Probing isotope shifts in 103Rh and 195Pt NMR spectra with DFT
نویسندگان
چکیده
Zero-point vibrationally averaged (rg 0 ) structures were computed at the PBE0/SDD/631G* level for the [Pt 35 Cln 37 Cl5-n(H2 18 O)] (n=0-5), cis-Pt 35 Cln 37 Cl(4-n)(H2 18 O)(H2 16 O) (n=0-4), fac-[Pt 35 Cln 37 Cl(3-n)(H2 18 O)(H2 16 O)2] (n=0-3), [Pt 35 Cln 37 Cl5-n( 16/18 OH)] 2 (n=0-5), cis-[Pt 35 Cln 37 Cl(4-n)( 16/18 OH)2] 2(n=0-4), fac-[Pt 35 Cln 37 Cl(3-n)( 16/18 OH)3] (n=0-3), cis-[Pt 35 Cln 37 Cl2-n( 16/18 OH)4] 2 (n=0-2) and [Pt 35 Cln 37 Cl1-n( 16/18 OH)5] 2 (n=01), [Rh 35 Cln 37 Cl5-n(H2O)] 2 (n=0-5), cis-[Rh 35 Cln 37 Cl(4-n)(H2O)2] (n=0-4), and fac-Rh 35 Cln 37 Cl(3-n)(H2O)3 (n=0-3) isotopologues and isotopomers. Magnetic shielding constants, computed at the ZORA-SO/PW91/QZ4P/TZ2P level, were used to evaluate the corresponding 35/37 Cl isotope shifts on the 195 Pt and 103 Rh NMR spectra, which are known experimentally. While the observed effects are reproduced reasonably well computationally in terms of qualitative trends and the overall order of magnitude (ca. 1 ppm), quantitative agreement with experiment is not yet achieved. Only small changes in M-Cl and M-O bonds upon isotopic substitution, on the order of femtometers, are necessary to produce the observed isotope shifts. a University of St. Andrews; Fax: (+44)(0)1334 463808, E-mail: [email protected] b Stellenbosch University; Fax: (+27)(0) 808 3342, E-mail: [email protected]
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