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Precise estimation of Sea Surface Salinity (SSS) is of prime importance to know marine physical and biochemical processes. In this manuscript we have utilized the Random Forest (RF) and Support Vector Regression (SVR) to estimate the SSS concentration. Particularly, we have utilized the global SSS values provided by the Copernicus Marine Services. We have also extracted the Aqua MODIS and Sentinel-3 data from the Google Earth Engine platform. The complete range of SSS varies approximately from 6 psu to 38 psu which enables the global application of the dataset. We have also studied the importance of different wavelength bands and their significance to SSS using the RF model. It is found that wavelengths around 400 nm have their highest significance due to the sensitiveness to Chromophoric Dissolved Organic Matter (CDOM) and other related constituents. For the regression analysis we have also utilized the Laplacian kernel in the SVR. It is found that the SVR with Laplace kernel outperforms the RF and SVR with Radial Basis Function (RBF) kernel. The trained algorithms are used to estimate the SSS content over the Bay of Bengal and the Arabian Sea regions which show interesting variations in SSS content due to diverse climatological conditions. [ABSTRACT FROM AUTHOR]

Quantum-chemical calculations have been performed to evaluate the geometries, bonding nature and harmonic frequencies of the compounds [EUX3] at DFT, DFT-D3, DFT-D3(BJ) and DFT-dDSc levels using different density functionals BP86, BLYP, PBE, revPBE, PW91, TPSS and M06-L. The stretching frequency of UN bond in [NUF3] calculated with DFT/BLYP closely resembles with the experimental value. The performance of different density functionals for accurate UN vibrational frequencies follows the order BLYP>revPBE>BP86>PW91>TPSS>PBE>M06-L. The BLYP functional gives accurate value of the UE bond distances. The uranium atom in the studied compounds [EUX3] is positively charged. Upon going from [EUF3] to [EUCl3], the partial Hirshfeld charge on uranium atom decreases because of the lower electronegativity of chlorine compared to flourine. The Gopinathan-Jug bond order for UE bonds ranges from 2.90 to 3.29. The UE bond dissociation energies vary with different density functionals as M06-L

Electronic, molecular structure and bonding energy analyses of the metal-aminosilylyne, -aminogermylyne,-aminostannylyne and -aminoplumbylyne complexes [(η5-C5H5)(CO)2M≡N(SiMe3)(Ph)] (M = Mo, W) and [(η5-C5H5)(CO)2Mo≡GeN(SiMe3)(Mes)] have been investigated at DFT, DFT-D3 and DFT-D3(BJ) levels using BP86, PBE, PW91, RPBE, TPSS and M06-L functionals. The performance of metaGGA functionals for the geometries of aminoylyne complexes is better than GGA functionals. Significant dispersion interactions between O···H, E···C(O) and E···H pairs appeared in the dispersion-corrected geometries. The non-covalent distances of these interactions follow the order DFT > DFT-D3(BJ) > DFT-D3. The values of Nalewajski-Mrozek bond order (1.22-1.52) and Pauling bond order (2.23-2.59) of the optimized structures at BP86/TZ2P indicate the presence of multiple bonds between metal and E atoms. The overall electronic charges transfer from transition-metal fragments to ligands. The topological analysis based on QTAIM has been performed to determine the analogy of non-covalent interactions. The strength of M≡N(SiMe3)(R) bonds has been evaluated by energy decomposition analysis. The electrostatic interactions are almost equal to orbital interactions. The M ← E σ-donation is smaller than the M → E π-back donation. Upon going from E = Si to E = Pb, the M-E bond orders decrease as Si > Ge > Sn > Pb, consistent with the observed geometry trends. The M-E uncorrected bond dissociation energies vary with the density functionals as RPBE < BP86 < PBE < TPSS < PW91. The largest DFT-D3 dispersion corrections to the BDEs correspond to the BP86 functional, ranging between 5.6-8.1 kcal mol-1, which are smaller than the DFT-D3(BJ) dispersion corrections (10.1-12.0 kcal mol-1). The aryl substituents on nitrogen have an insignificant effect on M-E-N bending. The bending of the M-E-N bond angle has been discussed in terms of Jahn-Teller distortion. The larger noncovalent interaction and smaller absolute values of ΔE (HOMO-LUMO) with the M06-L functional are responsible for lowering the M-E-N bond angle. [ABSTRACT FROM AUTHOR]

Geometry and bonding energy analysis of M-S2O bonds in the metal-disulfur monoxide complexes [(PMe3)2 M(S2O)] of nickel, palladium, and platinum were investigated at DFT, DFT-D3, and DFT-D3(BJ) methods using three different functionals (BP86, PBE, and TPSS). The TPSS/DFT-D3(BJ) yields better geometry, while the BP86 geometry is least accurate for studied complexes. The geometry of platinum complex optimized at TPSS/DFT-D3(BJ) level is in excellent agreement with the available experimental values. The M-S bonds are shorter than the M-S(O) bonds. The Mayer bond orders suggest the presence of M-S and M-S(O) single bonds. Both the M-S and M-S(O) bond lengths vary with the density functionals as TPSS-D3(BJ) < TPSS < PBE < BP86. The Hirshfeld charge distribution indicates that the overall charge flows from metal fragment to [S2O]. The Ni-S2O bond has greater degree of covalent character than the ionic. The contribution of dispersion interactions is large in computing accurate bond dissociation energies between the interacting fragments. The BDEs are largest for the functional TPSS and smallest for the functional BP86. The DFT-D3 dispersion corrections to the BDEs between the metal fragments [(PMe3)2 M] and ligand fragment [(S2O)] for the TPSS functional are in the range 7.1-7.3 kcal ·mol-1, which are smaller than the corresponding DFT-D3(BJ) dispersion corrections (9.4-10.6 kcal ·mol-1). [ABSTRACT FROM AUTHOR]

Abstract: Structure and bonding analyses of the complexes [(PNP)Ir(NX)]+ (X=O, S, Se; PNP=N(CHCHPMe2)2) were investigated at the DFT, DFT-D3 and DFT-D3(BJ) levels using BP86, BLYP, PBE, revPBE and TPSS functionals. The Ir–NX bond in the thionitrosyl complex is longer than that in the nitrosyl and selenonitrosyl complexes, which is consistent with the observed trend for their experimental values. The Ir–NX bond has essentially Ir NX double bond character, which supports the σ-donor and π-acceptor abilities of the [NX]+ ligands. The non-covalent P–NX distances decrease in the order DFT>DFT-D3>DFT-D3(BJ). The Ir–NX bond has a larger covalent character (85.7, 75.9 and 74.6%). Dispersion interactions between the metal and [NX]+ fragments are in the range 3.2–5.5kcal/mol (BP86), 3.2–5.4kcal/mol (BLYP), 1.9–3.1kcal/mol (PBE), 3.5–5.5kcal/mol (revPBE) and 2.6–3.8kcal/mol (TPSS), which are smaller than the corresponding DFT-D3(BJ) dispersion corrections 4.9–8.6kcal/mol (BP86), 5.2–7.9kcal/mol (BLYP), 2.7–4.0kcal/mol (PBE), 5.3–7.6kcal/mol (revPBE) and 2.7–5.2kcal/mol (TPSS). The dispersion corrected DFT (DFT-D3 and DFT-D3(BJ)) methods provide quite an accurate estimate of the dispersion energy, which can be judged by the observation that the experimental and optimized Ir–NX bond distances are consistent with the most accurate dispersion corrected DFT-D3(BJ) bond dissociation energy of Ir–NX bonds. [Copyright &y& Elsevier]

Abstract: Quantum-chemical calculations were used to investigate the molecular and electronic structures as well as bonding energies of the molybdenum–ylidyne complexes trans-[X(PMe3)4MoX=F, Cl, Br, I; E=Si, Ge, Sn, Pb) at the BP86/TZ2P/ZORA level of theory. The calculated geometrical results are in excellent agreement with the available experimental results. The Mostances are significantly short, and the calculated Pauling Mo–E bond orders are ∼2.40–2.65. The electronic structures of the Mohow the presence of genuine triple bond containing an σ-bond and two π-bonds in all studied complexes. The Mo-bonds are polarized towards the heavier group 14 elements while the π-bonds are polarized towards the molybdenum metal. The partial charges on the [EMes]+ fragments (0.67–0.93) indicate that the overall charges flow from the metal fragments to the [EMes]+ fragments. The nature of Molso investigated by means of energy decomposition analysis which reveals that the metal–ligand π-orbital interactions between [X(PMe3)4Mo]− and [EMes]+ fragments are the most dominant interactions, contributing (80–85%) to the total ΔE orb terms. The strength of Moainly depends on the π-acceptor ability of [EMes]+ group. It decreases when 14 group element becomes heavier in the trend Si>Ge>Sn>Pb and in the order F>Cl>Br>I. [Copyright &y& Elsevier]

Abstract: The electronic structures and bond dissociation energies of the hydrido- transition metal–ylidyne complexes trans-[H(PMe3)4 M≡ER] (M = Mo, W; E = Si, Ge, Sn, Pb; R = Mes, Xylyl) have been investigated using density functional theory at BP86/TZ2P/ZORA level. The calculated geometries are in excellent agreement with available experimental values. Pauling bond order shows that the M-E bonds in these complexes are nearly M≡E multiple bonds. The EDA results indicate that the absolute values of ∆E int., ∆E elstat, ∆E orb, ∆E Pauli and bond dissociation energies decrease in the order Si > Ge > Sn > Pb, and tungsten complexes have stronger bonding than the molybdenum complexes. The contribution of electrostatic interaction ∆E elstat to the M–ER bonding is comparable to, or in some cases even slightly larger than the covalent bonding ∆E orb. The σ-bonding interactions are significantly poor (less than 20%) and [H(PMe3)4 M]− → ER+ π back-donation is dominant interaction in the studied metal–ylidyne complexes. The WBI values of the M-E bonds are significantly large (1.78–2.06). The NBO analysis indicates that the σ-bonding and both π-bonding orbitals are well occupied (>1.703e). The M-E σ-bonding orbitals are slightly polarized towards the heavier group 14 element while the π-bonding orbitals are highly polarized towards the metal atom. [Copyright &y& Elsevier]

Abstract: Density functional theory (DFT) calculations have been performed to investigate the nature of the M–Bi bonds in dihalobismuth complexes of iron, ruthenium and osmium, [(η5-C5H5)(CO)2M(BiX2)] (M=Fe, Ru, Os; X=Cl, Br, I) and [(η5-C5H5)(PMe3)2Fe(BiX2)] (X=Cl, Br, I), at the BP86/TZ2P/ZORA level of theory. Pauling and Mayer bond orders of the optimized structures show that the M-Bi bonds in these complexes are nearly M–Bi single bonds. The π bonding contribution is, in all complexes, significantly smaller than the corresponding σ bonding contribution, representing only 5–14% of the total orbital interaction. Thus, in these complexes, [BiX2] behaves predominantly as σ donor. The values of the Mayer bond order of the M–Bi bonds in dihalobismuth complexes suggest a significant covalent contribution to the M–Bi bonds. These observations are supported by the greater contributions of the covalent interaction energy ΔE orb than the electrostatic interactions ΔE elstat in all the dihalobismuth complexes. The absolute values of the ΔE int, ΔE orb and ΔE elstat contributions to the M–Bi bonds decrease according to X=Cl>Br>I, while the values of these energy terms increases in all four sets of complexes in the order Fe

Abstract: Density Functional Theory calculations have been performed for the halophenylgallyl complexes of iron, ruthenium and osmium [(η5-C5H5)(CO)2M(Ga(X)Ph)] (M=Fe, Ru, Os; X=Cl, Br, I) at the DFT/BP86/TZ2P/ZORA level of theory. The calculated geometry of iron complexes [(η5-C5H5)(CO)2Fe(Ga(Cl)Ph)] and [(η5-C5H5)(CO)2Fe(Ga(I)Ph)] is in excellent agreement with structurally characterized complexes [(η5-C5H5)(CO)2Fe(Ga(Mes∗)Cl)], [(η5-C5Me5)(CO)2Fe(Ga(Mes∗)Cl)] and [(η5-C5Me5)(CO)2Fe(Ga(Mes)I)] (Mes=C6H2Me3-2,4,6; Mes∗ =C6H2 tBu3-2,4,6). The M–Ga bond distances as well as Mayer bond order of the M–Ga bonds suggest that the M–Ga bonds in these complexes are nearly M–Ga single bond. The π-bonding component of the total orbital contribution is significantly smaller than that of σ-bonding. Thus, in these complexes the Ga(X)Ph ligand behaves predominantly as a σ-donor. The contributions of the electrostatic interaction terms ΔE elstat are significantly smaller in all gallyl complexes than the covalent bonding ΔE orb term. The absolute values of the ΔE Pauli, ΔE int and ΔE elstat contributions to the M–Ga bonds increase in both sets of complexes via the order Fe

The molecular and electronic structures and bonding analysis of terminal cationic metal-ylyne complexes (MeCN)(PMe3)4M≡EMes]+ (M = Mo, W; E = Si, Ge, Sn, Pb) were investigated using DFT/BP86/TZ2P/ZORA level of theory. The calculated geometrical parameters for the model complexes are in good agreement with the reported experimental values. The M-E σ-bonding orbitals are slightly polarized toward E except in the complex [(MeCN)(PMe3)4W(SnMes)]+, where the M-E σ-bonding orbital is slightly polarized toward the W atom. The M-E π-bonding orbitals are highly polarized toward the metal atom. In all complexes, the π-bonding contribution to the total M≡EMes bond is greater than that of the σ-bonding contribution and increases upon going from M = Mo to W. The values of orbital interaction ΔEorb are significantly larger in all studied complexes I-VIII than the electrostatic interaction ΔEelstat. The absolute values of the interaction energy, as well as the bond dissociation energy, decrease in the order Si > Ge > Sn > Pb, and the tungsten complexes have stronger bonding than the molybdenum complexes. [ABSTRACT FROM AUTHOR]

Geometry, electronic structure, and bonding analysis of the terminal neutral dihalogallyl complexes of nickel, palladium, arid platinum trans-[X(PMe3)2M(GaX2)] (M = Ni, Pd, Pt; X = Cl, Br, l) were investigated at the BP86 level of theory. The calculated geometries of platinum gallyl complexes trans-[X(PMe3)2Pt(GaX2)] (X = Br, I) are in excellent agreement with structurally characterized platinum complexes trans-[X(PCy3)2M(GaX2)]. In the gallyl complexes of nickel and palladium, the M-Ga σ bonding orbital is slightly polarized toward the gallium atom, while in the platinum gallyl complexes, the M-Ga σ bonding orbital is slightly polarized toward the platinum atom. It is significant to note that gallium atoms along the M-Ga σ bonds have large p character, which is always >51% of the total AG contributions, while along the Ga-X σ bonds, the p character varies from 72% 1073%. The short M-Ga bond distances, in spite of the significantly small M-Ga π bonding, are due to the large s character of gallium (∼45-48%) along the M-Ga bonds. The calculated NPA charge distributions indicate that the metal atom carries negative charge and the Ga atom carries significantly large positive charge. The contributions of the electrostatic interaction terms, ΔEelstat, are significantly larger in all gallyl complexes than the covalent bonding ΔEorb term. Thus, the [M]-GaX2 bond in the studied gallyl complexes of Ni, Pd, and Pt has a greater degree of ionic character (65.7-72.5%). The π-bonding contribution is, in all complexes, significantly smaller than the σ bonding contribution. In the GaX2 ligands, gallium dominantly behaves as a σdonor. The interaction energy increases in all three sets of complexes via order of Ni

Abstract: Geometry and bond energy analysis of M–P bonds in the terminal phosphinidene complexes of manganese and rhenium [(CO)5M–PNR2]+ (R = Me, i Pr, t Bu) and [(PMe3)(CO)4M–PN i Pr2]+ were investigated at the DFT, DFT-D3 and DFT-D3(BJ) methods using functionals (BP86, revPBE, PW91 and TPSS). In all studied complexes, the π-bonding contributions to the total M–P bonds are significantly smaller (12.4–16.0%) than the σ-bonding components. The phosphinidene (PNR2) ligands are predominantly σ-donors. The electrostatic interaction ΔE elstat, in all complexes I–VIII, are larger than the orbital energies ΔE orb, which means, the M–PNR2 bonds in these complexes have greater degree of ionic characters (more than 50%). The DFT-D3 method provide quite accurate estimate of the dispersion energy for the studied complexes. The contribution of dispersion interactions is large in computing accurate bond dissociation energies between the interacting fragments. The BDEs are largest for the functional PW91 and smallest for the functional revPBE. The dispersion corrections are in the range 6.4–11.1 kcal/mol (BP86), 7.2–8.6 kcal/mol (revPBE) and 5.7–8.6 kcal/mol (TPSS), which are smaller than the corresponding DFT-D3(BJ) dispersion corrections 7.6–11.8 kcal/mol (BP86), 8.7–12.8 kcal/mol (revPBE) and 5.8–9.0 kcal/mol (TPSS). The dispersion corrections calculated by DFT-D3 scheme increase on going from M = Mn to M = Re and smallest for the complexes [(PMe3)(CO)4M(PN i Pr2)]+. [Copyright &y& Elsevier]

Density functional theory (DFT) calculations have been performed on the terminal dihalogallyl complexes of iron, ruthenium, and osmium (η(5)-C(5)H(5))(Me(3)P)(2)M(GaX(2)) (M = Fe, Ru, Os; X = Cl, Br, I) and (η(5)-C(5)H(5))(OC)(2)Fe(GaX(2)) (X = Cl, Br, I) at the BP86/TZ2P/ZORA level of theory. On the basis of analyses suggested by Pauling, the M-Ga bonds in all of the dihalogallyl complexes are shorter than M-Ga single bonds; moreover, on going from X = Cl to X = I, the optimized M-Ga bond distances are found to increase. From the perspective of covalent bonding, however, π-symmetry contributions are, in all complexes, significantly smaller than the corresponding σ-bonding contribution, representing only 4-10% of the total orbital interaction. Thus, in these GaX(2) complexes, the gallyl ligand behaves predominantly as a σ donor, and the short M-Ga bond lengths can be attributed to high gallium s-orbital character in the M-Ga σ-bonding orbitals. The natural population analysis (NPA) charge distributions indicate that the group 8 metal atom carries a negative charge (from -1.38 to -1.62) and the gallium atom carries a significant positive charge in all cases (from +0.76 to +1.18). Moreover, the contributions of the electrostatic interaction terms (ΔE(elstat)) are significantly larger in all gallyl complexes than the covalent bonding term (ΔE(orb)); thus, the M-Ga bonds have predominantly ionic character (60-72%). The magnitude of the charge separation is greatest for dichlorogallyl complexes (compared to the corresponding GaBr(2) and GaI(2) systems), leading to a larger attractive ΔE(elstat) term and to M-Ga bonds that are stronger and marginally shorter than in the dibromo and diiodo analogues.