Carbon-13 nuclear magnetic resonance evidence of a relaxation process dominated by scalar coupling with a quadrupolar nucleus in [Re3(µ-H)4(CO)10]–

Abstract

Carbon-13 n.m.r. spin–lattice relaxation times of the anion [Re₃(µ-H)₄(CO)₁₀]^– have been determined at various temperatures and field strengths in order to elucidate the different components of the relaxation mechanism. Scalar coupling with the quadrupolar Re isotopes (¹⁸⁵Re, ¹⁸⁷Re; I=5//₂) proved to be the main relaxation pathway at room temperature in the range 20–68 MHz. Analysis of the data allowed the estimation of the quadrupolar relaxation time of Re and of the coupling constant ¹J(¹⁸⁷Re–C). The latter has been determined for the first time.