Multiple Dimerization Modes in Thiocarboxylate Paddlewheel Complexes: A Comprehensive View of Energy Landscapes from DFT Calculations and Statistics

Thiocarboxylate paddlewheels (PWs) [MTr(SOCR) 4 L] (M = Pt, Pd; Tr = first‐row transition metal; L = Tr‐coordinated axial ligand) form a variety of dimeric structures via M···M' and M···S' contacts. We found that [PtVO(SOCPh) 4 ] ( 1 ), a molecular spin qubit, yields three crystalline toluene (tol) solvates, namely 1 ·0.875tol and two polymorphic 1 ·0.5tol phases. The crystals contain either staggered quasi‐coaxial dimers with short Pt···Pt' distances (3.17‐3.23 Å) or heavily bent noncoaxial molecular pairs supported by Pt···S' contacts (3.34‐3.38 Å). By contrast, in the known solvatomorphs 1 ·CH 2 Cl 2 and 1 ·0.5hex (hex = n ‐hexane), two collinear molecules compose a “square” dimer via a pair of reciprocating Pt···S' contacts (3.13‐3.16 Å). According to gas‐phase DFT calculations (PBE0/def2‐TZVPP/D3BJ), dimerization is energetically favored by 15–20 kcal mol −1 and is guided by a shallow potential energy surface, with staggered dimers as ground configurations but eclipsed and square dimers well within energetic reach. Inspection of the local energy minima also disclosed a previously unrecognized eclipsed arrangement with ∼45° twisting of both PWs relative to the metal plane, whose existence was confirmed by statistical analysis of PW structures in the Cambridge Structural Database. Our results led to a new classification scheme for these PW dimers relevant to molecular magnetism and quantum technologies.