The subject of the paper is the Russian binary subordinate conjunction ˹kak…, tak i…˺ ‘ ≈ immediately after the moment that…, then…’ The expression ˹KAK…, TAK I…˺ is a discontinuous idiom: its components are not linked to one another syntactically, and it has to be described together with its actantial variables, which ensure the connectedness, i.e. phrasal character, of the expression: KAK → Y, TAK I ← Х (Kak ob”javil on ej èto, tak ona i ruxnula ≈ ‘When he declared this to her, she fell unconscious’.) A typology of syntactic conjunctions is proposed and the particularities of binary conjunctions are characterized; full lexicographic descriptions of six Russian idioms are presented: ˹TAK I Х(V)˺1/2/3 (Sneg tak i valit ‘The snow is literally crashing down’. / Sneg tak s utra i idet ‘The snow has kept falling since morning’. / Sneg, odnako, tak i ne perestal ‘The snow, however, did not stop’.), ˹TAK Х Y-u I Z(V)!˺ (Tak ja emu i poexal v T´mutarakan´! ‘He is wrong to think that I will go to Tmutarakan!’), ˹KAK Y, TAK I X˺1 (a coordinate conjunction: kak doma, tak i v škole ‘both at home and at school’) and ˹KАК Y, ТАК И X˺2 (a subordinate conjunction: Kak ona vošla, tak on i zastyl…‘When she entered, he froze…’). The phraseological nature of Russian binary conjunctions is analyzed: some of these are idioms, while the others are collocations of a special type.