There have been a few schemes that apply a structure to Genesis 1; usually they are schemes to avoid the direct reading of the passage (e.g. the 'framework' hypothesis), but oddly, the authors of these schemes usually fail to deal with the passage's most obvious structuring scheme.
Joseph Pipa in his lecture on the doctrine of creation puts it this way:
Moses adopts a formula much more powerful and pervasive than the parallel between the days 1-3 and 4-6. It is a five-fold formula that is used fairly consistently with each of the six days, the work of each day is described by the five-fold formula:
1. the act of creation,
2. the declaration of fulfillment,
3. the statement of purpose,
4. the expression of delight and
5. the indication of time.
In each event the act of creation is described in a two-fold manner: firstly the word of creation, and that is complimented by the particular works of creation.
The word predominates as we read this chapter: "and God said", shaping the particular out of the initial 'mass' of creation.
