Counterion influence on dynamic spin properties in a V(iv) complex.

摘要: Using transition metal ions for spin-based applications, such as electron paramagnetic resonance imaging (EPRI) or quantum computation, requires a clear understanding of how local chemistry influences spin properties. Herein we report series four ionic complexes to provide the first systematic study one aspect on V(IV) – counterion. To do so, (Et3NH)2[V(C6H4O2)3] (1), (n-Bu3NH)2[V(C6H4O2)3] (2), (n-Hex3NH)2[V(C6H4O2)3] (3), and (n-Oct3NH)2[V(C6H4O2)3] (4) were probed by EPR spectroscopy in solid state solution. Room temperature, solution X-band (ca. 9.8 GHz) continuous-wave (CW-EPR) revealed an increasing linewidth with larger cations, likely counterion-controlled tumbling via ion pairing. In state, variable-temperature (5–180 K) 9.4 pulsed studies 1–4 o-terphenyl glass demonstrated no effect spin–lattice relaxation times (T1), indicating little role counterion this parameter. However, phase memory time (Tm) 1 below 100 K is markedly smaller than those 2–4. This result counterintuitive, 2–4 are relatively richer 1H nuclear spin, hence, expected have shorter Tm. Thus, these data suggest important methyl groups Tm, moreover instance lengthening Tm quantity molecule.