how to split string return first part and second part separately in sql server

// -- Declare variables

declare @Col1 varchar(10)='2\100'

// -- Left part

select left(@Col1,len(SUBSTRING(@Col1,0,CHARINDEX('\',@Col1))))

// -- Result 1- 2

// -- Right part

 select right(@Col1,len(SUBSTRING(@Col1,CHARINDEX('\',@Col1)+1,LEN(@Col1))))

// -- Result 2- 100