The stereochemistry of molecular systems is determined by their electronic structure and the transmutation symmetry of identical atoms. The latter means that from the viewpoint of symmetry the molecule must possess the spatial structure of the highest possible symmetry. However, depending on the electron state the high-symmetry nuclear configuration can become unstable, and the system is distorted. Any perturbation of the molecular system (excitation, ionization, coordination to transition metal complexes, molecular adsorption on solid surfaces, etc.) changes its electronic state and, as a consequence, can lead to distortion of its nuclear configuration. It has been proved that all the instabilities are electronically controlled via vibronic coupling, more specifically, via the Jahn-Teller (JTE) or pseudo JahnTeller effect (PJTE) [1, 2]. The electronic control of the instabilities via vibronic coupling is demonstrated on the examples of distortions of ketene and allene molecules coordinated in the complexes Pt(PPh3)2-H2C2O, VCp2H2C2O, and Fe(CO)4-C3H4. It is shown that the η2-(C-O) coordination and the in-plane distortion of ketene in the VCp2-H2C2O complex is due to the PJTE induced by the back donation on the LUMO 3b2 of ketene, while the η2-(C-C) coordination mode, as well as the out-of-plane distortion of the molecule in the Pt(PPh3)2-H2C2O complex can occur only as the result of diorbital metal-ketene interaction (Fig. 1). The distortion of coordinated allene can be explained by the common action of the JT and the PJT effects induced by the orbital charge transfers from the occupied ex MO to the unoccupied ex* one. The b2-type antisymmetric C-C-C stretching and the antisymmetric CH2 scissoring are due to the JTE, while the C-C-C bending and the out-ofplane C1H1H2 wagging are the results of the PJTE.