Complex sentence: Dillon served as President of the New York Metropolitan Museum, esp. building up its Chinese galleries; personally donating $20 million to the museum and leading a fundraising campaign that raised an additional $100 million.
Split into simpler sentences: Dillon served as President of the New York Metropolitan Museum, particularly building up its Chinese galleries. He personally donated $20 million to the museum and led a fundraising campaign that raised an additional $100 million.