Christian:

Access to information is the key to obtaining the answer to your question. This chip from Philips has abundant information available including all of the following:

Product Brief:
http://www.semiconductors.philips.com/pip/PCA95...564PW.html

Data Sheet:
http://www.semiconductors.philips.com/acrobat/d...9564_2.pdf

Application Note:
http://www.semiconductors.philips.com/acrobat/a...0148_1.pdf

Evaluation Board:
http://www.semiconductors.philips.com/acrobat/a...0149_1.pdf

Of course on an I²C bus the master generates the clocking signal so this chips clock rate generation is only of question when the chip is operated in the master mode. There are three control register bits that control the clock rate in master mode which can be changed on a transaction by transaction basis depending on the clock rate of the peripheral that is the target slave device. Program the bits CR2::CR1::CR0 to 000b to achieve a clock rate of 330 kHz which is the fastest master mode rate supported by the chip. Program these bits to 100b to get operation at 88 kHz. Note that the clocking rates generated by this chip are approximate and will vary according to voltage, temperature, and from part to part. The chip will operate all the way up to 400 kHz in the slave mode.

There are warnings about using the 100b setting of these bits when communicating to peripherals that have a top end specification of 100 kHz. So make sure you do read the data sheet. As a matter of fact it is mandatory that you have all the latest data sheets and application notes when you are designing and working with a part like this.

Michael Karas