An ideal synthesis of alkyl amines would involve the direct use of abundant and easily accessible molecules such as dinitrogen (N2) and feedstock alkenes1-4. However, this ambition remains a great challenge as it is usually difficult to simultaneously activate both N2 and a simple alkene and combine them together through C‒N bond formation. Currently, the synthesis of alkyl amines relies on the use of ammonia produced via the Haber-Bosch process and prefunctionalised electrophilic carbon sources. Here we report the hydroamination of simple alkenes with N2 in a trititanium hydride framework, which activates both alkenes and N2, leading to selective C‒N bond formation and providing the corresponding alkyl amines on further hydrogenation and protonation. Computational studies reveal key mechanistic details of N2 activation and selective C‒N bond formation. This work demonstrates a strategy for the transformation of N2 and simple hydrocarbons into nitrogen-containing organic compounds mediated by a multinuclear hydride framework.