Maleic anhydride (M 1) has been copolymerized by the radical mechanism with organotin derivatives of methacrylic acid (M 2), of the structure R 3SnOOC-C(CH 3) = CH 2, where R is CH 3, C 2H 5, n-C 3H 7 or n-C 4H 9. The reactivity ratios of these monomer pairs have been determined ( r 1 ∼ 0 and r 2=0·220, 0·122, 0·081 and 0·053) and the activity and polarity factors Q and e have been calculated for the methacrylate derivatives with (CH 3) 3Sn −, (C 2H 5) 3Sn −, (n-C 3H 7) 3Sn − and (n-C 4H 9) 3Sn − ( Q 2 = 0·31, 0·27, 0·23 and 0·18; e 2 = −0·64, −0·75, −0·81 and − 0·88). It is shown that the organotin copolymers and corresponding model compounds contain coordinate bonds of the type ▪. The effect of intermolecular coordination in radical copolymerization of maleic anhydride with trialkylstannyl methacrylates, which is responsible for alternation of the monomer units along the length of the polymer chain, has been discovered. It was found that as the length of the alkyl substituents on the tin atom increases the polarity and complex forming tendency of the trialkylstannyl methacrylates increase, but its rate of copolymerization with maleic anhydride decreases.