Given below are two statements about [Fe(ox)3]3- (tris(oxalato)ferrate(III)) complex:
Statement I: This complex is optically active and exists as d and l enantiomers.
Statement II: It can be resolved into its enantiomers using an achiral (non-chiral) resolving agent.
In the light of the above statements, choose the most appropriate answer:

Optical isomerism arises in coordination compounds when the complex and its mirror image are non-superimposable — just as left and right hands cannot be superimposed. This property is called chirality, and compounds that exhibit it are said to be optically active because they rotate the plane of polarised light. In coordination chemistry, optical isomerism most commonly occurs in octahedral complexes. For an octahedral complex M(AA)3 (where AA is a symmetric bidentate ligand like ethylenediamine, acetylacetonate, or oxalate), the three bidentate ligands can be arranged in a right-handed propeller arrangement (the Delta or d-form, dextrorotatory) or a left-handed propeller arrangement (the Lambda or l-form, laevorotatory). These two arrangements are mirror images of each other and are non-superimposable, making them enantiomers. The D/d designation (for dextrorotatory, rotates plane-polarised light clockwise) and L/l (for laevorotatory, rotates anticlockwise) refer to the direction of rotation of polarised light, while the Delta/Lambda notation refers to the absolute configuration of the complex based on the arrangement of ligands.

The Swiss chemist Alfred Werner won the Nobel Prize in Chemistry in 1913 for his coordination theory, but one of his most elegant contributions came in 1911 when he successfully resolved a coordination complex that contained no carbon atoms whatsoever into its enantiomers — definitively proving that chirality is a property of three-dimensional molecular geometry, not specifically of carbon atoms. The complex he resolved was [Co{Co(NH3)4(OH)2}3]Br6, an entirely inorganic complex. Werner and his student Victor King resolved it using the chiral silver d-alpha-bromocamphor sulfonate as the resolving agent, obtaining pure dextro- and laevorotatory crystals. This achievement conclusively demonstrated that the three-dimensional arrangement of ligands around a metal centre can be chiral, supporting Werner's octahedral geometry for six-coordinate cobalt complexes and disproving contemporary theories that attributed optical activity exclusively to carbon atoms. The tris(oxalato)ferrate(III) complex [Fe(ox)3]3- belongs to the same class of M(AA)3 chiral complexes that Werner first characterised.

Since enantiomers have identical energies and therefore identical physical properties (melting point, solubility, spectral properties) in achiral environments, they cannot be separated by conventional physical methods such as simple crystallisation, distillation, or extraction. The resolution of racemic coordination compounds into their constituent enantiomers requires the use of chiral (optically active) resolving agents. The classical resolution method for coordination compound enantiomers typically proceeds as: (1) React the racemic mixture (containing equal amounts of Delta and Lambda enantiomers) with a chiral ion or molecule to form two diastereomeric salts — for example, a cationic complex like [Co(en)3]3+ can be precipitated with a chiral anion such as d-tartrate, forming both [Delta-Co(en)3](d-tartrate) and [Lambda-Co(en)3](d-tartrate), which are diastereomers with different physical properties. (2) Separate the diastereomers by fractional crystallisation (exploiting their different solubilities) or by chromatography on a chiral stationary phase. (3) Remove the resolving agent (by metathesis or other means) to obtain the pure enantiomers of the original complex. The key principle is that an achiral resolving agent interacts identically with both enantiomers — the activation energies for its reactions with Delta and Lambda forms are equal, the resulting products have identical properties, and no separation is possible.

Both geometrical (cis-trans) isomerism and optical isomerism are types of stereoisomerism in coordination compounds, but they arise from different structural features and have different consequences. Geometrical isomerism arises when ligands can be arranged in different spatial arrangements around the metal centre: in square planar complexes, a complex of formula [MA2B2] can have cis isomers (like groups adjacent) and trans isomers (like groups opposite). In octahedral complexes, [MA4B2] can have cis (B groups on the same side) and trans (B groups diametrically opposite) isomers. Geometrical isomers always have different physical and chemical properties (different colours, melting points, dipole moments, solubilities, and often different biological activities). Optical isomerism arises when a complex is chiral — when it and its mirror image are non-superimposable. For octahedral complexes, optical isomerism is found in M(AA)3 complexes and cis-M(AA)2B2 complexes, but not in trans-M(AA)2B2 complexes which have a plane of symmetry. A crucial connection: cis-[Co(en)2Cl2]+ shows BOTH geometrical (it is one specific geometric isomer) and optical isomerism (the cis form has no plane of symmetry and exists as Delta and Lambda enantiomers), while trans-[Co(en)2Cl2]+ is the other geometric isomer which is optically INACTIVE (it has a plane of symmetry perpendicular to the C2 axis).

The formation of chelate rings (rings formed when a polydentate ligand coordinates through multiple donor atoms to the same metal ion) greatly enhances the thermodynamic stability of coordination complexes compared to complexes with the same number of monodentate ligands — a phenomenon known as the chelate effect. For example, [Ni(en)3]2+ (three bidentate ethylenediamine ligands) has a much larger formation constant (Kf ~ 10^18) than [Ni(NH3)6]2+ (six monodentate ammonia ligands, Kf ~ 10^8), despite both having six nitrogen donors coordinated to nickel(II). The chelate effect arises primarily from entropy: when a chelating ligand replaces monodentate ligands, the number of free molecules in solution increases (one en displacing two NH3 molecules releases one particle to solution, increasing disorder and therefore entropy), making the reaction thermodynamically more favourable. The stability of chelates also has a ring size dependence: five-membered chelate rings (as in ethylenediamine, glycinate, oxalate) and six-membered rings are most stable; three, four, seven, and larger rings are progressively less stable. EDTA (ethylenediaminetetraacetic acid) forms extremely stable 1:1 complexes with most metal ions because it is hexadentate, forming five five-membered chelate rings simultaneously and releasing a very large number of water molecules upon coordination.

The colour of coordination compounds — one of their most striking and familiar properties — can be explained by crystal field theory (CFT), which treats the ligands as point charges that split the d-orbitals of the central metal into groups of different energy. In an octahedral complex, the five d-orbitals split into two sets: the higher energy eg set (dx2-y2 and dz2, pointing directly at ligands, strongly repelled) and the lower energy t2g set (dxy, dyz, dxz, pointing between ligands, less repelled). The energy gap between these sets is called the crystal field splitting energy, delta_o. When white light strikes a coordination compound, frequencies of light with energy corresponding to delta_o are absorbed to promote electrons from the t2g to the eg level; the complementary frequencies are transmitted or reflected, giving the compound its characteristic colour. The colour observed is the complement of the colour absorbed. For example, [Ti(H2O)6]3+ absorbs green-yellow light (~500 nm) and appears violet-purple (the complement). The magnitude of delta_o depends on the nature of the ligands (measured by the spectrochemical series: I- < Br- < Cl- < F- < OH- < H2O < NH3 < en < CN- < CO) and the nature of the metal (higher oxidation state = larger delta_o; 4d and 5d metals have larger delta_o than 3d metals). High-spin (weak field ligands, small delta_o) and low-spin (strong field ligands, large delta_o) complexes have different numbers of unpaired electrons, different colours, and different magnetic properties.