A thiodisilane of formula: (R 1a R 1b R 1c CS) s (R 2 2 N) n (Si-Si)X x H h, wherein: subscript s is an integer from 1 to 6; subscript n is an integer from 0 to 5; subscript x is an integer from 0 to 5; subscript h is an integer from 0 to 5; with the proviso that sum s + n + x + h = 6; each H, when present in formula (i.e., when subscript h is 1 to 5), is independently bonded to the same or different one of the silicon atoms in formula; each X is a monovalent halogen atom F, Cl, I, or Br and, when present in formula (i.e., when subscript x is 1 to 5), is independently bonded to the same or different one of the silicon atoms in formula; wherein R 1a, R 1b, and R 1c are defined by limitation (a), (b), or (c): (a) at least one R 1a independently is (C 2 -C 20)alkyl or phenyl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (b) there is at least one group R 1a R 1b R 1c C that independently is a substituted or unsubstituted (C 6 -C 20)aryl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (c) any two of R 1a, R 1b, and R 1c (collectively R 1 groups), in the same or different R 1a R 1b R 1c C group, are bonded together to form a divalent group, -R 11 -, wherein -R 11 - is a CH 2 or a (C 3 -C 20)hydrocarbylene and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; each R 2 group independently is H or a (C 1 -C 20)hydrocarbyl; or any two R 2 groups may be bonded together to form a divalent group, -R 22 -, wherein -R 22 - is a (C 2 -C 20)hydrocarbylene and each of any remaining R 2 groups independently is H or a (C 1 -C 20)hydrocarbyl; each hydrocarbyl and hydrocarbylene independently is unsubstituted or substituted with from 1 to 5 substituents SUB; and each SUB independently is unsubstituted (C 1 -C 6)alkyl, unsubstituted (C 3 -C 6)cycloalkyl, unsubstituted (C 2 -C 6)alkenyl, unsubstituted (C 2 -C 6)alkynyl, unsubstituted (C 6 -C 7)aryl, fluoro, chloro, or bromo. subscript s is an integer from 1 to 6; subscript n is an integer from 0 to 5; subscript x is an integer from 0 to 5; subscript h is an integer from 0 to 5; with the proviso that sum s + n + x + h = 6; each H, when present in formula (i.e., when subscript h is 1 to 5), is independently bonded to the same or different one of the silicon atoms in formula; each X is a monovalent halogen atom F, Cl, I, or Br and, when present in formula (i.e., when subscript x is 1 to 5), is independently bonded to the same or different one of the silicon atoms in formula; wherein R 1a, R 1b, and R 1c are defined by limitation (a), (b), or (c): (a) at least one R 1a independently is (C 2 -C 20)alkyl or phenyl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (b) there is at least one group R 1a R 1b R 1c C that independently is a substituted or unsubstituted (C 6 -C 20)aryl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (c) any two of R 1a, R 1b, and R 1c (collectively R 1 groups), in the same or different R 1a R 1b R 1c C group, are bonded together to form a divalent group, -R 11 -, wherein -R 11 - is a CH 2 or a (C 3 -C 20)hydrocarbylene and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; (a) at least one R 1a independently is (C 2 -C 20)alkyl or phenyl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (b) there is at least one group R 1a R 1b R 1c C that independently is a substituted or unsubstituted (C 6 -C 20)aryl and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; or (c) any two of R 1a, R 1b, and R 1c (collectively R 1 groups), in the same or different R 1a R 1b R 1c C group, are bonded together to form a divalent group, -R 11 -, wherein -R 11 - is a CH 2 or a (C 3 -C 20)hydrocarbylene and each of any remaining R 1a, R 1b, and R 1c independently is H or (C 1 -C 20)hydrocarbyl; each R 2 group independently is H or a (C 1 -C 20)hydrocarbyl; or any two R 2 groups may be bonded together to form a divalent group, -R 22 -, wherein -R 22 - is a (C 2 -C 20)hydrocarbylene and each of any remaining R 2 groups independently is H or a (C 1 -C 20)hydrocarbyl; each hydrocarbyl and hydrocarbylene independently is unsubstituted or substituted with from 1 to 5 substituents SUB; and each SUB independently is unsubstituted (C 1 -C 6)alkyl, unsubstituted (C 3 -C 6)cycloalkyl,