With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Diabetes increases the risk of dementia.
text_B: A quintuple bond in chemistry is an unusual type of chemical bond , first reported in 2005 for a dichromium compound .. chemistry. chemistry. chemical bond. chemical bond. dichromium. chromium. Single bonds , double bonds , and triple bonds are commonplace in chemistry .. chemistry. chemistry. Quadruple bonds are rarer but are currently known only among the transition metals , especially for Cr , Mo , W , and Re , e.g. -LSB- Mo2Cl8 -RSB- 4 − and -LSB- Re2Cl8 -RSB- 2 − .. Chromium. Molybdenum. Tungsten. Rhenium. In a quintuple bond , ten electrons participate in bonding between the two metal centers , allocated as σ2π4δ4 .. In some cases of high-order bonds between metal atoms , the metal-metal bonding is facilitated by ligands that link the two metal centers and reduce the interatomic distance .. By contrast , the chromium dimer with quintuple bonding is stabilized by a bulky terphenyl -LRB- 2,6 - -LSB- -LRB- 2,6-diisopropyl -RRB- phenyl -RSB- phenyl -RRB- ligands .. terphenyl. terphenyl. The species is stable up to 200 ° C .. The chromium -- chromium quintuple bond has been analyzed with multireference ab initio and DFT methods , which were also used to elucidate the role of the terphenyl ligand , in which the flanking aryls were shown to interact very weakly with the chromium atoms , causing only a small weakening of the quintuple bond .. terphenyl. terphenyl. ligand. ligand. DFT. density functional theory. A 2007 theoretical study identified two global minima for quintuple bonded RMMR compounds  : a trans-bent molecular geometry and surprisingly another trans-bent geometry with the R substituent in a bridging position .. molecular geometry. molecular geometry. In 2005 , a quintuple bond was postulated to exist in the hypothetical uranium molecule U2 based on computational chemistry .. chemistry. chemistry. uranium. uranium. computational chemistry. computational chemistry. Diuranium compounds are rare , but do exist ; for example , the anion .. In 2007 the shortest-ever metal -- metal bond -LRB- 180.28 pm -RRB- was reported to exist also in a compound containing a quintuple chromium-chromium bond with diazadiene bridging ligands .. Other metal -- metal quintuple bond containing complexes that have been reported include quintuply bonded dichromium with -LSB- 6 - -LRB- 2,4,6-triisopropylphenyl -RRB- pyridin-2-yl -RSB- -LRB- 2,4,6-trimethylphenyl -RRB- amine bridging ligands and a dichromium complex with amidinate bridging ligands .. dichromium. chromium. amidinate. amidinate. Synthesis of quintuple bonds is usually achieved through reduction of a dimetal species using potassium graphite .. potassium graphite. potassium graphite. This adds valence electrons to the metal centers , giving them the needed number of electrons to participate in quintuple bonding .. Below is a figure of a typical quintuple bond synthesis .
not_related.