Chemical shifts of NMR lines appear with the joint interaction of the nuclei with electrons and the electrons with the external constant magnetic field. General theory of chemical shifts was developed by Ramsey [1] and in a slightly different form than in [2] was proposed by Slichter [2]. The autor calculated initially the currents, that appeared in the molecule at a constant magnetic field, which were created by these currents in the positions where the nuclei were located. In this paper the contribution of the electrons, which are in the triplet excited spin state, in the chemical shift of the NMR lines has bin considered. Such situation is realized particularly in the magnetic dimmer clusters formed by two identical ions with the spins S1 = S2 = 1/2. In this case, the electron ground state corresponds to spin singlet, the first excited level is a spin triplet and the singlet-triplet splitting for different magnetic dimmers is about of several hundred inverse centimeters (for example for monohydrate copper acetate Δst = (310 ± 15) cm-1 [3]. In the presence of such dimmers, the electrons in the excited triplet spin state will create local magnetic fields in the places of the nuclei location, the intensity of which, together with it and the chemical shift, will increase in magnitude with increasing of the temperature. This effect is the expected one which was observed in our laboratory experimentally.figureFig 1. Temperature shifts of 1H NMR lines for tert-butil alcohol (a), and tert-Butanol in the 0,1M aqua solution of MCA(b) (a,b: 1,2,3,4,5,6-20,30,40,50,60,70 oC).figureFig 2. Temperature dependence of 1H NMR line chemical shift due to triplet spin states of dimmer clusters.The Fig.1a shows the temperature dependence of the proton NMR spectrum of tert-Butanol adopted as a standard. Fig. 1b shows the temperature shift of the NMR line of the standard protons in the presence of monohydrate copper acetate (MCA). Temperature dependence of the shift of 1H NMR line for system standart + 0,1M aqua solution of MCA with respect to standard is presented in Fig. 2. The NMR method for estimation of the magnetic dimmers stability in coordination compounds in solution and determination of their concentration has been proposed.