How to express "saying things to please your manager"

I am trying to translate a phrase from Bulgarian and I can't seem to find good English equivalent. Imagine that in a company there is a "thank you" session where everybody can say thank you to anyone else. If I say "thank you" to my boss (and say that because they determine my salary/promotion), then what action am I doing? In particular I am trying to express "I am not just saying that to <missing word/phrase> you".

A lot depends on the context: the nature of your boss (weak and self-focussed, or strong and business-focussed); the extent to which you wish to be open and honest (do you try to discuss things as they are, or as they seem to be?); the degree to which your boss can determine your future (is there a promotion in prospect or are you about to change job?); what you are thanking for (praise or a pay rise) and was it given objectively (bonus for hitting sales target), or subjectively (promotion for being “better” than some other applicant).

If you can handle all these nuances of circumstance, you have a wide choice of comments available to you:

I am not saying that to ... be sycophantic ... be ingratiating ... be obsequious ... toady ... flatter ... be oily ... slime round ... brown-nose ... cosy up ... scratch your back ... be ass-licking ... be smarmy ... be over-grateful ... (others will add to this list).

Forgive me for not tediously listing easily-found references to these many options. Choose the wrong one and you may do yourself more harm than good!