the given complex [ Cr ( H _2 O )_4\, Cl ( NO _2)]\, Cl , the counter ion is Cl ^- and the ligands are H _2 O , Cl ^-, and NO _2^-. By exchanging the NO _2^- ligand inside the coordination sphere with the Cl ^- counter ion outside, we get the ionization isomer [ Cr ( H _2 O )_4\, Cl _2]

Question 19

Identify oxidation state of cobalt ion in the complex, [ Co(NH _3)_5 Br ] SO _4 .

Accepted Answer

Let the oxidation state of cobalt be x. The given coordination compound dissociates into a complex cation [ Co(NH _3)_5 Br ]^ 2+ and a sulfate anion SO _4^ 2- . The overall charge on the complex cation is +2. Ammonia ( NH _3) is a neutral ligand with an oxidation state of 0, and bromide ( Br ^-) has an oxidation state of -1. Summing the oxidation states of the central metal atom and the ligands: x + 5(0) + (-1) = +2 x - 1 = +2 x = +3 The oxidation state of cobalt in the complex is +3. Answer: +3

Question 20

Identify the number of unpaired electrons present and geometry respectively of [ Co(NH _3)_6]^ 3+ complex.

Accepted Answer

The oxidation state of Co in [ Co(NH _3)_6]^ 3+ is +3. The electronic configuration of Co is [ Ar ] 3d^7 4s^2. The electronic configuration of Co^ 3+ is [ Ar ] 3d^6. Since NH _3 acts as a strong field ligand for Co^ 3+ , pairing of electrons takes place in the 3d subshell. All 6 electrons pair up in the inner d-orbitals, leaving two 3d orbitals empty. The number of unpaired electrons is 0. The complex undergoes d^2sp^3 hybridization, resulting in an octahedral geometry. Answer: 0, octahedral

Coordination Compounds — Previous Year Questions & Solutions