How do you know this? Seriously. It may or may not be the case. I just wasn't aware that the experiment had been done (and published). Please elaborate. Individuals and even species with different chromosome arrangements CAN reproduce. Not always, of course, but sometimes. It's not determined simply by how the chromosomes are split up.
Your whole point that a chromosome level mutation automatically means that the chromosomes can't properly pair and match up during mitosis and meiosis is simply wrong. Some chromosomal mutations, such as centric fusions, can change chromosome numbers without even reducing (let alone eliminating) fertility at least in the heterozygous state.
In fact does anybody know if the number of centromeres -- or the number of chromosome "arms" -- actually differs in humans and apes?
See, what you are doing is reverting to the intellectually dishonest "anything's possible" gambit.
We do in fact know what sorts of variants can and cannot reproduce, which is why we do not have chimerae running around all over the place. You act as though the science of modern genetics doesn't have a century of research to determine what does and does not occur.
Reading through the pro-Darwinist comments above, I will conclude my visit by expressing my amazement that all Darwinists are not religious fanatics, given that the incredible suspension of disbelief necessary to defend your dogma greatly exceeds that necessary to conceive of a supernatural Creator. The sad part is that you give "science" a bad name by claiming that the sophistry that seeks to avoid the inevitability of the utter debunking of your demostrably fatally flawed theory is based upon actual scientifically deduced fact. In fact, Evolutionism has as much to do with science as does Scientology.