Templated Synthesis of Heterobimetallic Nd─Co Clusters

Abstract

ABSTRACT Heterometallic clusters are typically realized through the design of metal site‐specific coordination environments. Their unusual metal‐metal interactions and potentially synergistic effects toward small‐molecule activation and catalysis are two of the many attributes of fundamental importance. Synthetic heterometallic clusters containing f‐ and d‐block metals are challenging to design and synthesize, and lag far behind those only containing transition metals. To this end, we used compound LH 5 Nd ( 1 ), where LH 8 = cyclen(1,4,7,10‐tetra‐ o ‐NH 2 C 6 H 4 ) 4 , and subjected it to metalation with Co 2 (HMDS) 4 (HMDS = hexamethyldisilazide) resulting in LH 3 NdCo 2 (HMDS) 2 ( 2 ). Cluster 2 displays a Nd─Co distance of 3.276(12) Å, which is under the shortest distance previously reported for a Nd─Co interaction (3.294(4) Å). Exposing 2 to dry dioxygen results in a dimeric species containing a single oxygen atom in a pseudo‐planar geometry across two Nd and two Co atoms, (LH 3 ) 2 Nd 2 Co 2 (µ 4 ‐O) ( 5 ). The Nd─Co distance in 5 shortens significantly to 2.993(6) Å. X‐ray photoelectron spectroscopic studies reveal 5 to be best described as [Nd III 2 Co III 2 ], where the Co(III) centers remain high spin based on local structural metrics ( d avg (Co─N) = 2.02(4) Å and d avg (Co─O) = 1.920(2) Å). Overall, we report the design and synthesis of well‐defined heterobimetallic Nd─Co clusters and their metal‐metal interaction synergy to activate dioxygen.