Compounds, complexes, compositions, methods and systems for heating and cooling

A composition comprising:

• an ionic liquid;
• and
• carbon dioxide;
• wherein the ionic liquid has a CO2 binding enthalpy of from about (−)20 kJ/mol to about (−)40 kJ/mol;
• and
• wherein the composition is suitable for use in a vapor compression cooling or heating system.

A method of cooling or heating an enclosed space comprising:

• compressing a composition comprising an ionic liquid and carbon dioxide;
• cooling said composition;
• reducing the pressure of said composition;
• and
• contacting the enclosed space with said composition;
• wherein the ionic liquid has a CO2 binding enthalpy of from about (−)20 kJ/mol to about (−)40 kJ/mol.

A system for cooling or heating an enclosed space comprising:

• a composition comprising an ionic liquid and carbon dioxide;
• a compression device;
• a means for cooling said composition;
• an expansion device;
• and
• a heat exchanger;
• wherein the ionic liquid has a CO2 binding enthalpy of from about (−)20 kJ/mol to about (−)40 kJ/mol.