Robert W. Jenson states this principle that others take up much later in God After God: The God of the Past and the God of the Future, Seen in the Work of Karl Barth (Bobbs-Merrill, 1969). For instance, this way of defining Trinity is adopted by Wolfhart Pannenberg as well as John D. Zizioulas. It is not just Jenson's insight since there are many ways to arrive at this salutary conclusion, but he states it with a force and power and then explores it in a way in this book in a way I'm not sure he has elsewhere.
Robert W. Jenson has famously (or infamously depending on your point of view) identified a pneumatological deficit in Karl Barth (and by extension lots of theological positions) in his article "You Wonder Where the Spirit Went," Pro Ecclesia 2 (1993): 296-304.
That article should be seen in the light of this earlier work:
This gathering to the past, to the Beginning in which all has already been decided,pervades all Barth's thinking. The direction of trinitarian formulations toward the past is something Barth shares with the tradition. ... But if the true temporality of the triune God, and the true meaning of the doctrine of the Trinity, is at least to appear without ambiguity, this shadow must be banished. That is, the futurity of the triune God must be made plain. The formal pattern of the doctrine must be reversed, to give the Spirit some of the formal role which the Father has had. ... Instead of defining all three hypostases by their relation to origin, they must be defined by their relation to goal. The Spirit is the goal of the Trinity, and this doctrine must be given the function which has long belonged to the doctrine that the Father is the "fount of the Trinity."
God after God, p. 173-174.
After this quote, Jenson goes on to anticipate his later criticism.
In my own idiom, what is at stake here is that a God worthy of the name is a God who promises, who demands nothing except faith in that promise, whose graciousness is not the rescue of creation from its temporality and frailty into a timeless eternity or a pre-temporal election but its reclamation and conviviality.
But before this quote there are three chapters (and several afterward) that show in great detail how Jenson moves from Barth's (and Bonhoeffer's) criticism of religion to futurity and promise. These two categories are central to the book: the future and promise. These two immensely important theological concerns are the engine that drives his criticism of classical trinitarian theology.