# Are there any chemicals with this structural skeleton?

Is there a chemical that has the bond structure like below?

There are 5 atoms linking together. Two of them have 4 bonds. (They are different atoms.) Another two of them have 3 bonds. (They can be either same or different atoms.) The last atom has only 2 bonds.

Suggested SMILES for unknown $\ce{X}$ elements is [X]2[X]14[X]3[X]1[X]234

Are there such kinds of chemicals?

• To clarify - does the structure have to be composed solely of carbon atoms? With no hydrogens? Or is it a saturated alkane? – Richard Terrett Feb 25 '13 at 7:51
• The OP indicates that they can be different atoms. A compound with formula $\ce{C2B2O}$ has the correct valences to accomplish that structure, but I am unsure if it exists. – Ben Norris Feb 25 '13 at 11:36
• @BenNorris If it does, that is going to be one unhappy molecule, what with how far from tetrahedral that central carbon is. I suspect it would not exist for very long... – Canageek Feb 25 '13 at 15:27
• Extremely unlikely. However, if you allow ligands, a metallic cluster with this graph as part of the structure may be found. – permeakra Feb 25 '13 at 20:52
• Similar motifs include [1,1,1]propellane and white phosphorus. Neither of which is noted for its stability. – Aesin Feb 25 '13 at 21:10

CCDC doesn't contain any molecules of such geometry. The closest topology observed is among pnictogens such as $\ce{P, As, Sb}$, which form tetrahedron units $[\ce{P4}]$, $[\ce{As4}]$, $[\ce{Sb4}]$ which are readily coordinating with Au, Rh, Ag and Cu by edge-sharing:

The first publication (1) tetraphosphido-ligand presents the following structure of $\ce{Rh}$-complex:

The most relevant structure best fitting the required connectivity matrix would probably be bis(tricyclo[$1.1.0.0^{2,4}$]tetraphosphane)-gold (2):

Thanks to @TAR86 comment mentioning exotic boranes, I also found a research (3) on ab initio calculations for $\ce{B4}$ cores obtained via the following proposed reaction:

They also obtained crystal structure for bis(tetrahydropyran)-(tetra(t-butyl)tetraborane)-lithium where $\ce{B4H}$ core is present:

(1) Lindsell, W. E.; McCullough, K. J.; Welch, A. J. J. Am. Chem. Soc. 1983, 105 (13), 4487–4489. DOI: 10.1021/ja00351a067
(2) Forfar, L. C.; Clark, T. J.; Green, M.; Mansell, S. M.; Russell, C. A.; Sanguramath, R. A.; Slattery, J. M. Chem. Commun. 2012, 48 (14), 1970–1972. DOI: 10.1039/C2CC15291F
(3) Neu, A.; Mennekes, T.; Englert, U.; Paetzold, P.; Hofmann, M.; von Ragué Schleyer, P. Angew. Chem. Int. Ed. Engl. 1997, 36 (19), 2117–2119. DOI: 10.1002/anie.199721171