The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll" id="d1e19" altimg="si31.gif"><mml:mi>c</mml:mi></mml:math>-nilpotent Schur <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll" id="d1e24" altimg="si32.gif"><mml:mi mathvariant="sans-serif">Lie</mml:mi></mml:math>-multiplier of Leibniz algebras