Discovery of a Missing Link: Detection and Structure of the Elusive Disilicon Carbide Cluster.

The rotational spectrum of the elusive but fundamentally important silicon carbide SiCSi has been detected using sensitive microwave techniques aided by high-level ab initio methods. Its equilibrium structure has been determined to very high precision using isotopic substitution and vibrational corrections calculated quantum-chemically: it is an isosceles triangle with a Si-C bond length of 1.693(1) Å, and an apex angle of 114.87(5)°. Now that all four Si(m)C(n) clusters with m + n = 3 have been observed experimentally, their structure and chemical bonding can be rigorously compared. Because Si2C is so closely linked to other Si-bearing molecules that have been detected in the evolved carbon star IRC+10216, it is an extremely promising candidate for detection with radio telescopes.