“If” formula for the letter the value begins with?

I have 3 sheets in my excel document.  The first one is the main form and the other 2 are summaries that need to be populated and distributed the correct person depending if one value on  Sheet1 begins with a letter between A-O or P-Z. 

What I need on each summary sheet is this sequence:

On Sheet 2 in Cell A5 I need: If the Payable cell (Sheet1 A10:B10) begins with A-O, Populate this field with the payable cell (Sheet1 A10:B10).

Sheet2 Cell B5: If A5 is populated, this cell is equal to ='Sheet1'!C9:D10

On Sheet 3 in Cell A5 I need: If the Payable cell (Sheet1 A10:B10) begins with P-Z, Populate this field with the payable cell (Sheet1 A10:B10).

Sheet3 Cell B5: If A5 is populated, this cell is equal to ='Sheet1'!C9:D10

Thanks for all your help!!

Try this for starters in sheet2!a5:

=if(and(left(sheet1!a10,1)>="a",left(sheet1!a10,1)<="o"),sheet1!a10,"")

I think you need to ensure upper-case values

=IF(AND(CODE(LEFT(Sheet1!A10,1))>=CODE("A"),CODE(LEFT(Sheet1!A10,1))<=CODE("O")),Sheet1!A10,"")