A　rare　3-D　Mn-organic　framework,　[(CH3)(2)NH2](3)[Mn-5(btc)(4)(Ac)(H2O)(4)]5H(2)O　(1),　based　on　pentanuclear　manganese　clusters　as　building　blocks　has　been　prepared　and　structurally　characterized　by　EA,　IR,　TGA,　PXRD,　and　single-crystal　X-ray　diffraction.　Structural　analysis　indicates　the　pentanuclear　manganese　cluster　in　1　has　a　bow-like　configuration,　which　is　the　first　found　to　act　as　secondary　building　unit　in　the　field　of　metal-organic　framework.　Gas　adsorption　measurements　reveal　that　1　can　absorb　a　considerable　amount　of　N-2　and　CO2.　[GRAPHICS]　.