for example mercury oxide has neurotoxic properties but isn't organic so, it isn't soluble in lipids and so doesn't cross the blood brain barrier when ingested, however, methylmercury chloride is organic and soluble in lipids thus it can cross the blood brain barrier
Tetraethyl lead (bp 180 °C) and tetramethyl lead (bp 110 °C) are easily resorbed through the lungs and the intact (!) skin. They pass the blood-brain barrier without any problems. The half-life for the elimination from the brain is about 500 days.
(Source: Günter Fred Fuhrmann, Toxikologie Für Naturwissenschaftler: Einführung in Die Theoretische und Spezielle Toxikologie, Springer-Verlag, 2006, p 209)
These compounds are neurotoxic and the literature is full of reported cases of intoxications and - sometimes - successful treatment, such as here.