1 Regions of Organic Proton Shifts 2 Shoolery Chemical Shift Rules 3 • The different effects on chemical shifts have been tabulated. • Most of the effects are additive, meaning that if we can estimate the different effects on the chemical shift from different groups and bonds, we can estimate chemical shift by adding all the effects together. • There are several empirical rules, derived mostly by Shoolery in the late 50s/early 60s. • In order to use them, we first have to identify the type of proton we have, such as aliphatic CH3, CH2, CH, olefinic CH2 or CH, aromatic, α or β to a ketone or alcohol, belonging to an a α,β-unsaturated system, etc. They will have a base value. • Then we look up the contributions from different groups attached to carbons in the surrounding of our system, and add them up to obtain the estimated chemical shift. 4 1H NMR Chemical Shift Increments  = 0.23 + Si () CH3Cl (calc) = 2.76 (exp) = 3.1 CH2Cl2 (calc) = 5.29 (exp) = 5.3 CHCl3 (calc) = 7.82 (exp) = 7.27 Aliphatic compounds Methane (1H) = 0.23 ppm Shoolery chemical shift rules 5 1H NMR Chemical Shift Increments Aromatic compounds Benzene (1H) = 7.27 ppm  = 7.27 + Si () X o m p 6 1H NMR Chemical Shift Increments  = 5.28 + Si () Olefinic compounds Ethylene (1H) = 5.28 ppm H RGEM RCIS RTRANS 7 Regions of Inorganic Proton Shifts Organometallic hydrides Highly shielded 5 to 60 ppm [H-Rh(CN)5]3 10.6 ppm multiplet? unpaired electrons ? H M M M M M M Highly deshielded [HRu6(CO)18] 16.4 ppm [HCo6(CO)15] 23.2 ppm 8 1H NMR of Boranes 1 10 5 6 8 7 2 3 4 9 HH H H nido-Decaborane(14) bridging B2H 2.12 ppm terminal BH (2,4) 0.62 (5,7,8,10) 3.13 (1,3) 3.63 (6,9) 3.90 9 1H NMR Organometallic Hydrides unpaired electrons ? 10 1H NMR of Paramagnetic Compounds 1H NMR spectra of Fe(acac)3 CH3 CH 11 Regions of Organic Carbon Shifts 12 13 13C NMR Chemical Shift Increments X ipso o m p (13C) = 128.5 ppm +/- substituent X increments for each carbon (ipso, o, m, p) 14 Regions of 31P NMR Shifts 15 Regions of 19F NMR Shifts 16 Regions of 77Se NMR Shifts 17 Regions of 29Si NMR Shifts SiO6 200 ppm 18 Silicate Anions in Aqueous Alkaline Media Detected by 29Si-NMR M = OSiR3 D = O2SiR2 T = O3SiR Q = O4Si Q0 = O4Si Q1 = O3SiOSi Q2 = O2Si(OSi)2 Q3 = OSi(OSi)3 Q4 = Si(OSi)4 19 Regions of 17O MAS NMR H2 17O 20 Linear Correlations of the NMR Parameters with the Number of Arene Methyls Is diamagnetic or paramagnetic shielding affected? B. Stibr, M. Bakardjiev, J. Holub, A. Ruzicka, Z. Padelkova, P. Stepnicka Inorg. Chem. 2011, 50, 3097–3102 B12 H12 n = number of arene methyls 21 Octahedral Metal Clusters How many derivatives and isomers for 2 different L ?????????????? Song Jin, Jennifer Adamchuk, Bosong Xiang, and Francis J. DiSalvo* J. AM. CHEM. SOC. 2002, 124, 9229-9240 22 NMR Identification of the Clusters W6S8LnL'6-n For 2 different L, L´ there are 10 complexes How many signals in 31P NMR if L´ = PR3 ??? 23 NMR Identification of the Clusters Series of 200 complexes 12 Signals in 31P NMR 24 NMR Identification of the Clusters P-W-W-P coupling through the cluster core in the 31P{1H} NMR spectra W6S8(PR3)n(L)6-n 25 NMR Identification of the Clusters 183W (I=1/2) the satellite peaks flanking the main P peaks W6S8(PR3)n(L)6-n 26 NMR Identification of the Clusters Dean-Evans relation a two-parameter linear relation W6S8(PR3)n(L)6-n 27 NMR Identification of the Clusters Dean-Evans relation = a two-parameter linear relation (31P) =  ref + pC + qT  ref two variables (p and q, the number of ligands L in the cis or trans position to PR3, respectively) two constants (C and T, characteristic of a given ligand L) 28 NMR Identification of the Clusters Dean-Evans relation = a two-parameter linear relation (31P) =  ref + pC + qT