The polynucleating bridging ligands L(1) and H(3)L(2) were simply prepared via a Heck coupling of 4-vinylpyridine or 4-methoxystyrene with 1,3,5-tribromobenzene; in the trinuclear complexes of L(1) and L(2) with a paramagnetic (Mo(NO)(BH(C(3)HN(2)Me(2)-3,5)(3))Cl) moiety [BH(C(3)HN(2)Me(2)-3,5)(3) = tris(3,5-dimethylpyrazol-1-yl) hydroborate] at each binding site the EPR spectra demonstrate that all three unpaired electrons are in 'fast exchange' between all three metal centres