Toward Two-Dimensional Metallic Topologies in Atomically Precise Nanoclusters.

While topology-property relationships are well established in covalent two-dimensional (2D) materials, their extension to metallic systems is hindered by the nondirectional nature of metallic bonding and an intrinsic tendency toward three-dimensional (3D) close-packed structures. Herein, we develop a Hub-Driven Ring Fusion (HDRF) strategy for constructing extended metallic topologies beyond discrete motifs. Guided by this strategy, we synthesize an atomically precise Pd11 nanocluster featuring a rare fused tri-pentagonal metal-ring network. Magnetic shielding and nucleus-independent chemical shift (NICS) analyses reveal pronounced spatial anisotropy and discontinuous shielding distributions, indicating a breakdown of global electronic coherence and the formation of partitioned electronic domains across fused rings. These "topology-induced electronic domains" connectivity-governed electronic fragmentation, rather than uniform delocalization, defines the intrinsic electronic landscape of the cluster and clarifies that it is not merely a simple size expansion of Pd5. Pd11 exhibits significantly enhanced performance in the electrocatalytic hydrogenation of nitrobenzene, achieving 98.1% conversion, 97.4% aniline yield, and 99.3% selectivity, outperforming Pd5 and Pd8 clusters. Density functional theory (DFT) calculations further demonstrate that the fused tri-pentagonal topology optimizes electron distribution, enhances interfacial reactivity, and lowers the overall reaction barrier, providing a mechanistic basis for the observed catalytic enhancement.