Dirac–Fock one-centre calculations show (114)H 4 to resemble PbH 4

TLDR: In this paper, the relativistic treatment becomes imperative to predict the chemical behaviour of the superheavy elements and the tetrahydride of the element 114 or eka-lead.

Abstract: RELATIVISTIC effects have a considerable influence on the chemical behaviour of the heavier elements. Our Dirac–Fock one-centre expansion calculations1–3 indicate that the X–H bond lengths, Re, suffer a relativistic contraction of about 5% for PbH4 (ref. 1) or AuH (ref. 2) and 7% for TlH (ref. 3). If the relativistic effects are included, however, these Re values mostly agree with experiment to within 2–3%. Relativistic effects also seem to be the main cause of the chemical difference between silver and gold2 and, possibly, of the dominant monovalency of thallium3. A relativistic treatment becomes imperative to predict the chemical behaviour of the superheavy elements. Following evidence for primordial superheavy elements4, we present here results for the tetrahydride of the element 114 or eka-lead. We believe that such a calculation gives a reasonable estimate for the covalent radius of this element. Although the dominant valency of 114 is expected to be 2, some tetravalent compounds are also expected to be stable7. As the latter valency is more convenient for calculations, having closed shells, we here consider (114)H4.