Organosilicon functional boron amine catalyst complexes have an organosilicon functional organoborane portion of the complex that contains at least one silicon atom. The complexes can be used as components in curable compositions containing (i) a free radical polymerizable monomer, oligomer or polymer; (ii) the organosilicon functional boron amine catalyst complex; and (iii) an amine reactive compound having amine reactive groups. The curable compositions may contain a component capable of generating a gas, as well as various other optional ingredients. These curable compositions can be used as rubbers, tapes, adhesives, protective coatings, thin films, thermoplastic monolithic molded parts, thermosetting monolithic molded parts, sealants, foams, gaskets, seals, o-rings, pressure sensitive adhesives, die attachment adhesives, lid sealants, encapsulants, potting compounds, conformal coatings, and electronic components. The compositions can also be used in composite articles of manufacture in which substrates are coated or bonded together with the composition and cured, such as in connectors, diving masks, or other integrally bonded parts.