IOSR Journal of Applied Chemistry (IOSR-JAC) e-ISSN: 2278-5736.Volume 13, Issue 6 Ser. I (June. 2020), PP 48-54 www.iosrjournals.org DOI: 10.9790/5736-1306014854 www.iosrjournals.org 48 |Page Quantitative Study of Racah Parameter of Manganese Ions in Co- ordination Compounds Deepak Kumar 1 and R.P. S. Chauhan 1,* 1 (PG Department of Chemistry, Magadh University, Bodh Gaya, Bihar 824234) Abstract: The origin of the spectrochemical series and the diff erent dependence of crystal-field splitting (10Dq) and Racah parameters on the metal-ligand distanceis explored through rigorous calculations on Manganese Complexes.For this purpose, both periodic and cluster calculations have been performed. Background: The importance of the transition metal complexes formed has significance in all areas of science due to its particular properties. The transition metal complexes are widely involved in active centers of proteins, catalysts, molecular electronics, electroluminescent devices, solid-state lasers, gemstones, high-pressure manometers.The spectrochemical series discuss many parameters very clearly. Such as it shows that monoatomic ionic ligands usually cause a poor perturbation in respect to polyatomic molecules or ions. The other series of ligands is ‘Nephelauxetic series’ which expresses the covalent tendency of ligands with respect to bond formation with the central metal ion. The magnitude of Nephelauxetic effect is expressed as the nephelauxetic ratio, (β = B’/B, which is given by the ratio of a given inter electronic repulsion parameter, i.e., Racah parameter value for metal ion in the complex (B’) to its value in the gaseous ion (B). The current study gives a nice overview of the Racah parameters of An octahedral MX6q- complex involves a central cation, M, and halide ligands, X (X = Cl, 2,4,5-trimethoxybenzaldehyde-S-benzyl dithiocarbazone (BBTC), NO3, CH3COO-) by exploring the metal-ligand distance through rigorous calculations on Manganese Complexes. Materials and Methods: An octahedral MX6q- complex involves a central cation, M, and halide ligands, X (X = Cl, 2,4,5-trimethoxybenzaldehyde-S-benzyl dithiocarbazone (BBTC), NO3, CH3COO-).For this purpose, both periodic and cluster calculations have been performed. Results: The current study gives a nice overview of the Racah parameters of An octahedral MX6q- complex involves a central cation, M, and halide ligands, X (X = Cl, 2,4,5-trimethoxybenzaldehyde-S-benzyl dithiocarbazone (BBTC), NO 3 , CH 3 COO-) by exploring the metal-ligand distance through rigorous calculations on Manganese Complexes. The study shows that the Nephalauxetic effect (β) has been explored it is found that the manganese complexes [Mn(BBTC) 2 Cl 2 ], [Mn(BBTC) 2 (NO 3 ) 2 ], and [Mn(BBTC) 2 (CH3COO) 2 ] have Nephalauxetic effect of 6.66354, 4.5579, 7.06699. The calculation also shows that Racah parameters are 3.45413, 3.2802, 3.4273, respectively for all discussed complexes. Conclusion:The study shows that the Nephalauxetic effect (β) has been explored it is found that the manganese complexes [Mn(BBTC) 2 Cl 2 ], [Mn(BBTC) 2 (NO 3 ) 2 ], and [Mn(BBTC) 2 (CH3COO) 2 ] have Nephalauxetic effect of 6.66354, 4.5579, 7.06699. The calculation also shows that Racah parameters are 3.45413, 3.2802, 3.4273, respectively for all discussed complexes. Key Word: Racah Parameter; Manganese Ions; Co-ordination Compounds. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 21-06-2020 Date of Acceptance: 10-07-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction The importance of the transition metalcomplexes formed in all areas of science such as physics, chemistry, and biology due to its particular properties. The transition metal complexes are widely involved in active centers of proteins, catalysts, molecular electronics, molecular magnets, pigments,electroluminescent devices,solid-state lasers, gemstones,high-pressure manometers, and systems with ferroelectric distortions as well as giant magnetic anisotropy. The spectrochemical series discuss many parameters very clearly. Such as it shows that monoatomic ionic ligands usually cause a poor perturbation in respect to polyatomic molecules or ions. Secondly, the polarizability of ligand is also an important factor in creation of a weak or a strong field. Thirdly, the ability of the ligand toparticipate in "-bonding with certain metal ion seems to enhance its perturbing power.Although these reasons are very important, but it is, however true that 10Dq is a complex quantity having contribution from at least four sources purely electronic perturbationeffect of π-lone pairs belonging to the ligandseffect of metal-ligand dπ-dπ bonding andeffect of ligand-metal pπ-dπ bonding.