New data for the euro zone added pressure to markets on Monday, after Markit's latest flash purchasing manager's index (PMI) showed business growth in the region had hit a 16-month low in May. It came in at 52.9, down from April's 53.0.
However, Germany's PMI rose to 54.7 in May from April's 53.6; France's hit a seven-month high of 51.1.
One key point of interest was German chemicals group Bayer, who offered to acquire Monsanto for $122 per share in cash, valuing the U.S. firm at $62 billion.
Speaking to CNBC, Bayer's CEO Werner Baumann said he didn't see any major regulatory or other risks from the proposed transaction, describing the companies as "highly complementary."
Shares of Bayer, however, reacted negatively, closing down 5.7 percent.
Elsewhere in the chemicals space, OCI was Europe's worst performer, closing almost 10 percent down, after the fertilizer producer and CF Industries terminated their planned merger deal.