There is no meaningful link between the duration of an elected official's term and corruption.
In general, almost by definition, corruption is something that subverts the formal rules, so changing the formal rules wouldn't make a difference.
This isn't to say that term of office durations don't matter, or that all choices are equally good. But, they basically govern parameters about issues like the time horizon of legislators and how quickly the electoral process responds to changes in public opinion, not to corruption or the lack thereof. Many democratic Republics have multiple different terms for different offices, but these details don't correlate with corruption (at least absent immense extremes like 30 days terms, or 30 year terms).
The E.U. Presidency manages with six month terms. The U.S. Senate has six year staggered terms. The U.K. House of Commons has indefinite terms of up to five years sometimes extended for up to ten years in times of war. It wouldn't be reasonable to argue that corruption or the lack thereof in those bodies has much to do with those particular differences in isolation. In the U.S. state and local government bodies with four year terms aren't meaningfully more or less corrupt than those with two year terms.
Selected Factors That Do Lead To Corruption
Presidents Before Parliaments
One distinction that has been demonstrated empirically is that in countries with semi-Presidential system with a President and a Prime Minister that both have significant power, that coups are less likely if the parliament, rather than the President, is the first person elected with civilian independent rule is established following colonial or military rule (I'll link to the citation if I can find it).
Often, if the President is elected first, the Parliamentary elections never end up being held.
Cousin Marriage And Secret Societies
Another factor that has been empirically strongly linked to corruption is the rate of cousin marriage in a society (more cousin marriage is associated with more corruption and there are solid arguments that this is causal rather than a historical accident).
More generally, any informal structure that commands greater allegiance than the formal governmental requirements and obligations of officials can have the same effect. The Anti-Masonic movement in the 19th century U.S. was concerned about this kind of ideologically based corruption.
Unreasonable Or Impossible Laws
Yet another factor that is associated with corruption is the existence of laws that for some reason of political process or reality can't be changed, but are undercut by powerful grass roots forces to disobey.
Some historical examples of this are alcohol prohibition in the U.S., drug prohibition in Mexico, and the prohibition of divorce in Ireland and Italy.
Likewise, any system that demands the impossible tends towards corruption.
For example, newly independent Sudan designed its judiciary in a way that made it necessary to have legally trained judges in all of its courts, but had only about 200 legally trained professionals in the entire country, some of whom were engaged in non-judicial legislative and civil service posts, when it needed thousands of legally trained professionals to make its judicial system work, and this resulted in a great deal of corruption before the initially independent regime collapsed in part due to corruption.
Failing to pay civil servants what they need to make a decent living is a classic driver of corruption.
A close variation of this problem is when legislators or civil servants lack sufficient resources of their own to do their jobs and must rely on private interested parties for those resources instead.