Bridging ligand, weak interaction

The binding properties of the t74 2-5H-benzocycloheptene ligand resembles that of t 4 CH-1,3-cycIoheptadiene ligand in 39n. In place of the C—H—Cr bridge, a weak interaction with C-10 and C-ll is recognized. A comparison of the Cr—C bond lengths of 40 with those of 38o shows a surprising similarity for the coordinated diene unit, and for C-5 in 38o with C-10 in 40. 

For compounds 3, 10 and 11 in which the Cu3(hedpH)2(H20)x double chains are separated either by ammonium cations or by long bridging ligands, antiferromagnetic interactions are also observed. This interaction however, is much weaker compared with that in compounds 1-2 because the copper(II) centers in 3,10 and 11 are purely linked by O-P-O bridges (Fig. lb). The weak antiferromagnetic exchange is evidenced by the lack of maximums in the Xm vs T curves down to 2 K. 

Layer-by-layer Ru3 cluster-based multilayers were fabricated onto preorganized self-assembled monolayer gold electrode surfaces by Abe et al. [15], in which [Ru3(q3-0)( i-0Ac)6(4,4/-bpy)2(C0)] was utilized as the synthetic precursor. The stepwise connection of oxo-centered triruthenium cluster units onto the gold electrode surface is a feasible approach for construction of Ru3 cluster-based oligomers on a solid surface, in which the bridging ligand 4,4 -bipyridine appears to mediate weak cluster-cluster electronic interaction between the Ru3 cluster centers. 

---