A benzil-based semi-rigid dinuclear organometallic acceptor 4,4′-bis[trans-Pt(PEt3)2(NO3)(ethynyl)]benzil (bisPt-NO3) containing a Pt-ethynyl functionality was synthesized in good yield and characterized by multinuclear NMR (1H,31P, and 13C), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffraction analysis of the iodide analogue bisPt-I. The stoichiometric (1:1) combination of the acceptor bisPt-NO3 separately with four different ditopic donors (L1-L4; L1 = 9-ethyl-3,6-di(1H-imidazol-1-yl)-9H-carbazole, L2 = 1,4-bis((1H-imidazol-1-yl)methyl)benzene, L3 = 1,3-bis((1H-imidazol-1-yl)methyl)benzene and L4 = 9,10-bis((1H-imidazol-1-yl) methyl)anthracene) yielded four [2 + 2] self-assembled metallacycles M1-M4 in quantitative yields, respectively. All these newly synthesized assemblies were characterized by various spectroscopic techniques (NMR, IR, ESIMS) and their sizes/shapes were predicted through geometry optimization employing the PM6 semi-empirical method. The benzil moiety was introduced in the backbone of the acceptor bisPt-NO3 due to the interesting structural feature of long carbonyl C-C bond (∼1.54 Å), which enabled us to probe the role of conformational flexibility on size and shapes of the resulting coordination ensembles. © 2015 Schweizerische Chemische Gesellschaft.